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BR[TISH-Ai~ERICAN TOBACCO COMPANY L~D
Westminst'sr House 7 MS/bank London SWI - Te]~ephone Abbey 1222
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Confidential
CaWoon copy No. 0
Photo copy No.13
Eesearc~ and Development B.A.T. Germany/Eo-mburg
FE~eport No.IS
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Title:
Active Charcoal as a Constituent of
Cigarette Filters
Authors: H. Borowski and M. Jacob±
Coauthor: E- .Dep~e
~,,~I~,.,~ b7: F. Seehofsr
S e 'i ...... " P
Distribute~ by:
• M'r. S.J. Green
11
Herr E. Soring
Herr _~. Sottorf
He_~r W. Se!bmann
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Conten~s
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i. Introduction
I.I General notes on active charcoal
1.2 Terminology for filtration and sorption processes
1.5 Factors fo~ evaluation.
2. Test results
2.1 }Tature of samples
2.Z Preseiectlon
2.5 Activity towards test chemicals.
3. Tests on c lgarette filters with active charcoal
5.1 Activity towards individual smoke constituent substances
5.2 Comparison with competitors' products
~.3 Taste evaluation.
4. Discussion
4.1 Summary of results
4.2 Discussion of procedures and filter types
@.5 Discussion of Patent and legal situation.
5. Recommendations (in accordance with present state of knowledge)
6. Plan for further work
Append ix, I
I~! Figures and tables of data (see special index)
i/2 Description of test methods
1/2.1 Test methods in use
i/2.2 0ther known test methods
I/3 List of charcoal types under test
Appendi~ II
II/l Patent Specifications
II~l.! List of patent specifications evaluated to date
II/1.2 Other patent specifications with short statement
of contents
II/2 Literature references.
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Special index for i/!.
List of Figures
Relating to 2.3: Activity towards test chemicals.
2.51 Survey of all types under test~ chlorobenzene
2.32 Survey of selected types~ adsorption
2.33 Phenol adsorption
2.54 Hydrogen cyanide adsorption
Relating to 3.1: Activity towards cigarette smoke
3.11 Amount of aldehydes in main smoke
3.12 Volatile organic acids in main smoke
3.13 Phenol content in main smoke
3.14 Ciliate test on particle phase
3.15 Cilia test on gas phase
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List of Tables
3.16 Summarising chart of the most important
analytical parameters.
Relating to 5.1: Table of data referrin~ to the Figures 5.Ii Phehol adsorption (Fig.2j33)
5.12 Hydrogen cyanide adsorption (Fig.2o34)
5.13 Amount of aldehydes in main smoke (Fig.3.11)
5.14 Volatile organic acids in main smoke (Fig.3.12)
5.15 Phenol content in main smoke:
Ciliate test on particle passe (Fig.3.13/3.14)
and full smoke analysis
5.16 Cilia test on gas phase (Fig.3.15)
5.3 List of charcoal tToes under test (Fig.2.3~2.32)
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I. Introduction
I.I General notes on active charcoal
A charcoal rich in pores with a more or les~ extensive
internal surface area is formed during a suitable
carbonisation of plants. Such types of charcoal possess
a high adsorption capacity, and they are therefore known
as "active charcoal". The production of a gooa active
charcoal is not altogether simple. It has been found
that not all plants and plant parts can be considered
suitable for the preparation of an active charcoal. The
most suitable materials for this purpose are wood, peat,
coconut shells, bitumen residues and similar substances.
Normal heating of these materials admittedly only produces
a charcoal with a low adsorption capacity because the tar
formed at the same time blocks up the fine pores of the
charcoal so that these cannot adsorb vapours and gases.
go,ever, the active charcoal industry can nowadays produce
charcoals with an extraordinarily high activity. The
excellent adsorption qualities of active charcoals have
therefore for some time been exploited in many fields of
chemistry and of chemical technology for the purification,
decolourlsatiou and detoxicatlon of liquids, gases, aerosols
and smoke gases. It is therefore obvious that consider-
ation should be given to the activity of active charcoals
in relation to the filtration of cigarette smoke.
Charcoal adsorbs all volatile materials and really has no
specific selectivity. The adsorption capacity is
inversely proportional to the saturation vapour pressure,
i.e. in general terms, subs=shoes with a higher boiling
point are adsorbed more strongly than those with a lower
boiling point.
The adsorption capacity of a charcoal depends on its active
surface area, i.e. the sum of the surface areas of all
pores and channels.
Since it is possible for 1 g of active charcoal to have a~
active surface area of about 1200-1400 sq.m. and more, it
will be evident that the pore diameter can only be of the
order of a few molecules. A reduction In the particle
size (external surface area) only increases the total
active surface area of a charcoal by a smail amount which I
can be neglected.
!
A minimum requirement of i0 (mete!c) tons of active char- !
coal is required for the meekly production of a brand at '
the rate of i00 million cigarettes/mouth (for I00 mg/tip), i
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1.2 Terminolo~ for filtration and sorption processes.
"Sorption" is the inclusive term for the physical and ohemica!
individual processes durin~ a filtration operation. In
general, this refers to the take-up of a material (sorbant)
by a material (sorbent). However, if the material is already
present in a sorbed state in or on the material, it is said
to be sorbed or aasorbed:
The inclusive term "sorptlon" mainly comprises four
subsidiary Seres:
!. Adsorption: This implies the concentration of a vaoour or
gas on ~he surface of a solid material without the formation
of solid solutions or chemical reactions
(Example: gas adsorption through active charcoal, nicotine
adsorption in an acetate Xilter).
2. Capillary condensation: This is a special case of adsorption
and occurs when a condensation (liquefaction) of the ad-
sorbant is ea~sed by an increase in its concentration within
the capillaries of porous materials.
(Example: benzene vapour condensation in active charcoal)
3. Absorotion: A solution process occurs during absorption,
and during this process the absorbant is dissolved in the
absorbent.•
(~mple: hydrogen absorption by palladium or platinum)
4. Chemosorption: When the sorbant is chemically combined
w'ith the sorbent, chemosorption occurs.
(Example: chemosorption by CO2 by caustic alkali or water).
When the overall efficiezcy of a cigarette filter is consideredI
without a detailed separate investigation of special processes,!
it is usual to refgr to a "filter effect" which may be good or i
poor, or may be high or low. When it is intended to
characterise the efficiency of a filter in relation to the
whole smoke or individual comoonents in smoke by means of a i
quantitative expression (say in terms of percentages, as usual)i
it is best to employ the term "retention" (filter retention)
originating from the Anglo-American usage. ,.
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!
The term "filter adsorption" or "filter absorption" as often
emoloyed is definitely wrong. We can only refer to
"nicotine adsorption" or "phenol adsorption", etc.
When certain components in smoke are preferentially retained
by a fil~er, this has a "selective" activity and exhibits a
degree of seleeti#ity.
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According to a more recent definition, it is possible to
refer to a cigarette filter having a ~'positive selectivity"
when the difference (or the quotient) of the retention
activity towards a substance x and the dry main smoke
MS(dr) condensate is greater than I
or > I
- 1 SCdr. ) R ,mCdr)
A better reference basis than MS(drJ would be a smoke
constituent without a vapour pressure which can readily
be analysed "(e.g. solane sol, scopoletine, etc.).
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1.5 Factors for evaluation.
It has already been pointed out that active charcoal does not
adsorb selectively, and it is therefore relatively difficult
to decide from which angle an evaluation of a charcoal type
for its usefulness as a cigarette filter should be carried out.
The following properties are inter alia desirable from the
point of view of its satisfact-~-~--pr--~ical appllcatio~.
Retention of aldehydes, acrolein, phenol, hydrogen cyanide,
volatile organic acids, volatile organic bases, favourable
behaviour during biological tests, the least possible influence
on taste, optimum processing characteristics, etc.
Since our laboratory is of course not equipped with the
apparatus required for the methods of investigation normally
employed in the active charcoal industry, it was necessary to
develop or apply more practical methods for the evaluation of
active charcoal from our point of view.
Since the object of the work of investigation in the field of
active charcoal was ultimately directed towards the discovery
of a type of charcoal whose activity in a biological test should
be at least equivalent to that of the material in a Lark filter,
the decisive quality looked for related to this factor during
the final selection. For this purpose, two independent
biological tests, the ciliate test on paramecia {CAT) and the
cilia test on mussels (C~T), were employed for evaluation.
The CAT establishes the activity of the particle phase and the
C~ the activity of the gas phase. During the final selection,
the degree of phenol retention was employed as a further
useful parameter.
2. Test results.
2.1 Nature of samples
The active charcoal types which are commercially available
were obtained through the normal trade channels. For this
purpose, an approach was made to the normal chemical suppliers
as well as to the special suppliers and to the active charcoal
industry in general. Closer contact was established with
two firms in order to characterise samples of special
charcoals:
Ringsdorff-Werke, of ~ehlem, and
~I " 1 I1
Drager-Wsr~, of L~beck.
However, after it had become apparent in the pertinent
industrial circles that the cigarette industry has become
interested in active charcoal, samples and offers of active
charcoal were also received without request from other sources.
2.2 Preselection.
In view of the large commercial supply of active charcoal, it
is appropriate to carry out a general prsselection operation
orior to the start of soecial test procedures. In technology,
charcoals not intended for any special field of auplication areO
characterised according to their adsorption capacity for a
benzene vapour/air mixture. The increase in weight up to the ~
attainment of the degree of saturation is termed the
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maximum charge capacity. We have therefore prese!ected the
charcoal types available in commerce according to their
maximum charge capacity, except that we employed chlorobenzene
instead of benzene3 owing to its higher ~ensity and equally
good lipophilic properties.
The most active charcoal types established according to this
method were subjected to an activity test towards test
chemicals. Thereafter, their behaviour towards cigarette
smoke was investigated.
2.5 Activit~ towards test chemicals.
2.32 Chlcrobenzene adsorption (cf. Fig. 2.34 and Table 3.16~.
The top performance group with maximum adsorption
qualities consists of the two types Ringsdorff and
Lurgi (Desorex 21).
2.83 Phenol adsorotion (cf. Fig. 2.33 and Table 5.11)o
It is worth noting the relatively poor adsorption
efficiency of the type "Fluka, granulated" compared
with the top performance group.
