Synergy between Fenton reagent and solid waste-based solidifying agents during the solidification/stabilization of lead(II) and arsenic(III) contaminated soils.

Due to the different physicochemical properties of lead (Pb) and arsenic (As), coupled remediation processes of contaminated soils containing Pb and As have always been a technical challenge. In the present study, a novel solidifying agent (BER) was synthesized using alkaline oxygen furnace slag (BOFS), modified electrolytic manganese residue (EMR) and red mud (RM). The solidifying agent was synergistically used with Fenton reagent for solidifying/stabilizing Pb- and As-contaminated soils. The experimental results indicated that the low stability of Ca-As(III) complexes, which serve as the primary fixation mechanism for As in BER-solidified soil, led to inadequate stabilization of As by BER. As a result, the leaching concentration of As in the BER-solidified soil reached 2.61 mg/L. The incorporation of Fenton reagent had minimal effect on the strength of the solidified soil and Pb stabilization, but it substantially improved As stabilization. The immobilization efficiency of the BER-Fenton for lead and arsenic reached 99% and 98%, respectively. The strength of solidified/stabilized soil using BER-Fenton was close to that of cement-based solidified/stabilized soil. Microscopic analysis showed that the incorporation of Fenton reagent increased the content of goethite and ettringite, which effectively filled the soil pores and enhanced the adsorption of Pb and As. The use of BER and Fenton reagent increased the content of As(V) to 88%, which promoted the complexation between As and Fe(III)/Mn(IV). This study provides a novel method for efficient remediation of heavy metal-contaminated sites, as well as a useful reference for ensuring the safe reuse of hazardous wastes.