Controllable synthesis of N-vinylimidazole-modified hyper-cross-linked resins and their efficient adsorption of p-nitrophenol and o-nitrophenol.

A series of N-vinylimidazole-modified hyper-cross-linked resins was prepared, and the porosity and polarity of these resins were effectively tuned by altering the feeding amount of N-vinylimidazole in the polymerization. The results indicated that the Brunauer-Emmett-Teller surface area sharply decreased from 1258 to 74m/g, the micropore area lowered from 494 to 0m/g, the total pore volume greatly decreased from 1.14 to 0.49cm/g, and the micropore volume rapidly reduced from 0.39 to 0cm/g with increasing the feeding amount of N-vinylimidazole from 10% to 50% (mol/mol), and the pore size distribution showed a large population of pores in the microporous region extending to a higher part of mesoporous region. Meanwhile, the polarity of the resins obviously improved with increasing the feeding amount of N-vinylimidazole. The nitrogen content increased from 0.579% to 7.68% (w/w), and the contact angle decreased from 89.0° to 31.0°. The adsorption experiments indicated that these resins had large equilibrium capacities to p-nitrophenol and o-nitrophenol from aqueous solution, and they could be completely regenerated by a mixed solvent containing 80% (v/v) of ethanol and 0.01mol/L of NaOH aqueous solution.