The earliest scale inhibitor dispersant is polyacrylic acid (sodium), which has good scale inhibition properties for calcium carbonate scale, but has a very low inhibitory effect on calcium phosphate deposition. Such a polycarboxylic acid type scale inhibitor not only has agglomeration and dispersion, but also causes lattice distortion of the crystal during growth, thereby hindering the firm deposition of the scale layer on the metal heat transfer surface. It was later found that the acrylic copolymer was excellent in suppressing both, and thus gradually replaced polyacrylic acid (sodium). The organic polyphosphonate is an anionic corrosion inhibitor and a non-stoichiometric chelating scale inhibitor. It not only has a significantly low limiting effect on calcium, magnesium, zinc, iron and other ions, but also has synergistic effects on other agents. Used in cooling water treatment. Organic phosphonates are cationic corrosion inhibitors, and the scale inhibition mechanism is mainly lattice distortion. It is a corrosion inhibitor for metallic iron, but also has the effect of controlling calcium scale; the amount is smaller than that of phosphonate and can be hydrolyzed, so there is no accumulation of drug amount and sewage problem, and the hydrolyzed product can be biodegraded.
Since the 1980s, new products of sulfonate groups and phosphate group copolymers have been developed, which have excellent scale inhibition and dispersion properties and have a certain inhibition effect. Liang Haiyan et al. synthesized a copolymer containing a phosphine group, a carboxyl group and a sulfonic acid group. It combines the advantages of organic phosphonic acid, carboxylic acid and sulfonic acid groups. It has good resistance to calcium carbonate scale and calcium phosphate scale in water, and good particle dispersibility. It can be considered as a multifunctional agent. It can be widely used in industrial circulating cooling water and boiler water in industries such as steel, metallurgy and chemical industry.