Abstract
This paper addresses the precipitation of calcium phosphate from aqueous solution at pH 8.50 and 50°C. The aim of the study was to investigate the role of cationic polymer (CP) on the performance of several anionic calcium phosphate inhibiting polymers.The anionic polymers studied include poly (acrylic acid), P-AA; poly (maleic acid), P-MA; poly (acrylic acid: 2-acrylamido-2-methylpropane sulfonic acid: sulfonated styrene), P-AA:SA:SS; poly (maleic acid:sulfonated styrene), P-MA:SS; and poly (acrylic acid: 2-acrylamido-2-methylpropane sulfonic acid), P-AA:SA. It has been found that addition of low concentration (from 0.5 to 1.5 ppm) of cationic polymer has a marked antagonistic effect on the performance of polymers in terms of inhibiting calcium phosphate precipitation. The inhibition data of several polymers indicate that the performance of the polymers depends upon the functional group. The overall ranking of polymers in terms of CP tolerance is: P-AA:SA:SS>P-AA:SA>P-MA:SS>> PAA~PMA.
