Amino Trimethylene Phosphonic Acid (ATMP) is one of the most widely used organophosphonates in industrial water treatment. Its structure consists of a central nitrogen atom bonded to three phosphonic acid groups ($-\text{CH}_2\text{PO}_3\text{H}_2$), giving it exceptional chelating ability and strong threshold scale inhibition properties.

Technical Specifications

Items	Index
Items	Standard	Solid
Appearance	Clear, Colorless to pale yellow aqueous solution	White crystal powder
Active content, %	50.0min	95.0min
Chloride (as Cl^-), %	1.0 max	1.0 max
pH (1% water solution)	2.0 max	2.0 max
Fe, mg/L	20.0max	20.0max
Density (20℃), g/cm³	1.30 min	-

Key Features & Mechanisms

Threshold Effect: ATMP operates far below stoichiometric ratios. Even at very low dosages (sub-ppm to a few ppm), it adsorbs onto active crystal growth sites, distorting the crystal lattice and stopping calcium carbonate scale from hardening onto equipment walls.
Multi-Ion Chelation: It forms stable hexadentate complexes with divalent and trivalent metal ions like $\text{Ca}^{2+}$, $\text{Mg}^{2+}$, $\text{Fe}^{3+}$, and $\text{Zn}^{2+}$, keeping them solubilized.
Corrosion Inhibition: Works synergistically with zinc salts and chromates/molybdates to form a thin, protective passivating film on carbon steel surfaces.
Limitation (Chlorine Sensitivity): Unlike HEDP or PBTC, ATMP is vulnerable to degradation by free chlorine and oxidizing biocides, which cleave the central $\text{C}-\text{N}$ bond.

Primary Applications

1. Industrial Circulating Cooling Water

Used as a primary scale and corrosion inhibitor in thermal power plants, petroleum refineries, and HVAC cooling towers operating under moderate water hardness and alkalinity.

2. Boiler & Oilfield Water Systems

Oilfield Injection: Prevents calcium scale formation in produced water and reinjection wells.
Low-Pressure Boilers: Controls scale deposits on heat exchanger tubes, often blended with polycarboxylic acid dispersants (like PAA or MA/AA).

3. Textile Processing & Bleaching

Serves as a chelating stabilizer in hydrogen peroxide bleaching baths, complexing trace heavy metal ions ($\text{Fe}^{3+}, \text{Cu}^{2+}$) that otherwise trigger catalytic decomposition of peroxide and damage fabric fibers.

4. Detergent & Metal Finishing

Functions as a metal cleaning agent, scale builder, and de-rusting additive in heavy-duty industrial cleaners and printed circuit board (PCB) processing baths.