Acid dye dissolution method

Acid dyes usually contain hydrophilic groups such as sulfonic acid groups (-SO₃H). In theory, they are easily soluble in water, but in some cases, they may be difficult to dissolve (such as high water hardness, pH mismatch or dye structure differences). The following are solutions.

1. Adjust pH (acidic conditions)

Principle: Acid dyes are more soluble in acidic environments with a pH of 2-6, and the dissociation of sulfonic acid groups is enhanced, which enhances hydrophilicity.

Method: Add a small amount of weak acid (such as acetic acid, formic acid) or acid salt (such as ammonium sulfate) to adjust the solution to slightly acidic.

2. Use organic solvents to assist dissolution

Applicable situations: If it is difficult to dissolve in water, you can try organic solvents that are miscible with water:

Ethanol, methanol: Mix with water (such as 30%-50% ethanol solution) to improve solubility.

Acetone, DMSO: Effective for some complex structure dyes, but compatibility needs to be tested.

3. Heating to promote dissolution

Method: Appropriate heating (such as 40-60°C), but high temperature should be avoided to cause dye decomposition.

Note: Some dyes may be sensitive to temperature, please refer to the product instructions.

4. Add surfactants or dispersants

Function: Reduce surface tension and help disperse dyes.

Common reagents:

Anionic surfactants (such as sodium dodecyl sulfate, SDS).

Nonionic surfactants (such as Tween series).

Dispersants (such as lignin sulfonates).

5. Use cosolvents

Urea or thiourea: destroy hydrogen bonds between dye molecules and improve solubility.

Ethylene glycol, glycerol: polar solvents that enhance the solubility of water systems.

6. Pre-treat water quality

Hard water softening: If the water hardness is high (containing Ca²⁺, Mg²⁺), EDTA or sodium citrate can be added to chelate metal ions to prevent dye precipitation.

If you want to know more about dyeing solutions, please contact: info@tiankunchemical.com