A pore-size tunable superhydrophobic membrane for high-flux membrane distillation

Abstract

Membrane distillation (MD) has recently attracted attention as a promising solution to the freshwater crisis. We report a pore-size tunable superhydrophobic membrane for application in the MD process. The tuning of the pore size is accomplished by applying mechanical strain to the stretchable superhydrophobic (SS) membrane. The SS membrane was made using a simple fabrication process that involved electrospinning and electrospraying. Various parameters of the membrane, including the pore size, the pore-size distribution, the contact angle, and the liquid entry pressure, were tested while mechanical strains were applied. The SS membrane was used in direct contact membrane distillation. The MD performance of the membrane, according to the applied mechanical strain, was studied, and the optimal strain applied was determined in terms of the permeate flux, the rejection rate, and the membrane longevity. As anticipated, increasing the pore size of the membrane enhanced the permeate flux. With the optimal mechanical strain, the SS membrane exhibited one of the highest permeate flux values ever reported at 36.5 L/m(2)h and stable permeate conductivity for a transmembrane temperature of 40 degrees C (3.5 wt% NaCl salt feed) over 5 h of MD operation. Furthermore, the MD performance of the SS membrane, according to the applied mechanical strain, was theoretically studied through computing simulation and was compared to the experimental results. The pore-size tunable superhydrophobic membrane presented in this study would provide a means of exploring what type of impact the membrane pore size has in MD both experimentally and theoretically.