Rod-coated PVA interlayer induced nanofiltration membrane: Method development and application for separation of dye/NaCl with greater performance

The textile industry consumes large quantities of freshwater and discharges large quantities of dye/salt wastewater, causing serious environmental problems. Nanofiltration (NF) has proven to be able to achieve efficient dye/salt separation. However, conventional polyamide (PA) NF membranes are often constrained by the trade-off between selectivity and permeability. Herein, we developed a highly dye/NaCl selective nanofiltration membrane with a rod-coated PVA interlayer. The rod-coating approach allows better control of PVA dosage to create a perfect PVA interlayer. The formation and effect of rod-coated PVA interlayer significantly improved the permeability. With an optimal PVA dosage of approximately 0.32 g/m 2 , the permeance of the iTFC membrane (>30.0 L/(m 2  h bar)) was almost 3 times that of the control membrane. Moreover, the iTFC-PVA membrane had an outstanding Rhodamine B rejection (99.8 %), low sodium chloride (NaCl) rejection, and maximum NaCl/dye selectivity ratio as high as 428. It is anticipated that the iTFC membrane has great potential in the field of dyehouse wastewater treatment . Furthermore, our study proves that the Mayer rod-coating approach is suited to fabricating high-performance PA-NF membranes with PVA interlayers. It is anticipated that organic-containing wastewater can better be treated by the developed membrane to achieve a better water environment and resource recovery.