A novel passivator based on electrolytic manganese residues and calcite for arsenic sorption and heavy metal passivation of contaminated soil

Abstract

Arsenic-containing wastewater and arsenic-contaminated soils can cause serious environmental pollution. In this study, mixtures of electrolytic manganese residues (EMRs) and calcite were superheated to different temperatures to prepare a novel passivator for arsenic [As(V)] removal in an aqueous environment, as well as for passivating As and other heavy metals (HMs) (e.g. Cr, Cd, and Pb) in the soil. The results showed that the optimal passivator superheated at 800 °C (C-EMR-800) and had a maximum As(V) adsorption capacity of 35 mg/g in solution. The excellent adsorption performance could be modelled using a second-order kinetic model, which demonstrated that adsorption is more consistent with chemisorption. The leaching concentration of As in contaminated soil amended with C-EMR-800 was reduced from 62.81 to 5.84 μg/L within 10 d, which is lower than that of the Chinese national standard (GB/T 5085.3–2007); C-EMR-800 also showed excellent passivating effects on other HMs (Cr, Cd, and Pb). The mechanisms for As removal by C-EMR-800 are linked to chemical reactions (e.g. precipitation), adsorption, and microbial passivation. Collectively, this study demonstrates an eco-friendly “waste-to-soil remediation” strategy that can address issues related to the reutilization of solid waste and remediation of HM-contaminated soil.