Research On Recycling Heavy Metals From Electroplating Sludge Using Ionic Liquids

Electroplating industry as one of the basic industries which has made tremendous contributions to China's rapid economic development.But at the same time,the electroplating industry produced a large number of electroplating sludge which contains much toxic and harmful heavy metals.It would has serious impact on the environment if was not handled effectively.Ionic liquids as a new green solvents was widely used in various industries.In this paper,the characteristic of extraction of metals was used to recover the heavy metals in the electroplating sludge,therefore,the electroplating sludge can achieve the aim of turning waste into treasure.1 In this paper,the microwave-assisted two-step method was used to synthesis 1-butyl-3-methylimidazolium hexafluorophosphate,1-hexyl-3-methylimidazolium hexafluorophosphate,1-octyl-methylimidazolium hexafluorophosphate,and their viscosities were measured.The extraction of Pb²⁺,Zn²⁺,Ni²⁺,Cd²⁺ and Co²⁺ ions by three kinds of ionic liquids was studied.The results showed that [BMIM][PF₆] had the best extraction rate to five metals.Hence,the structure and the content of [BMIM][PF₆] was determined by FT-IR,1HNMR and HPLC.2 The extraction rate of Zn²⁺,Ni²⁺,Pb²⁺ Cd²⁺ and Co²⁺ were studied by using,[BMIM][PF₆],[BMIM][PF₆]-dithizone,respectively.The effect of temperature,time,p H,initial concentration of metal ions on the extraction rate were investigated at the optimal extraction system of [BMIM][PF₆]-dithizone,and the Pb²⁺?Zn²⁺?Ni²⁺ ions' s best extraction conditions was confirmed by the experiment of orthogonal test.3 Using the electroplating sludge as raw material,and optimized the sulfuric acid leaching process,the effects of liquid-solid ratio,time and temperature on metal leaching were investigated,the best condition was,the liquid-solid ratio was 1:10,the leaching time was 100 min,and the leaching temperature was 40 ?.4 Using the sulfuric acid leaching solution as raw material,the metal ions in solution was separated by step precipitation and solvent extraction.The copper extractant and its stripping agent were LIX984 N and sulfuric acid.The extraction conditions were as follows: extraction solvent and metal solution volume ratio of 1:3,p H=1.5,stirring time was 3 min,extraction temperature was 45?,the extraction rate was 96.7%,while the optimum stripping condition is that the concentration of sulfuric acid was 5mol/L,and the stripping rate was up to 84.2%.Zinc extraction and stripping agent were [BMIM][PF₆]-dithizone and sulfate acid.Zinc was extracted in four levels,the extraction rate of 95.5%;The Zn stripping grade is 3,stripping using 3mol/L sulfuric acid,the stripping rate was 81.7%.On the basis of the above research,the electroplating sludge is subjected to amplification treatment.It was treated by acid leaching,step precipitation,extraction steps,and then copper sulfate,nickel sulfate and zinc sulfate were obtained.The recovery rate of Cu is 77.37%,Ni is 78%,Zn is 73.9%?...