Electroextraction of low-concentration redox-active heavy metals with E <sup>θ</sup> < 0 V from acid mine drainage
Abstract
Electrochemical recovery of heavy metals from acid mine drainage (AMD) offers a sustainable solution to global AMD contamination, yet remains challenged by thermodynamic and kinetic barriers in reducing redox-active metals with negative standard reduction potentials (E θ < 0 V), especially at low concentrations. Here, using Cd as a model system, we demonstrate that the formation of a metastable intermediate, Cd 2 SO 4 (OH) 2 , plays a crucial role in facilitating the efficient electrochemical reduction of low-concentration Cd(II) to metallic Cd 0 in acidic solutions. A combination of experimental and theoretical analyses reveals that in situ generated OH − at the cathode, in conjunction with bulk-phase SO 4 2− , drives the formation of this metal-inorganic complex, which mediates electron transfer by overcoming redox limitations. By optimizing flow dynamics and incorporating hierarchical electrode configurations, we enhance intermediate formation and achieve 96.81% Cd recovery from real AMD, with effluent Cd concentrations below 0.5 mg L −1 . Economic analysis estimates a net-positive return of 2.32 CNY per ton of treated AMD. Life cycle assessment further shows that the electroextraction process substantially outperforms lime neutralization with respect to all major environmental indicators. This work establishes a mechanistically driven, economically viable, and environmentally superior strategy for recovering valuable metals from AMD, advancing the prospects of circular resource recovery and sustainable wastewater management.
Article Details
Journal Info
Proceedings of the National Academy of Sciences
National Academy of Sciences
Authors (14)
Ziyuan Huang
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Chunhua Feng
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Fengchang Wu
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences
Zhenqing Shi
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Yang Wang
Zhuoyu Zhang
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Rimei Huang
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Weijian Duan
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Li Tian
Yijin Lv
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Xinying Gong
State Key Laboratory of Bridge Intelligent and Green Construction, School of Environmental Science and Engineering, Southwest Jiaotong University
Zhengjun Gong
State Key Laboratory of Bridge Intelligent and Green Construction, School of Environmental Science and Engineering, Southwest Jiaotong University
Zhi Dang
Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology
Fangbai Li
Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, National-Regional Joint Engineering Research