Insight into the Catalytic Performance of a Zinc-Pillared Curcumin/Bentonite Composite for Enhanced Oxidation of Ibuprofen Residuals into Environmental Products: The Pathway and Toxicity

Abstract

Environmental organo bentonite synthesis using curcumin-derived chemicals is used as catalyst support for zinc with a Zn-pillaring structure (Zn@CU/BEN). The obtained composite was assessed as an affordable, highly effective, and multifunctional photocatalyst for enhanced oxidation of ibuprofen (IBU) residuals in water supplies. The Zn@CU/BEN composite (0.4 g/L) displayed significant catalytic activities, resulting in the complete oxidation of IBU (25 mg/L) after 80 min. Then, the complete mineralization based on the full elimination of TOC content was recognized after 160 min, with significant indications about the formed intermediates. The identified intermediates, together with the identification of hydroxyl radicals as the essential oxidizing agent, declared an oxidation pathway of IBU over Zn@CU/BEN that involved three steps: hydroxylation, decarboxylation/demethylation, and ring-opening processes. The toxic properties of raw pollutants as well as the oxidizing product at different durations were assessed based on the cell viability results of kidney (HEK293T) and liver (HepG2) cell lines. The partially oxidized sample in the initial duration displayed a higher toxicity impact than the raw IBU. However, the treated sample after 160 min reflected high biosafety and non-toxic properties (cell viability > 97%). The synergetic impact of bentonite and bentonite organo-modified by curcumin extract reflects enhancements in the adsorption as well as the oxidation performance of pillared zinc as a catalyst.