A Review on the Removal Technologies of Nickel(II) Ion from Aqueous Solution

Background: The pollution created by heavy metals has caused a difficult situation for the entire ecosystem because of their ill-effects on both the abiotic and biotic components of the environment. Nickel is one such heavy metal which is released at various concentration ranges from the different industrial activities, and if not treated properly may have enormous effects on life. Thus, suppression of the level of nickel from industrial release before its disposal into the water bodies is a necessity. Objective: This paper aims to explore a comprehensive review on the existing treatment technologies used for the nickel removal in terms of their outcome, advantages and drawbacks. Method: The paper reviews the existing treatment techniques such as elctrocoagulation, membrane sep-aration, chemical precipitation, ion exchange, biological methods and adsorption adopted for an effective decontamination of nickel-bearing wastewater. Some recent adsorbents relating to Ni(II) adsorption are outlined in this article. In addition, a collection of 10 patent documents was also elucidated briefly. Results: Various limitations of the conventional treatment processes can be overcome by employing an effective adsorption process. The paper put forward some suggestions to improve the adsorbent charac-teristics. Conclusion: Adsorption processes have various advantages like ease of operation and control, flexibility towards the flow variation under diurnal and seasonal conditions. As a result, the present review suggests significant features in which adsorption phenomena can be adopted for improving the process efficiency.