Enhanced photocatalytic degradation of acephate pesticide over MCM-41/Co3O4 nanocomposite synthesized from rice husk silica gel and Peach leaves

Abstract

Novel green nanocomposite from mesoporous MCM-41 and Co₃O₄ was synthesized from rice husk based silica gel and using the green extract of Peach leaves as reducing reagent. The composite was labeled as RH-MCM-41/Co₃O₄ and characterized by different techniques as green photocatalyst in the degradation of Acephate pesticide under visible light illumination. The composite showed well developed spherical MCM-41 particles decorated by nano Co₃O₄ nanoparticles with stunning surface area and low bandgap energy (1.51 eV). The composite displayed superior photocatalytic activities in the oxidation of Acephate which reflected in a complete degradation of different concentrations of it after 40 min (50 mg/L), 60 min (100 mg/L), 100 min (150 mg/L) and 140 min (200 mg/L) using 0.25 g of the composite. The complete removal of the present TOC for treatment of 100 mg/L acephate was achieved using 0.25 g after 70 min reflecting the formation of intermediate compounds during the oxidation steps. The reported intermediate compounds are CH₃C(O)NH₂, CH₃O(CH₃S)P(O)NH₂, (CH₃O)₂P(O)SCH₃, CH₃OP(O)(OH)₂, CH₃SS(O)₂CH₃, and (COOH)₂. All the formed intermediate compounds were degraded under the visible light photocatalytic activity of RH-MCM-41/Co₃O₄ into NO₃^-, SO₄^2-, PO₄^3-, and CO₂ as final products.

Keywords: Acephate pesticide; Co(3)O(4); MCM-41; Peach leaves; Photocatalyst; Rice husk.