Physicochemical characteristics of acid mine drainage, simultaneous remediation and use as feedstock for value added products

Abstract In this study, the use of acid mine drainage as alternative source of ferric ion for the synthesis of iron nanoparticles was investigated. The physical and chemical characteristics of acid mine drainage from Navigation coal mine and the West Rand mine, South Africa were conducted. The synthesised iron nanoparticles were compared with iron nanoparticles prepared from commercial reagents by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, high resolution transmission electron microscopy and Brunauer–Emmett–Teller surface area determination. The iron nanoparticles were utilised for the treatment of acid mine drainage. Experimental results showed that the characteristics of acid mine drainage samples differ from site to site due to the differences in their geological composition, chemical deposition, rate of oxidation, and availability of pyrite ores. The Toeseep acid mine drainage feedstock from Navigation coal mine was found to contain the highest concentration of iron (4219.14 mg L −1 ) thus; it was regarded to be a suitable source of iron, sulphate (21,317.79 mg L −1 ) was the predominant anion. The synthesised iron nanoparticles were crystalline and spherical in shape, with average particle size of 31.8 nm or 28.05 nm and Brunauer–Emmett–Teller surface area of 88 ± 3.16 m 2  g −1 or 91 ± 3.08 m 2  g −1 for the iron nanoparticles synthesised from acid mine drainage or ferric chloride, respectively. The optimisation of the iron nanoparticles dosage and contact time for the treatment of Navigation Toeseep acid mine drainage was determined to be 0.1 g and 60 min, respectively. The toxic elements in the raw acid mine drainage were removed with over 75% efficiency.