Electroextraction of low-concentration redox-active heavy metals with Eθ < 0 V from acid mine drainage

• 成果类型: Article
• 署名作者: Huang, Ziyuan; Feng, Chunhua; Wu, Fengchang; Shi, Zhenqing; Wang, Yang; Zhang, Zhuoyu; Huang, Rimei; Duan, Weijian; Tian, Li; Lv, Yijin; Gong, Xinying; Gong, Zhengjun; Dang, Zhi; Li, Fangbai
• 署名单位: South China University of Technology; Chinese Research Academy of Environmental Sciences; Southwest Jiaotong University; Guangdong Academy of Sciences; Institute of Eco-environmental & Soil Sciences, Guangdong Academy of Sciences
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2519564122
• 发表日期: 2025-12-23
• 页码: e2519564122
• 关键词: electrochemical metal recovery; redox-active metals; metastable intermediate; acid mine drainage; resource sustainability; RECOVERY; cadmium; remediation; CDS; spectroscopy; EXAFS

摘要

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-theta < 0 V), especially at low concentrations. Here, using Cd as a model system, we demonstrate that the formation of a metastable intermediate, Cd2SO4(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 SO42-, 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.