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Removal of Cu (II), Ni (II) and Cr (III) Ions from Wastewater Using Complexation-Ultrafiltration Technique

In the recent years, the complexationultrafiltration technique has been shown to be a promising technique for removal of heavy metals in solution. In this study, a polymerenhanced 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 functions of the metal-CMC complexation are to increase their molecular weight and their size. 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 polyethersulfon membrane with a 10000 Daltons 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 and metal/CMC ratio have been investigated. Results obtained revealed that the maximum percentage of the metals rejection was achieved at pH ≥ 7 with increasing of the CMC concentration. Advantages of that technology over the other conventional technologies are the low energy requirements involved in ultrafiltration, the very fast reaction kinetics, and the high selectivity of separation.