جستجوی مقالات مرتبط با کلیدواژه "گوگردزدایی زیستی" در نشریات گروه "مهندسی شیمی، نفت و پلیمر"

Biological desulfurization by microorganis msisasuit able method to remove sulfur containing compounds from fossil fuels.The aim of the present research was to introduce indigenous microorganisms with the ability to biologically remove of sulfur.In order to isolating native microorganisms, oil contaminated soil samples taken from Abadan oil refinery were transferred to the microbiology laboratory.Enrichment of oil-contaminated soil samples was performed during 4 subcultivations in BSM medium with 0.5 mM DBT as the only source of sulfur during which 20 bacterial isolates were obtained.Superior isolates were selected based on growth rate and turbidity caused by the consumption of DBT.In order to investigate the possible metabolic pathway of desulfurization in isolates, the most common metabolic pathway of desulfurization, i.e. 4S pathway, was tracked through the Gibbs assay, and the production of blue color could confirm the existence of this pathway in microorganisms.GC-MS method was used to check the amount of dibenzothiophene reduction.Isolates BDS9, BDS18 and BDS37 were able to remove 95.7%, 95.5% and 86.5% of DBT over a period of 72 hours, respectively.

In bio-desulfurization (BDS) process, microorganisms are used for fossil fuel sulfur elimination. The goal of this project is the isolation of thermophilic microorganisms which are able to support bio-desulfurization activity from DBT as the sole sulfur source and to find an optimized media culture for growth and bio-desulfurization activity. To identify the cell growth and bio-desulfurization activity, Basal Salt Medium containing DBT has been used. For optimization of the culture medium, different carbon and nitrogen sources and also different concentrations of sulfur source were used. Moreover, the findings illustrate that the maximal cell growth was achieved after 96 h incubation. In addition, the Gibbs results have shown that this strain eliminates the sulfur in DBT by 4S pathway and 2-hydroxybiphenyl, as the end product of the desulfurization process has been produced at the maximal concentration (26.1 mg/L) at 72 h. Finally, the results of research illustrate that the isolated thermophilic strain is capable of eliminating sulfur in DBT, and this process may be improved by optimizing the culture media.

Nowadays، due to environmental concerns، there has been great attention to recycling and reclaiming of tires. Different methods have been used for reclaiming or desulfurization of rubber. One of these methods، in which desulfurization of rubber happens with no damage to the polymer structure، is desulfurization by biological microorganisms. In this research the application and performance of thermophilic and sulfur oxidizing bacteria، Acidianus brierleyi for this purpose was investigated. Ground tire rubber was detoxified with organic solvents، and the optimum conditions for growing microorganisms in the existence of rubber powder in the shaker flasks were determined. In order to accelerate the process، the suitable conditions for growth of bacteria and desulfurization in the bioreactor were adopted. Fourier transfer infrared spectroscopy and scanning electron microscopy were employed to characterize desulfurization of bio-treated powder from bioreactor. The results indicated that morphological changes on powder surface and reduction of sulfur bonds have occurred. Samples from bioreactors، with and without bacteria and also untreated rubber powder were compounded with virgin styrene butadiene rubber. Tensile and dynamic properties were investigated using uni-direction tensile test and dynamic-mechanical-thermal analysis، respectively. Although some differences in dynamic-mechanical-thermal properties of samples pointed to stronger interaction between rubber matrix and treated rubber powder، no significant improvements in the mechanical properties of vulcanizates containing A. brierleyi-treated powder were observed. Low concentration of sulfur in rubber vulcanizates، chemical bonds of sulfur، and low efficiency of A. brierleyi in breaking sulfur bonds and reclaiming rubber were considered as the reasons for low efficiency of this treatment process.