Separation and recovery of copper from aqueous solutions using tri-n-butyl phosphate in benzene

Purification of aqueous stream of sulphate containing copper ions (Cu2 +) has been studied by reactive extraction technique. Dissolved Cu2 + ions are removed from the aqueous solution with the help of tri-n-butyl phosphate (TBP) as a promising extractant with benzene used as a diluent to decrease the mass transfer resistances exists in the organic phase. The effect of parameters namely initial copper concentration (20 ppm, 60 ppm and 100 ppm), extractant composition (10 vol.% to 50 vol.%: 0.365 to 1.825 mol·L− 1), organic/aqueous phase ratio (O/A ratio = 1:3 to 3:1), pH (2 to 11) and temperature (298 K to 333 K) are studied on the removal efficiency. 98% of copper is extracted at the conditions of [Cu2 +]in = 20 ppm, O/A ratio = 3:1, pH = 6, temperature = 298 K, and [TBP] = 1.825 mol·L− 1 or 50 vol.%. The organic phase is regenerated in a two stage stripping process using 4 N H2SO4 as the stripping agent and at 353 K. This regenerated organic phase is further used to remove copper from the aqueous solution. From the thermodynamic analysis it is inferred that the extraction process is exothermic, and favourable at low temperatures forming stable Cu-TBP complexes.