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

[Display omitted] •The cimetidine was decomposed efficiently by the hybrid TiO2 photocatalytic system.•Increasing the microwave intensity increased the rate of CMT degradation rate.•Increasing the pH increased the rate of CMT degradation rate.•There is an optimal condition for DO concentration in the decomposition reaction of CMT.•CMT was mineralized through three kinds of reaction intermediate products. 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.