Toxic heavy metal contamination of industrial wastewater is a significant universal problem. These toxic metals can cause accumulative poisoning, cancer and brain damage when found above the tolerance levels. Exposure to nickel, for example, can cause dermatitis and allergic sensitization. Many processes have been used for the removal of heavy metals from industrial effluents. Chemical precipitation, coagulation, biosorption, solvent extraction, membrane separation, ion exchange and adsorption are commonly applied in the treatment of industrial wastewater containing heavy metals. For dilute heavy metals solutions， reverse osmosis , electrodialysis and ion exchange can be applied. However, reverse osmosis has low water recovery and high operating cost, electrodialysis is not an economical process because of its high electrical resistance and the development of concentration polarization phenomena, which makes ion exchange universally used for heavy metals’ removal from dilute solutions. However, regeneration of ion exchange resins is carried out using concentrated acidic or alkali solutions and the liquids produced by the necessary operation give rise to secondary pollution issues. Hence, an alternative process for the removal of heavy metals from dilute solutions has been required. Electrodeionization (EDI), also known as the packed-bed electrodialysis, is a novel hybrid separation process combining ion exchange resins and ion exchange membranes in one unit. The process has been suggested to conciliate the advantages and overcome the disadvantages of ion exchange and electrodialysis techniques, which is capable of achieving high levels of purification and concentration of dissolved ionic solutes without the use of chemical regenerants from dilute solutions in a continuous process. Therefore, the performance of EDI for the purification and concentration of nickel electroplating rinse water was studied in this paper.
展开▼
