Separation and recovery of alkali cellulose wastewater with high concentration of salts by cross-linked poly(vinyl alcohol)/polytetrafluoroethylene ultrafiltration membrane

Carboxymethyl Cellulose Sodium (CMC) is widely used in paper-making and textile industries, and the treatment of CMC wastewater containing salt and alkali has become one of the hot spots in the field of wastewater treatment . In this study, poly(vinyl alcohol) (PVA)/polytetrafluoroethylene (PTFE) membranes were prepared through non-solvent induced phase inversion (NIPS) and cross-linking for the separation of CMC and salt-alkali. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and surface properties of the membranes. The results showed that both heat cross-linking and chemical cross-linking with glutaraldehyde (GA) improved the structural stability of the PVA/PTFE membranes. The salt-alkali optional transmitting rate (OTR), the CMC rejection rate, and the flux of the heat cross-linked PVA/PTFE membrane and chemical cross-linked PVA/PTFE membrane are 93.0%, 99.3%, 220.00 (L/m 2 h) and 93.4%, 99.4%, 89.20 (L/m 2 h) at 0.2 MPa, respectively. Besides, the GA cross-linked PVA/PTFE membrane showed stable and efficient separation performance in the test of separating CMC. Therefore, the resultant membrane can be used for the separation of CMC, salt, and alkali, providing a new idea for the treatment of high-salt-alkali cellulose wastewater.