Chemical | Sodium Hydroxide (NaOH)

Sodium hydroxide (NaOH) as an aqueous solution, also known as Caustic Soda or lye, is used for industrial processes in different concentrations. It is typically produced in concentrations of 48.0 % to 50.0 %, which can be easily measured with an Anton Paar refractometer.

Caustic soda is a strong alkali (base). It is used as flakes, granules or as an aqueous solution. NaOH is used in many industries:

  • Pulp and paper: for bleaching processes and to separate lignin from cellulose fibers
  • Chemical processing: for downstream products, e.g. solvents, plastics, fabrics, adhesives, herbicides, dyes, inks, pharmaceuticals
  • Textiles: in polyviscose fiber production, cotton and dye processing, synthetic fibers
  • Soap and detergents: in saponification (converting fat, tallow and vegetable oils into soap) and to manufacture anionic surfactants
  • Petroleum exploration and processing: as an additive in drilling mud, to increase alkalinity in bentonite mud systems, to neutralize acid gas
  • Food and beverage: water treatment, food processing, cleaners for beverage bottles

Conventional concentration determination of sodium hydroxide solution is done by titration, which is a time-consuming and labor-intensive process. Additionally, sodium hydroxide’s hygroscopic behavior can lead to changes in concentration over the time taken to complete titration. The longer the titration process, the greater the deviations in concentration could be. Reduced accuracy of the concentration measurement would be the result.

Instead of titration, the easy-to-use refractometers from Anton Paar can be used for content determinations (g/100 g or % mas) of sodium hydroxide in water within seconds. Abbemat refractometer from Anton Paar directly shows the concentration of NaOH within seconds. By using a micro flow cell made of perfluoro-alkoxy alkane, which is resistant to strong acids, only some microliters of the sample are required. This reduces the costs of waste disposal and the process is more environmentally-friendly compared with conventional titration.

Get the document

To receive this document please enter your email below.