Production of Sodium Sulfide Depending on the Local Conditions

Archive of SID

17th Iranian Chemistry Congress Vali-e-Asr University of Rafsanjan 1-3 september 2014

Amir Seraji,* Fatemeh Teimouri

Department of Chemistry, Islamic Azad University- Saveh Branch, P. O. box 39187-366, Saveh, Iran. [email protected]

Background: Sodium sulfide (Na2S) is the most important and applicable compound among alkali and alkaline earth sulfides. Na2S is used in a process for producing poly (phenylene sulfide) and polysulfide polymers. It also is used in reduction of polynitroaromatics and in engine oils [1]. In the laboratory,

anhydrous Na2S can be prepared by reaction of sulfur with sodium in anhydrous ammonia or in dry THF with a catalytic amount of naphthalene [2]:

2 Na + S → Na2S

◦ Industrially Na2S is produced by reduction of sodium sulfate with carbon, in the form of coal at 700- 900 C [3]:

Na2SO4 +2C→Na2S+2CO2

Methods: In this research we wish to report optimized process for the synthesis of Na2S using Na2SO4 and coal. Raw materials of the reaction are grinded very well in mortar which pass trough sieve with mesh 100.

The mix of Na2SO4 and coal is heated in electrical furnace. After evolution of CO2 and CO begins the reaction mass becomes very fluid on further heating, it becomes pasty and finally solid. The produced sodium sulfide that contains excess carbon, ash components and other solid impurities is leached with water, and the undissolvable components are removed by filtration. The filtrate is concentrated by evaporation and solidifies by cooling.

◦ Results: Optimized weight ratio of Na2SO4 to coal was 3.94:1. Best yield obtained at 800 C for 2 hours. In leaching step weight ratio of water to solid product mass was 2.4:1. Purity of the evaporated final product was 60% and solidification temperature was 90 ◦C.

Conclusion: In summary, we found an economical and locally dependent procedure for production of Na2S. The features of this method are high yields, operational simplicity and the environmentally friendly method.

Keywords: Sodium sulfide; Sodium sulfate; Coal; Leaching.

References

[1] Schmidt M., Inorg. Macromol. Rev. 1970, 1, 101-113. [2] So J.-H., Boudjouk P., Hong H. H., Weber W. P., Inorg. Synth. 1992, 29, 30-35. [3] Bellussi G., Bohnet M., Bus J., Drauz K., Ullmann's Encyclopedia of Industrial Chemistry, John wiley & sons 1999,17.