Various trivia about scale inhibitors

With the widespread use of scale inhibitors, many different types and properties of scale inhibitors have been produced to meet the needs of various industries, providing convenience for our use. To facilitate selection, we need to understand their types.

　　1. Polycarboxylic acid scale inhibitors and dispersants
　　Polycarboxylic acid compounds have a good scale-inhibiting effect on calcium carbonate scale, and the dosage is also very small. Commonly used ones include polyacrylic acid (PAA), hydrolyzed maleic anhydride (HPMA), AA/AMPS, and multi-component copolymers.

　　2. Organic phosphonates
　　Organic phosphonates are effective in inhibiting calcium sulfate scale, but less effective in inhibiting calcium carbonate scale. They have low toxicity and are easily hydrolyzed.

　　3. Organic phosphonic acid scale inhibitors
　　Commonly used ones include ATMP, HEDP, EDTMPS, DTPMPA, PBTCA, and BHMT, which are very effective in inhibiting the precipitation or deposition of calcium carbonate, hydrated iron oxide, or calcium sulfate.

　　4. Polyphosphates
　　Commonly used polyphosphates include sodium tripolyphosphate and sodium hexametaphosphate. They generate long-chain anions in water that easily adsorb onto tiny calcium carbonate crystals. These anions also readily replace CO32-, thus preventing the precipitation of calcium carbonate.

Mechanism of scale inhibition

1. Complexation and solubilization: After dissolving in water, the copolymer ionizes to form negatively charged molecular chains, which form water-soluble complexes or chelates with Ca2+, thereby increasing the solubility of inorganic salts and achieving scale inhibition.

　　2. Lattice distortion: Some functional groups in the molecule occupy certain positions on the inorganic salt nuclei or microcrystals, hindering and disrupting the normal growth of inorganic salt crystals, slowing down the crystal growth rate, and thus reducing scale formation.

　　3. Electrostatic repulsion: After dissolving in water, the copolymer adsorbs onto the microcrystals of inorganic salts, increasing the repulsive force between the particles, hindering their aggregation, and keeping them in a well-dispersed state, thus preventing or reducing scale formation.

　　Therefore, scale inhibitors can effectively disperse insoluble inorganic salts, and the chemicals in them can effectively hinder the aggregation of scale, thus achieving the effect of scale inhibition. They also have great development prospects in industry.

Performance of scale inhibitors

Scale inhibitors have a scale-inhibiting effect because they prevent the growth of small carbonate crystals and cause lattice distortion, preventing carbonates in circulating cooling water from forming hard scale on the heat exchanger surface. Also, due to the characteristic of organic phosphates and other components in their composition forming a protective film with metals, they can combine with calcium ions in circulating cooling water to prevent metal corrosion.

Understanding the performance of scale inhibitors allows for their widespread application in various industries, enabling their full potential to be utilized. With continuous technological advancements, the performance of scale inhibitors is also constantly improving, expanding the range of applications and promoting the development of scale inhibitors.