Sequential desulfurization of thiol compounds containing liquid fuels: Adsorption over Ni-doped carbon beads followed by biodegradation using environmentally isolated Bacillus zhangzhouensis

Abstract Desulfurization of liquid fuels over a wide concentration range continues to be challenging. This study recommends a novel hybrid route to efficiently desulfurizing the thiols or organosulfur compounds containing liquid fuels. The tests performed on the dibenzothiophene (DBT) and thiophene (TH) containing n-octane over sulfur concentration range 300–1200 mg/L showed adsorptive desulfurization followed by the bacterial treatment to be efficient in decreasing the concentration level to 3–15 mg/L at 30 °C and 1 atm pressure. Adsorption performed using the Ni nanoparticles-dispersed porous carbon beads of ~ 0.8 mm size was effective at relatively higher concentrations. Upon nearly saturation in the adsorption step, further removal of the thiol compounds to low concentrations was possible by bacterial degradation using Bacillus zhangzhouensis isolated from the wastewater effluent of a petroleum industry. Fresh and spent adsorbents were characterized using various analytical techniques. Bacterial characterization involved the Christian gram staining and 16S  rRNA sequencing. The data demonstrate for the first time ~ 99% removal of the thiol compounds, at rates faster than adsorption alone. The proposed sequential approach in this study can be effective in meeting the globally ever increasing stringent regulations for low sulfur content in fuel oils.