Polymer-enhanced ultrafiltration process for heavy metals removal from industrial wastewater

Recently, the complexation–ultrafiltration technique has been shown to be a promising technique for removal of heavy metals in solution. In this study, a polymer-enhanced ultrafiltration process has been investigated for removal of toxic heavy metals such as Cu(II), Ni(II), and Cr(III) from synthetic wastewater solutions. Carboxy methyl cellulose as a water-soluble polymer was used for complexing the cationic forms of the heavy metals before filtration. The size of the complex has to be larger than the pores of the selected membrane so the complex can be retained. Permeate water is then purified from the heavy metals. Filtration experiments were performed with ultrafiltration membrane system, equipped with a polyethersulfone membrane with a 10,000 Da cut-off. The pressure was fixed at 1 bar with a permeate flow rate of 7.5 L/h. Different parameters, affecting the percentage rejection of the metals, such as pH, metal ion concentration, CMC/metal ratio, and permeate flux (F) have been investigated. Metal rejection in aqueous solution containing Ni(II), Cu(II) and Cr(III) ions simultaneously was also evaluated. Results obtained revealed that the maximum percentage of the metal rejection was achieved at pH ≥ 7 with increasing of the CMC concentration.