Model description of dibenzothiophene mass transfer in oil/water dispersions with respect to biodesulfurization

• Published in: Biochemical engineering journal 2003, Vol.16 (3), p.253-264
• Main Authors: Marcelis, C.L.M, van Leeuwen, M, Polderman, H.G, Janssen, A.J.H, Lettinga, G
• Format: Article
• Language: English
• Subjects: Bacteria; Biodesulfurization; Biological and medical sciences; Bioreactor; Biotechnology; crude-oil; desulfurization; Dibenzothiophene; drop breakup; Fundamental and applied biological sciences. Psychology; hydrocarbons; hydrodesulfurization; Mass transfer; microbial desulfurization; middle-distillate; Mixing; Modeling; selective desulfurization; sp strain p32c1; sulfur; tank; Viscosity
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/S1369-703X(03)00041-X

A mathematical model was developed in order to describe the mass transfer rate of dibenzothiophene within the oil droplet to the oil/water interface of droplets created in a stirred tank reactor. The mass transfer rate of dibenzothiophene was calculated for various complex hydrocarbon distillates and model solvents in the temperature range of 20–60 °C, at volume fractions of oil of 10 and 25% (v/v). The viscosity of the various oil phases used appeared to be the most critical physical parameter governing the dibenzothiophene mass transfer rate, while density and interfacial tension were found to be of minor importance. Based on the model calculations, we estimated that the mass transfer rate of dibenzothiophene within the oil droplet to the oil/water interface is at least a factor 10 up to 10 4 higher compared to experimentally determined specific dibenzothiophene conversion rates. Due to the prevailing mass transfer resistance from the oil/water interface to the bacterium it is essential to maximize the specific surface area to enhance the surface contact between the bacteria and the oil droplets. The microbial desulfurization rate is the overall rate-limiting process step.