NaOH-activated persulfate-assisted mechanochemical mechanism and removal of lindane from contaminated soil

Abstract Mechanochemical (MC) treatment combined with activated persulfate (PS) oxidation has been developed as an advanced oxidation process for the degradation of organic pollutants. Efforts toward the degradation of lindane, which is a widely used organochlorine pesticide, has attracted considerable attention. For the first time, this study investigated PS-assisted MC degradation of lindane in contaminated soil, and the degradation mechanism was identified. The results indicated that Fe was not suitable for the activation of PS for the treatment of contaminated soil, and NaOH performed better than CaO to assist PS in the mineralization of organic chemicals. With PS–NaOH as the reaction additive, lindane in soil can be completely destroyed after grinding for 4 h. Under optimum reaction conditions with mass ratios of PS:NaOH:lindane = 0.35:0.15:5, degradation was completed within 2 h and mineralization was completed within 4 h. Electron spin resonance tests confirmed the generation of ˙OH and SO4−˙, providing evidence that MC treatment with PS activated by NaOH could efficiently degrade lindane in contaminated soil. Finally, the degradation mechanism of lindane in contaminated soil by the NaOH–PS–MC treatment system was identified, and initiation pathways were proposed.