Effects Of Ionic Liquids On Metals Recovery From Waste Printed Circuit Boards By Electrokinetic Process

Due to the rapid innovation in electronic industry,the average lifespan of electronic devices decreases drastically,leading to a massive amount of waste electric and electronic equipment(WEEE),also called as electronic waste or E-waste.As an essential part of E-waste,waste printed circuit boards(WPCBs)show an extremely high content of metals and it could contaminate the environment seriously if it is disposed of improperly.Hence,green and cost-effective approaches for WPCBs reuse and recycling are of great importance in the economic and environmental perspectives.In this study,first,the effect of substation rate of ionic liquid[BSO3HPy]HSO4 to H2SO4 in the electrolyte on Cu recovery from WPCBs by slurry electrolysis was discussed.Second,the effect of substation rate of ionic liquid[MIm]HSO4 to H2SO4 in the electrolyte on metal and non-metal separation from WPCBs by slurry electrolysis was investigated.Finally,five ionic liquid[MIm]HSO4.[BSO3HMIm]HSO4,[BSO3HMIm]OTf,[BS03HPy]OTf,[BSO3HPy]HS04 were used as additives to discuss their effect on metals and nonmetals separation from WPCBs by slurry electrolysis.The results are as followings:1.Ionic liquid was applied in slurry electrolysis for recovery of copper metal from WPCBs,and the results show:[BSO3HPy]HSO4 could improve copper recovery rate and current efficiency;however,it may increases the concentration of Cu2O in the obtained copper powders.Ionic liquid[BSO3HPy]HSO4 could inhibit copper crystal growth rate and reduce its diameter.When 10/%H2SO4 is replaced by[BSO3HPy]HSO4,the copper recovery rate,current efficiency,purity and particle size of copper powders is 90.94%,70.68%,81.69%and 2.30 ?m,respectively.Under these conditions,the obtained copper powders is super-fine single crystal.2.The experimental results of metal and nonmetal separation from WPCBs by slurry electrolysis with[MIm]HSO4 show:the increase of ionic liquid[MIm]HSO4 substitution rate could decrease the separation rate of Mg,Zn,Cu,Ni,Sn and Pb,increase the separation rate of Ba,while the separation of metal Fe and A1 first increases and then decreases as the increase of substitution rate.The separation rate and current efficiency of the total metal decrease with the increase of[MIm]HSO4 substitution rate.[MIm]HSO4 could effectively inhibit the growth rate of crystal,thus reducing its particle size.When the substitution rate of the ionic liquid[MIm]HSO4 is 80%,the average particle size,D50 and D90 of the metal powder is the smallest,which is 3.768 ?m.3.414 ?m and 7.291 ?m,respectively.However,[MIm]HSO4 shows a little influence on the phase composition of the obtained metal powders.3.The experimental results of a comparative study on metal separation from WPCBs by slurry electrolysis with five ionic liquids show:[MIm]HSO4 and[BSO3HMIm]HSO4 posess imidazole group and hydrogen sulfate,and they have a similar influence on the separation rate of total metal.[BSO3HMIm]OTf and[BSO3HPy]OTf,both include trifluoromethanesulfate,and they have a similar influence on the total metal separation rate.However,[BSO3HPy]HSO4 is different from the other four kinds of ionic liquids.Under their optimum dosage,five ionic liquids[MIm]HS04,[BS03HMIm]HSO4,[BS03HMIm]OTf,[BSO3HPy]OTf and[BSO3HPy]HSO4 show the best total metal separation rate of 70.96%,96.32%,80.12%,79.83%,54.07%,respectively.[BSO3HPy]HSO4,[MIm]HSO4 and[BSO3HMIm]HSO4 posess hydrogen sulfate,and they have a similar influence on particle size of the obtained metal powders,while[BSO3HMIm]OTf and[BSO3HPy]OTf also show a similar influence on particle size of the obtained metal powders.Under their optimum dosage,the particle size of the obtained metal powders separately with the five ionic liquids[BSO3HMIm]HSO4,[BSO3HMIm]OTf,[BSO3HPy]OTf,[BSO3HPy]HSO4 and[MIm]HSO4 is 3.594 ?m,4.255 ?m,3.406 ?m,3.739 ?m 4.473 ?m,respectively.