The widespread application of DTPMPA is primarily attributed to its three core functional mechanisms: chelation, scale inhibition, and corrosion inhibition. These mechanisms work synergistically to address the key challenges of scaling and equipment corrosion in industrial systems, particularly in water treatment processes. Understanding these functional principles is crucial for optimizing the application of DTPMPA and maximizing its performance.
The chelating mechanism of DTPMPA is rooted in its molecular structure, which contains multiple phosphonic acid groups (-PO₃H₂) and amino groups. These groups act as ligands, binding to the empty orbitals of metal ions to form stable chelates, effectively “locking” free metal ions in aqueous solutions. This process reduces the concentration of metal ions such as calcium and magnesium, preventing them from combining with anions like carbonate and sulfate to form insoluble scales. Moreover, DTPMPA can chelate metal ions in oxide layers, enabling the剥离 of oxides from metal surfaces and achieving rust and scale removal effects.
In terms of scale inhibition, DTPMPA exerts its effect through two main pathways. For carbonate scales, it not only reduces Ca²⁺ concentration via chelation but also disrupts the normal growth of calcium carbonate crystals through lattice distortion. By adsorbing on the active growth points of crystals, it prevents the formation of dense, hard scales, leading to the production of loose flocculent precipitates that can be easily discharged with sewage. For sulfate and barium scales, which are common in oilfield water injection systems, DTPMPA utilizes dispersion to make small scale particles charged, creating electrostatic repulsion to prevent aggregation and growth.
The corrosion inhibition mechanism of DTPMPA involves the formation of a protective film. Its phosphonic acid groups can adsorb onto metal surfaces, forming a dense, stable film that isolates corrosive ions in water from the metal substrate, thereby reducing electrochemical corrosion. When compounded with corrosion inhibitors such as zinc salts and polyphosphates, its corrosion inhibition effect is significantly enhanced, making it suitable for protecting metal pipelines and heat exchangers in circulating cooling water and boiler systems. This multi-functional synergy ensures DTPMPA’s comprehensive performance in industrial applications.