BACTERIAL SULFATE PRODUCTION BY BIODESULFURIZATION OF AROMATIC-HYDROCARBONS, DETERMINED BY ION CHROMATOGRAPHY

The use of bacteria to remove sulfur from crude oil or petroleum disti llates is a novel concept that presents an alternative biotechnology t o the current technology of hydrodesulfurization (HDS). Sulfur must be removed from crude oils prior use. The burning of fossil fuels contai ning sulfur releases sulfur dioxide into the atmosphere causing acid r ain. The aim of this work is to determine the sulfate concentration by ion chromatography (IC), and calculate the percentage of transformati on of organic bound sulfur, that is converted to sulfate, and estimate the efficiency of bacteria in desulfurization. IC is a suitable metho d for sulfate concentration determination. However, when chloride conc entrations are significantly high, interference of the sulfate signal does occur. In this case, it could be avoided by diluting samples. A D ionex Model 2000i/SP IC system, with an anionic pre-column (Dionex AG4 A), an anion separator column (Dionex AS4A), a suppresor column (Dione x AMMS-II), and a conductivity detector was used. The eluent (21 mM Na OH) and regenerant (electrolyzed 18 M Omega/cm water) flow-rates were 1.0 and 2.0 ml/min, respectively. The sample loop volume was 10 mu l a nd the conductivity sensitivity was 30 mu S. The diluted samples were filtered through a 0.45-mu m filter before injection. The highest sulf ate concentration detected was 24.10 mg/l, corresponding to a maximal conversion rate of 10% in a month. Sulfate ions were not detected in c ontrol samples. The correlation coefficient for a linear least squares fit was 0.99 (p<0.001). The minimal concentration that we can read wa s 0.02 mg/l and this concentration corresponded to the limit of detect ion obtained under the conditions employed in this study. IC is an eco nomical, sensitive and accurate way to estimate the sulfate concentrat ions in microbiological samples. (C) 1998 Elsevier Science B.V. All ri ghts reserved.