Concept of the development of scale inhibitors

Abstract

Referring the inhibition effect of polyacrylic acid (PAA) against the formation of calcium carbonate scale, a concept for search of silica scale inhibitor was tried to build up. To elucidate the inhibition mechanism of PAA, the interaction between calcium ion (Ca2+) and PAA was investigated. It was found that only slight complexation of Ca2+ to carboxyl groups (COOH) occurred, suggesting that the inhibition may possibly be caused by inhibition of growth of nuclei due to adsorption of PAA on its surface. For the formation of silica scale, two models for the nuclei of silica scale were designed: (1) aluminum hydroxide (Al(OH)3) with positive surface charges and (2) silica containing the trace amount of Al with negative surface charges. According the properties of nuclei of silica scale, two polymer reagents (acumer 5000 and tiron type DADMAC) were selected as silica scale inhibitors.