Acid mine drainage pollution remediation using hybrid chelating ion-exchange/HZrO2 nanocomposite adsorbents

Abstract

Environmental pollution due to acid mine drainage (AMD) is a worldwide concern because of its high content of toxic metals and acidity. The toxic metal species present in AMD tends to affect negatively the whole ecological system where it is discharged, and this requires an elective solution to remedy the environment. In this study, hydrated ZrO2 nanoparticles (HZO) were irreversibly dispersed within chelating ion-exchange resins using the precipitation method, resulting in HZO-260, HZO-207, HZO-214, HZO-4195 and HZO-900 organic/inorganic nanosorbents which were used for the removal of metals from AMD. The synthesized nanosorbents were characterized using SEM–EDS, FTIR and XRD. The effect of time, adsorbent dosage and pH on Al(III) adsorption was investigated using the batch technique. The SEM–EDS confirmed the incorporation of HZO within all the parent resins, while XRD showed that the hybrid materials were amorphous. The adsorption of Al(III) occurred through physisorption and was favourable only onto HZO-260 as revealed by the data modelling. Metal levels were determined using the ICP-OES technique. The HZO-260 removed 100% Al(III) in acidic conditions and was successfully regenerated for reuse using a NaCl–NaOH binary solution (pH > 12). HZO-260 removed selected metals (Al, Cr, Mn, Fe, Ni, Co, Cu, Zn, Pb and Cd) from environmental AMD. Therefore, HZO-260 has a promising potential as an adsorbent for AMD remediation.