Selective hydrophilization of the permeate surface to enhance flux in membrane distillation

• Direct contact membrane distillation (DCMD) on a selectively hydrophilized membrane is demonstrated.
• Enhancement of water vapor flux was observed with the hydrophilization of the permeate side of the membrane.
• The mechanism of water vapor transport for the hydrophilized membrane is presented.

This paper reports the development of novel hydrophilized membrane for water desalination using direct contact membrane distillation (DCMD). The permeate side of a porous polytetrafluoroethylene (PTFE) membrane on polypropylene (PP) support was hydrophilized by chemical treatment with oxidizing agents to enhance the rapid condensation and removal of permeated vapors. Depending upon the process conditions, permeate flux was as high as 61 L/m2 h, and as much 73% higher than an unmodified membrane. 58% increase in overall mass transfer coefficient was also observed with the hydrophilized membrane. In short, hydrophilization of membrane surface showed enhanced flux at lower temperature, making this a more energy efficient process.