Enhancement of bunker oil biodesulfurization by adding surfactant

Abstract

Biodesulfurization (BDS) is a promising method to remove sulfur compounds from diesel and gasoline. However, the information on BDS of heavy oil is scanty, which might be due to their "undesirable" physical properties and more complicated sulfur diversities. In this study, the BDS of one kind of heavy oil, bunker oil MFO380 was investigated. The biocatalyst was obtained by the enrichment with oil sludge as the seed and using dibenzothiophene (DBT) as the sole sulfur source. The enriched biocatalyst (microbial mixed culture) could selectively remove sulfur from DBT and DBT was transformed into 2-hydroxybiphenyl, which indicates that the BDS process is beneficial to non-destructive carbon bonds and thus can maintain the calorific value. The bunker oil BDS results showed that after 7 days of incubation, the removal efficiency of sulfur in MFO380 was only 2.88 %, but this could be significantly improved by adding surfactants Triton X-100 or Tween 20. This effect could be attributed to greatly reduced viscosity of heavy oil and increased mass transfer of sulfur compounds in heavy oil into water. Adding Triton X-100 achieved the highest removal efficiency of sulfur, up to 51.7 % after 7 days of incubation. The optimal amount of Triton X-100 was 0.5 g/50 ml medium. When toluene was added as an organic solvent for MFO380, the BDS activity was improved, while lower than the effect of adding surfactants.

Biodegradation of dibenzothiophene and its application in the production of clean coal

“…The growth of the M6 sulphur reducing bacteria was not hampered significantly in the presence of surfactants during this study and the rate of biodesulphurization of Bunker-C oil was also greater in the presence of the non-ionic surfactant [116]. A similar study was carried out by Li and Jiang [117] to increase the biodesulphurization of bunker oil by the addition of surfactant. They carried out separate experiments for the biodesulphurization of bunker oil MFO380 in the simultaneous presence of 2 different surfactants (Tween 20 and Triton-100 ×) and a biocatalyst enriched with oil sludge and DBT as the sole sulphur source.…”

Isolation and classification of a soil actinomycete capable of sulphur-specific biotransformation of dibenzothiophene, benzothiophene and thianthrene

“…), Klebsiella sp. 13T (Bhatia and Sharma ) and a bacterial consortium (Li and Jiang ) are few examples of desulphurization strains obtained using the enrichment technique.…”

Metabolic and process engineering for biodesulfurization in Gram-negative bacteria

“…or Triton X-100 was found to be essential for the sulfur removal in bunker oil (Li and Jiang, 2013). Other surfactants, such as Tween 80, have also been satisfactorily used in BDS (Feng et al, 2006).…”