Analysis of lead(II) retention from single salt and binary aqueous solutions by a polyamide nanofiltration membrane: Experimental results and modelling

Influence of ion interaction on lead removal by a polyamide nanofiltration membrane

“…This might be due to the occurrence of isoelectric point of the membrane at the natural pH of solutions. Similar results have been reported in previous studies [20,35,36]. Childress and Elimelech [46] explained that this observation is related to three factors that include membrane pore size, electro-viscous effect and osmotic pressure gradient at the membrane surface.…”

“…3. Membrane charge is a function of several phenomena where adsorption of differently charged solutes of the electrolyte and detachment of functional groups of the membrane [20] are the most important factors. As shown, the zeta potential (ζ) varies with the pH.…”

“…Increasing the pressure at high feed concentrations had less effect on the lead ion rejection. When the transmembrane pressure increases, two phenomena eventuate, simultaneously: 1) by increasing the pressure, more solute is forced to the membrane surface that leads to concentration polarization which consequently solute rejection will be decreased; 2) by increasing the pressure, the solvent flux will be increased, but the solute transport across the membrane is hindered by steric and electrical effects [20]. As a result, an increase in solute rejection is obtained as water permeation becomes greater at higher pressures.…”

“…Nanofiltration (NF) technology has been used to treat lead containing wastewaters. In this method, the rejection of lead ion can be high enough to achieve acceptable quality for the filtered water [17][18][19][20]. Nanofiltration is a membrane filtration process that stands between ultrafiltration and reverse osmosis in which the separation characteristics are based on the sieving effect and membrane surface charge, though the NF membranes have been modified in many commercial applications [21].…”

“…However, in the real industrial wastewaters, there is a mixture of several heavy metals in which the interfering cations can influence on the desired cation removal. Nevertheless, there are a few studies dealing with lead ion removal in the mixtures consisted of interfering cations [19,20,26]. To the best of our knowledge, there is only one study about the effect of anions nature on the lead ion rejection and permeate flux that is related to lead ion removal in the presence of a single salt [27].…”