Application of nanofiltration hollow fibre membranes, developed by photografting, to treatment of anionic dye solutions

New hollow fibre nanofiltration membranes have been developed by UV-photografting using sodium p-styrene sulfonate (NaSS) as a vinyl monomer. The influence of different parameters on the grafting process such as irradiation time, quantity of received UV energy by the membrane and addition of photoinitiator, on the performances and the characteristics of the membranes were examined. The molecular weight cut-off of the grafted hollow fibres was estimated using different PEG solutions. The grafted membranes were also evaluated for the removal of different anionic dyes (Acid, Direct and Reactive dyes) with an aim to reuse the dye and the water in the process house. It is observed that the newly developed hollow-fibre membranes show performances which are close to that of an “ideal” membrane adapted to the treatment of dye effluents. For example, a negatively charged hollow fibre with a 4500 Da cut-off can be used to concentrate a saline direct red 80 solution with a high flux (15 × 10−5 l h−1 m−2 Pa−1 (15 l h−1 m−2 bar−1)), a high dye rejection (R > 97%) and a salt retention lower than 2%.