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With the development of industry, heavy metal (HM) pollution of soil has become an increasingly serious problem. Using passivators made of industrial by-products to immobilize HMs in contaminated soil is a promising in-situ remediation technology. In this study, the electrolytic manganese slag (EMS) was modified into a passivator (named M-EMS) by ball milling, and the effects of M-EMS on adsorption of As(V) in aquatic samples and on immobilization of As(V) and other HMs in soil samples were investigated under different conditions. Results demonstrated that M-EMS had a maximum As(V) adsorption capacity of 65.3 mg/g in the aquatic samples. Adding M-EMS to the soil reduced the leaching of As (from 657.2 to 319.8 μg/L) and other HMs after 30 d of incubation, reduced the bioavailability of As(V) and improved the quality and microbial activity of the soil. The mechanism for M-EMS to immobilize As in the soil are complex reactions, ion exchange reaction with As and electrostatic adsorption. This work provides new ideas of using waste residue matrix composites for sustainable remediation of Arsenic in the aquatic environment and soil. [Display omitted] • A novel EMS/pyrite-based passivator (M-EMS) was developed. • M-EMS can passivate As and other heavy metals in soil and reduce their bioavailability. • The immobilization mechanisms include precipitation, adsorption, and ion exchange. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • A novel EMR/calcite-based passivator (C-EMR-800) was developed. • C-EMR absorbed As(V) in solution and passivated As, Pb, Cd, and Cr in soil. • Mechanisms for HMs removal include precipitation, adsorption and microbial passivation. • Solid waste reutilization and remediation of HM-contaminated soil were addressed. • The function of the microbial community is altered for soil remediation. [ABSTRACT FROM AUTHOR]