Fabrication of tight GO/PVDF hollow fiber membranes with improved permeability for efficient fractionation of dyes and salts in textile wastewater

In this study, a graphene oxide/polyvinylidene fluoride (GO/PVDF) tight hollow fiber membrane (HFM) with improved permeability was fabricated via one-step direct spinning process to fractionate the dyes and salts (NaCl and Na 2 SO 4 ) in textile wastewater. Scanning electron microscopy (SEM) indicated that the GO/PVDF HFM possessed a smooth and tight outer selective layer and a relatively porous and loose inner surface. The optimized HFM not only possesses a small mean pore radius of 1.14 nm, but also has a high pure water flux of 24.8 L/m 2 ·h·bar. The stronger negative charge (− 40 mV at pH = 7) was obtained by the GO/PVDF HFM. Due to the synergistic effects of size exclusion and charge repulsion, the resultant HFM exhibited excellent rejection for dyes (i.e., close to 100% for Congo red and Methyl blue, 98.9% for Eriochrome black T) and low salts rejection (i.e., 1% for NaCl, 11% for Na 2 SO 4 ). Besides, with appropriate addition of hydrophilic GO to the doped solution, the resultant membrane exhibited good hydrophilicity, antifouling property and excellent stability. The newly developed tight HFM would be of great significance for effective fractionation and treatment of textile wastewater.