2.34 Hydrogen cTanide adsorption (cf. Fig. 2.34 and Table 8.12).
Separ~bion of the charcoal types into three different
activity classes:
1. Top performance type (Merck 1.5 mm, granulated)
2. Intermediate group (Ringsdorff suecial with Cu and Fe;
Riedel de H~"en, pure, granulated;
Ringsdorff ~0r', activated 1
3. Poor type (Fluka, granulated ).
3. Tests on cigarette filters with active charcoal.
3.1. Activity towards individual smoke constltuen~ substances.
8.11 Aldehydes (cf. Fig. 8.11 and Table 5.!3)
Separation of the charcoal types into three different
activity classes :
I. Top performance type (Rin~sdorff "0", activated)
2.
!ntermediate group (Riedel de H~en, pure, granulated;
Merck l.S me. granulated)
3. Poor type (Dr~ger K 238)
3.12 Volatile organic acids (cf. Fi~.$.12 and Table 8.14)
Separation into two different actlvity classes.
1. Top performa=ce type (Ringsdorff 0 , activated)
2. Eauivalent intermediate group [Merck 1.8 m~., granulated;
" Riedel de Haen, pure,
granulated; .
Dr~ger K 285)
5.13 Phenols (cf. Fig. 3.13 and Table 5.15)
Superiority of the chamber filters compared with the
Filtrona-Bonded Filters. The constant order
of ~he activity of the charcoal types for a given
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type of filter on comparison with a different type is
particularly marked.
Top performance type: Ringsdorff "0", activated.
5.14 Ciliate test on particle phase (of. Fig. 3.14 and
Table 5.15)
The top performance type in the chamber filter arrangement
is far superior to the Lark filter and the Filtroua-
Bonded Filters.
3.15 Cilia test ion ~as phase (cf. Fig. 3.15 and Table 5.16)
The distinct superiority of the top performance type
"Ringsdorff "0" activated" in relation to the Filtrona
and Lark filters is especially marked in this test.
5.2 Comparison with competitors,' products
The following summary provides a survey of the physical date
for the charcoal filters of cigarette brands commercially
available.
3.3 A taste evaluation is extremely important during the development
of a cigarette wi~h a charcoal filter.
Attempts were therefore first of all made to discover whether
certain tobacco varieties are particularly suitable for applicat- i
ion in cigarettes with charcoal filters. The following smoking
evaluations by experts indicate that all tobaccos which have been
air dried or naturally processed (in the widest sense) do indeed
provide better smoking results than Virginia varieties. These
experiments were carried out with the same charcoal filter
(Filtrona FF 561).
After the selection of active charcoals according to chemico-
biological criteria had been completed, a smoke taste evaluation
was carried out on a homogeneous tobacco mixture. The smoking
evaluation by experts during this test which is also given below
has indicated the distinct superiority of the Lurgi sample.
_This smoking evaluation is of interest since it makes possible
some fundamental conclusions regarding the problem of the cause
!
of
the..
"strange
taste due to charcoal".
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It follows that an increase in the "charcoal taste" is not i
necessarily related to an increase in the adsorption efficiency i
of a charcoal type (otherwise, a different order of preference
would have been established). It appears in fact that the result i
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of a smoking test deteriorates as the level of the dust fraction
in the sample rises. Since this recognition will allow us to
redtme the charcoal taste, though it cannot be wholly eliminated,
coupled with the fact that exhaled smoke filtered through
charcoal has an unpleasant smell (see below), we may propose the
following hypothesis :
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"off-taste" due to charcoal depends on at least two factors:
i. The discharge of negative taste components to the main
smoke (e.g. dust)
2. The removal of positive taste components from the main
smoke ( "unbalanced smoke").
Attempts were made to reduce the "off taste" due to charcoal
by means of flavouri~g agents or other additives:
a) Flavour: The essential oils from dill, sage and parsley (?)
provided good results. An appropriate f~avouring recipe
has been developed, by way of proposal. Since however no
suitable tobacco mixture is at present available for
experiment, the further development of this theme has had
to be put off for the future.
b) Additives: It has unexpectedly been discovered that an
impregnatior~ of the charcoal with triacetin leads to a marked
red~ction in the r'charcoal taste". The reasons for this
• effect are not yet known; it also remains to see whether
the treatment results in a decrease~of the adsorption
" efficiency. The test was carried out on TEMPO cigarettes
C~A) •
In connection with this paragraph, it is still necessary to
mention an observation which is obviously typical and reproduc-
ible, although at the present time only theoretical considerat-
ions can be contributed for its explanation:
When one enters a room in which cigarettes with c~harcoal
filters had previously been smoked, the impression of the cold
smoke in the room is characteristically different, in an
unpleasant manner, compared with the normal smell sensation.
This fact clearly indicates that considerationmight from the
outset have to be extended to a deliberate aromatisatlon of
the side smoke from cigarettes with charcoal filters.
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AMERICAN ClIARCOAL FILTER CIGARETTK'S
Brand
Lark
Duke of ~urham
Devon
York
TemDo
Galaxy
Multifilter
~ultifilte~ 2
York
I,uclry StriWe
Hamburg,
Pf/Heu
Type of filter Charcoal taste
Chamber Hardly any
Chamber
Chamber
Double/bonded
Double/bonded
Double/black
acetate with gran-
ulated charcoal
II II U
Double/white
acetate with gran-
ulated charcoal
Triple/acetate
with charcoal
dust
4 December 1984
Absolutely
Getectabls
Absolutely
detectable
Present to
medium extent
Strongly marked
~resent, light
to medium
Absolutely
detectable
Present to
medium extent
Hardly any
Strongly marked
Unde si rable
taste of main
smoke during
pauses between
puffs
None
~resent, though
affected by flavou~
Present
Some present
Present to e
stronger extent
Some present
PreseDt
Some present
Some present
Present to e
s~ronger extent
After-taste
None
Present
Hardly
~resent
Pre sent
Present to a
stronger extent
Some present
Pr e s ant
Present
None
Present to a
stronger
extent
Tobacco
end
flavour
taste
Present
None
Hardly
present
Still
present
None
~rese~t
Hardly
present
Still
present
Present.
Notob~cco
taste, but
flavour
taste
Remarks
Charncter o f
cigarette deter-
mined by flavou
Undistin@uished
cigarette
Undistinguished
cigarette, spar
from menthol
effect
About equal dis-
tribution of
charcoal end
tobacco taste
Charcoal taste
predomlna~es
Charcoal taste
overshadows
tobacco taste
About equal dis-
tribution of
charcoal end
tobacco taste
Charcoal taste
combined with
flavour ssste
J
Physlosl examlnation of charcoal filters
Brand Filter t~pe designation
.... • ,
Devon S-Piece Ifelth Acetate/charcoal
granulea/acetnte
Tempo Bo~ded Charcoal Acetate/bundles
~f charcoal~rf~lule~
York Oomp~essed Charcoal " / " "
York Charcoal Acetste/scatate covered
with charcoal granules
Avalon Triple Acetate/acetate w~Ith
charcoal dust/paper
Philip Multifi Acetate/acetate with
Morris
Lark
Galaxy
Riggio
Lucky
Strike
charcoal granules
3-Piece Keith Acetate/charcoal
~hndles/acetste
Double-Fi Acetate/acetate with
------~srcoal granules
ChBrcoal Acetate/bundles of
charcoal granules
Charcoal Acetate/acetate with
charcoal dust/acetate
14.7.64, 3.12.64
Fi it er
~fth
/6/7
20, i0/i0
20, lO/lO
20, i0/I0
~o, s1915
20, 7.5/
12.5
20, 7.5/~
/V.5
90, 8/12
16, 8/8
~0, 5.5/
10/4.5
Fil~er
diameter
(mm) Whole
8.05
8.].0
8.i0
8.].0
8.15
8.05
8 .i0
8 • 05
8.i0
8. O0
Draw resistance (mm H20) of
Acetate Paper"
section -, section
fil~er
55
V5.2
4O
47.8
13.8 x 2
50.0
20.V
23.5
rharcoa~
sectionJ
24.4
(osZo)
26.5
64.2 22.2
V4.6 24.4
80.4
38.4 x 2
13.7
40.0
3.6
(tale}
68.6 32.0
38.6 23.V
48.3 22.0
(talc)
36.0
14.9
(calc)
26.3
25.3
A/
Weight
OverallI
0.31V
0.325
0.361
0.244
0.23V
0.315
0.331
0.317
0.273
0.216
(gm}
Charcoa~
pieces
0.134
0.2VI
0.120
O. 080
0.192
0.108
0.161
0.098
(÷ sheath
t0069£ 0
To Mr. Borowski
Main Laboratory, Bahrenfeld
Internal report from
Raw Tobacco Dept.
....
Hamburg, 27.7.64.
Subject: Various brands prpvided manually with charcoal filters.
Reference: Your letter" of ~@ July~ 1964. •
The cigarettes submitted to us:
Reval
Hoth H~nd le
Reyno
Gold Dollar
Krone
0rienta and
Players Medium
has been tested, with the following observations:
Roth H~nd le:
At the start of smoking, the tobacco taste was still
quite marked, but as smoking proceeded this decreases
and a detectable charcoal taste is experienced.
No tobacco taste, but charcoal taste predominates.
pla~ers Medium:
No tobacco taste, but charcoal taste predominates.
The cooling effect of menthol has disappeared. A slight
menthol taste mixed with charcoal taste still from the
first and second puff, but later only charcoal taste.
No tobacco taste can be detected throughout.
Gold Dollar:
No tobacco taste, but charcoal taste predominates.
Orients:
The cigarette was completely neutral amd void; neither
tobacco taste nor charcoal taste can be recognlsed.
Copy to:
In connectlou with thlsexuerimental series, it is worth
noting that all clgarettes other than Roth E~ndle and
Orients have a Charcoal taste, leading to the hypothesis
that it is likely that a charcoal taste is more intensive-
ly detectable from cigarettes which contain either only
Virginia tobaccos or mainly Virginia tobaccos, compared
with other cigarettes such as, e.g. black cigarettes
(Roth H~ndle) and pure Oriental cigarettes (Orients).
