Retention of Cu(II) and Ni(II) ions by filtration through polymer-modified membranes

• Modification of organic membranes by polyelectrolytes multilayer films.
• Characterization of modified membranes (quartz crystal microbalance, total organic carbon).
• Filtration of mixed metal ions solutions through modified membranes.

Organic polyethersulfone (PES) membranes were chemically modified by polyelectrolyte multilayer films of different nature. Amongst the polyelectrolyte assemblies used, poly(allylamine hydrochloride)/poly(sodium-4-styrene sulfonate) (PAH/PSS) film was found to be the most efficient system to remove metallic cations from contaminated aqueous solutions through ultrafiltration experiments. The growth of the PAH/PSS film on PES substrates was studied in situ using quartz crystal microbalance experiments. Total organic carbon analysis was also performed to demonstrate that the chemical modification of PES membranes by PAH and PSS polyelectrolytes was effective and to show the absence of polyelectrolyte desorption from the membranes when the modified membranes were immersed in aqueous solutions. The filtration parameters (immersion time of the membrane, pH of the metal solutions) affecting the removal of copper and nickel ions were also optimized. In addition, the filtration of a solution containing both copper and nickel ions was successfully achieved through PAH/PSS-modified membranes. The ageing of these latter was tested and it was shown that both the integrity of the modified-membranes and their ability to decontaminate aqueous solutions were not affected by successive filtrations.

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