[No abstract submitted] / Science, Faculty of / Chemistry, Department of / Graduate

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 113-119).

Odour emissions resulting from reduced sulphur compounds in the kraft pulping industry are frequently found in dilute, high flowrate air streams that are costly to treat using incineration and thermal oxidation. Biofiltration, an air treatment method involving passing air through a packed bed of microorganisms, has emerged as a promising treatment strategy for these dilute waste gas streams. However, biodegradation of dimethyl sulphide (DMS) in biofilters is rather poor and is limiting the application of biofiltration to odour streams rich in DMS. Recently, our group has shown that co-treatment of DMS with methanol can increase DMS removal significantly. In this thesis, the effect of methanol on the microbiology of two biofilters treating DMS was explored. Microbial community analysis revealed that the addition of methanol led to a significant increase of up to an order of magnitude in the abundance of Hyphomicrobium spp. in a biofilter co-treating DMS and methanol compared to a biofilter treating DMS alone with no significant difference in the abundance of Thiobacillus spp. between the two biofilters. Further to the biofiltration experiments, the growth kinetics of Hyphomicrobium spp. and Thiobacillus spp. on DMS and methanol in an enrichment culture created from a biofilter co-treating DMS and methanol were studied. A specific growth rate of 0.099 h-1 and 0.11 h-1 was determined for Hyphomicrobium spp. and Thiobacillus spp., respectively, growing on DMS at pH 7, double the highest maximum specific growth rate for bacterial growth on DMS reported to date in the literature. As the pH decreased from pH 7 to pH 5, the specific growth rate of Hyphomicrobium spp. decreased significantly by 85% in the mixed culture while the specific growth rate of Thiobacillus spp. remained similar through the same pH shift. When methanol was used as a substrate, the specific growth rate of Hyphomicrobium spp. declined much less over the same pH range (up to 30%). These results suggest that addition of methanol to biofilters co-treating DMS and methanol can increase DMS removal rates by increasing the abundance of DMS-degrading Hyphomicrobium spp. at pH levels not conducive to high growth rates on DMS alone.

No description available.

Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Photographic X-ray diffraction data were used to determine the crystal and molecular structure of dimethyl sulfoxide near 5C. Of the total 868 unique X-ray reflections collected, 507 had measurable intensity, 270 were unobserved, and 91 were extinct. Near 5°C, dimethyl sulfoxide is found to be monoclinic with a = 5.303 +/- 0.005 A, b = 6.829 +/- 0.003 A, c = 11.693 +/- 0.010A, and B = 94°30' +/- 15'. The space group is P21/c with Z = 4. [TRUNCATED] / 2031-01-01

Odour emissions resulting from reduced sulphur compounds in the kraft pulping industry are frequently found in dilute, high flowrate air streams that are costly to treat using incineration and thermal oxidation. Biofiltration, an air treatment method involving passing air through a packed bed of microorganisms, has emerged as a promising treatment strategy for these dilute waste gas streams. However, biodegradation of dimethyl sulphide (DMS) in biofilters is rather poor and is limiting the application of biofiltration to odour streams rich in DMS. Recently, our group has shown that co-treatment of DMS with methanol can increase DMS removal significantly. In this thesis, the effect of methanol on the microbiology of two biofilters treating DMS was explored. Microbial community analysis revealed that the addition of methanol led to a significant increase of up to an order of magnitude in the abundance of Hyphomicrobium spp. in a biofilter co-treating DMS and methanol compared to a biofilter treating DMS alone with no significant difference in the abundance of Thiobacillus spp. between the two biofilters. Further to the biofiltration experiments, the growth kinetics of Hyphomicrobium spp. and Thiobacillus spp. on DMS and methanol in an enrichment culture created from a biofilter co-treating DMS and methanol were studied. A specific growth rate of 0.099 h-1 and 0.11 h-1 was determined for Hyphomicrobium spp. and Thiobacillus spp., respectively, growing on DMS at pH 7, double the highest maximum specific growth rate for bacterial growth on DMS reported to date in the literature. As the pH decreased from pH 7 to pH 5, the specific growth rate of Hyphomicrobium spp. decreased significantly by 85% in the mixed culture while the specific growth rate of Thiobacillus spp. remained similar through the same pH shift. When methanol was used as a substrate, the specific growth rate of Hyphomicrobium spp. declined much less over the same pH range (up to 30%). These results suggest that addition of methanol to biofilters co-treating DMS and methanol can increase DMS removal rates by increasing the abundance of DMS-degrading Hyphomicrobium spp. at pH levels not conducive to high growth rates on DMS alone.

