Time evolution of electrokinetic flow-induced streaming potential and flux in dead-end and cross-flow filtration of colloids through nanopores

The comparative behavior of particle deposition in the dead-end as well as the cross-flow filtrations was investigated with the latex colloid under different particle concentrations, where the repulsive interaction exists between membranes and particles. We found that the time evolution of the electrokinetic streaming potential during the filtration of colloids can provide useful real-time information on particle deposition onto the outer surfaces of membranes. With the progress of filtration, the magnitude of streaming potential in fully retentive pores at the dead-end mode becomes evidently decreased, whereas the opposite behavior is shown at the cross-flow one. Experimental results of the filtrate flux concerning the streaming potential indicate that both the cake layer thickness and the particle concentration in the cake layer for dead-end case show higher values than those of cross-flow one. Regardless of the filtration modes, these properties are increased with the increase of particle concentration. Compared to the dead-end filtration with flat-plate membrane, the cross-flow characteristic allows the particles to stay in a suspended state above the outer surface of hollow-fibers instead of being deposited.