Kinetics of metals adsorption in acid mine drainage treatment with blast furnace slag

This investigation employed granulated blast furnace slag as functional adsorbent to study adsorption phenomena in single and multiadsorbate systems of synthetic acid mine drainage containing Cu²⁺, Mn²⁺, Cd²⁺, Fe²⁺ and Co²⁺ ions. Batch experiments were conducted as function of initial pH, phase ratio, mixing time, slag particle diameter and Initial metal concentration. The structure of slag was studied using various materials characterization techniques. The efficiency and adsorption rates increased with decrease in particle diameter, decrease in initial metal concentration, increase in slag mass and increase in initial pH as expected. A high pH promotes adsorption possibly by precipitation and/or ion exchange processes. Interestingly, metal adsorption drastically reduced in multi adsorbates relative to single adsorbates. Pseudo second order model is most appropriate theory to satisfactorily describe experimental data. At high slag mass, coarse particle sizes and high initial concentration, film and intraparticle diffusion appear to limit adsorption based on Intraparticle model.