Sulfonated polyethersulfone membranes in the desalination of aqueous solutions

The behaviour of sulfonated polyethersulfone membranes in the reverse osmosis treatment of aqueous solutions containing ammonium, cyanide and sulphate ions is described in this paper. Experimental tests were performed in an INDEVEN planar membrane test module, which provides data concerning the behaviour of the membrane in cross flow conditions with a minimal surface area, low feed and short times. Aqueous solutions of different concentrations of ammonium, cyanide and sulphate were treated in the test module, with both concentrate and permeate being recycled in order to keep the feed concentration practically constant, and so simulate a continuous process in a quasi-stationary state. The results show that this kind of membrane can be used satisfactorily to reduce concentrations of these ions in water, with rejection coefficients equal or higher to ninety percent. The water permeability coefficient and the solute permeability coefficients, of ammonium, cyanide and sulphate, have been obtained according the solution-diffusion model.

The behaviour of sulfonated polyethersulfone membranes in the reverse osmosis treatment of aqueous solutions containing ammonium, cyanide and sulphate ions has been studied. The stationary state is reached after 180 min of operation for ammonium and sulphate but only after 450 min for cyanide. The results show that this kind of membrane can be used satisfactorily to reduce concentrations of these ions in water, with rejection coefficients equal to or higher than 90%. The water permeability coefficient and the solute permeability coefficients, of ammonium, cyanide and sulphate, were obtained according to the solution-diffusion model. The water permeability constant obtained was of the same order as that obtained with other membranes and the solute permeability constants were lower than those obtained with other membranes.