Reaserch On Disposing The Nickel Wastewater With Membrance Electrolysis

With the advancement of China’s technology and economy, and the rapid development of the electronics industry, the demand for nickel is increasing rapidly. But nickel is non-renewable resource, nickel consumption has far exceeded the amount of nickel produced. Therefore, the metallic nickel recycling and regeneration became inevitable road of development. In addition, nickel metal is rare heavy metals, which had high economic value, and nickel and its compounds will be adversely affected on human health. So, whether from the social, economic or environmental benefits, recycling nickel are potential in the pipeline.The first part of this experiment is enrichment and concentration of nickel. Because the ion concentration of nickel-containing wastewater is different, the concentration is too low will affect the test results of membrane electrolysis. So the low concentration of nickel-containing wastewater must be enrichment of Ni2+by Na cation resin before using electrolytic recovery, and the Na cation resin need pretreatment. Ion exchange process is inflowed from the bottom and outflowed of the top.The flow rate of nickel-containing wastewater by ion-exchange is2.5m/h, and the resin will reach saturation after180minutes exchanging. Wherein the concentration of nickel ion in treated water are less than1mg/l, which is reaching the national standards, the wastewater can be direct discharged. The regeneration agent is Na2SO4solution, and the concentration is5%, and regeneration method uses the countercurrent fashion, which is inflowed from the top and outflowed of the bottom. After this treatment, the concentration of nickel ion in the eluent reaches10.0g/l, which is arrived the requirement of membrane electrolysis for nickel ion.The second part of this experiment is to recover nickel with the membrane electrolysis. Membrane electrolysis has various advantages of electrolysis and electrodialysis, which is a comprehensive electrolysis. Since the selective permeability of ion-exchange membrane, the leaking of hazardous and toxic substances can be avoided effectively during the electrolytic process, reaching the purpose of recovering metals without contaminating the environment. The experiments were conducted using no diaphragm electrolysis device、the electrolysis process of single positive membrane、the electrolysis process of Anion positive membrane、 the electrolysis process of double ion membrane three rooms, and compared with each other. Through those experiments, the optimal process parameters as follows:the best consequent is using the electrolysis process of Anion positive membrane, which is at room temperature (25℃), the electrolysis voltage is6V, the electrolysis time is about28h, and the electrolytic solution is between pH4and4.5. In this case, the removal of nickel ions can reach more than95%, the current efficiency can reach above80%, and gets a good recovery, which is a very effective treatment process. The precipitation rate of the electrolysis process of double ion membrane three rooms is low in the membrane electrolysis experiment, and the total device power consumption is high, but the product can be used again. Therefore, The electrolysis process of double ion membrane three rooms can be associated with other treatment process.Finally, the economic benefits of the whole test conducted preliminary estimates, analysis shows:the recycled of nickel uses concentrates-electrolytic recovery processing, and the nickel will be got nicely by appropriate technology factors and experimental conditions. This technology will not only protect the environment, and promote the development of industry, avoiding the heavy metal pollution, and waste can produce more than1200yuan per ton of economic benefits. The double win can be got on environmental protection, social benefits and economic benefits.