INHIBITION AND CONTROL OF COLLOIDAL SILICA: CAN CHEMICAL ADDITIVES UNTIE THE 'GORDIAN KNOT' OF SCALE FORMATION?

摘要

Colloidal silica is one of the most unwanted deposits in the water treatment industry. Its control is a complicated issue and the decision on which control method to apply is frequently based on a number of factors. Our goal is the discovery, design and application of organic additives (preferably “green” and environmentally friendly) that have some effect on silicate polymerization. This paper reports the inhibition efficiency of a variety of polymeric additives and some combinations in retarding silicate polymerization is supersaturated aqueous solutions. There are three classes of polymeric additives studies: (1) neutral, (2) cationic of varying positive charge density, and (3) combinations of anionic and cationic polyelectrolytes. As a neutral polymer PEOX (poly(2-ethyl–2–oxazoline)) was tested. Cationic additives included PEI (polyethyleneimine),PALAM (polyallylamine)and PAMALAM (poly(acrylamide-co-diallyl-dimethylammonium chloride)). Blends of cationic/anionic polymers were PEI+CMI (CMI = carboxymethylinulin), PEI+PAA (PAA = polyacrylate)). All aforementioned additives and/or blends exhibited inhibition features from “good” to “excellent”. Inhibition efficiency was found to depend on a multitude of factors, such as cationic charge density, inhibitor dosage, time, etc.