H. Fischer.
Eerr Se!bmann, Herr Sottorf, Dr. Seehofer.
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To: Dr. Seehofer
Ealn Laboratory, Bahrenfeld
Internal report from
Eaw Tobacco Dept.
Hamburg, 28.7.64
Subject: Charcoal filters on HB M~.xture and the components of
the mixture
The test on 7 different cigarette brands fitted manually
with charcoal filters (see eva!uatio~ by Raw Tobacco Department
reported o~ 27.7.64) caused us to separate EB mixture into its
components and to manufacture cigarettes with charcoal filters
therefrom, in order to establish how the various tobacco groups
react towards the charcoal filter during smoking. The following
cigarette specimens were prepared:
I) Original HB mixture
2 ) ~ " "
3) HB stems .
) HB Bur ley Group
5) HB Virginia G~oup
6) EB Oriental Group
without stems
A smoke evaluation produced the following results:
For I):
No tobacco taste can be established any longer,
but an intensive charcoal taste is experienced.
For 2): As for I.
For 5):
Stem taste predominates, and some charcoal taste
is only experienced durimg continued smoking but
this intensifies as the cigarette burns down
towards the end.
For 4):
For 5):
For 6):
The Bur!ey taste can still be readlly discerned at
the start but it decreases fast as smoking is
continued when the charcoal taste predominates..
As for I.
No charcoal taste can be found during the first
2-3 puffs, and then some charcoal taste is discerned
but this is not as marked as with 1-5. No tobacco
taste is present. The cigarette is almost neutral.
The best results for a suppression of the charcoal taste
are therefore provided by
the cigarette from the Oriental fraction
the cigarette from the Burley fraction
the cigarette from the stem fraction.
H. Fischer
Copy to: Herr Selbmann, Herr Sottorf.
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File Note
318
Subject :
Smoke evaluation on experimental charcoal filters.
The experimental filters prepared in the laboratory
with the use of various charcoal types for test purposes
have been evaluated by us as follows with regard to
taste:
IT
Rin~sdorff and Draser:
Very marked undesirable "off taste" (charcoal taste)
PittsburF:
Still a marked charcoal taste, though better than the
two varieties above.
By far the best variety with regard to taste. The
charcoal taste has been repressed to a large extent.
Ther~ is reason to assume that when this charcoal
type is used in conjunction with an appropriately
-cased and flavoured mixture, no undesirable side
taste will be experienced.
It is important not to dlsresard the smell of smoke
during an evaluation of charcoal filters. The smoke
which is exhaled and also the main smoke escaping
during the pauses between puffs through the ~ilter
both stink in the case of the Ringsdorff, Drager and
Pittsburg varieties. Ho undesirable effects in this
respect are only experienced in the case of the
Lurgi variety.
E. Pfennig.
Hamburg, 12 November 1964
Copy to: Herr Sottorf, Herr Selbmann,
Main Laboratory.
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4. Discussion
4.1 S~mnary of results
The points mentioned below have to be remembered during
any interpretation of the following Figures and Tables:
The "chamber filters" and "bonded filters" made manually
by the Filter Production Department largely consisted of
charcoal. The acetate discs for sealing the filter
were only 3 mm long so that the total draw resistance of
the specimen filters only amounted to about 20 mm H20.
The data obtained with the filters obtained by this
method therefore mainly provide information on the
charcoal ou its own and thus are essentially limited to
changes in the gas phase. In practice, the retention
effect of an acetate filter of appropriate length and
draw resistance would have to be added.
After taking into consideration the comparative
evaluation of results from the chemical and biological
tests, the Tables and curves lead to the following
order of merit:
i. Ringsdorff charcoal
2. Pittsburg charcoa!
3. Drager charcoal
4. Lurgi charcoal
A few generally important points may be emphaslsed:
All the 4 charcoal varieties seem to be more efficient
than the Lark filter or the Filtrona Bonded Filter FF 561,
from the point of their overall activity.
There is no evidence of an appreciable difference between
their suitability for a chamber filter or for a bonded
filter. Their effect is controlled via the amount of
charcoal employed. The activity lost due to the bonding
agent in a bonded filter is compensated by approximately
doubling the amount of substance.
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4.2 Discussion of procedures and filter types.
in the meantime, cigarette brands with a wide variety of char-
coal filter constructions have appeared on the international :
market. It is fundamentally possible to differentiate between
four main possibilities for the arrangement of active charcoal I
i~ a cigarette filter.
The first of the possibilities consists in charging or dispers-
ing fine active charcoal powder on paper filters. The absolute
amounts of active charcoal which can be applied by this method
ar~ relatively low, and are likely to be of the order of 30-50
mE/tip. The best known examples of brands in this class are
Tareyton (USA), Tennyson (S~itzerland, Germany, Finland] and
Carlton (USA).
A second possibility consists in charging or dispersin~ fine
active charcoal powder or even larger granules of active
charcoal on white or black cellulose acetate. As a rule, the
cellulose acetate is not in that case compounded with plasti-
c!sets. The absolute amounts of active charcoal which can be
a~plied by this method were initially very low, but at present
amounts of I00 mg or more per tip have been achleved.
Ezamo!es in this class include York (USA), Galaxy (USA!, Lucky
StriKe Filter (USA) and Philip Morris Multifilter (USAJ.
A third possibility consists in loosely filling active charcoal
into a chamber formed between two ordinary filter pieces, eithez
of cellulose acetate, e.g. Lark and Devon (USA) or of a paper
filter, such as e.g. Duke of Durham (USA). The amount of char-
coal which can be applied by thls method amounts to about
130 rag,
The fourth method employs active charcoal granules in a double
filter in which the charcoal grains have been more or less
firmly with a bonding agent. A polyethylene or similar
plastic product ~s usually employed as the bonding agent. The
best known example in this class is Tempo (USA) as well as
Eiggio (South Africa) and a special form of York (USA). The
amount of charcoal which can thus be applied in this filter
amounts to 200 mg and more.
A!thou~h the opinion was first of all expressed that the ad-
sorptlon efficiency of a charcoal filter inter alia depends on
the arrangement of active charcoal in a filter, our present
state of knowledge indicates that the adsorption capacity of a
filter is largely a function of the amoun~ of charcoal. It
m~Ast nevertheless be recognised that the arrangement of active
charcoal in a cigarette filter is evidently of extreme import-
ance from the point of view of the taste of smoke. According
to the experience obtained to date, filters of the chamber type
with loose granulates (the third possibility) affect the taste
of smoke least. The remaining order of merit is
charcoal granulate on tow (second possibility), followed by
bonded charcoal filter (fourth possibility).
Although the first method apparently affects the taste of smoke
even less than the third, this method can nevertheless be dis-
O
re~arded during an evaluation because the amounts of active
charcoal which can be applied by this procedure are much too
low for this type of filter to be accorded special attention
at the present time.
O~
CD
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- l0 -
A general comparison of the procedures now Known and applied
reveals that the chamber filters evidently offer most promise
for future further development.
This is because if sorptien additives other than active
charcoal should become more important, a chamber filter
could readily be filled wlth any other materials. This
condition is not fulfilled directly for the other types of
charcoal filter, either for the bonding ef charcoal granules
on tow or for a bonding of charcoal granules to each other:
in each of these cases, a special modification would have te
be developed for each new adsorption medium:
4.3 Discussion of Patent and legal situation.
Since in Germany, cigarettes as well as cigarette filters
are subject to the Regulatlens ef the Food Act, it would be
necessary to apply to the Federal Ministry of the Interior
for the grant of an exemption permission or experimental
permission for the application of active charcoal in cigarette
filters prior to every case of introducing a cigarette brand
with a charcoal filter. The above mentioned bonding agent
polyethylene has already been detailed in the Tobacco
Regulations, and no special application would have to be made
for its use, but special permission would have to be sought
for the application of any other bonding agent in any Intended
bonded filter.
If it should be intended to manufacture a previously known
type of charcoal filter, according to a previously known
process for the production of charcoal filters, the situation
with regard to Patent Law is likely to be of secondary
importance, since any problems encountered in this respect
would primarily concern the manufacturers of filter machines.
However, should the development of a novel filter type or the
development of a novel process for tb~roducmlon of filters
be envisaged, the patent situation would have to be very
critically examined since a large series of older and more
recent patent specifications concerning the problem of char-
coal filters has been published. A llst of the patent
specifications on this topic which have so far been discovered
by us will be found in the Appendix.
CD
L~
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- ll-
5. Recommendations.
From the chemical point of view, an active charcoal with the
adsorption capacity of the Ringsdorff charcoal is absolutely
recommended for processing in cigarette filters. Special
interest shoul~ be paid to the form presented by the Lurgi
charcoal, i.e. short moulded cylindrical rods, for physical
and taste reasons. Appropriate steps have already bow been
taken to solve the problem of the possible production of
Ringsdorff charcoal in the Lurgi shape, it might be possible
to prepare a novel optimum active charcoal product by such
a method.
A certain degree of preference should be accorded to the -
chamber filter type in comparison with other ty~es of charcoal
filters, in order to take account of future developments.
This type of filter would be most readily modified for other
fillings, e.g. silica gel, or for an activated or impregnated
carrier material, should the emphasis of the discussion
regarding adsorption by a filter be displaced in other
directions, say towards oxides of nitrogerL, nitroaamines,
formaldehyde, organic acids or the like. As far as the
tobacco mixture is concerned which should be applied in
cigarettes with charcoal filters, special importance undoubt-
edly attaches to the tobaccos which have been "air cured~
within the widest sense of the term.
A product prepared by the most careful attention to the
above considerations will nevertheless undoubtedly still
exhibit some "charcoal taste". We therefore do not think
that a thorough casins and flavouring, included from the
start in any planning, can be dlspensed with for a
cigarette with a charcoal fil~er. These ~actors provide
the final possibility of masking or overshadowing the
residual cha.~coal taste which is bound to remain.
p-.
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6. Plan for further work.
According to the experiences obtained in the field of
charcoal filters, it will be essential to try and maintain
the following sequence of work during the development o£ a
cigarette with an active charcoal filter:
I. Establishment of the filter type (chamber,
Bonded-Filter, etc .)
2. Establishment of the required adsorption capacity:
a) which substances should be adsorbed?
b) at waat level should the percentage
adsorption be?
