Hydrophilic modification of PVDF membranes for oily water separation with enhanced anti-fouling performance

Abstract

The main purpose of this work is to improve the hydrophilicity and antifouling properties of hydrophobic polyvinylidene fluoride (PVDF) microfiltration membranes through modification. Pyrogallol (PG), polyethyleneimine (PEI), and (3-chloropropyl) trimethoxysilane (CTS) formed a stable hydrophilic network by Michael addition/Schiff reaction in alkaline solution Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the surface chemical composition, surface and cross-section morphology of the membrane. In addition, the properties of the membrane were tested systematically. The as-prepared PVDF-PG/PEI/CTS membranes showed a smaller water contact angle down to 21.1± 4.8°. The pure water flux of the modified membrane increased significantly by about 18 folds, from 377.0 ± 61.0 to 6745.0 L m−2 h−1, the separation efficiency for the four types of oil-in-water emulsions were all greater than 98.8%. In addition, the modified membrane showed high stability under various conditions of acidity, weak alkalinity and high salt content, showing great potential in the actual treatment of oily wastewater.