The role of clinoptilolite nanosheets in catalytic ozonation process: Insights into the degradation mechanism, kinetics and the toxicity

Degradation of nalidixic acid (NA) was investigated through heterogeneous catalytic ozonation process using natural clinoptilolite nanosheets (NCNs). Diverse analysis were carried out to evaluate the physical and chemical characteristics of NCNs. The kinetics, mechanism and the main oxidant species generated during the reaction were thoroughly studied. The kinetic of the degradation process was properly fitted to the pseudo-first order equation. The influence of various scavenger compounds such as t-butanol, bicarbonate, p-benzoquinone, EDTA and NaF on reactive oxidizing species (ROSs) was studied. The obtained results showed that not only hydroxyl and superoxide radicals, but adsorption phenomenon and the catalyst active sites were also responsible for effective degradation of NA. The main intermediates generated in the degradation of NA were recognized by GC-MS technique. The toxicity of NA and the by-products, generated during the catalytic ozonation process were assessed on a species of duckweed, Spirodela polyrhiza (S. polyrhiza). The results confirmed a significant decrease in toxicity of the NA effluent under the degradation process. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.