Liquid-Lubricated Nanofibrous Membrane for Scaling Mitigation in Solar-Driven Membrane Distillation

Abstract

Recently, localized heating membrane distillation (MD) driven by solar energy has attracted much attention for desalination, but salt accumulation on membrane surface is still challenging and needs to be tackled properly. In this work, liquid-lubricated nanofibrous membrane was fabricated by dip-coating of liquid polydimethylsiloxane (PDMS) whilst maintaining the interconnected pore structure for scaling mitigation in solar-driven membrane distillation. Due to the nanoscale dynamic characteristics of liquid PDMS molecules, the coated membrane demonstrated excellent properties in minimizing salt scaling with prolonged lifespan by a factor of 2 or more. AFM measurement confirmed that decreased attachment strength of the liquid-lubricated surfaces plays a vital role in obstructing the adsorption of salt crystals on the surface. Furthermore, the interconnected structure of the nanofibrous mat endowed the membrane with a distillate flux of as high as ~8.3 L·m-2·day-1 under natural light. These results evidenced that the as-prepared membrane can be taken as a potential candidate for durable MD applications by fully taking advantage of renewable solar energy.

Keywords: membrane distillation, liquid coating, photothermal, electrospinning, Solar energy