Kinetic study of photocatalytic degradation of several pharmaceuticals Assisted by SiO[2] / TiO[2] catalyst in solar bath system

ABSTRACT

The photo-catalytic degradation of five pharmaceuticals using TiO[2] modified with SiO[2], and sun light was monitored. The initial concentrations used in the solar bath system were 100 microg/L for caffeine, diclofenac, glimepiride and ibuprofen, and 25 microg/L for methotrexate. Kinetic disappearance of caffeine, diclofenac, giimepiride and ibuprofen shows pseudo- first order kinetics, while methotrexate shows a zero order kinetic degradation which was monitored using HPLC/UV at lambda, = 225 nm, F = 1ml/min and on a C8 reversed phase column. The rate constants for diclofenac [wastewater 0.3238 sec[-1], distilled water 0.4057 sec[-1], glimepiride [wastewater 0.2203 sec[-1], distilled water 0.2771 sec[-1]], ibuprofen [wastewater 0.2802 sec[-1], distilled water 0.2411 sec[-1]], caffeine [distilled water 0.416 sec[-1]] and methotrexate [distilled water 3.1407 mole L[-1] sec[-1]]. The removal efficiency for the drugs was ranged between 79% and 96%