Hydrophobization of PET track-etched membranes for direct contact membrane distillation

Abstract

Membrane distillation is a promising method for water desalination and wastewater treatment. This method requires membrane with high hydrophobicity, efficiency and low cost. In this study, track-etched membranes based on poly(ethylene terephthalate) (PET TeMs) with hydrophobic surface were prepared by modification using dichlorodimethylsilane and 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane. Modification of the surface of PET TeMs with pore size of 221 nm and thickness of 12 μm led to increasing of contact angle up to 134°. Prepared membranes were investigated by x-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX), goniometric analysis, liquid entry presser (LEP) analysis and gas permeability test. The performance of the membranes at different salinities was evaluated using direct contact membrane distillation (DCMD) process. The results show maximum permeate flux of 1189, 812, 510, and 125 g/m2 · h (dT = 75 °C) during 24 h saline solution operation (1.5, 10, 15 and 30 g l−1 respectively) with efficiency of 99.5%.