The photocatalytic destruction of cimetidine using microwave-assisted TiO2 photocatalysts hybrid system

Abstract

Microwave/Microwave discharge electrodeless lamp/Dissolved Oxygen/TiO₂ photocatalyst hybrid system was applied to evaluate the photocatalytic degradation behavior of cimetidine, one of the waste drug components. The effects of microwave intensity, pH and dissolved oxygen (DO) concentration on the reaction rate of cimetidine (CMT) degradation were experimentally evaluated. In addition, the CMT decomposition reactions were compared by the combination of unit technologies of the hybrid system. As the microwave intensity and pH of the aqueous reactant solution increased, the CMT decomposition rate increased, and the DO concentration of the aqueous reactant solution had an optimum efficiency concentration. The highest CMT degradation efficiency was obtained by microwave/microwave discharge electrodeless lamp/TiO₂ photocatalytic hybrid system at pH and DO concentration conditions (pH 10, DO 40 ppm). These results show that operation parameters and combination methods affect hydroxyl radical formation and CMT decomposition reactions on TiO₂ surfaces, and efficient CMT decomposition reactions are formed through optimized hybrid systems. CMT is mineralized to CO₂ and H₂O through chemically active species (superoxide anion radical and hydroxyl radicals) via cimetine sulfoxide, 4-methyl-5-hydroxymethylimidazole, and sulfinyl-containing N-cyano-N',N'-dimethyl-guanidine.

Keywords: Cimetidine; Dissolved oxygen; Microwave; TiO(2)photocatalyst; pH.