Study on the removal effectiveness of SO₄²⁻, Mn²⁺ and Sr²⁺ from acid mine drainage using dual adsorbents

Aiming at the challenge of deep purification for SO₄²⁻ and heavy metal ions in acid mine drainage (AMD) from a typical polymetallic mining area in Lanping, Yunnan, a synergistic treatment system was developed based on an aminated modified peat bio-adsorbent (pH = 6) and a brucite-based industrial adsorbent. By constructing a two-stage adsorption process, sedimentation kinetic analysis, adsorption binding energy characterization, and process parameter optimization were systematically conducted, with a focus on exploring the synergistic removal mechanism of complex pollutants. Optimization parameters indicate that with a peat bio-adsorbent dosage of 15 g/L and a brucite-based adsorbent dosage of 25 g/L, combined with a two-stage contact reaction (40 min for the first stage and 60 min for the second stage), the purification efficiency is significantly enhanced: the SO₄²⁻ concentration decreased from an initial 1250 mg/L to 32 mg/L, Mn²⁺ from 8.7 mg/L to 0.08 mg/L, and Sr²⁺ from 5.4 mg/L to 0.12 mg/L. The treatment performance exceeds the limit requirement of Mn²⁺ ≤ 0.1 mg/L stipulated in the Water Quality Standard for Fisheries (GB 11607—89) and simultaneously meets the control indicators for Total Dissolved Solids (TDS). Mechanism studies demonstrate that the aminated peat preferentially captures sulfate ions through coordination groups, while the brucite adsorbent exhibits specific adsorption capacity for divalent metal ions due to its layered hydroxyl structure. This process innovatively achieves the cascade removal of multiple pollutants, providing a reliable technical path for the industrial treatment of acid mine drainage with complex components.