Point of Zero Charge and Isoelectric Point of Alumina

摘要

The point of zero charge, pH_(pzc), and the isoelectric point, pH_(iep), of a commercial alumina sample was investigated in KNO_3 solutions. The influence of the concentration and the initial pH value of KNO_3 solution used for preparation and equilibration of the alumina suspension, as well as of the alumina/solution ratio on pH_(pzc). and pH_(iep) were investigated. The obtained results indicate that pH_(iep) values are dependent on initial pH values of KNO_3 solutions used for equilibration of alumina suspensions. Simultaneously with isoelectric point determination, the particle size of alumina was also measured. It was shown that the particle size of alumina increases with increasing suspension pH due to agglomeration, reaching the maximum value at pH_(iep).