RECOVERY OF NICKEL FROM SOLUTION OF IRON, NICKEL AND CHROMIUM USING DUOLITE A7 RESIN

Abstract

Recovery of nickel from solution containing nickel, chromium and iron was conducted using precipitation and adsorption techniques. Iron was removed from the solution by precipitation while nickel was recovered from nickel and chromium mixture using Duolite A7 resin. The effect of pH was investigated for preccipitatn of iron while the effects of pH, ionic strength, resin dosage, temperature and equilibration time was investigated on the recovery of nickel. The optimum pH at which iron precipitated out while the other two metals are still in solution was 2.0. Upto 91% adsorption of nickel by the resin was observed at the pH of 4.5. Adsorption of nickel also increased with increasing ionic strength. The uptake was rapid with maximum adsorption being observed at 10 minutes equilibration time after which a steady state of equilibrium was observed. Increasing resin dosage also favoured the adsorption of nickel. However, decrease in adsorption of nickel was observed with increase in temperature. Negative value of ΔGo and ΔHo showed that the adsorption is spontaneous and that the reaction is exothermic. Adsorption of both metal can best be described by pseudo second order model and the process can be fitted to Freundlich model. FTIR spectra of the unloaded and the loaded resin showed that duolite A7 resin is suitable for optimum recovery of the metal ion from the solution. Upto 85% of nickel and 82% of Chromium were recovered from the loaded resin eventually.