Microfiltration of micro-sized suspensions of boron-selective resin with PVDF membranes

In this paper microfiltration (MF) separation of fractionized ion exchange Amberlite IRA743 resin from aqueous solutions using polyvinylidene fluoride membranes with the pore sizes of 0.1, 0.22 and 0.45 μm was studies. The effect of membrane pore size, transmembrane pressure, pH and concentration of the resin suspensions, presence of NaCl, MgCl2 and Na₂SO4 salts on permeate flux has been evaluated. It was shown that the dominant membrane fouling mechanism during MF of the resin suspensions is formation of a cake layer from deposited resin on the membrane surface. The flux declines with increasing operating pressure and suspension concentration, while it increases with the presence of inorganic salts and feed pH. Changes in zeta potential of resin particles and the membranes as well as agglomeration and electroviscous effects should be considered while analyzing these findings. It was shown that the resin particles after boron sorption can be efficiently regenerated and reused in combined adsorption-microfiltration (AMF) process of boron removal from water, however a sharp drop in membrane flux during MF separation of the resin suspension should be further addressed to develop the efficient AMF procedure.