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A process for making modified activated carbon from an activated carbon substrate. The activated carbon substrate is pre-treated to make an exposed surface of the activated carbon substrate substantially hydrophilic, coated with a carbon precursor to form a coated activated carbon, and then the coat

A process for making modified activated carbon from an activated carbon substrate. The activated carbon substrate is pre-treated to make an exposed surface of the activated carbon substrate substantially hydrophilic, coated with a carbon precursor to form a coated activated carbon, and then the coated activated carbon substrate is heated to carbonize the carbon precursor to from the modified activated carbon. The modified activated carbon comprises a uniform porous carbon membrane formed on an exposed surface of the activated carbon substrate. The carbon membrane can mediate the absorption and/or adsorption kinetics of the activated carbon substrate. The modified activated carbon, which can be incorporated into one or more components of a cigarette, can selectively remove gaseous constituents from mainstream smoke during smoking.

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1. A process for making modified activated carbon, said modified activated carbon comprising an activated carbon substrate and a uniform porous carbon membrane formed on an exposed surface of the activated carbon substrate, the process comprising: (i) providing an activated carbon substrate;(ii) pre

1. A process for making modified activated carbon, said modified activated carbon comprising an activated carbon substrate and a uniform porous carbon membrane formed on an exposed surface of the activated carbon substrate, the process comprising: (i) providing an activated carbon substrate;(ii) pre-treating the activated carbon substrate to make an exposed surface of the activated carbon substrate substantially hydrophilic;(iii) coating the pre-treated activated carbon substrate with a carbon precursor to form a coated activated carbon substrate; and(iv) heating the coated activated carbon substrate in an oxidizing atmosphere and at a temperature of from about 150° C. to 400° C. to carbonize the carbon precursor to form the uniform porous carbon membrane,wherein the carbon membrane has an average thickness having a standard deviation that is less than about 25% of the average thickness and the carbon membrane has an average thickness ranging from about 1 micron to 0.1 mm. 2. The process of claim 1, wherein the activated carbon substrate is a substrate selected from the group consisting of beads, granules and fibers and/or the activated carbon substrate has an average particle size of from about 100 microns to 5 mm or from about 200 microns to 2 mm. 3. The process of claim 1, wherein the activated carbon substrate has an average pore size of less than about 500 Angstroms, the activated carbon substrate has a pore size distribution comprising greater than about 20% micropores and fewer than about 80% mesopores and/or the activated carbon substrate has an average surface area of greater than 50 m2/g or greater than 200 m2/g. 4. The process of claim 1, wherein the pre-treating comprises spraying the activated carbon substrate with and/or immersing the activated carbon substrate in a solution comprising from about 1 to 99 wt. % surfactant wherein the surfactant optionally comprises cetyltrimethylammonium chloride and/or the solution optionally comprises from about 1 to 25 wt. % surfactant. 5. The process according to claim 1, further comprising drying the activated carbon substrate at a temperature of less than about 120° C. prior to coating and/or further comprising drying the coated activated carbon substrate at a temperature of less than about 120° C. prior to carbonizing. 6. The process according to claim 1, wherein the coating comprises spraying the activated carbon substrate with and/or immersing the activated carbon substrate in a solution comprising the carbon precursor, the solution optionally comprising from about 1 to 99 wt. % carbon precursor or from about 20 to 60 wt. % carbon precursor. 7. The process according to claim 1, wherein the carbon precursor is selected from the group consisting of saccharides, disaccharides, polysaccharides, fructose and ethyl cellulose. 8. The process of claim 1, wherein the coating is carried out to provide from about 1 to 150% by weight of the carbon precursor in and/or on the activated carbon substrate or the coating is carried out to provide from about 20 to 80% by weight of the carbon precursor in and/or on the activated carbon substrate. 9. The process of claim 1, wherein the coating is carried out without heating the activated carbon substrate or the coated activated carbon substrate is carbonized at a temperature of from about 150° C. to 400° C. to form the carbon membrane. 10. The process of claim 1, wherein the modified activated carbon has an average surface pore size that is at least 10% less than or at least 25% less than the average surface pore size of the activated carbon substrate and/or the modified activated carbon has an average surface area of at least 50 m2/g or at least 200 m2/g. 11. The process of claim 1, wherein the carbon membrane covers at least 80% of the exposed surface of the activated carbon substrate. 12. The process of claim 1, wherein the modified activated carbon has an average surface pore size that is at least 10% less than the average surface pore size of the activated carbon substrate. 13. The process of claim 1, wherein the pre-treating comprises spraying the activated carbon substrate with a solution comprising from about 1 to 25 wt. % cetyltrimethylammonium chloride. 14. The process according to claim 1, further comprising drying the coated activated carbon substrate at a temperature of less than about 120° C. prior to carbonizing. 15. The process according to claim 1, wherein the coating comprises spraying the activated carbon substrate with a solution comprising the carbon precursor, the solution comprising about 20 to 60 wt. % carbon precursor. 16. The process according to claim 1, wherein the pre-treating consists of treating the activated carbon substrate with a solution or emulsion consisting of a surfactant and a solvent.