Metal silicate deposits have been noted in several water treatment facilities, but they are more common in geothermal systems. Herein, chemical approaches for the inhibition of metal silicate formation will be presented, focusing on two silicate scales, namely, magnesium and aluminum silicate. First, results will reveal the true nature of these scales. Then, results will be presented on the inhibitory effect of several chemical additives. The additives evaluated are (poly)phosphonic acids. They are PBTC (2-phosphonobutane-1,2,4-tricarboxylic acid), HEDP (hydroxyethylidene-1,1-diphosphonic acid), AMP (amino-tris(methylenephosphonic acid)), HDTMP (hexamethylenediamine-tetrakis (methylenephosphonic acid)) and BHMTPAMP (bis- hexamethylenetriamine-pentakis(methylenephosphonic acid)). Possible structure/function relationships are discussed that lead to the mechanism of inhibition, which is based on Mg2+ or Al3+ chelation by the anionic phosphonate additives.

Subject
Acids, Precipitation (solids), Precipitates, Additives, Aluminum, Phosphonates, Silicates, Dosages, Silica, Acidity, Solutions, Corrosion inhibitors, Magnesium
Keywords:
magnesium silicate, aluminum silicate, deposition, scale, water treatment, inhibition, phosphonates, additives
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2019
Association for Materials Protection and Performance (AMPP)
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