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

This research focused on degradation of carbaryl in water using TiO 2 -coated glass-fiber filter under sunlight irradiation. The coating substances were 0.3–2% w/v TiO 2 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 TiO 2 . 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 TiO 2 and 1 wt% PEG6000 with the kinetic rate constant of 0.022–0.025 min −1 . The point of zero charge of 1% w/v TiO 2 + 1% wt% PEG6000 occurred at pH 7.5, while the pH of carbaryl solution was 7.3 ± 0.3. Thus, TiO 2 was neutral, and repulsive force did not exist in this optimum coating. With the optimum TiO 2 loading of 1–2 g/L, 100% carbaryl degradation was obtained in 150 min.