Selective adsorption of zeolite towards nitrosamine in organic solution

Experiments were carried out to study the adsorption of four nitrosamines (N-nitrosohexamethyleneimine (NHMI), N-nitrosopyrrolidine (NPYR), N-nitrosonornicotine (NNN) and N-nirosodiphenylamine (NDPA)) by zeolites in organic solvents. It was found that zeolites of different pore structures and hierarchy exhibited different selectivity towards the nitrosamines. The behavior was generally governed by geometric matching between the adsorbate and adsorbent: zeolites with smaller pores favored the trap of smaller nitrosamines whereas mesoporous zeolites captured more bulky nitrosamines. Nevertheless the adsorption of bulky NDPA and NNN was found to take place on type A zeolite, which has a smaller pore size than the molecular diameter of the two nitrosamines. Meanwhile, the presence of other compounds with nitro group in the system appeared to interfere with the adsorption. Among the zeolites studied, CsA and KA could distinguish the bulky nitrosamines such as N-nitrosodiphenylamine (NDPA) and nitro compounds (nitrobenzene). The influence of the solvent on the adsorption was also studied.