Study on the remediation of Zn‐, Pb‐, and Cd‐contaminated soil by potassium pyrosulfate leaching: Effectiveness, conditions, and evaluation via ryegrass growth

Abstract Chemical washing is a promising technology for remediating heavy metal‐contaminated soils, which ensures reasonableness, efficiency, and cost‐effectiveness on the simultaneous elimination of various elements. This study aimed to evaluate Potassium pyrosulfate (K 2 S 2 O 7 ) as an innovative eluent for the simultaneous removal of Zn, Cd, and Pb. By investigating the washing efficiencies under different concentrations, times, and solid–liquid ratio conditions, the optimal washing parameters are determined. The treated soil is subjected to comprehensive analysis using XRD, FT‐IR, SEM‐EDS, and XPS to evaluate changes in its mineralogy, chemistry, and morphology. Through ryegrass plant growth experiment and monitoring of soil enzyme activity data over 15–75 days, the short‐term phytotoxicity of the remediated soil and its long‐term impact on soil properties are assessed. Under optimal conditions (0.1 mol/L K 2 S 2 O 7 , 360 min, S/L = 1:20 g/mL, 120 rpm), remarkable removal efficiencies of 92.46% for Zn, 84.67% for Cd, and 56.28% for Pb were achieved. This study demonstrates that K 2 S 2 O 7 is a viable, multi‐functional eluent for the remediation of multi‐metal contaminated soil. It effectively removes heavy metals, improves soil fertility with potassium supplementation, and does not cause structural degradation, presenting a promising solution for field‐scale application. Therefore, chemical washing by K 2 S 2 O 7 for the remediation of multiple heavy metal‐contaminated soil is a viable industrial‐scale solution.