Thesis (M.Sc.) -- University of Adelaide, Dept. of Human Physiology and Pharmacology, 1976. / Typescript (photocopy).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvi, 240 p.; also includes graphics (some col.). Includes bibliographical references (p. 231-240). Available online via OhioLINK's ETD Center

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Dimethylacetamide (DMA) solvent is oxidized catalytically to CH₃CON(CH₃)CH₂OOH and CH₃CON(CH₃)CHO under H₂/0₂ mixtures at 50°C in the presence of the dimethylsulfoxide complex RhCl₃(DMSO)₃ (I) at a rate which is much faster than peroxide-initiated autoxidation of DMA under O₂ alone. The hydroperoxide is thought to be the initial product, and the N-formyl derivative its decomposition product. An accompanying metal-catalyzed hydrogenolysis of 0₂ leads to H₂0₂ and H₂0. Hydrogen peroxide and CH₃CON(CH₃)CH₂OOH are the only products formed in the early stages of the catalytic reaction. The maximum rate of gas uptake in this initial region is independent of the partial pressure of 0₂, but shows linear dependences on Rh and H₂. Stoichiometry, rate and spectral data are consistent with an initiation reaction between complex I and H₂, and then 0₂ to give a catalytically active RhIII (0₂=) (DMA) species (II) (eq. 1) [formula omitted] The autoxidation of DMA and the hydrogenolysis of 0₂ are postulated to occur via independent pathways involving II (eqs. 2 and 3). [formula omitted] In the absence of H2, II degenerates to catalytically inactive species. The role of H₂ in the DMA autoxidation is thought to be the regeneration of Rh I species and hence II, from deactivated forms of II. Eventual slow, irreversible deactivation of the catalyst and the probable participation of the H₂0₂ product in peroxide initiated free-radical autoxidations complicate the interpretation of later stages of reaction. Diphenylsulfide (DPS) is catalytically oxidized to the sulfoxide by complex I under H₂/O₂ in DMA at 50°C, but accompanying oxidation of the solvent persists even in the presence of a 100-fold excess of DPS over Rh. Oxidation of the sulfide is thought to involve H₂0₂ liberated in the catalytic hydrogenolysis of 0₂. Complex I in CH₂C1₂ or C₂H₄CL₂ reacts with CO to give the dimethylsulfide complex RhCL₃(DMS)₃ via a facile reduction of DMSO ligands. Dimethylsulfoxide is reduced also by RhI species in CH₂CL₂ in the presence of two equivalents of acid to yield DMS, RhIII and H₂0. However, Rh I /2H⁺/DMS0 systems are relatively stable in DMA, because of the proton affinity of the solvent. Complex I reacts also with the strongly basic tertiary amine NEt₃ via a redox process in which the RhIII is reduced to Rh I with an accompanying dehydrogenation of the amine (eq. 4). RhCl₃ + 3NEt₃ → RhCl + 2NEt₃ HCl + CH₂=CHNEt₂ (4) The resulting ethenamine then reacts with I to give the ƞ¹-ylidic complex, RhCl₃(DMS̠O)₂(⁻CH₂CH=⁺NEt₂). Data from an earlier thesis, on a reaction between complex I and 1,8-bis(dimethylamino)naphthalene (or Proton Sponge), are reinterpreted in terms of a similar redox reaction that gives an N-carbene fragment (eq. 5),which is stabilized within the RhIII complex, RhCl₃(DMS̠O)₂(=CH-N(Me)-C₁₀H₆NMe₂•HCl). [formula omitted] / Science, Faculty of / Chemistry, Department of / Graduate