Simultaneous improvement of wetting resistance and permeability in membrane distillation using MXene-foam coating layer with heterostructural channels

Abstract

To alleviate global water scarcity, membrane distillation (MD) has been identified as a promising technology for desalination. However, there exists a trade-off effect between membrane permeability and anti-wetting performance, impeding the intensive application of MD. To address this problem, inspired by the ion-sieving effect and the special nanostructure of aquaporins to break the trade-off between permeability and selectivity, a porous MXene coating layer with heterostructural channels in fusiform shape was designed on a PVDF membrane through a hydrazine-induced approach. The coating layer was in a foam shape with hydrophobic surfaces and outstanding stability in water. The delicate-designed fusiform channels endowed the membrane with enhanced permeability (the average flux of the optimum modified membrane was 55.59 kg/m2h with a temperature gradient of 60 °C (feed temperature: 70 °C and permeate temperature: 10 °C) and flow velocity of 400 ml/min, nearly 2.5 times as high as that of the virgin membrane) and resistance to simultaneous sault induced and foulant-induced wetting performance. This paper proposed a novel strategy for engineering porous nanostructures with dual-spacing channels on the membrane surface to ensure high permeability and stable excellent desalination performance.