3. Se!ectiou of the charcoal type cousldered suitable.
4. Selection of the suitable tobacco types with this
fi it er.
5. Compromise solution from 3. and 4. with the
assistance of casings and flavour.
The commercial active charcoals need to be subjected to
constant investigations with improved apparatus and methods.
A constant study of interesting competitors~ products seems
particularly necessary.
O
O~
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O
2.31
2.32
2.33
2 .~4
3.11
3.12
3.13
3.14
3.15
Cap,ions to ?igumes 2.32 to 5.15.
Charcoal sc reenin~.
Abscissae: Time, in hours (Std)
Ordinates: Adsorption of CeHsCI, % referred to dry charcoal
weight ,
rein = pure gekornt = granulated Muster der Rinas-
reins~ = purest trocken = dry dorff-Werke -
aus Zigaretten = from cigarettes specimens from
pulv. = powdered p.a. = reagent grade Ri~saorff works.
Chlorobenzene adsorption of active charcoal in % b7 weight
as a function of ~ime.
Abscissae: Time, in hours (Std)
OrOina~es: Increase in weight, %.
Phenol ams9rption
Abscissae:
Ordinates:
Charcoal types
Merck, 1.5 mm. granulated
Ringsdorff ~0~, activated
Eiedel de H~en, pure
Merck for Gas Chromatography
Fluka, granulated
Adsorption (%).
Hydrogen cyanide adsorption
Ringsdorff spez.m.Cu v.Fe = Ringsdorff, special, with
Cu and Fe.
Detected amounts of aldehyde in main smoke
Abscissae: Charcoal types
Standard-S~rang = standard twist
Ordinates: Aldehydes, mcg/cigarette.
De~ec~ed amounts of organic acids in main smoke
Abscissae: Charcoal types
Ordinates: Organic acids, mcg/cigaret~e.
Phenol content in main smoke (particle phase)
Abscissae:
Ordinates:
HB K~rper = HB s~ock
Kammer Filter = chamber fil~er
Phenols, mcg/cigarette
CAT (particle phase)
Ordinates: Length of life (se~.)
C~_~_~ (gas phase)
Ordinates: Length of life (sec.)
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40
40
o
m
o
o
,-..4
4~
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u~
,!e
o
0
4o
Table~s (3.16 - 5.3)
"O
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- ~iiii
.H
• o~Bqo ~nq~T~
~oo~ ~I
~oo~s ~H
t~ ,-4
.:
Ol ,-4
o u~ tO I
,-4 "~
~D
~.. ~ ~ 0
o~ o co A
O~ ~o O~
~4 ~o
LO U) t~ I
,
O2
OO ~
no
o~
~0
5 .I!
Phenol adsorDtlon
Merck, 1.5 zm, granulated
Riedel, pure, granulated
Ringsdorff "0" activated
Merck for Gas C~romatograpay
Ringsdorff special with Cu and Fe
Fluka, granulated
Phenol ads orp.tion
% "'U."
93.9
92.3
92.4
91.7
59.2
5.12
Hydrogen czanlde adsorption
Merck, 1.5 mm, granulated
Riedel, pure, Eranulated
Eingsdorff "0" activated
Merck for Gas Chromatography
Ringsdorff special with Cu and Fe
Fluka, granulated
HCH adsorption
%
78.2
68.5
65,8
69.4
46.2
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5.13
Aldehydes in main smoke, as mgg/cigare~e.
Standard
merck
Ried e i
Ringsdorff-Werke
n
Drager
In~ ividual readings
995
175
180
55
255
lOOS 1020
170 185
190 175
60 70
260 270
~ean
i010
177
180
65
26O
% Reduction
it
m
82.4
82.4
94.5
74.2
5.14
Organic acids iu main smoke, as mcg/clgarette.
Standard
Merck
Riedel
Ringsd orff-Werke
n
Drager
Individual readings Mean
945
564
520
322
555
97O
520
47O
34O
582
98O 985
540 540
465 485
530 55O
565 570
% Reauc~iou
R
44
80
65.6
40.8
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Q
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+
HB stock
PIB Bah~enfeld, normal
LA.~K s=ock
LARK normal
s ~ ock+ LARK
HB s~ock*FILTR01~
Bonded Filtem
sdorff charc
Dr~ger charcoal
Lurgi charcoal
Pi$$sburgh
Rin£saorff charc
Dr~ger charcoal
Lurgi chsrcoal
Pittsburgh
cO
c~j
cD
~r
I
ro
oi
J,
c~
o
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Q~
o~
0~
"v
Ol
o
G)
-a
cD
Do
0
bo i.~ p.-, ~ i.,o ~
[.n :~.~ o co o o
i-~ i~ i~ ~ i~
I-~ i.~ i~ I.~ ~.~
HB s~ock
o1 HB-Ba~enfeld, normal
0
.L~. ~g s~ock
o1 LARK normal
O
O1 O1 (D O1 ~ O1
~O ~-~ ~-. ~.~ ~-~
O ~- t" O o1 O
O10 O1 O [ O'I
I
tn O O1 O1 O
O
['0 ~0 CO I-~ ~0
O1
0 GO On ~. D1 0
o1 0"~ OI 01 O1
C'O 0 0 0
•,0 ,,
'~ L"O BD ~0 Ca
O~ 0". (D -.a 0
O~ (D 0 O1 0
~ ~ (D -~ O
(D G) O On O
O1
m.
O1
I o1
~ ~ ~
¢m CD Ot ¢.n O~
00~ 0 0 .0
HB stock÷LARK fil~er
lib stock+ Filtrona
Bonded Filter
Pi~ ~ sbum&h charcoal
Lurgi charooal ~
_ ,, ~ w~
~rager charcoal
Ringsdorff charcoal
0
Pittsburgh char co~l ~
O
Lurgi charcoal ~ •
Dr~ger ~har coal
Ringsdorff charcoal ......
.
I
01
.
5.3 Active charcoals examined to date
Samples in the order of merit according to the charge
capacity for chlorobenzene vapour.
Type
~eight
increase
(%)
RiedeI, pure, granulated
Merck, Io5 ram, granulated
Ringsdorff-Werke "0", activated
Lurgi (Desorex 21)
2t
Drager K 23S
Serva Norit pract.
Drager K 238
K Roht supra raffin
FI ~uka (Darko G 60)
Merck, 2.8 ram, granulated
!Merck (0.5 - 0.75)
Pittsburgh O1 20 . 50
Lurgi (Desorex ~, 0.5 - 1.S ram)
Merck pure
Merck purest
Riedel, chem. pure, dry
Philip Morris, from cigarette filters
Tempo, from cigarette filters
Dr~ger K 228
Riedel, pure, powdered
Pittsburgh PCB 12 . 30
Merck, anal. grade (Hellige
Reag. R 444)
Galaxy, from cigarette filters
Lark, from cigarette filters.
Riedel, anal. grade, powdered
Fluka, granulated
Ringsdorff-Werke 50C r20~
40C t20~
40C rlOx
50C rlO~
40C ~40~
40C t80-~
77.1
75.6
71.I
71.0
68.1
67.1
66.0
65.8
65.0
64.5
64.0
65.2
58.8
53.8
55.0
51.8
~20 conten~
3.0
5.4
3.9
10..5
2.0
5.2
4.1
4.8
5.5
,,B
~.8
4.0
6.7
51.0 12.9
49.9 6.5
49.4 6.5
48.9 11.4
48.7
47.4 9.9
44.3 I0.5
41.5 12.3
57.2 12.8
5.4 5.9
4.3 4.7
4.1 5.0
5.8 4.9
5.7 4.4
3.6 4.6
5.I 4.8
x
First delivered samples.
0
O'x
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0
5%,.0
APPENDIX I/2
DESCRIPTION OF TEST ~ETHODS
@
Directions for the 2reselection of active charcoals
In industry, charcoal~not destined for a specific field of
application are classified according to their adsorption
capacity for benzene vapour/air mixtures. The increase in
weight until the saturation point has been achieved is
described as the "maximum charge capacity".
Owin~ to its higher density, chlorobenzene was employed as
the adsorbant in lieu of benzene; they both have the same
iipophillc characteristics.
Procedure:
S-10 g Active charcoal are accurately weighed out in weighing
bottles and dried at 130°C for 90 rain (to constant weight)o
They are thereafter allowed to cool down in an evacuated
desiccator for 30 minutes and reweighed. . The difference
in weight provides the water content (which includes all
constituents volatile under these conditions). The dry
active charcoal is transferred to a desiccator in which an
atmosphere saturated with ehlorobemzene vapour is constantly
present. This is attained by sucking an al~ady saturated
weak current of dry air through the ch!orobenzene present
in the bottom of the desiccator.
The desiccator is evacuated for a short time after the
active charcoal has been placed iu it.
Four hours later, an intermediate weighin~ is carried out,
and the final weighing follows after 20 hours' exposure
when the maximum charge capacity has been achieved.
A curve representing the increase in weight as a function
of the exposure time indicates the capacity of the
charcoal and its affinity for chlorobenzene.
3~
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nirections for estimatin~ the phenoI adsorption on active charcoal
Princ iule :
A phenol-alr mixture is passed from a constantly maintained
source beyond the desorp~ion limit through an active charcoal
column and the phenol not adsorbed by the charcoal is chemo-
sorbed in a receiver.
C ond itions:
Two narrow wash bottles with a G i sintered glass fitting
arranged in series are employedas ~he source. Each is filled
with SO ml of a saturated aqueous phenol solution in the
presence of a sediment of phenol. Their temperature is
maintained at 20°C.
A U-~ube of a useful column length of 140 mm and 8 mm internal
diameter is employed as the receptacle for the charcoal samples.
1 8 Charcoal is introduced into the U-tube and plugged at each
end with a small wad of cotton wool.
A U-shaped sorption vessel is used as the final closure, one
of whose limbs consists of 3 glass spheres drawn out to join
each other and the other of a glass tube of internal diameter
21 mm and filled with 40 g of fine glass pearls. The sorption
vessel contains 15 ml N_/10 KOH.
The whole apparatus is now connected to a rotary vacuum pump.
An air current at a rate of 6 ml/sec is then passed through
by means of a rotameter for eight minutes.
