Response of zeta potential to cake formation and pore blocking during the microfiltration of latex particles

The responses of zeta potential of membrane, ζobs, to the pore blocking and cake formation during microfiltration of latex particle suspension were studied by monitoring both the filtration resistance and streaming potential during the filtration. The pattern of the change in ζobs during the filtration was quite different between the cake filtration and the pore blocking filtration. In the cake filtration ζobs changed from the intrinsic zeta potential of membrane, ζm, to the zeta potential of cake layer, ζc, depending on the proportion of the hydraulic resistance of the cake layer to the total filtration resistance. In the pore blocking filtration followed by the cake filtration ζobs jumped from ζm to a certain value between ζm and ζc just after the start of the filtration and became almost stable. The zeta potential at the blocked pore, ζb, depended on the gap between surfaces of the blocked pore and the blocking particle and indicated the extent of pore blocking. It was confirmed that the change in ζobs during filtration will reflect both the location of pressure drop and the local zeta potential.