Abstract
Many industries, such as tanning, metal processing, electroplating, etc., include copper in their processes and discharge it in wastewater streams. The permissible limit of copper in wastewater is 1.3mg/L, accordingly, industries must lower their copper limits to meet their local legal guidelines. This can be done by numerous methods including chemical precipitation, oxidation-reduction, ion exchange, etc. Electrocoagulation (EC)/floatation (ECF) technique, however, is an effective, cheap and simple electrochemical method for treating wastewater containing copper (Cu(II)) ions, which involves generation of coagulants using sacrificial electrodes when a DC voltage is applied; simultaneously generating hydrogen gas at the cathode which can help in the floatation of the formed particles. In the present work, a specially devised and innovated bench-scale EC apparatus was constructed and used in the removal of Cu(II) ions from aqueous solution. Numerous factors were investigated for their effect on the efficiency of removal of Cu(II) ions and those were: initial Cu(II) ion solution concentration, speed of magnetic stirring in the EC cell, number and type of sacrificial electrodes (aluminium (Al) or iron (Fe) electrodes), mixed electrodes, aspect ratio of the EC cell and the addition of a supporting electrolyte. It was found that lower initial concentrations required the minimum time to effect 100% removal of the Cu(II) ions, and that there existed an optimum speed of magnetic stirring in the EC cell, it was found that when C-0 was 3g/L it took only 25min for complete removal of Cu(II) ions at 300rpm, whereas, when C-0 was 10g/L it required 45min at 120rpm for complete removal, while at medium C-0 (6.5g/L) 30min were needed to effect 100% removal at 240rpm, and that Fe electrodes were more efficient in removing Cu(II) ions than Al. Regarding the floatation chamber (FC), it resulted in the production of totally clean water at its outlet and decreased the time required for complete Cu(II) removal to one third its value without FC which proved its importance in effecting good separation.