A study on acid reclamation and copper recovery using low pressure nanofiltration membrane

In this study, nanofiltration membrane is used to separate proton (H+) and copper ions from a ternary ions mixture (H+, Cu2+, SO42−). The performance of membrane in separating Cu2+ and H+ was tested under the effect of pressure, concentration and different acid strength (pH). It was found that the H+ rejection is independent of the applied pressure. Permeability of solution decreased linearly with the increase of CuSO4 concentration. In terms of H+ rejection, there is a continuous drop in rejection from 0.1 mM CuSO4 to 10 mM CuSO4 solution. H+ was poorly retained and concentrated in the permeate stream in corresponding to the electro-neutrality requirements, on the other hand, the rejection of copper ion was almost constant with pH. In overall, optimum acid reclamation and copper recovery can be achieved at higher volume flux. A Three Parameters-Combined Film-Extended Nernst-Planck Equation (CF-ENP) model is successfully applied to predict the performance of nanofiltration membrane in separating the ternary ions.