Dehydroxylation-assisted self-crosslinking of MXene-based pervaporation membranes for treating high-salinity water

Abstract

In this study, an additive-free self-crosslinking technique was optimized to prepare pervaporation desalination membranes for brine treatment. MXene-coated membranes that were about 100 nm thick were synthesized using the facile vacuum filtration technique. The MXene nanosheets were then crosslinked at different temperatures from 25 °C to 180 °C, inspired by weight loss through thermogravimetric analysis. The MXene membrane self-crosslinked at 140 ℃ (M140) proved to be the optimal membrane in terms of the permselectivity of brine with a stable d-spacing of 1.43 nm in distilled water and 1.48 nm in a 10 wt% NaCl solution. Fourier-transformed infrared spectroscopy and X-ray photoelectron spectroscopy revealed Ti[sbnd]O[sbnd]Ti bond formation induced by reverse hydrolysis of MXene, leading to increased surface roughness and decreased swelling tendency. M140 generated a permeation flux of 70 kg m-2h−1 with salt rejection up to 99.9 % for 100 g/L of NaCl solution at a feed temperature of 70 °C. Furthermore, M140, tested with simulated brine for a 48 h operation test, showed successful suppression of salt transport on the permeate side, while maintaining ∼ 50 kg m-2h−1 flux and 99.9 % salt rejection. M140 is recommended for pervaporation desalination, where a high salinity feed is expected. © 2022 The Korean Society of Industrial and Engineering Chemistry