5 ml of the 0.! N K0H containing the phenol in the form of
phenate is withdrawn by means of a pipette, made up to 28 ml,
filtered off and subjected to photometry at the absorption
maximum of 288 ~uln a spectrop~o~ometer. A calibration
solution was erupted to show that i scale division on the
extinction scale (0.001) corresponds to 5.V6 g pheno~100 ml
so lutlon.
CD
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Directions for the estimation of steam volatile phenols i~
9 igarette smo ke (c olorime ~V).
Principle of the method:
The procedure is in accordance with the directions specified in
R &D Report No. L-V2 R.
The main smoke is precipitated on Cambridge filters, and the
Cambridge filter is thereafter introduced into water containing
sulphurlc acid, when the volatile phenols are expelled by passing
steam through. An aliquot portion is withdrawn from the steam
distillate, and converted, in a solution made alkaline with
bicarbonate, to a red quinone dyestuff by means of N,N-dimethyl-
parapheny!ene diamine with the addition of potassium ferricyanide.
The dyestuff is extracted with CC14 under standard conditions and
thereafter subjected to photometry at 588 nm. Under these
conditions, phenols substituted at the pars position will not react.
Cigarette filters are treated like Cambridge filters.
Smokln~:
13 Cigarettes are smoked in accordance with the Industry Standard
Specification (smoking machine), and the smoke is precipitated on
3 Cambridge filters arranged in parallel. In order to estimate
the efficiency of a filter, t~'e- cigarette filters are collected
and further processed like the Cambridge filters.
S team dist illatlcm:
The three smoke-charged Cambridge filters are introduced into a
500 ml round-bottomed flask with deliverZ tube and covered with
some water. After acidification with l0 ml 6H HoS0a, the contents
are steam distilled into a receiver charged wi%'h ~ ~l. of a
saturated NaECO~ solution until about 280 ml distillate have been
collected. Th~ contents are transferred to a 300 ml graduated
flask, made up to the mark, and 50 ml are withdrawn for the phenol
estimation, corresponding to an amount of 100-200 mcg phenol.
C olour reaction:
50 ml of the phenol solution (containing 100-200 mcg phenol and
2 ml saturated NaHU03 solution) are pipetted into a I00 ml seoarat-i
img funnel, treated with 2 ml diamine solution and shaken. There-i
after, 2 ml potassium ferricyanide solution are added and shaking
is repeated. After 15 minutes precisely (stop watch), the contents
are extracted with one 20 ml portion and then one i0 ml portion of
CCla, the extracts dried over Na2S04, filtered through a little
cotton wool into a graduated flask and mame up to 50 ml. Photo-
metry is carried out at 565 nmcompared with H20.
Reagents •
i. NaHC03 solution (saturated), 12 ml~analysis
2. H2S04, 6~, I0 ml/analysis
3. N,N-dimethyl-p-phenylene diamine sulphate (300 mg/!00 ml H20)
(to be stcred in a dark bottle for not longer than 14 days,
2 ml/analysis
4. CC14, 30 m!/analysis
(ID
5 Na2SO~
61 K C- e cN)J, a g/lOO ml H2o, treated lil e the dlamlne solution,
2m~I/analysls
7. (once for calibration curve) 30-40 mg purest grade phenol.
~ "~0
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Auoaratus :
=z- ~ .., .
Smoking mac hlne.
3 Cambridge ~filters arranged in parallel
1 500 ml round bottomed flask and delivery tube
i Steam distilling apparatus
1 300 ml receiver with 2 ground glass Joints ~S 14.~/23
i Adsorption flask with compound
2 Graduated flasks (300 ml, 50 ml)
I B0 ml pipette
2 2 ml pipettes
1 I00 separating funnel
1 Cotton wool filter funnel
G Cylinders (20 ml, I0 ml).
Calibration curve :
30-40 mg of purest grade phenol are weighed out accu~ate!y and
dissolved in a graduated flask by the a~dition of l0 ml saturated
NaHU03 solution before being made up to I00 ml with water. I0 m!
of this solution are plpetted into a 1000 ml graduated flask and
39 ml saturates NaHC05 solution are added before it is diluted to
i000 ml. The colour reaction is carried out on 50 ml of this
solution as described above.
By weighing out different amounts of phenol, a calibration curve
can be obtained, but a single weighing will in practice be
sufficient since the Beer Law is strictly obeyed within the
stated limlts.
Calculation:
The content corresponding to a single extinction unit is calcu-
lated from the calibration result:
Examule: 192 meg phenol were employed durin~ the ea!Ibratiom
read ing.
Observed extinction value = 0.720 (in short 720).
.'. 19217z0 = 0.267 meg per extinction unit.
To calculate the phenol content per filter or its content in the
main stream smoke per cigarette, the following factors are
employed.
Examule: Observed extinction values: Standard = 720
Filter = 525
, Cambridge filter = ~61
. . Filter contains 267 x 525 x 0.923 = 129.H meg/filter
Cambridge filter contains 267 x 361 x 0.923 -- 89.0
mc g/maiu smoke
• . Total phenol content = 218.5 mcg/clgarette.
T~e filter efficiency for phenols (Oph) is obtained by the
"absolute method" as
lZ~.S/Zl8.5 x 1O0 = 59.~.
= 59.3%
J~
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Directions for the estimation of hyorosen cyanide adsorption
on active chkr~oals.
Princio le :
By analogy with the phenol adsorption, the hydrogen
cyanide liberated from a source is passed in an air
current beyond the limiting surface and through am
active charcoal column, when the HDN not adsorbed by
the charcoal is chemosorbed in a receiver.
C onditi0ns :
A 400 ml wash bottle with a sintered glass fitting
G3 serves as the source which is filled with I00 ml
84 KCN solution at O°0. At the start of the test,
iO ml concentrated H3PO~ is added without cooling.
A i00 ml conical flask for separating carried-over
liquid droplets and then a U-tube for the receptlon
of the charcoal sample are arranged beyond the wash
bottle. The U-tube, whose useful column length is
IS.0 mm and whose internal diameter is 8 ram, is
filled with I g active c~arcoal so that the column
extends from the first limb to the centre of the
bend. It is plugged at both ends by a smail~cotton
woo! pad. A narrow Wash bottle filled with B0 ml
0.! N K0H arranged in aeries behind the U-tube
chem~sorbs the HDN not adsorbed by the charcoal.
The apparatus is connected to a rotary oll vacuum
pump via a rotameter and a Woulffe bottle. The
current of air/gas mixture .passes t~-rough the
charcoal at a rate of 2 ml/sec for 3 minutes.
The hydrogen cyanide not adsorbed on the charcoal
is present in the form of KCN in the receiver, and
is estimated by the argentome~ic method due to
Liebig (of. Gerhard-0tfried Muller: Praktikum tier
quantitativen chemlschen Analyse = Practical
Quantitative Chemical Analysis, 4th Edn., p.327,
equations 5 and 4).
The end point of the titration is recognised by the
turbidity, resulting from insoluble silver dicyanc-
argentateor silver cyanide, but can also be deter-
mined by ~the red colour imparted ~o an indicator
( p-d ime t hy lamino-b e nzylid ine- thl oc yanamine
(PDB Rhodamine ) ) •
The adsorption of the prussic acid by active
charcoal is calculated from the difference compared
with the resul~s of a blank without charcoal.
4~
0
O~ .
0
!
Directions for the estimation of aliphatic aldehydes in
cigarette ~moke.
Allphatlc aldehydes react with methylamlne and o-aminobenz-
aldehyde, with the~formation of a yellow dyestuff. W~en the
method of determination described below is carried out, as
based on this reaction, a reproducibility of + 5% is achieved;
the method is not suitable for aromatic and he~Jerocycllc aldehydes.
Execution:
1-2 Cigarettes, selected according to weight and draw resistance,
are smoked under standard con~itions down to a stub length of
23 mm. The gas phase of the smoke is recovered by means of a
cold trap in liquid air after it had been stripped from the
particle phase in a Cambridge filter. Whilst still cold, the
trap is rinsed with a total of 50 ml ethauol, the ethanol is
transferred to a lO0 ml graduated flask and this is made up to
the mark with water.
An aliquot portion of 2 ml is transferred to a I0 ml graduated
flask and treated with 8 ml of an aqueous solution which is
0.2 ~ with respect to sodium pyrop~osphate (NaaP207 • lO H20)
and U.2 M with respect to methylammonium chloride.
It is thereafter treated with I ml 0.04 M aqueous o-aminobenz-
aldehyde solution and made up to the mart with an ethanol/water
mixture (proportion l:l by volume). The extinction is read
18 minutes later at a wave length of 440 m~ on a 1 cm cuvette
(l~essler tube) in a spectrophotometer by 6omparison with the
reagent solution.
The absolute values can be read from the extinction readings
in a calibration curve based on acetaldehyde.
CD
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Directions for the estimation of steam volatile acids in
clgs~ette smoke.
3-5 Cigarettes, selected according to weight and draw
resistance, are smoked under standard conditlcns do.~n to a
stub length of 23 ram. The smoke is precipitated in 2 smoke
traps arranged in series and cooled with dry Ice/acetone.
The contents of the traps is rinsed into a separating funnel
with 8 portions of 5 ml 0.02 N NaHC0~ solution followed by
5 portions of 8 ml diethyl ether, ang the phases are qeparated
after they have completely divided. T~e ether phase is
rinsed wit~ 2 portions of 5 ml NaHU0~ solution (0.02N) and
all the solutions in NaHU03 are combined.
The combined solutions are heated at 80oc on a water bath
for I0 minutes, cooled, acidified with 2_N H2S04 and subjected
to steam distillation which is finished after about 150 ml
distillate have been collected. This is tltrated with
0.025 N Na0H with the addition of 5 drops of indicator solution
(foot,to missing In German text).
The estimation of the accuracy is carried out with a known
amount of acetic acid which is subjected to the entre
analytical procedure. The calculation is in terms of acetic
acid.
0
C~
0
Directions for carryin~ out the ciliate test CAT.
The solution under investigation is withdrawn from the first
i00 ml of the steam distillate obtained from the smoke condensate
electrostatlcally precipitated during the smoking of 50 cigarettes
(MEURATH phenol dete~ination, modified).
