NNO stands for sodium naphthalene formaldehyde oxidized, which is a type of sodium naphthalene formaldehyde (SNF) that has been oxidized or aged.

Some key points about dispersant NNO:

  • It is produced by controlled oxidation of SNF under alkaline conditions using oxidizing agents like sodium hypochlorite or hydrogen peroxide. This leads to some sodium naphtholate groups being converted to sodium carboxylate groups.
  • Oxidation makes the molecule more hydrophilic and enhances its wetting and dispersing power in aqueous solutions.
  • NNO dispersants are more efficient than regular SNF, needing lower concentrations to disperse particles. They have greater compatibility with other formula components.
  • The oxidation renders NNO dispersants anionic, giving them added substantivity towards positively charged surfaces. This improves absorption and retention on surfaces.
  • Key applications of NNO are as dye dispersants in textile dyeing, dispersants for pigments and pesticides, and in building materials like cement to disperse silica particles.
  • In mining, NNO is used to disperse clays, silts and other gangue particles to help separate ores by froth flotation. It prevents their aggregation.
  • In detergents, NNO dispersants help prevent redeposition of dirt particles and soils during washing.