Methods and apparatus for the selective removal of constituents from aqueous tobacco extracts
Methods for the selective removal of specific constituents of tobacco extract include contacting an extract with a nitrosamine selective adsorption agent, a metal selective adsorption agent and/or a nitrate selective adsorption agent. Preferred characteristics of such agents are identified.
1. A method of selectively removing tobacco specific nitrosamines (TSNAs) from an aqueous tobacco extract comprising the steps of:
preparing an aqueous tobacco extract; and
contacting the extract with a TSNA selective adsorption agent comprising a copolymer of styrene and divinyl benzene, wherein the TSNA selective adsorption agent comprises resin beads and has a TSNA selectivity index of at least about 8,
wherein the copolymer of styrene and divinyl benzene contains a chelating moiety, wherein the chelating moiety is an oxygen or nitrogen-containing group.
2. The method of claim 1 further comprising the steps of concentrating the aqueous tobacco extract before contacting the extract with a TSNA selective adsorption agent.
3. The method of claim 1 wherein the TSNA selective adsorption agent has an average pore size of less than 100 Å and an internal surface area of from about 300 to about 1100 m 2 /g.
4. The method of claim 1 wherein the TSNA selective adsorption agent has an internal surface area of at least about 1000 m 2 /g and a total porosity of about 1.15 (cm 3 /g) or greater.
5. The method of claim 1 wherein the TSNA selective adsorption agent is said copolymer of styrene and divinyl benzene and is post-cross linked in a swollen state with a crush strength of greater than about 500 (g/bead).
6. The method of claim 1 wherein the TSNA selective adsorption agent has a TSNA adsorptivity index of at least 50.
7. The method of claim 1 wherein the TSNA selective adsorption agent has a TSNA adsorptivity index of about 70 or greater.
8. The method of claim 1 wherein the TSNA selective adsorption agent has a TSNA adsorptivity index of about 80 or greater and a TSNA selectivity index of at least about 10.
9. The method of claim 1 wherein the TSNA selective adsorption agent has a TSNA adsorptivity index of about 50 or greater and a TSNA selectivity index of greater than about 10.
10. The method of claim 1 wherein the extract and the TSNA selective adsorption agent are contacted using a counter-current arrangement.
11. The method of claim 1 wherein the extract and the TSNA selective adsorption agent are contacted in a contacting vessel having a ratio of length to diameter of less than about 2 to 1.
12. The method of claim 1 wherein the TSNA selective adsorption agent has a TSNA selectivity index of at least 15.3.
13. The method of claim 1 , wherein the chelating moiety is an iminodiacetic acid group, a nitrilotriacetic acid group or an ethylenediamine tetra-acetic acid group.
14. The method of claim 1 , wherein the TSNA selective adsorption agent has a cadmium adsorptivity index of at least about 60 or a cadmium selectivity index of at least 15.
15. The method of claim 1 , wherein the TSNA selective adsorption agent has a cadmium adsorptivity index of at least about 75 or a cadmium selectivity index of at least 20.
16. A method of selectively removing tobacco specific nitrosamines (TSNAs) from an aqueous tobacco extract comprising:
preparing an aqueous tobacco extract; and
contacting the extract with a TSNA selective adsorption agent comprising a macrorecticular copolymer of styrene and divinyl benzene, wherein the TSNA selective comprises resin beads having a crush strength of greater than about 500 g/bead and a particle size from about 20-50 mesh, and has a TSNA selectivity index of at least about 8,
wherein the copolymer of styrene and divinyl benzene comprises an anionic copolymer of styrene and divinyl benzene, or a copolymer of styrene and divinyl benzene containing a chelating moiety, wherein the chelating moiety is an oxygen or nitrogen-containing group.
17. The method of claim 16 wherein the copolymer of styrene and divinyl benzene comprises a macroreticular copolymer of styrene and divinyl benzene.
18. The method of claim 16 wherein the copolymer of styrene and divinyl benzene comprises the anionic copolymer of styrene and divinyl benzene.
19. The method of claim 18 wherein the anionic copolymer of styrene and divinyl benzene contains a tertiary or quaternary amine or quaternary ammonium functional group.
20. The method of claim 16 , wherein the chelating moiety is an iminodiacetic acid group, a nitrilotriacetic acid group or an ethylenediamine tetra-acetic acid group.
21. A method of selectively removing tobacco specific nitrosamines (TSNAs) from an aqueous tobacco extract comprising the steps of:
preparing an aqueous tobacco extract; and
contacting the extract with a TSNA selective adsorption agent comprising an acrylic resin and/or a macroreticular copolymer of styrene and divinyl benzene, wherein the TSNA selective adsorption agent comprises resin beads and has a TSNA selectivity index of at least about 8,
wherein the macroreticular copolymer of styrene and divinyl benzene comprises an anionic copolymer of styrene and divinyl benzene, or a copolymer of styrene and divinyl benzene containing a chelating moiety, wherein the chelating moiety is an oxygen or nitrogen-containing group.
22. The method of claim 21 , wherein the chelating moiety is an iminodiacetic acid group, a nitrilotriacetic acid group or an ethylenediamine tetra-acetic acid group.
23. A method of selectively removing tobacco specific nitrosamines (TSNAs) from an aqueous tobacco extract comprising the steps of:
preparing an aqueous tobacco extract; and
contacting the extract with a TSNA selective adsorption agent comprising an anionic copolymer of styrene and divinyl benzene, wherein the TSNA selective adsorption agent comprises resin beads and has a TSNA selectivity index of at least about 8.
24. The method of claim 23 wherein the anionic copolymer of styrene and divinyl benzene contains a tertiary or quaternary amine or quaternary ammonium functional group.