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Sonocatalytic removal of ampicillin by Zn(OH)F: Effect of operating parameters, toxicological evaluation and by-products identification

Mirzaei, Amir, Haghighat, Fariborz, Chen, Zhi, Yerushalmi, Laleh
Journal of hazardous materials 2019 v.375 pp. 86-95
ampicillin, byproducts, chemical oxygen demand, mineralization, sonocatalysis, tandem mass spectrometry, toxicity, toxicity testing, zinc, zinc oxide
Zinc hydroxyfluoride (Zn(OH)F) sonocatalyst was prepared by using solvothermal method and was characterized by using various techniques. The sonocatalytic degradation of ampicillin (AMP) in water by sonolysis, bare ZnO and Zn(OH)F was investigated in terms of AMP removal, mineralization, detoxification of solution, and remaining by-products at the end of process. Results revealed that the sonocatalytic performance of Zn(OH)F was significantly greater than that of bare ZnO. Under the optimum conditions, the removal percentage of AMP by Zn(OH)F was ∼97% after 90 min reaction, while 51% and 36% COD and TOC removal were achieved after 120 min reaction, respectively. The study of Zn(OH)F stability revealed that the degradation efficiency of AMP was reduced by only 5% even after being reused for four experiments. The toxicity of initial and treated solutions was assessed by using agar-well diffusion method and ToxTrak™ toxicity assay, and the results indicated a substantial reduction in the toxicity of solution after the treatment. The formation of some by-products during the sonolysis and sonocatalysis was evaluated by LC-HR-MS/MS method. LC-HR-MS/MS results showed that the concentration of most by-products, which were produced after 90 min treatment by US/Zn(OH)F process, was considerably lower than those obtained during sonolysis and US/ZnO processes.