Mof-Based Photothermal Janus Membrane with Robust Anti-Fouling Performance for Enhanced Membrane Distillation

Abstract

As a promising desalination technology, photothermal membrane distillation (PMD) is faced with problems such as low yield of freshwater and membrane pollution. Herein, we introduce a copper-based metal-organic framework (Cu-CAT) into a hydrophilic/superhydrophobic polyvinylidene fluoride (PVDF) Janus tree-like nanofiber membrane Janus (TLNMs) to construct photothermal Janus TLNMs (P-Janus TLNMs) for enhanced PMD. Owing to the high photothermal efficiency of the hydrophilic Cu-CAT layer and the small pore size and high porosity of the superhydrophobic PVDF TLNMs, the P-Janus TLNMs showed excellent desalination performance when assembled into a PMD system. Under 1 kW·m-2 solar illumination, the P-Janus TLNMs exhibited a remarkable surface temperature of 88 °C, achieving a permeation flux of 1.46 L·m-2h-1, a salt rejection rate exceeding 99.99%, and an energy utilization rate of 81%. Furthermore, after 20 days of continuous operation with simulated seawater containing oil and surfactant, the P-Janus TLNMs presented a salt rejection of 99.9% and a stable permeation flux of 1.71 L m−2 h−1. This work presents a novel membrane with great potential for enhancing permeation flux and anti-fouling properties towards PMD, thus advancing the field of sustainable seawater desalination.

Keywords: electrospinning, Polyvinylidene fluoride, Cu-CAT, Photothermal membrane distillation, Janus Membrane