Evaluation of charcoal ash nanoparticles pollutant removal capacity from acid mine drainage rich in iron and sulfate

Acid mine drainage is globally recognized as one of the environmental pollutants, due to its highly toxic metals and sulfate concentration. In this study, the effect of metal and sulfate removal capacity of Namibian hardwood charcoal ash from acid mine drainage was investigated. The experimental results have shown that charcoal ash has dual pollutant removal capacity via adsorption and precipitation. For adsorption, insoluble charcoal ash minerals and precipitates produced during treatment are responsible. While soluble metal oxides and sparingly soluble carbonates are essential for neutralization of the acid mine drainage and metal hydroxide precipitation. Based on the treated acid mine drainage analysis results, almost complete and partial removal of toxic metals and sulfate from acid mine drainage was observed, respectively. Unlike commonly used lime or limestone obtained by purchasing and also which requires crushing to form a powder, charcoal ash obtained for free, need no modification due to its nanoparticle size (20-96 nm) and environmentally friendly nanomaterials. Collection and use of charcoal ash for pollution remediation is one way of creating a clean environment. Overall, charcoal ash performed well in metals and sulfate removal and has been found an attractive and novel-alternative for acid mine drainage treatment, with an added-value of resource recovery. (C) 2019 Elsevier Ltd. All rights reserved.