Mechanisms of Cu 2+ Immobilization Using Carbonyl Iron Powder–Biochar Composites for Remediating Acidic Soils from Copper Sulfide Mining Areas

Shuting Wang, Jinchun Xue (), Min He (), Xiaojuan Wang and Hui Qi
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Shuting Wang: School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang 330013, China
Jinchun Xue: School of Software Engineering, Jiangxi University of Science and Technology, Nanchang 330013, China
Min He: School of Software Engineering, Jiangxi University of Science and Technology, Nanchang 330013, China
Xiaojuan Wang: School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang 330013, China
Hui Qi: School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology, Nanchang 330013, China

Sustainability, 2025, vol. 17, issue 10, 1-25

Abstract: Soil heavy metal contamination poses critical challenges to ecological sustainability in mining regions, particularly in acidic soils from copper sulfide mines. This study developed a sustainable remediation strategy using a carbonyl iron powder–biochar composite (CIP@BC) derived from agricultural waste (rice husk) and industrial byproducts. The composite was synthesized through an energy-efficient mechanical grinding method at a 10:1 mass ratio of biochar to carbonyl iron powder, aligning with circular economy principles. Material characterization revealed CIP particles uniformly embedded within biochar’s porous structure, synergistically enhancing surface functionality and redox activity. CIP@BC demonstrated exceptional Cu 2+ immobilization capacity (910.5 mg·g −1 ), achieved through chemisorption and monolayer adsorption mechanisms. Notably, the remediation process concurrently improved key soil health parameters. Soil incubation trials demonstrated that 6% CIP@BC application elevated soil pH from 4.27 to 6.19, reduced total Cu content by 29.43%, and decreased DTPA-extractable Cu by 67.26%. This treatment effectively transformed Cu speciation from bioavailable to residual fractions. Concurrent improvements in electrical conductivity (EC), cation exchange capacity (CEC), soil organic matter (OM), and soil water content (SWC) collectively highlighted the composite’s multifunctional remediation potential. This study bridges environmental remediation with sustainable land management through an innovative waste-to-resource approach that remediates acidic mine soils. The dual functionality of CIP@BC in contaminant immobilization and soil quality restoration provides a scalable solution.

Keywords: heavy metal immobilization; mine ecological restoration; acid soil reclamation; carboxyl iron powder–biochar composite (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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