Characterisation of the secondary properties of alumina - Measuring the isoelectric point by a streaming potential method

The isoelectric points (IEP) of different alpha-alumina powders in aqueous suspensions have been determined by a streaming potential method in combination with an acid-base titration. The results show that the IEP of a suspension can be characterised with good accuracy. That of pure alumina was measured to be 9,30 (0,07). The measurement of suspensions containing citric acid led to a determination of the citric acid saturation Value for different aluminas between 3,0 and 5,2.10(-4) g/m(2). The values are in reasonable agreement with literature data.