Sodium dithiophosphate

Sodium dithiophosphate
Identifiers
13721-37-4 YesY
Properties
Na3PS2O2
Molar mass 196.072 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Sodium dithiophosphate is the salt with the formula Na3PS2O2, although the solid is usually encountered as the hydrate. It is also supplied as an aqueous solution together with other thiophosphates. It is a colorless compound, but commercial samples can appear dark owing to the presence of impurities. It is used to facilitate the isolation of molybdenum from its ores.

Preparation

The compound has been prepared in a multistep process starting with the base hydrolysis of phosphorus pentasulfide to give dithiophosphate, which is isolated as its barium salt:[1]

P2S5 + 6 NaOH → 2 Na3PO2S2 + H2S + 2 H2O

The salt is isolated as the hydrate Na3PO2S2.(H2O)11. It is prone to hydrolysis, especially when it is heated as an aqueous solutions:

Na3PO2S2 + 2 H2O → Na3PO3S + H2S

Applications

This salt is used as a flotation agent in molybdenite mineral concentration from ores, where it is usually known as "Nokes reagent." The salt is generated by the reaction of phosphorus pentasulfide with sodium hydroxide, often using impure reagents to obtain a mixture of the desired salt and related thiophosphates and oxidized species. Molybdenite particles, which are normally hydrophobic, become hydrophilic in the presence of this salt. In this context, the Nokes reagent is called a "depressant," since it suppresses the flotation tendency of the solids.[2]

See also

References

  1. R. Klement "Phosphorus" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 571-2.
  2. Baki Yarar, "Flotation" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Wienheim, 2005.
Wikimedia Commons has media related to Sodium dithiophosphate.


This article is issued from Wikipedia - version of the 5/11/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.