Superhydrophobic MXene/PVDF composite membrane with in-situ Joule heating for ultra-high water production

Conventional Seawater desalination membrane distillation technology suffers from reduced efficiency due to temperature polarisation, severely limiting its practical application. To address this challenge, this study employs surface grafting modification of MXene with HTEOS to fabricate MXene-based composite membranes with hydrophobic properties. The composite membrane exhibits outstanding Joule heating response under DC voltage, demonstrating excellent cycling stability with the cycle-to-cycle peak-temperature fluctuation remained below 2.6% over 20 on/off cycles. Building upon this, a novel in-situ heating-enhanced sweep gas membrane distillation (SGMD) system was established to investigate the influence of operating parameters—including gas flow rate—and in-situ heating on transmembrane permeation flux. Experimental results indicate that the optimum MXene-to-HTEOS hydrolysate volume ratio was 10:2, yielding a water contact angle of 145.0 °. Compared with the PVDF membrane without Joule heating, the maximum flux enhancement of MXene-P@PVDF membrane reached 134.4% at a gas flow rate of 0.1 m 3 ·h −1 under 10 V. At a feed temperature of 40℃, a gas flow rate of 0.3 m 3 ·h −1 , and a liquid flow rate of 10 mL·min −1 , the permeation flux increased from 0.793 to 1.827 kg·m −2 ·h −1 . This substantially improves MD efficiency while mitigating temperature polarisation effects.