An effective method to remove organic sulfur in coal: Effects on the physicochemical properties and combustion kinetics

The present work investigated an effective method to remove organic sulfur in coal utilizing different microorganisms (Nocardia mangyaensis and Pseudomonas putida). The most obvious finding to emerge from the sulfur forms analysis is that the organic sulfur removal of these two bacterial strains on Yunnan bumuga high-sulfur coal were 61.58% and 54.19%, respectively. This result may be confirmed by the Fourier transform infrared spectroscopy (FTIR) analyses that there were obvious decreases of intensity after biotreatment in the C-S bond. Besides, the results of X-ray diffraction and X-ray photoelectron spectroscopy showed that major mineralogical phases in the forms of kaolinite and pyrite exist in raw coal. And more than 80% of thiophene and sulfoxide in the raw coal were removed by N. mangyaensis and P. putida. In addition, the results of the thermogravimetric analysis indicated that the combustion performance of biotreated coal samples was better than that of raw coal, and the most probable models to describe the combustion kinetics for biotreated coal and raw coal at different stages were obtained by the Arrhenius method and Coats-Redfern method.