Dispersant NNO is an anionic dispersant: its molecules carry negative sulfonate groups. That charge is how it disperses particles, and it also explains its limits, such as incompatibility with cationic products. This page covers what “anionic” means here and how a dispersant differs from a surfactant used for wetting or washing.
What Makes NNO Anionic
NNO is a sodium naphthalene sulfonate formaldehyde condensate. In water the sodium ions separate and the polymer chain is left with many negatively charged sulfonate groups. Adsorbed on a particle, it gives the particle a negative surface charge.
Dispersant or Surfactant?
| Dispersant (NNO) | Wetting or cleaning surfactant | |
|---|---|---|
| Main job | Keep particles apart in a liquid | Lower surface tension, wet surfaces, remove soil |
| Effect on surface tension | Small | Large |
| Foam | Low | Often high |
| Typical example | NNO, lignosulfonate, MF | Alkyl naphthalene sulfonates, SLES |
NNO is sometimes called an anionic surfactant because it is surface-active, but it does little wetting. For wetting, see sodium alkyl naphthalene sulphonate.
Practical Consequences
- Works across a wide pH range and in hard water.
- Can precipitate or lose effect when mixed with cationic softeners, fixing agents or cationic surfactants. Test compatibility first.
- Adds little foam, which suits dyeing machines and pumped slurries.
Grades
| Grade | Content | Dispersing power (vs. standard) | Sodium sulfate | pH | Other limits |
|---|---|---|---|---|---|
| Grade A (GAC-NNO-A) | 95% min | 95% min | 5% max | 7 – 9 (1%) | Ca + Mg 0.4% max; insolubles 0.05% |
| Grade B (GAC-NNO-B) | 92% min | 90% min | 18% max | 7 – 9 (1%) | Ca + Mg 0.4% max; insolubles 0.05% |
| Grade C (GAC-NNO-C, HG/T 2562-2012) | Not listed | Not listed | 22% max | 7 – 9 (1%) | Water 8% max; free formaldehyde 200 ppm max |
| High-Purity (GAC-NNO-HP) | Solids 93% min | Not listed | Sulphate about 3% | 7.0 – 9.0 (2%) | Free naphthalene <5 ppm; free formaldehyde <50 ppm; quinoline <200 ppm |
Product details: Dispersant NNO product page.
Frequently Asked Questions
Is Dispersant NNO anionic?
Yes. Its sulfonate groups carry a negative charge in water, so it is an anionic dispersant.
What is the difference between a dispersant and a surfactant?
A dispersant keeps particles apart; a wetting or cleaning surfactant mainly lowers surface tension. NNO is a dispersant with little wetting action.
Can NNO be used with cationic products?
Usually not directly: anionic and cationic products can precipitate together. Test compatibility before mixing.
