Electrokinetic property of ZrO2/cordierite composite MF membrane and its influence on the permeate flux

摘要

ZrO2/cordierite composite microfiltration (MF) membrane was prepared by the combination of extrusion and slip casting techniques. The electrokinetic properties of as-prepared membrane were characterized by streaming potential measurements operated in tangential microfiltration mode. The influences of pH, electrolyte species and concentrations of filtered solutions on the electrokinetic properties and permeate flux were investigated. Results show that the streaming potentials are dependent on the pH, types of the electrolyte and concentrations of filtered solutions. The isoelectric point (IEP) of membranes moved from 4.2 to 5.4 with different types of 10~(-3) M electrolyte solutions. The change of ionic concentration of NaCl solution does not alter the IEP of the membranes, but does make the streaming potential tend to be zero at high salt concentration. The specific adsorption of Ca~(2+) and SO_4~(2-) ions in CaCl_2 and Na2SO4 solutions onto the pore wall can alter the IEP and the net charge sign of the membrane. The as-prepared ZrO2/cordierite membrane shows a maximal permeate volume flux near the IEP.