Recovery of nickel from aqueous solutions by complexation-ultrafiltration process with sodium polyacrylate and polyethylenimine

► Nickel removal rate of 99.5% could be reached using complexation-ultrafiltration process. ► The mechanism of adding salt on metal removal could be the compressing electric double layer. ► Diafiltration technology was effectively used to regenerate the polymer. ► Langmuir-type binding isotherm equation was effectively used to evaluate nickel bound to polymer.