A Comparison of Activated Carbons of Differing Physical Characteristics in Cigarette Filters

1. A Comparison of Activated Carbons of Differing Physical Characteristics in Cigarette Filters A D McCormack & M J Taylor Filtrona Technology Centre Jarrow, United Kingdom 25th September 2007

3. Materials Tested Coconut-based carbons Two commercially available carbons - �medium� and �high� activities One �ultra-low� activity carbon prepared by a university carbon laboratory Coal-based carbons Three commercially available carbons - �low�, �medium� and �high� activities All samples were selected to the same particle size range (30/70 US mesh)

4. Carbons Tested - Physical Analysis

5. Carbons Tested - Porosimetry Data

6. Filter Designs and Assembly Hand-assembled triple granular filters, ensuring that 100% granular fill of the cavity was obtained Two fixed weights - 60 mg and 100 mg carbon Two fixed cavity volumes - 3mm and 5mm length Carbons dried prior to filter assembly

7. Test Filter

8. Test Cigarettes

9. Analytical Procedures Methodology Cigarette tested around 3-weeks after assembly Standard ISO Smoking - Vapour phase collected in gas sampling bag for analysis by GC-MS Compounds Measured Aldehydes � Acetaldehyde, Acrolein, Propionaldehyde, Butyraldehyde and Crotonaldehyde Ketones - Acetone and Methyl Ethyl Ketone Hydrocarbons � 1,3 Butadiene, Isoprene, Benzene and Toluene Cyanides � Acrylonitrile

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

11. Retention of Aldehydes - 60mg Weight

12. Retention of Aldehydes - 100mg Weight

13. Retention of Aldehydes - 3mm Cavity

14. Retention of Aldehydes - 5mm Cavity

15. Retention of Hydrocarbons - 60mg Weight

16. Retention of Hydrocarbons - 100mg Weight

17. Retention of Hydrocarbons - 3mm Cavity

18. Retention of Hydrocarbons - 5mm Cavity

19. Retention of Ketones and Acrylonitrile - 60 mg Weight

20. Retention of Ketones and Acrylonitrile - 3mm Cavity

21. Effect of Carbon Weight and Carbon Surface Area per Tip on VP Retention

22. Conclusions - 1 As expected, the retention of all compounds in the Vapour Phase by a carbon filter increases as a function of increasing carbon weight, increasing carbon bed length and increasing carbon activity Very low activity carbon (non-commercial) gives very little Vapour Phase retention benefit Coconut and coal-based carbons of similar activity gave similar removal efficiency, with the exception of the more volatile compounds (e.g. acetaldehyde and 1,3-butadiene) for which coconut carbons gave greater retention The data is consistent with previous observations that carbon gives a significant reduction of a wide range of compounds in smoke, although there is some indication that lower activity carbons may be less selective towards certain compounds (e.g. Acrylonitrile)

23. Conclusions - 2 Within a fixed volume, higher activity carbons do provide some higher retention capability, but the performance benefits are relatively small The Vapour Phase retention of many of these filters was very high and in such cases there would be little benefit in using greater carbon quantities or higher carbon activities. It would be interesting to carry out similar experiments at lower carbon weights and for different cigarette filter types More work is required to explore the relationships between fundamental carbon properties and their effect on cigarette filter performance

24. Thank you for your attention