Recovery of heavy metals from industrial sludge using various acid extraction approaches

摘要

Heavy metals were removed from industrial sludge by traditional and microwave-assisted acidnextraction approaches. The effects of acid concentration, extraction time, sludge particle size andnsolid/liquid (S/L) ratio on copper-extraction efficiency were assessed. Leaching with increasednacid concentrations increased the yield of heavy metals from the industrial sludge. In microwave-nassisted acid extraction, reducing the S/L ratio and sludge particle size increased copper-nextraction efficiency. These experimental findings indicate that S/L ratio most strongly influencednmicrowave-assisted acid extraction. Both traditional and microwave-assisted acid extractionndemonstrate that sulfuric acid was an effective extractant, and the copper fraction in extractednsludge shifted from being primarily bound to Fe–Mn oxides and organic-matter partition, to beingnmostly bound to organic matter, remaining as a residue during acid extraction.