Separation of phthalocyanine-like substances from humic acids using a molecular imprinting method and their photochemical activity under simulated sunlight irradiation.

To elucidate the existence of phthalocyanine-like (Pc-like) substances in humic acids (HA) and their roles in photochemical transformation of organic pollutants, Pc-imprinted polymers (MIP) were synthesized successfully and employed to separate Pc-like substances from HA. The fraction bound by MIP (F(mip-b)) presented better photochemical activity for degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution irradiated by simulated sunlight. The pseudo-first-order rate constant of 2,4-D photodegradation with the presence of F(mip-b) was 2.5 times as high as that in solution containing effluent fraction (F(eff)). These results show the key role of some HA with special structures in photochemistry and are helpful for better understanding phototransformation of environmental contaminants in natural aquatic systems.