摘要
Effective recovery of high-value heavy metals from electroplating wastewater is of great significance,but recovering nickel ions from real electroplating wastewater as nickel sheet has not been reported.In this study,the pilot-scale fixed-bed resin adsorption was conducted to recover Ni(Ⅱ)ions from real nickel plating wastewater,and then the concentrated Ni(Ⅱ)ions in the regenerated solution were reduced to nickel sheet via electrodeposition.A commercial cation-exchange resin was selected and the optimal resin adsorption and regeneration conditions were investigated.The resin exhibited an adsorption capacity of 63 mg/g for Ni(Ⅱ)ions,and the average amount of treated water was 84.6 bed volumes(BV)in the pilot-scale experiments.After the adsorption by two ion-exchange resin columns in series and one chelating resin column,the concentrations of Ni(Ⅱ)in the treated wastewater were below 0.1 mg/L.After the regeneration of the spent resin using 3 BVof 4%(w/w)HC1 solution,1.5 BV of concentrated neutral nickel solution(>30 g/L)was obtained and used in the subsequent electrodeposition process.Using the aeration method,alkali and water required in resin activation process were greatly reduced to 2 BV and 3 BV,respectively.Under the optimal electrodeposition conditions,95.6%of Ni(Ⅱ)in desorption eluent could be recovered as the elemental nickel on the cathode,llie total treatment cost for the resin adsorption and regeneration as well as the electrodeposition was calculated.
