Kinetic Study of Photocatalytic Degradation of Several Pharmaceuticals Assisted by SiO2/ TiO2 Catalyst in Solar Bath System

The photo-catalytic degradation of five pharmaceuticals using tio2 modified with sio2, and sun light was monitored. the initial concentrations used in the solar bath system were100 µg/l for caffeine, diclofenac, glimepiride and ibuprofen, and 25 µg/l for methotrexate. kinetic disappearance of caffeine, diclofenac, glimepiride and ibuprofen shows pseudo- first order kinetics, while methotrexate shows a zero order kinetic degradation which was monitored using hplc/uv at λ = 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%.