Removal of heavy metals by ultrafiltration

Large amounts of polluted water are often obtained from the chemical process industry, which require a mandatory treatment before being disposed of. Heavy metals are employed as homogeneous catalyst in numerous processes, so that recovering and/or recycling of those metals to the reaction unit is essential. In this study, ultrafiltration is presented as a useful technique to recover heavy metals present in aqueous solutions, without the need of adding further substances. Specifically, recovery of mixtures of iron (II) and iron (III), copper (II) and chromium (III) is presented. Ceramic membranes are mechanically, chemically and thermally more resistant than those polymeric. Thus, given the acidic nature of the studied effluents, a 5-kDa commercial ceramic membrane has been selected for this investigation. The effect of transmembrane pressure and pH are presented. The results show that chemical speciation of metals in aqueous solution is strongly correlated with the retention, which suggests a possible interaction between metallic species and membrane material.