Preparation of Nanofiltration Membranes via UV Photo-grafting Technique for Separation of Acid Dyes at Different pH Values

The purpose of this work is to investigate the performance of nanofiltration membrane for separation of acid dyes. Nanomembranes have been developed by UV photografting technique. Acrylic acid was used for the modification of polysulfone ultrafiltration membrane that prepared via wet phase inversion method. The modified membrane characteristics were measured and the most suitable nanofiltration membrane was chosen for treatment of dye effluents. It was observed that selected UV-photograftedmembrane showed acceptable performance both in terms of flux and rejection. Acid dye retention was between 86 and 99.7% and hydraulic permeability was 7.6 L/m2 h bar. It was observed that increase of either dye molecular weight or dye charge leads toimprove of dye separation that confirm the effectiveness of sieving and Donnan repulsion mechanism, respectively, in nanofiltration membranes. The influence of pH on the performance of membrane in terms of permeability and dye retention was established. It was found that by changing the pH (3, 6 and 9), membrane surface and dye have different behaviors that influence the final performance of selected nanomembrane. According to results, pH=9 of dye bath provides the best condition for dye separation. J. Color Sci. Tech. 2(2009), 237-247.© Institute for Colorants, Paint and Coatings.