After the pH value of the original solution ~as been established,
this is treated with 15% of a ci~ric acid/p~osphate buffer
solution at pH 7.0 on a spotting plate (0.17 ml of solution under
investigation and 0.05 m! buffer solution) (of. D'Ans-Lax:
"Taschenbuch f. Chemiker und Physiker" = Pocket Book for Chemists
and Physicists, 2nd Edition, 1949:: 6624, Buffer Solutions,
p. 1592, NO.B).
0.12 ml (5 drops') of the solution under investigation, now
buffered to pH 7.0 + 0.2, are transferred by means of a pipette
to the ground hollo~ of a microscope slide held on the slide
stand under a microscope.
The paramecia living under the pe!licle in a culture vessel are
removed wi~h a platinum loop, and these are carefully stirred into
the liquid on the slide mount. This is also the start for time
recording by means of a stop watch. A magnification of about
50 times will suffice for a determinatlou.
(Should no pure culture of paramecia be available, the procedure
is as follo~s~
An Infusion is prepared from fresh hay and aquarlumwater and
kept at 5~°C In an incubation chamber for abo~t ~ - 5 days whilst
illuminating fro~ above. The pellicle with the parameeia
swimming within It and below it is carefully liftsd o~ and shaker
gently i~ an open conical flask with glass beads and a little of
the filtered substrate.
The total substrate is filtered off from the solid hay con-
stituents through a soft filter, recomblned with the paramecia
and the constituents of the subdivided pellicle, and replaced
in the incubation chamber.
This standard culture remains satisfactory for use only during
a few days but can be employed for inoculatln~ novel infuslons~
The straigh~ line motion of the paramecia is changed much by the
agents in the solution under test. The end point of the time
recording is characterised by the fact that even the eccentric
rotat£on movement about the axis of their bodies ceases, after
the end of local movement in the projection plane, for about
~0~ of the individuals.
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Directions for carrying out the cilia test CMT.
The gill lamellae of the sweet water mussel which are covered
with cilia are carefully removed and stored in a Corse-Allen
nutrient solution fc~ i hour. The gill lame!is lobes which
have ~n area of about 1/8 sq.cm. (only the internal lobes,
i.e. those attached to ~he foot) are introduced into a smoke
chamber (of volume 2.2 cc) and charged wi~h smoke as follows:
The gas p~ase of the next to last draw (50 ml} from a cigarette
smoked under standard conditions is aspired into a Fortuna
glass syringe and thereafter passed over the lame!Is lobes at
a rate of 8 mi/45 see which is automatically controlled. The
beat.of the lat4ral cilia is then observed uutil it stops
altogether. Consideration is o.nly extended to those mussels
exhibiting a cilia stop of 128-155 sec during the ninth draw from
the HB stock.
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5.22 Other known test methods. •
• #
A brief summary of test methods and characteristic terms for
data used in various branches of industry for characterising
active charcoals.
Water content:
a) Drying at 120°C for 2-3 hours, to constant weight.
b) Xylene method (separating water by distilling the charcoal
wit h xyle ne )
Powder density, bulking density:
Weight of charcoal per unit volume after
a) pouring
b) pouring followed by bulking with a defined number of
impacts of a defined magnitude.
Hardness and abrasion:
Charcoal is subjected to the abrasive and impact effect of
porcelain balls in a ball mill, under defined conditions.
Literature: Pittsburgh Chemical Co. Methods.
Sieve ana!~sis :
Fractionation of charcoal through sets of sieves according
to German Standard DIN 4188.
Phenol adsorotion:
Shaking of a defined amount of charcoal in a defined amount
of aqueous phenol solution (largely for water purification
charcoal), according to German Standard DIN 19 603.
Decolourisation of methylene blue (methylene blue index):
A certain amount of charcoal is shaken with vazTing amounts of
a methylene blue solution at a defined concentration until
decolourisation occurs (test for medicinal charcoals, known as
H-charcoals, according to Deutsches Arzneibuch = German
Pharmacopeia 6).
Literature : Pittsburgh Chemical Co. Methods.
Iodine index:
Absorption of iodine, in mg, per gram of charcoal from a
0.02 N iodine solution.
Literature: P~%sburgh Chemical Co. Methods.
Activity towards carbon tetrachloride:
Maximum percentsge increase in weight of the charcoal after
passing an air current saturated with CC14 through it.
Literature: Pittsburgh Chemical Co. Methods.
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Adsorption capacity for benzene:
The maximum charge capacity is attained when the charcoal
exhibits constant weight during a process when a partially
saturated benzene vapour/air mixture is passed through c~tarcoal
columns (particularly for active charcoals destined for solvent
recovery).
Deco!ourisipg capacity for a solution of molasses:
Amount of charcoal required ~o bring about 60% decolourisation
of a solution of molasses having a defined colour intensity
(test in the sugar products industry).
Heat of wetti~:
Temperatttre increase cf benzene after treatment with dried
activated charcoal (rapid method).
Determination of resistance time:
Time which elapses until the start of a physiological irritation
when a mixture of irritants a~ air is passed through defined
columns of charcoal (test of gas mask filtering charcoals).
Charge required for desorption:
The amount of a substance adsorbed by a defined charcoal column
(per unit of weight or volume) until the substance first passes
through, from mLxtures of air with the substance (test of gas
mask filtering charcoals).
Bromine adsorption:
Maximum increase in weight of charcoal after storage in an
atmosphere of bromine vapou~ (developed by ourselves).
Literature : Aktive Kohle und ihre industrie!le Verwendung
T= Actlve'Charcoal and its industrial Applications) by
G.E~ILLF~UL, K.BPJ~TZ~, W.EKRBERT and W.VOLL~ 4th edition.
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The AREA-meter., a laboratory aoparatus for a. non-vacuum
series determination of surface areas of finel7 divided
materials by nitro,~en adsorotion at low temperatures.
By R. Bollenbach (D~sseldorf).
Eeramische Zeitschrift 1964, No.2, 87-88.
A knowledge of the specific surface area of finely
divided and porous solids is becoming increasingly important in
industry. A novel differential measuring process based on the
EET method is described; it gives rapid and reliable results.
The apparatus developed for this process does not require a
high vacuu~n, has a simple construction and can be easily operated.
The method and appsratus are suitable for series determination
during the control of manufacturing processes. The procedure
and potential of the novel method are indicated.
I. General.
The extent of the surface area of all fine particle
solids, such as raw materials and starting materials, semi-
finished and finished products, and synthetic as well as natural
materials is an important fundamental characteristic. A
knowledge of this extent is often a decisive factor during an
evaluation.of the usefulness of employing a number o~materials
for manufacturing operations and for the procedures ~mployed in
production for many branches of industry; it also serves for
the regulatio~ and constant control of production as well as for
the quality characterisation of the products. Thus, it will for
instance play an important part in the industries concerned with
ceramic products, fillers, pigments, adsorbents, fertilisers,
building materials, silicates, catalysts and ths like. The
surface area ~as already for a long time been a subject of
research in the field of pure science owing to its effective
influence on physical processes and chemical reactions; however,
determinations of surface area are also being increasingly
conducted in the test laboratories of industry. The growing
importance of this quantity is quite evident from the literature
published in recent years.
The surface area of a solid is defined as its
interfacial area with an environmental phase, e.g. a gaseous
phase. Apart from the external surface, it also includes the
internal surface area available to a gas from the outsi~e, as
given by its porosity. As an example of an adsorbant used in
many types of application and characterised by a particularly
high extent or surface area and porosity, mention may be made
of active charcoal. The known remarkable efficiency of
heterogeneous catalysts in initiating and accelerating reactions
are largely ascribed to the influence of the extent and shape
of their surface. A knowledge of the specific surface area is
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important in the ceramic industry for the characterisatlon of the
very fine particles of starting material as well as for following
the sintering processes.
There are many methods for determining the specific
surface area. The standard method adooted is that of nitrogen
adsorption at low temperatures, due to Hrunauer, Emmet and Teller
(--~T method). In comparison with other methods, the results of
this procedure are regarded as the most reliable and most accurate.
From the point of view of employing it in practice in industry,
this method does however suffer from the disadvantage that it is
time consuming and ~quires the application of a high vacuum
apparatus with a correspondingly high cost of operation.
More recently, R.Haul and G.D~bgen (I) have proposed
au appreciably simpler process based on the HET method. This also
takes into account a number of suggestions already previously made
by other authors:
I. The application of an arrangement for differential reamings
dispenses with the need for a ~dead volume" correction, and
at the same time it makes possible the measurement of
relatively small surface areas with a satisfactory degree ..
of accuracy.
2. By limiting the adsorption isotherms to a single reading,
the measurement and evaluation are considerably accelerated.
8. Rinsing of the sample in a current of the heated gas employed
for the determination dispenses with the need for the high
vacuum apparatus wnich is expensive to purchase and requires
much labour to operate.
During the further development of the new apparatus
(Pig.l), the arrangement for measurement was further simplified.
A mercury manometer originally employed for measuring the
equilibrium pressure a~tained curir~ the adsorption pr~ ess could
be omitted ~nce the equilibrium pressure can now be calculated
from otb~r pressure readings. This considerably reduces the
breakage risk of the apparatus, and this is important with regard
to its application in works laboratories.
I!. Principle of measurement.
An adsorption vessel withthe sample and an empty
comparison vessel of the same volume are filled at room temperatttre
with nitrogen at the same pressurej usually atmospheric pressure.
When the vessels are cooled to the temperature of liquid nitrogen,
the adsorption of nitrogen on the sample brings about a pressure
difference between the two vessels, and this is measured ~ith a
d~.~ferential oil manometer. T~e surface area of the sample can
be calculated from the pressure difference as well as the initial
pressure durin~ filling (atmospaeric pressure). The equilibrium
uressure in the adsorption vessel is automatically adjusted to
within the EET range due to cooling, and can also be established
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from the pressure difference and the initial pressure during
filling, without need for a further pressure measurement.
II!. Preparation of the samples.
