Sustainable and efficient degradation of chlorpyrifos by the synergy mixed Fe–Al (ZVI@Almix) bimetallic particles: Performance and mechanism

Abstract

Chlorpyrifos (CPF) is one of the most widely used pesticides in the world, and its improper use will cause serious pollution to ecological safety and water environment. There is an urgent need for an efficient, environmental-friendly, and cost-effective removal technology. ZVI@Almix (mixed zero-valent iron and aluminum) is a potential technology for degrading CPF by combining it with ZVI (zero-valent iron), ZVAl (zero-valent aluminum) and ZVI@Alsup (supported zero-valent iron and aluminum). This technology can efficiently degrade CPF, achieving a removal rate of 93.47% and a complete mineralization rate of 62.15% at the concentration of 10 mg/L, pH of 7.0, temperature of 25 °C, and ZVI@Almix dosage of 0.30 g/L, and can effectively alleviate the interference of anions and HA in actual wastewater. The elemental evolution and solution composition of ZVI@Almix indicates that the material has an activation effect on O2 in solution. The existence of •OH and O2−• in the reaction and the degradation of CPF were confirmed by quenching experiments and electron spin resonance. In addition, Al provides electronic output for ZVI, which prolongs the life of ZVI and guarantees the sustainable degradation ability of ZVI@Almix. The detection of pollutant degradation intermediates initially proposed two degradation pathways, the cleavage of C–O–P bonds, and the substitution of S and methyl groups. DFT calculation proves that pathway Ⅰ is more favorable in the reaction process, and the toxicity assessment also shows that the product toxicity of pathway Ⅰ is slightly lower than that of pathway Ⅱ. Finally, ZVI@Almix has strong reusability, the removal rate of CPF in the fourth reuse process can still reach 80.91%, and the material recovery in the fifth time can still reach 80.46%. This study proposed a mechanism to degrade CPF using cheap bimetallic particles and confirmed its feasibility through practice and theory. These findings not only provide an efficient, green, and economical pollution control technology for the removal of organophosphorus pesticides in the wastewater but also provide new ideas for the application of ZVI-based bimetallic materials in the field of environmental governance.