| Waste printed circuit boards(WPCBs)is an essential part of e-waste.WPCBs are the substance with high harmfulness.Hence,attention should be paid on its potential in environmental problems,especially during the resource recycling.Research reports on comprehensive utilization of WPCBs by hydrometallurgical process have been published extensively.However,few studies focused on the behavior of pollutants migration/transformation during these utilization processes.Ionic liquid is called as "green solvent" because of low vapor pressure,strong acidity and it has been applied wildly.However,few studies researched its application in WPCBs.This research started from the hy drometallurgical technologies for WPCBs,first discussed the interaction behaviors of copper/zinc/lead by three industrialized acids,sulfuric acid,nitric acid and hydrochloric acid;then,five typical ionic liquids,[BSO4HPy]HSO4,[BSO3HMIm]HSO4,[BSO3HMIm]OTf,[MIm]HSO4,[BSO3HPy]OTf,were selected to study the interaction of copper/zinc/lead during the leaching processes;finally,inter-relationships of copper/zinc/lead in inorganic acid system and acidic ionic liquid system were comparatively studied from the angle of statistical analysis.The following results have been achieved:(1)The result of WPCBs leaching by inorganic acids showed that copper,zinc and lead can be leached out effectively by sulfuric acid,hydrochloric acid and nitric acid except lead of sulfuric acid system.Copper,zinc and lead leaching rate reached 90.16%,94.86%,30.84%;98.65%,98.84%,99.70%and in acid system,99.80%,98.24%,99.44%,respectively in sulfuric acid,hydrochloric acid and nitric acid systems under the optimal conditions.Copper,zinc and lead leaching rate increased with the increase of acid concentration,hydrogen peroxide adding amount,temperature and the decrease of pulp density except lead of sulfuric acid.The lead of sulfuric acid system remained at a low leaching level.A high temperature and hydrogen peroxide adding amount showed an adverse effect on copper,zinc and lead leaching except nitric acid system.(2)The result of WPCBs leaching by ionic liquids showed that copper and zinc leaching rate basically above 93%,which was high.On the contrary,the leaching rate of lead was basic below 10%.For[BS04HPy]HS04,[BSO3HMIm]HS04,[MIm]HS04,[BSO3HMIm]OTf,and[BSO3HPy]OTf,the maximum value of copper and zinc leaching rate was 99.75%,99.48%,75.71%,99.86%,99.77%and 93.02%,99.29%,99.02%,93.06%,74.88%,respectively under the optimal conditions.The tendency of copper and zinc leaching rate with acid concentration,hydrogen peroxide adding amount,temperature and solid/liquid was similar to that of sulfuric acid and hydrochloric acid system.The tendency of lead was similar to that sulfuric acid system.(3)The statistical results of WPCBs leaching tenology showed that correlations of copper and zinc,copper and lead,zinc and lead were statistically significant and positive in inorganic acid systems.Among them,nitric acid was the highest(copper and zinc,copper and lead,zinc and lead correlation coefficient is 0.929,0.908,0.855,respectively).For[BSO3HMIm]HS04,[BS04HPy]HS04,[MIm]HS04,correlations of copper and zinc,copper and lead,zinc and lead were statistically significant and positive.And they were close.Among them,correlation of copper and zinc(correlation coefficient is 0.857,0.854,0.752,respectively)was highest.For[BSO3HMIm]OTf,[BSO3HPy]OTf,correlations of copper and zinc,zinc and lead were significant.However,correlation of copper and lead was insignificant.Correlation of zinc and lead is negative(correlation coefficient is-0.434,-0.636,respectively).Correlations of copper and zinc,copper and lead,zinc and lead(correlation coefficient is 0.810,0.337,0.284,respectively)were statistically significant without considering the leaching agents.Correlation of copper and zinc was obviously higher than that of copper and lead,zinc and lead. |
PDF Full Text Request