Surface Charge and Ion Sorption Properties Influencing the Fouling and Flow Characteristics of Ceramic Membranes

Abstract

Ion exchange and sorption characteristics of a range of calcined oxides which constitute the active layers of ceramic membranes have been determined using new automated titration methods employing ion selective electrodes. The effects of pH and salt concentration on exchange capacities have been evaluated and explained mechanistically. These were shown to be consistent with the exchange mechanisms of non-calcined oxides determined previously (1-6). The sign of the surface charge and the exchange capacities for each counterion may be altered in a predictive way, by changing the pH and the activity of the sorbing ion. The effects of altering pH and salt concentration on the flow characteristics of whole ceramic membranes have been determined. Studies on the minimisation of fouling by charged substrates on ceramic membranes have been initiated, with promising results.