Periodic Na2S addition enables in-situ FeS loading on permeable reactive barrier for sustainable removal of Cd2+/Cu2+ from acid mine drainage

作者：Junxiao Luo, Danyu Huang, Xiaolei Wang, Madinai Abulimiti, Yixuan Wang, Cheng Cheng, Dongmei Zhou · 发表于：Chemical Engineering Journal · 年份：2025 · DOI：10.1016/j.cej.2025.169954 · 被引用次数：3 · 研究领域：Mine drainage and remediation techniques、Arsenic contamination and mitigation、Metal Extraction and Bioleaching

Acid mine drainage (AMD) poses significant environmental risks due to its high concentrations of bioavailable toxic heavy metals (e.g., Cd, Cu), which migrate into agricultural systems and threaten human health through biomagnification. Current AMD remediation technologies often fail to achieve both treatment efficiency and long-term stability simultaneously. To address this challenge, a permeable reactive barrier (PRB)-based strategy was employed to attain continuous sequestration of heavy metals (e.g., Cd, Cu) via in situ FeS formation, utilizing exogenous Na 2 S supplementation and inherent Fe 2+ in AMD. In simulated AMD experiments, a single Na 2 S addition maintained effective removal of Cd 2+ and Cu 2+ for 88.8 pore volumes (PV), while periodic Na 2 S replenishment sustained PRB efficacy (89.3 ± 10.1 PV). Mechanistic studies revealed that chemical precipitation, driven by FeS dissolution (S 2− release) and subsequent formation of metal sulfides, is the primary removal pathway. When applied to real AMD (pH 3.32), the system prevented Cd 2+ and Cu 2+ breakthrough over 36.6 PV despite competing ions, whereas extreme acidity (pH 2.85) induced earlier breakthrough (8.8 PV), underscoring pH's critical influence. These findings demonstrate that periodic Na 2 S addition can enable PRBs to achieve long-term in situ removal of sulfide-precipitable heavy metals from moderately acidic AMD (pH > 3), offering a practical solution for sustainable remediation.