Reduction of Zn(II) ions in Acid Mine Drainage by Adsorption Using Adsorbent Prepared from Bone Coal

Abstract

This study proposed a method to reduce Zn(II) ions concentration in the acid mine drainage using a novel activated bone coal. Bone coal was activated using NaOH solution with varied concentration. The effect of independent variables such as adsorption time, activator NaOH concentration and initial concentration of Zn(II) ions on adsorption capacity of activated bone coal (A-BC) was investigated. Metal content analysis using AAS (Atomic Absorption Spectroscopy), functional group analysis using Fourier Transformation Infrared Spectroscopy (FTIR) and morphological analysis using Scanning Electron Microscopy (SEM) were conducted. The Zn(II) ions adsorption onto the A-BC had excellent fitting with correlation coefficient (R2 = 0.86) to the pseudo second-order adsorption kinetic. It followed Langmuir isotherm with R2 being 0.89. Optimum condition of A-BC and Zn(II) ions solution system was obtained at 27°C consisted of 1 g of adsorbent with 0.4 M NaOH activator in 100 mL Zn(II) ions solution at pH 4.5 stirred at 150-rpm, and Zn(II) ions adsorption capacity of activated bone coal was 11.223 mg/g.