Photocatalytic degradation of carbaryl in aqueous TiO2 suspensions containing surfactants.

The effect of ionic and non-ionic aliphatic surfactants on the photocatalyt ic degradation of Carbaryl (1-naphtyl-N-methylcarbamate) in aqueous solutio ns containing suspended TiO2 (anatase) particles, under irradiation with si mulated AM1 solar light, was investigated. A neat inhibitory effect on the degradation rate was observed, depending on the nature of the surfactant an d on the initial pH of the solution. The decay profiles of the primary proc ess corresponded to the usual pseudo-first order kinetics for surfactant co ncentrations below the critical micellar concentration range, whereas a mor e complicate behaviour was observed in the presence of micellar aggregates. Mineralization of the pesticide to CO2, NO3- and NH4+ was evidenced also i n the presence of added amphiphiles, suggesting the feasibility of photocat alytic treatment of surfactant-containing aqueous wastes. (C) 1999 Elsevier Science Ltd. All rights reserved.