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Hydro-cracked light gas oil biodesulphurisation by immobilised Pseudomonas aeruginosa cells on polyvinyl alcohol

Khosh Ravesh Hussein, Sadeghi Soroor, Sharifi Sara

Ecological Chemistry and Engineering. S

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2023

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Vol. 30, nr 4

567--580

EN

Refining petroleum fractions containing heterocyclic sulphur compounds to produce sulphur-free fuels, requires efficient desulphurisation methods. A new biocatalyst has been synthesised by immobilising Pseudomonas aeruginosa cells on polyvinyl alcohol by adsorption for hydro-cracked light gas oil bio-desulphurisation. The surface functional groups and biocatalyst morphology have been investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. The bio-desulphurisation of dibenzothiophene as a heterocyclic sulphur model compound of gas oil was achieved with an aqueous-oil ratio (v/v) of 50 %, where the removed mass was 0.3826 mg per gram of biocatalyst at equilibrium condition, bio-desulphurisation rate of 0.375 h–1 and removal percentage was 95.65 %. The biodegradation of dibenzothiophene and its derivatives in hydro-cracked light gas oil has been determined after a batch process using 0.5 g of the biocatalyst after 5 h of contact time at 37 °C. According to gas chromatography - mass spectrometry, ethyl and trimethyl derivatives of dibenzothiophene have been degraded by higher efficiencies in comparison with other derivatives. Also, thiophenes and mercaptans of the gasoil sample have been degraded simultaneously to some extent. Equilibrium data have been observed to obey the pseudo-first-order kinetic model. The cell immobilisation facilitates the interaction of surface functional groups with sulphur compounds. The synergistic effect of cell immobilisation on the bio-activity of bacterial cells was due to the maintenance of the heterotrophic, bacillus morphology of the cells after immobilisation. This approach provides a simple, economical method with mild operating conditions to produce low-sulphur light gas oil through the biodegradation of heterocyclic sulphur compounds.

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Kinetic analysis for biodesulfurization of dibenzothiophene using R. rhodochrous adsorbed on silica

Canales C., Eyzaguirre J., Baeza P., Aballay P., Ojeda J.

Ecological Chemistry and Engineering. S

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2018

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Vol. 25, nr 4

549--556

EN

Experimental biodesulfurization (BDS) data for dibenzothiophene (DBT) (1.0-7.0 mM) with Rhodococcus rhodochorus immobilized by adsorption on silica, were adjusted with liquid-film kinetic model (Fisher coefficient, F = 592.74 and probability value p << 0.05 and r 2 = 0.97). Simulations predict the presence of considerable amounts of DBT surrounding the particles, which would be available for the cells adsorbed on the surface of silica. The greatest percentage removal (50 %) was obtained for adsorbed cell system over the suspended bacterial cells (30 %), showing that sulfur substrates are more bioavailable when the bacterial cells are adsorbed on silica. The liquid-film modelling with diffusional effects provides proper theoretical basis to explain the BDS performance obtained using adsorbed cells.

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Biodesulphurization of thiophene as a sulphur model compound in crude oils by Pseudomonas aeruginosa supported on polyethylene

Karimi A. M., Sadeghi S., Salimi F.

Ecological Chemistry and Engineering. S

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2017

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Vol. 24, nr 3

371--379

EN

A new biodesulphurization method has been considered using Pseudomonas aeruginosa supported on polyethylene (PE) for biodesulphurization (BDS) of thiophene as an aromatic sulphur model compound of crude oils. Also the biodegradation of thiophene has been modified in the presence of potassium hexacyanoferrate(III) as a terminal electron acceptor to approach the maximum biodesulphurization efficiency. The obtaining results according to UV-Spectrophotometry at 240 nm, 83.3% of thiophene at the primary concentration of 50 mg/dm3, pH = 7, by 0.5 g of biocatalyst in 37°C after 4 h of contact time has been removed. The bacterial cells exhibited a greater and faster biodegradation in the presence of potassium hexacyanoferrate(III) and 94.8% of thiophene has been removed after 3 h of contact time. Kinetic study predicted chemisorption of thiophene on the surface of the biocatalyst, as it followed the pseudo-second-order rate equation. Morphology and surface functional groups of the biocatalyst have been investigated by SEM and FT-IR, respectively.