Desulphurization of Dibenzothiophene by Different Bacterial Strains: An Eco-Friendly Approach to Obtain Clean Fuel from Coal

Abstract

Coal is an important energy resource and many deposits contain a significant quantity of organic sulfur compounds. Combustion of coal releases SO₂, CO₂ and other gases into atmosphere and causes negative impact on the environment. Biodesulphurization of dibenzothiophene could be a prominent method for the removal of sulfur from coal. Here we successfully employed bacterial strains to degrade dibenzothiophene, and characterized through chromatography, high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Strains of Ralstonia sp., Pseudoxanthomons sp. and Rhodococcus sp. were used in the present investigation. Only Rhodococcus sp. converted dibenzothiophene (DBT) into 2-hydroxy biphenyl (2-HBP) and was able to additionally break the C-S bond without disturbing heterocyclic structure of DBT ring. This is also complemented by blue color of Gibb’s assay which is indicative of DBT conversion into 2-HBP while brown color indicates complete consumption of DBT by bacteria. After two days of bacterial treatment, there was no further removal of DBT. DBT conversion into 2-HBP was monitored through HPLC during six days of experiment. Thus Rhodococcus sp. could be a proficient candidate for biodesulphurization of dibenzothiophene and eventually for biodesulphurizing organic sulfur rich coal with an eco-friendly and energy economical process. Though it is encouraging technique for desulphurization however more studies on coal are still required to support the industrial scale biodesulfurization.

Keywords:

• Biotransformation
• desulphurization
• dibenzothiophene
• 2-hydroxy biphenyl
• Rhodococcus sp.

Acknowledgements

The authors (ALS and PKS) acknowledge the Departments of Botany and Department of Geology, Banaras Hindu University respectively for the necessary facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Table 1. Comparison of desulphurization using different bacteria by various workers.

Additional information

Funding

The author (AK) thank fully acknowledges the University Grants Commission, New Delhi, India, for extending financial support in form of DSK post-doctoral Fellowship Research Grant [No. F.4-2/2006(BSR)/ES/18-19/0031].