Adsorption of Iron and Manganese Ions from Mine Acid Water Using Manganese Green Sand in Batch Process

Fe and Mn metal ions in acid mine drainage can contaminate water bodies and soil, endangering human health. In this study, the adsorption of Fe and Mn in acid mine drainage was carried out using manganese greensand. This study aimed to obtain 1) the adsorption model of Fe and Mn isotherms using manganese greensand and 2) the surface morphology of manganese greensand before and after the adsorption process. This study used laboratory-scale experimental methods with variable concentrations of Fe (325, 400, 475, 550, 625 mg/L) and Mn (432, 507, 582, 657, 732 mg/L). The Freundlich and Langmuir adsorption isotherm models were used to determine the adsorption capacity of Fe and Mn by manganese greensand. Test for Fe and Mn content using the AAS method and test the surface morphology and content of manganese greensand using SEM-EDX. The results showed that: (1) the Freundlich equation test yielded for Fe: in a constant R 2 of 0.9862, n = 0.6912, KB = 0.2180 mg/g, while the Langmuir equation test yielded in a constant R 2 of 0.8836, b = 0.0051 L/mg, q m = 169.4915 mg/g; the Freundlich equation test yielded for Mn: in a constant R 2 of 0.9923, n = 0.8651, KB = 1.0445 mg/g, while the Langmuir equation test yielded in a constant R 2 of 0.6615, b = 0.0010 L/mg, q m = 500 mg/g; (2) The surface morphology of manganese greensand before contact with acid mine drainage contains needle-shaped particles of uniform size with a hexagonal structure, whereas, after contact with acid mine drainage, the particles are clumped like cotton and form needles with varying sizes.