Biodesulfurization of Dibenzothiophene by Decorating Rhodococcus erythropolis IGTS8 Using Montmorillonite/Graphitic Carbon Nitride

Abstract

Fossil fuels are the main sources of human energy, but their combustion releases toxic compounds of sulfur oxide. In the oil industry, using the optimal methods to eliminate sulfur compounds from fossil fuels is a very important issue. In this study, the performance of montmorillonite/graphitic carbon nitride (a new hybrid nanostructure) in increasing the biodesulfurization activity of Rhodococcus erythropolis IGTS8 was investigated. X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy were used for the characterization of the nanoparticles. The effective factors in this process were determined. Optimum conditions for microorganisms were designed using the Design Expert software. Experiments were performed in a flask. The results indicated that the biodesulfurization activity of a microorganism in the presence of the nanostructure increases by 52%. In addition, in the presence of the nanostructure, the effective factors are: 1. concentration of the nanostructure; 2. concentration of sulfur; 3. cell concentration. In the absence of the nanostructure, the only effective factor is the concentration of sulfur. Through analysis of variance, the proposed models were presented to determine the concentration of the 2-hydroxy biphenyl produced by the microorganisms (biodesulfurization activity) in the presence and absence of the nanostructure. The proposed models were highly acceptable and consistent with experimental data. The results of a Gibbs assay showed that the biodesulfurization efficiency of in the presence of the nanostructure was increased by about 52%, which is a very satisfactory result. The biodesulfurization activity of decorated cells in a bioreactor showed a significant increase compared with nondecorated cells. Almost a two-fold improvement in biodesulfurization activity was obtained for decorated cells compared with free cells.