Adsorptive removal of iron and manganese from acid mine drainage by low-cost materials

This study investigated the effectiveness of a composite low-cost adsorbent, comprising coconut shell-based activated carbon, zeolite, and claystone, in removing iron (Fe) and manganese (Mn) from acid mine drainage (AMD) generated by coal mining activities. Batch adsorption experiments were conducted at laboratory scale to evaluate the influence of contact time and adsorbent dosage. The adsorbents were immersed in AMD samples with an initial pH of ۲.۶ and stirred under controlled conditions. The removal efficiencies were measured over time, and kinetic modeling was applied to assess the adsorption mechanism. The composite adsorbent successfully increased the AMD pH from ۲.۶ to ۶.۳ and achieved a ۵۸.۷۳% improvement within the first ۵ minutes. Iron concentration was reduced from ۱۳.۰۰۶ ppm to ۰.۰۲۱ ppm with ۲.۵ g of adsorbent in ۱۵ minutes, corresponding to a ۹۹.۸۴% removal efficiency. Manganese removal was less consistent, achieving a maximum reduction of ۵۳.۴۲% under the same conditions. Adsorption capacities for Fe and Mn were ۱.۲۹۹ mg/g and ۱.۴۸۷ mg/g, respectively. Kinetic analysis indicated that Fe removal followed a pseudo-second-order model, suggesting chemisorption, while Mn removal exhibited a slower, less predictable behavior. The results highlighted the composite's strong potential as a rapid and environmentally friendly treatment option for AMD, particularly for effective iron removal. The adsorbents demonstrated significant efficiency in Mn removal under the tested conditions, although with less consistency than Fe. This approach offers a sustainable solution using locally available materials, contributing to improved water quality management in mining-affected areas.

کلیدواژه ها:

Acid mine drainage ، Adsorption ، composite adsorbent ، Fe ، Mn