What are the uses and functions of chelating dispersants?

Chelating dispersants are multi-purpose organic chelating agents that perform dual functions by complexing metal ions and dispersing inorganic precipitates. They are widely used in textile printing and dyeing, water treatment, and industrial cleaning.

Basic Definition and Chemical Properties

Chelating dispersants are chemical agents composed of polyvalent organic compounds. They appear as white powders or pale yellow liquids and are readily soluble in water, with a pH typically ranging from 5.5-6.5 (1% aqueous solution). Their molecular structure contains multiple ligands that bind metal ions like "crab claws" to form stable complexes.

Core Mechanism of Action

Metal Ion Chelation: Effectively complexes metal ions such as Ca²⁺, Mg²⁺, and Fe³⁺ in water, preventing them from reacting with dyes and auxiliaries to form insoluble precipitates.

Inorganic Dispersion: Through charge repulsion and steric hindrance, they prevent existing deposits such as silica scale and calcium soap from reattaching to equipment or fabric surfaces. ‌

Main Application Areas

‌Textile Printing and Dyeing

Pretreatment Processes

‌- Desizing: Complexes iron ions to protect the desizing enzyme activity and prevent film hardening. ‌

- Bleaching: Controls the decomposition rate of hydrogen peroxide, reducing the rate of defective products due to holes by over 30%. ‌

‌Dyeing Process

- Acts as a leveling agent to prevent dye aggregation, improving color fastness by 0.5-1 levels. ‌

- Complexes metal ions in hard water to ensure color stability of reactive dyes. 

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‌Industrial Water Treatment

‌Boiler Scale Inhibition: Dissolves calcium carbonate scale at a pH of 8-10, extending equipment cleaning cycles by 3-5 times. ‌

‌Cooling Water Systems: Simultaneously achieves corrosion and scale inhibition, reducing chemical usage by 20%-40%.