a comparison of granular additives for use in cigarette filters

1. A Comparison of Granular Additives for Use in Cigarette Filters Dr M J Taylor Scientific Services Manager Filtrona Technology Centre

3. Granular Materials

4. Test Filter

5. Test Cigarettes

6. Calculation of Compound Retention % Retention = (Control Cigarette Yield � Test Cigarette Yield) x 100 Control Cigarette Yield

7. Materials Tested

8. Analytical Methods Standard ISO smoking for Tar (NFDPM), Nicotine and Carbon Monoxide. An aliquot of the Propanol solution used for water and Nicotine analysis used for the determination of Phenolic compounds by Liquid Chromatography Vapour phase collected in gas sampling bag for analysis by GC-MS Specially modified Cambridge Filter holder used for trapping other compounds of interest

9. Smoke Trap

10. Analytical Methods For Formaldehyde and Hydrogen Cyanide the trap is filled with silica gel and extracted with water after smoking. The aqueous extract is analysed using a continuous flow analyser with colorimetric determination For Pyridine, Quinoline and Styrene the trap is filled with XAD4 and extracted with Methanol after smoking. The extract is analysed using GC-MS using deuterated internal standards

11. Compounds Measured Carbonyls � Formaldehyde, Acetaldehyde, Acrolein, Propionaldehyde, Butyraldehyde, Crotonaldehyde, Acetone and Methyl Ethyl Ketone Hydrocarbons � 1,3 Butadiene, Isoprene, Benzene, Toluene and Styrene Cyanides � Hydrogen Cyanide and Acrylonitrile Phenolic Compounds � Phenol, o-Cresol, m-Cresol, p-Cresol, Catechol, Resorcinol and Hydroquinone Semi-Volatile Bases � Pyridine and Quinoline

12. Compound Grouping

13. Retention of Cyanides

14. Retention of Carbonyls

15. Retention of Hydrocarbons

16. Retention of Styrene and Phenol

17. Retention of Pyridine and Quinoline

18. Retention of Cresols and Di-hydroxy Phenols

19. Conclusions Carbon Carbon is an excellent material for use in cigarette filters and gives a significant reduction of a wide range of compounds in smoke Increasing the surface area of the carbon increases the level of compound reduction from smoke Carbon alone is not very selective to specific compounds as it tends to adsorb all vapour compounds available in smoke to a similar extent Carbon can be used as a support for reagents to give selectivity to toxic materials such as Hydrogen cyanide

20. Conclusions Silica Gel Silica Gel is a more selective material than carbon for the reduction of smoke components It has a better reduction of polar compounds such as aldehydes but low reductions of hydrocarbons Due to its more even pore size distribution the relationship between surface area and overall reduction is more complicated than for carbon It appears that the kinetics of smoke adsorption require large pores at the surface of the adsorbent so that high surface area small pore size Silica Gels are not necessarily better than lower surface area large pore size materials

21. Conclusions Other Materials Ion exchange resins can give relatively high reductions of a range of compounds in smoke They also exhibit selective effects to some chemicals in smoke. A wide range of materials are available with different chemical functionalities so other ion exchange resins may be available to selectively reduce other compounds in smoke Sepiolite in its current form gives the lowest efficiency for smoke removal of the materials considered here

22. Conclusions General Carbon is the best granular additive for cigarette filters for the overall reduction of vapours from cigarette smoke For the five materials studied the efficiency for smoke compound removal would be impregnated carbon > carbon > ion exchange resins > silica gel > sepiolite Further work is needed on the interaction between surface area, pore size, surface nature and the use of impregnants to develop new selective filtration media for cigarette filters

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