Solar photocatalytic degradation of carbaryl in water using TiO2-coated filters with different binders and effect of the operating conditions.

Abstract

This research focused on degradation of carbaryl in water using TiO2-coated glass-fiber filter under sunlight irradiation. The coating substances were 0.3-2% w/v TiO2 mixed with 5 different binders, DURAMAX B1000, PEG molecular weight of 1000, 2000, 4000, and 6000, in a concentration of 0.3-2 wt% of TiO2. Optimum concentration of coating substance was investigated for the best degradation efficiency in terms of reaction kinetic rates. Sorption of carbaryl and zeta potential of coating substance were also studied.The results revealed that carbaryl sorptions on the coated filters were 2% or less. The optimum concentration of coating substance was 1% w/v TiO2 and 1 wt% PEG6000 with the kinetic rate constant of 0.022-0.025min-1. The point of zero charge of 1% w/v TiO2 + 1% wt% PEG6000 occurred at pH 7.5, while the pH of carbaryl solution was 7.3 ± 0.3. Thus, TiO2 was neutral, and repulsive force did not exist in this optimum coating. With the optimum TiO2 loading of 1-2g/L, 100% carbaryl degradation was obtained in 150min.