The experimental and time requirements for the
preparation of samples are of some importance for the economic
viability of a measuring procedure. The removal of any foreign
molecules already adsorbed at room temperature is essential prior
to s~arting the measurement. The novel apparatus dispenses with
the degasificatlon in a high vacuum whlch in the ~ast proved very
expensive in te~ms of apparatus and labour, and thls process is
replaced by the rinsing of the samples with the heated gas
employed for measurement. The slmolification achieved thereby
also produces an appreciable saving'in time.
A p~rging thermostat (Fig.2) developed for this purpose
makes possible the simultaneous rinsing of none vessels with
samples. Thus, the preparation of samples is carried out in an
entirely separate procedure from the actual measuring operation
an~ does not involve an increase in the time allowance to be
applied during a measurement.
IV. Evaluation.
The evaluation can be based only on a knowledge of
the initial pressure during filling (atmospheric pressure reading
on a barometer) and of the pressure difference read on the
differential manometer. Although the evaluation is not difficult
it can be further simplified with the aid of a nomogram. The
apparatus also allows the registration of isotherms throughout
the entire ~ range, by varying the initial pressure during
filling; for this purpose a normal water filter pump and a
monometer will only be required.
It is also an advantage of the process and its
application in a works laboratory that commercial nitrogen may
be employed as the gas for measurement. Whom liquid nitrogen
is employed as the cooling medium, oxygen Qr argon ca~ be COn-
veniemtly employed as the gas for measurement. It is also
possible to operate the apparatus with carbon dioxide as the gas
for measurement and solid carbon dioxide as the cooling medium;
this procedure might be considered suitable for certain relative
measurements, but it would then be necessary to apply empirical
calibration factors.
V. Potential of the~EA-meter.
The apparatus is characterised by its very hiEh
reproducibility. When adsorption measurements are repeated on
the same weight of the same sample~ the maximum error of
individual readings amounts to _+ I,~. A series of test
measurements on a wide variety of substances, such as non-porous
materials of high surface area, abo~t ICO sq.m/g (e.g. carbon
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black and silica fillers) and of low surface area, I-I0 sq.m/g
(e.g. pigments) as well as on porous substances with a large
specific surface area (e.g. silica gel), by comparison with the
standard B~-~ method. The values for surface area determined with
the AREA-meter agree with those from the standard BET method
within a few percent.
A suitable choice of the'amount of sample weighed out
and, where necessary, a simple calculation correction for the
volume of substance allows the determination of specific surface
areas in the range of 0.3 to 1000 sq.m/g. It is again necessary
to point out the comparatively low investment of capital and
requirement of labour.
The adsorption measurements require a time of about
half an ho~r per sample, and as indicated above this time is not
affected by any additional allowance for the preparation of the
samples. Thus, up to 16 samples can be subjected to a deter-
mination within a working day of 8 hours.
I
The apparatus is supp_~ed by Memsrs. Strohlein ~ Co.,
Fabrik chemischer Apparate, (4),D~sseldorf I.
Literature: (I) R.Haul and G.Dt~mbgen: Ch~m.Ing.Techn.32, 3a_9
(1960) 2rid Communicatio~
in press •
Fi@.l: Diagram of arrangement for measurement.
Vergleichsgef~ss = Cdmparison vessel
~dsorptlonsgef~ss mlt Probe = Adsorption vessel with sample
~oerdruckveutil = Excess pressure relief valve
I!
Stromungemesser = Flow meter
B~u~el-Trockenrohr = Blue gel drying tube
K~itebad= Cooling medium
(please copy figures from German text)
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APPE IX
Patent Specifications.
5.4 Patent Specifications.
5.41 List of patent specifications discovered so far:
(a) General Multlfilter
USA
USA
USA
USA
USA
USA
USA
USA
USA
USA
U&~
USA
USA
USA
USA
USA
USA
USA
Patent No. Issued on
2 649 761 25 Aug 1953
2 740 409 3 Apt 1956
2 821 200 28 Jan 1958
2 858 0~_6 28 Oct 1958
2 882 970 21 Apt 1959
2 898 998 11 Aug 1959
2 902 040 1 Sept 1959
2 935 069 3 May 1960
2 944 654 12 July 1960
2 952 105 13 Sept 1960
2 953 875 27 Sept 1960
2 955 600 11 Oct 1960
2 957 285 25 Oct 1960
2 958 365 1 Nov 1960
2 963 026 6 Dec 1960
2 979 058 I! Apr 1961
2 984 245 16 May 1961
2 988 198 13 June 1961
Edwards/Filter Tips Ltd. Pall Mall
F~
K~rber/~rber & Co.
KSrber
Pollmann/Kurt "
Korber & Co.
Schur/Olin Mathies on Chemical Corp.
Schur/01in Mathleson Chemical Corp.
K~rber et al
Molins et al/Molins Machine Co.Ltd.
8ehubert/Hauni-Werke E~rber & Co. i
Schur/Olin ~thleson Chemical Corp.~
Schur/Olin Mathieson Chemical Corp.
Mollns/Molins Machine Co. Ltd.
Mollns/Molins Machine Co. Ltd.
Molins et al/Molins Machine Co.Ltd.
Molins et al/Molins Machine Co.Ltd.
Schur/Olin Mathieson Chemical Corp.
Philips Jr./American Machine &
Four~ ry C o.
Pinkham/American Machine & Foun~ ry Co.
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USA
USA
USA
USA
USA
USA
USA
USA
USA
USA
USA
USA
USA
USA
2 988 199
2 988 402
2 990 8~1
3 010 ~57
3 025 879
3 036 581
3 039 36'7,
3 039 373
3 O58 475
3 081 778
30SS 359
3 094 128
3 099 989
3 118 454
13 June 1961
13 June 1961
4 July 1961
28 Nov 1961
27 March 1962
29 May 1962
15 June 1962
19 June 1962
16 Oct 1962
19 March 1963
7 May 1963
18 June 1963
6 Aug 1963
21 Jan 1964
Pinkham/American Machine
Foundry Co.
Policansky
Mollns/Molins Machine Co.Ltd.
n:
Schubert/Kur~ Kerber & Co.
Molins/Molins Machine Co. L~d,
Dearsley/American Machine &
Foundry Co.
Ste Izer/Hauni-Werke "
Korber & Co,
Rud s z Inat/F~uni-We rke K~rber
& Co.
Gamberini/American Machine &
Foundry Co.
Dearsley/AmericanMaehine &
Four~ry Co.
Schur/Oiin Mathleson Chemical
Corp.
Dearsley/American ~aehine &
Foundry Co.
Rudszlnat et a~Hauni-Werke
KSrber & Co.
Rowlands/Molins Machine C o.Ltd •
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b) Special charcoal fil~ers
Patent No. Issued on
LIE 741 429 7 Dec 1955 Hedwig Gamble
DE 741 419 ~ - -
Portugal 40 999 29 May 1963 Liggett ~ Myers
Switzerland 189 399 - - -
Switzerland 193 329 - - -
Switzerland 531 834 30 Sept 1958 01in Mathieson Chemical
Corp.
German Regd. Design 1 721 159 26 April 1956 Dr.Muth/AC0 Filter-
gese!Ischaft
Germany 612 737 23 Sept 1933
Germany 879 823 15 June 1953
USA 2 819 720 14 Jan 1958
USA 2 968 305 17 Jan 1961
Carbo-Nori~-Umion
Otto Reinac her
Henry Burbig
J.M~zar Barnett.
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Filters Having Activated Carbon Bonded To Or Mixed With 0~her Filter
Materials :
Swiss
3~1,834
Swiss
333,897
283, 296 Granted in 1882 to Kinney, assignor to Kinney Tobacco
Companyl This patent discloses a tobacco smoke filter
having charcoal, tea, coffee, benzoic acid, arsenic of soda,
lichen or balsam incorporated in a filter made of cotton.
2,325,~86 Granted in 1943 to Frank. This patent disdloses a tobacco
smoke filter having activated charcoal, al,muina or silica
gel adhered to striws of paper, cellophane or vegetable
parchment by means of rubber latex.
2,8fil,638 Granted in 1957 to Schur, etal, assigner to the Americam
Tobacco Company. This patent discloses a filter made of
paper weighing not more than 30 g/M2 having particles of
activated charcoal of between 100 and 300 mesh secured to
the individual fibers of the paper. This patent and the
succeeding patent are very important, and give very broad
protection to paper filters incorporating activated carbon.
2,9!5,069 Granted in 1959 to Schur, assignor to 011n Mathieson
Chemical Corporation. This patent discloses and covers a
multl-element fil~er in which at least one of the filter
elements is the same as that covered by the preceding
pat ent.
2,988,088 Granted in 1961 to Schur, assignor to Olin Mathieson
Chemical Corporation. This patent relates to a cigarette
having a paper filter incorporating activated charcoal,
cuprous chloride, aluminum hydroxide or other adsorbents in
which a plurality of apertures are provided t~mough the
cigarette wrapper between the filter and tobacco sections
to cool the smoke. The first claim of the patent rather
broadly covers a cigarette of this type.
3,G46,994 Granted in 1962 to Schur, assignor to Olin Mathieson
Chemical Corporation. This patent discloses an improvement
on the preceding patent.
Both granted in 1958 to Olin Mathieson Chemical Corporation.
These patents are based upon U.S. Patent Nr. 2, 918, 069
1.126,458 Granted in 1956 to the American Tobacco Company. This
(Erench) patent is based upon U.S. Patent Nr. 2, 801, 038.
2;88i 77 Gra ted in 1959 to G.P. Tomoy, assignor to
Kodak. This patent rather broadly covers a tobacco
smoke filter made of filaments having finely divide~
carbon powder bonded thereto.
3,043,736 Granted in 1962 to G.P. Touey, assignor bo Eastman Kodak.
This patent rather broadly covers th4method for applying
a powdered additive, such as charcoal', to filters made
of synthetic filaments by applying to tS~ filaments both
the bondin~ agent and the powdered additive.
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2,956,329 Granted in 1960 on application of G.P. Touey, assignor
to Eastman Kodak. This patent discloses a filter made
of cellulose acetate filaments having silica gel incor-
porated therein. The claims of the patent cover a method
of making tobacco smoke filters by incorworating finely
J . -
divided silicagel or absorbent materlal in a solution of
cellulose acetate, spinning the selection into the fila-
ments, forming the filaments into a tow bundle, then
crimping the tow and finallycompacting in into a filter
rod.
