A high-flux polystyrene-reinforced styrene-acrylonitrile/polyacrylonitrile nanofibrous membrane for desalination using direct contact membrane distillation

High-flux composite MD membranes were fabricated using high-productive electroblowing and air-assisted electrospraying processes. Top layer thickness of dual-layer nanofibrous styrene-acrylonitrile (SAN)/polyacrylonitrile (PAN) membrane was designed to be as small as possible to balance the mass and heat transfer resistance to gain better permeability. In this regard, the nanofibrous PAN layer was firstly fabricated by the electroblowing process as the support layer for the SAN nanofibers. Mechanical strength and wetting resistance were improved considerably After the hot-pressing operation. Upon fabricating polystyrene (PS) microbeads on the hot-pressed SAN/PAN membrane, a superhydrophobic surface with a water contact angle (WCA) of 155.9 degrees was formed. The single-layer SAN, dual-layer SAN/PAN, and the PS-reinforced membranes (PS/SAN/PAN) were then used for 35 g/L feed water desalination by direct contact membrane distillation (DCMD). The permeate flux (37.16-84.4 kg/m2 h) of the fabricated membranes was higher than the commercial polytetrafluoroethylene (PTFE) membrane and high salt rejection of 99.9% was measured for all of the tested membranes. Our proposed composite membranes can significantly impede the pore wetting problem and low permeation as the most pronounced challenges of the membrane distillation (MD) process.

Automated summary

High-flux composite MD membranes were successfully fabricated using electroblowing and hot-pressing techniques, achieving high permeate flux and high salt rejection rates, addressing the pore wetting and low permeation challenges in the MD process.