Insulator-based dielectrophoretic antifouling of nanoporous membrane for high conductive water desalination

Abstract

Nanoporous membrane (NPM) based water desalination plays an essential role in remedying the global water scarcity crisis. However, the NPM always suffers from fouling issue because of various nanoparticles existed in sea/waste water. Based on the electrical insulation property of NPM and its ultra-small pore size, insulator-based dielectrophoresis (iDEP) is promising for manipulating the nanoparticle behavior in NPM and serves as an effective antifouling technique. Besides, the alternating current electrothermal (ACET) flow occurs due to the temperature dependent variation of water dielectric property, and it also affects the nanoparticle behavior via electrohydrodynamic (EHD) force. In this paper, the AC electrokinetic antifouling mechanism of NPM for water desalination is numerically investigated under several parametric conditions. The results indicate that iDEP force is effective for nanoparticle antifouling in NPM while ACET EHD force has a suppressing influence. Fortunately, due to its dominant magnitude, iDEP force makes the AC electrokinetic based NPM antifouling technique successful. Furthermore, the NPM with circular cone nanopore is highly recommended instead of that with circular cylinder nanopore in order to eliminate the nanoparticle “trapping zone” during antifouling process. The current investigation demonstrates the potential of handling NPM fouling issue using AC electrokinetics for membrane based water desalination technologies.