Treatment of textile dye effluents using a new photografted nanofiltration membrane

A nanofiltration membrane has been developed by UV-photografting. Sodium p-styrene sulfonate was used for the modification of a polysulfone ultrafiltration membrane. The membrane cut-off was estimated. The grafted membranes have been evaluated for the removal of five different dyes with an aim to reuse water in the process house. The effect of different parameters such as dye class, pH and the presence of salt was evaluated. It is observed that the newly developed membranes show acceptable performance both in terms of flux and rejection. Dye retention was higher than 97% and hydraulic permeability 0.23–0.28 m3.m–2.d–1 at 0.4 MPa. The influence of pH on the performance of membranes in terms of fouling and retention was established and compared to a commercial membrane (Desal 5DK).

Fig.6 R (%) RO16 RO16 (mix.) Na2SO4 0.03M Na2SO4 (mix.) Time (min) Fig.7 R (%) AO10 AO10 (mix.) Na2SO4 0.03M Na2SO4 (mix.) Time (min) Fig.8 R (%) The present work demonstrated that the membranes developed, based on UV-photopolymerisation of sodium p-styrene sulfonate monomer on an UF membrane, can be successfully used for the treatment of dye effluents. The results showed that the grafted membrane is far less sensitive to fouling than polyamide membrane. Experiments done at different pH values also showed that pH has no longer an influence on the retention or flux of the dye solution. The evaluation of the salt effect showed that, in the practice, it would be preferable to change the electrolyte from a divalent anion to a monovalent anion. Future work is still needed to complete the characterisation of the grafted membranes to model the filtration performance more quantitatively. It is also planned to optimise both the support and the photografting process.