Catalytic activity of Mn(III) porphyrin complex supported onto cross linked polymers in the green oxidation of malathion with hydrogen peroxide in aqueous solution

Abstract

Developing effective, affordable, and recoverable heterogeneous catalysts is one of the foremost challenges in modern chemistry. Mn(III) complexes of 5-(4-aminophenyl) −10, 15, and 20-triphenyl porphyrin 1 immobilized covalently on polymethyl methacrylate (PMMA) 2 and poly(methyl methacrylate –co- styrene) (PMMA/ST) 3 were synthesized, characterized, and applied for degradation of malathion with H2O2 in aqueous solution. Mn(III) porphyrin complex anchored on cross linked polymers 4 and 5 show high catalytic activity for malathion (pesticide) degradation in an aqueous solution with green oxidant H2O2. The catalytic efficacy of malathion degradation was highest with the Mn(III) porphyrin complex covalently anchored on (polymethyl methacrylate-co-styrene) 5. The optimum conditions, including the effect of pH, catalyst concentration, and H2O2 concentration on the degradation of malathion, were investigated. The reuse and stability of catalysts were examined, and the findings proposed that the Mn(III) porphyrin complex 5 has no noticeable changes in the removal efficiency up to five consecutive cycles. GC–MS analyses showed that the degraded compounds and intermediates formed from malathion degradation were non-toxic to E. coli bacteria. For the degradation of dissolved malathion pesticides in an aqueous solution, the use of Mn(III) porphyrin complex 5 in the presence of H2O2 has the potential to be advantageous.

Keywords

• Malathion. Metalloporphyrin
• Polymethyl methacrylate
• Poly(methyl methacrylate-co-styrene)
• Catalytic oxidation