Effect of pH on separation of Pb (II) and NO3− from aqueous solutions using electrodialysis

Pb2+ and NO3− are major water pollutants with severe environmental effects. Several methods were used for treating them, but most of the intended solutions failed to treat these ions simultaneously. Electrodialysis (ED) may be able to treat them, particularly after the recent progress in membrane manufacture that has led to significant improvements in the performance. In this paper, we investigated the effect of pH on ED separation of Pb2+ and NO3− in terms of concentration ratio (CR), concentration polarization (ilim), current efficiency (η), and energy consumption (EC). The results showed that, pH between 3 and 5 was the most effective for removal of these ions. Additionally, the distribution of ions among the charged sites on the membrane surfaces was governed by pH. At low electric potentials (< 10 V), ion exchange/adsorption was the prevalent phenomenon occurring on the membrane surfaces, while at voltages over 25 V the membranes were regenerated. Consequently, cation and anion exchange membranes could be used for water treatment at low voltages, then regenerated at higher voltages.

► Effect of pH on Pb2+ and NO3− concentrations ratios. ► The variation of outlet concentrated and diluted pH at difference level of feed pH. ► Effect of pH on the concentration polarization. ► Effect of pH on Pb2+ and NO3− current efficiency and energy consumption. ► Membrane condition after the experiment.