Visible light-driven photoactive L-Methionine (CNS tripledoped)-TiO2/ZnO nanocomposite aiming for highly efficient photodegradation of xenobiotic compounds in wastewater

Abstract

Inspired by the most promising green technology for xenobiotics degradation, this work proposes novel visible-light-responsive L-Methionine (CNS tripledoped)-TiO2/ZnO photocatalysts successfully synthesized by sol-gel technique with various loadings of L-Methionine and different mass ratios of TiO2/ZnO. Subsequently, their application for photodegradation of direct red 16 (DR16) and biologically treated palm oil mill effluent (POME) were investigated. The prepared nanocomposites were thoroughly characterized to assess their morphological, optical, and structural properties. The effects of pollutant concentration, photocatalyst loading, irradiation time, and initial pH on the photodegradation process of DR16 and biologically treated POME were investigated using response surface methodology (RSM). The obtained RSM results showed that DR16 was completely removed at pH of 4, 15 mg/L of DR16, and 1 g/L of photocatalyst after 60 min. The complete degradation of biologically treated POME was obtained at original pH, 300 mg/L of COD concentration, 2 g/L of photocatalyst, and irradiation time of 3 h.