Insights into the glyphosate removal efficiency by using magnetic powder activated carbon composite

In this study, co-precipitation was used to prepare Fe₃O₄ magnetic powder activated carbon (PAC) (Fe₃O4-PAC) and MnFe₂O₄ magnetic PAC (MnFe₂O₄-PAC) for the in-depth treatment of glyphosate pesticide wastewater. Magnetic adsorbent characterization results indicate that MnFe₂O₄ was successfully loaded on the activated carbon powder. Adsorption experiment results show that the maximum adsorption capacity of MnFe₂O₄-PAC for glyphosate is two to three times that of the original PAC. The adsorption of glyphosate by using magnetic PAC conforms to the Langmuir adsorption isotherm, and the adsorption kinetics is consistent with the quasi-second adsorption kinetic model. The adsorption capacity of Fe₃O₄-PAC and MnFe₂O₄-PAC showed the same trend effect with the change in pH, temperature, and adsorbent dosage. The adsorption capacity of Fe₃O₄-PAC and MnFe₂O₄-PAC for glyphosate decreased with the increase in pH and magnetic PAC and rises with temperature. Regeneration experiment results showed that the order of the regeneration method of MnFe₂O₄-PAC is: microwave combined Fenton reagent regeneration > wet microwave regeneration > microwave combined hydrogen peroxide regeneration. MnFe₂O₄-PAC after regeneration still exhibited good magnetic properties and adsorption capacity.