Profound “turn-off” effects of anionic polymers on the inhibitory activity of cationic polyallylamine in the prevention of silica scale

• A. Spinthaki, A. Stathoulopoulou and K. D. Demadis

Crystal Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete, Voutes Campus, Crete, GR -71003, Greece

Abstract: Colloidal/amorphous silica (SiO2·nH2O, n is variable) is considered as the most undesirable inorganic precipitate that forms during various processes in silica-supersaturated industrial waters. In this paper we present how certain polymeric chemical additives can prevent silicic acid polymerization to form colloidal silica, which may lead to deposition onto industrial equipment. More specifically, stabilization of silicic acid is accomplished by using a cationic polymer, polyallylamine hydrochloride (PALAM), in supersaturated silica solutions (starting silica concentration in the form of silicate 500 ppm, or 8.3 mM sodium orthosilicate, Na2SiO3·5H2O, expressed as SiO2) at pH = 7. PALAM is a linear homopolymer that carries one amine side functional group every two carbon atoms, so it becomes protonated at circumneutral pH, rendering the molecule cationic. Its blends with anionic polymers such as carboxymethylinulin (CMI), poly(acrylamide-co-acrylic acid) (PAM-co-AA) and phosphonomethylated chitosan (PCH) are also studied for their silica scale inhibition efficiency.

Keywords: silicic acid stabilization, silica, inhibitors, deposits, water systems, inhibitors, polyallylamine, carboxymethylinulin, polymers

Int. J. Corros. Scale Inhib., 2015, 4, no. 1, 85-95 PDF (431 K)
doi: 10.17675/2305-6894-2015-4-1-085-095

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