Hexadecyltrimethylammonium-activated and zinc oxide-coated nano-bentonite: A promising photocatalyst for tetracycline degradation

Abstract

In the present work, we examined the UV-photocatalytic process of tetracycline degradation using the prepared nano-bentonite activated with hexadecyltrimethylammonium and coated with zinc oxide nanoparticles (HDTMA–BEN/ZnO) as a catalyst. The catalyst was analyzed and characterized using several analytical methods, including field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) method, diffuse reflection spectroscopy (DRS), and Fourier-transform infrared (FTIR) spectroscopy. The HDTMA–BEN/ZnO catalyst exhibited good efficiency for tetracycline degradation, with complete degradation at a pH of 9, tetracycline concentration of 20 mg/L, HDTMA–BEN/ZnO dose of 0.005 g/L, and reaction time of 180 min. From the results of the tetracycline degradation study, the degradation kinetics were consistent with the pseudo-first-order (PFO) equation. Moreover, from the reusability test results, the degradation after six cycles showed a mere 9% efficiency reduction. Furthermore, the removal efficiencies of chemical oxygen demand (COD) and total organic carbon (TOC) were 77.45% and 59.11%, respectively, implying that the suggested method resulted in a high mineralization rate. In conclusion, the UV-photocatalytic process using the HDTMA–BEN/ZnO catalyst exhibited appreciable effectiveness and applicability for the treatment of antibiotic-containing wastewater released from the pharmaceutical and industrial processes.