3, I0i, 72~ Granted in 1962 to Seligman, etal, assignor to Philip
Morris Incorporated. This patent relates to a filter made
either of synthetic filama~ts or pamer having activated
charcoal or adsorbents secured thereto b~ooly~_nyl
pyrrlldone. This bonding material is sp~ced to bond the
adsorbent particles in place without clogging the pores or
deactivating the material. The claims are limited to a
filter of this type using the above specified pending
material.
2,121:614 Granted in 19~9 to Striefling. This patent shows a cigar-
ette having a filter in the form of a porous disc, saturated
with a slurry of alumina or silica. The claim is limited
to a cigarette having a fibrous wrapper and a fibrous
porous filter both impregnated with a material of this
type.
2,77,2~!
Granted in 1956 on application of Winkler, assignor to
American Cello Corporation. This patent disclmses a
tobacco smoke filter made of polyurethane foam having
an adsorbent such as silica gel pellets incorporated
therein. One form of filter shown in the patent has two
filter elements; one made of polyurethane foam and
another made of cotton.
3,006,346 Granted in 1961 to Goldlng. This patent shows a multi-
element filter made of polyurethane or other plastic
foam in which the filter elements are secured together
by a porous adhesive having a finely divided adsorbent,
sach as activated charcoal, incorporated therein.
Other Patents of Interest Showing the Use of Adsorbents:
2,839,084 Granted in 1953 to Milton, assignor to Union Carbide Corp.
This patent discloses a smoking tobacco filter made of a
molecular sieve material such as meollte. The patent
broadly covers the use of an activated crystalline molecular
sieve in a smoking tobacco product.
3,030,421 Granted in 1962 to Kaden, assignor to Minerals a Chemlcals
Philipp Corp. This patent relates to a smoking tobacco
oreoaration having m~¢ed therewith alumina in laminar form
to perform an adsorbent filtering function. The claims cover
a preparation of this type.
2,938,S!8 Granted in 1960 to Specht, assignor to Minerals & Chemicals
Corp. This patent relates to a cigarette having mixed
the tobacco acid activated clay and hydrated
lime.
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Multi-Element Filters IncludinE Activated Carbon:
Pat en~ No.
2 V92 006
2 819 720
189 399
(Swiss)
Summary
Granted in 1957 on application to Marek et al. This is a ~ry
important patent. It discloses a cigarette filter employimg
activated carbon made by treating lignin with acid until
carbon, approximately 99% pure, is obtained. The patent dis-
closes several forms of filter using the activated carbon th~s
made. One form is a 3-element filter in the fore of two soaced
filter elements made either of "cellulose wool or paper" wl~h
the carbon interposed therebetween. The resemblance of this
filter to the LARK filter is quite apparent. The L~RK filter
would appear to differ in that the filaments are made of
cellulose acetate rather than cellulose wool or paper and the
LAB~ package states that the carbon granules are "reinforced.'
Granted in 1958 on application of Burbig. This patent
discloses a 3-element filter formed of two conventionally
spaced filter elements separated by a ring coated on its
inner surface with charcoal. The patent states that the
smoke passing between the filter element will contact the
carbon surface due to the turbulence.
Granted in 193V. This patent shows several forms of
multl-elemeut filters. 0he form of Filter has three
separate elements as follows:
(I) a cotton filter element
(2) an element containing a flavouring material,
menthol and
(3) an element made of clay or charcoal.
such as
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Activated Carbon Having Additives Adsorbed Thereon
2 739 593
2 815 760
337 200
(British)
338 006
(British)
Granted in 1956 to Eirich, assignor to R.S.Aires and
Associates. This patent discloses a filter for tobacco smoke
consisting of an ion exchange material disposed on a suit-
able carrier. The patent suggests the use of cation and
anion exchanges. Among the carriers suggestea are charcoal, :
silica and almmlna gels.
Granted in 1937 On application to Schreus, etal. This pat-
ent discloses a filter cartridge for smoking tobacco con-
sisting of an ion exchange material and activated carbon
having volatile amino compound adsorbed ~hereon.
Granted in 1930. This patent discloses for smoking tobacco
made of "cellulose" "cotton, wool" filtering paper or some
other suitable fibrous material which is carbonided with
acid and then impregnated ~ith a heavy metallic salt, such
as iron chloride. The patent states it also may be impreg-
mated with citric acid, tartaric acid, tannic acid.
This patent is important and might have a bearing on the
filter used in Montclair cigarettes. It discloses a filter
made of an adsorption material, such as highly activated
carbon or silica gel having adsorbed thereon flavoring
~aterials, such as "etherlc oils, suc~ as peppermint oil
and the like ...". The patent states that the activated
carbo~ or silica gel ~y he subjected to a preliminary
treatment with a sodium h~roxide or sodium carbonate, or
cane sugar, common salt, or tannic acid, or barbituric
acid, or ozone or substances hindering the oxidation, or
sod lure hydrosulfite.
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SUM~L~RY OF PaTERTS
Ir~,TAit~ING TO USE OF CHARCOAL OR CARBON IN FILTERS
Patents Disclosing Loose or Packed Activated Carbon Particles:
Patent No. Summary
936 088
Granted in 1909 on application of T.B.Bradford. This patent
discloses a pipe having a filter containlr~ charcoal gran-
ules in the stem thereof.
1 985 840
Granted in 1927 on application of Sadtler. This patent shows
tobacco ~moke filters in the form of pellets made of a
pressed m~xtuTe of charcoal and clay.
1 8S8 469
Granted in 1932 on application H,H.Broadway. This paten~
discloses a pipe with a filter cartridge beneath the bowl
or in the stem and packed with activated carbon granules,
2 373 296
Granted in 1945 on application of Donnelly. This patent
discloses a pipe containing a filter cartridge in the stem
or in the lower portion oft he bowl formed of activated
carbon made from tobacco.
3 632 4-45
Granted in 1962 on application of Hamon, assignor to Union
Carbide Corporation. The first column of this patent recites
that "filters have been made of ,activated charcoal'." The
patent itself relates to a different type of filter.
The following additional patents disclose the use of activated carbon
granules and are discussed in detail under the heading "Multi-Element
Filter~ l~cludin~ Activated Carbon:"
United States Patent No. 2 792 006
Swiss Patent No. 189 399
The following patents disclose the use of activated carbon granules and
are discussed in detail under the heading "Activated Carbon Having
Additives Adsorbed Therein:~
United States Patent No. 2 739 598
United States Patent No. 2 815 760
British Patent No. 338 006
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II/~ Literature references.
ID
Aktive Kohle und ihre industrielle Verwendung
G. Bailleul, K. Bratzler, W. Herbert und W. Vollmer
Ferdinand Enke Verlag, Stuttgart 1962, 4. Auflage
~m
Lehrbuch der anorganischen Chemie
H. Remy
Akademische Verlagsgesell~chaft, Leipzig 1959, 9. Auflage
~o
Praktikum der quantitativen c hemischen Analy~e
G.O. Miller
S. Hierze!-Verla~, Leipzig, 1987, 4. Auflage
4. Pittsburgh-Methoden f~r die Aktivkohle Untersuchung
Pittsburgh Chemical Company, P~.nnsylvania
5. Taschenbuch f~r Chemiker und Physiker
D'Ans - Lax.E.
Springer Verlag, Heidelberg, 1949, 2. Auf!age
6. Cigarette smoke filtration
Research & Development Establishment, 1960
7. The filtration of cigarette smoke
W.B. Fordyce, I.W. Hughes, M.G. Ivinson
Research & Development Establishment, 1960
So
Bonded granular rod -I
N.E. Willis
Engineering Report E a-l-R, 196a-, Southampton
9,
Examination of filters from Belmont, York and Tempo cigarettes
E.G. Horsewel!
Laboratory Report L 120 -R, 1964
I0. Filter and cigarette design
H.W. Naynor
Brown & Williamson, Monthly Report April 1964, Project 3600
ll. Appraisal of active carbon D.M. Carrol
Report R~D, RD 311-R, 1964, Southampton
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12. Menthola~ng Rewinder
Engineering Report E 39-F, Southampton 1964
13. Granular filter adsorbents
S.J. Green
R.I.S° 1002, Southampton 1964
14. The role of gaseous diffusion in the filtration of vapours by
solid absorbants
R,G, Hook
File Note: 0~02, 6th February, 1964
15. Effect of cigarette smoke on lateral cilia frequency
Prlvat~Information
W. George AM. Celanese , 12/63
16. The important~dlfferent way to use activated charcoal
New Philip Morris Multifilter
Intelligence Letter No.20, 1964
I~ Surgeon General's Report - Reference to "Lark" Filter
Intelligence Letter Ne. 22, 1964
18. Components of cigarette smoke with ciliary-depressant activity:
Their selective removal by filters containin~ activated c~arcoal
granules
C.J. Eensler, S.P.Battista
New. Engl. J.Med. 269 (i$65) !!61
19. Safer smokers, Wall Street Journal 9~h March 1964
Intelligence Letter 25, 1964
20. Evaluation of the Fiitrona charcoal filters, coded R-V28A~ and
DS-IOI
Intelligence Letter No. 26, lO64 (5~AIrFA~I~.)
21. TE~PO
Intelligence Letter No. ~0, 1964
22. Report Dr. Wynder - compressed charcoal and charcoal granules
Test
Intelligence 1~tter No. ~l, 1964
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23.
24.
25.
Visit and Discussion of Dr. Marais to U.ToC , 17th April 1964
Intelligence Letter No. 36, 1964
Perforated cigarette papers -Ecusta- ~!emorandum to Mr. Simpson
Intelligence Letter No. 37, 1964 (Montclair and Carlton)
Riggio and Ransom
Intelligence Letter No. 40, 1964, 21st July 1964
(Re-Intelligence Letter)
26.
Rlggio and Ransom
Intelligence Letter No. 40(6),. 1964,
(Ee-lntelligence Letter)
5th September 1964
29.
28.
Ransom bonded carbon filter - South Africa
Intelligence Letter No. 40, 1964, IGth September 1964
(Re-Inte lligence Letter~
Advice on commercial carbon filters
Intelligence Letter No. 47, 1964
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