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Herman Van Langenhove - One of the best experts on this subject based on the ideXlab platform.

  • removal of Dimethyl Sulfide in a thermophilic membrane bioreactor
    Journal of Chemical Technology & Biotechnology, 2008
    Co-Authors: Munkhtsetseg Luvsanjamba, Amit Kumar, Herman Van Langenhove
    Abstract:

    BACKGROUND: Several sources such as the paper and pulp industry and waste treatment plants emit waste gases containing volatile organic sulfur compounds at elevated temperature. Since cooling the hot gases increases the operational cost of biological reactors, application of thermophilic microorganisms could be a cost-effective solution. The objectives of this study were to investigate the possibility of removal of Dimethyl Sulfide from waste gases under thermophilic conditions (52 °C) in a membrane bioreactor and to examine the long-term stability of the reactor at elevated temperature. The effects of operating conditions such as gas residence time, nutrient supply, temperature decrease and short-term shutdown on elimination capacity were investigated. RESULTS: A maximum elimination capacity of 54 g m−3 h−1 (0.108 g m−2 h−1) was obtained at a mass loading rate of 64 g m−3 h−1 (0.128 g m−2 h−1) with a removal efficiency of 84% at a gas residence time of 24 s. The long-term operation of the thermophilic membrane bioreactor was followed for 9 months. Although the removal efficiency decreased to 50% after 3 months of continuous operation, it recovered (>96%) after the excess biomass was removed by applying high-velocity liquid recirculation. CONCLUSION: This study demonstrated that the Dimethyl Sulfide removal is possible in a thermophilic membrane bioreactor with an elimination capacity of 54 g m−3 h−1 (0.108 g m−2 h−1) at a gas residence time of 24 s. Copyright © 2008 Society of Chemical Industry

  • long term operation of a thermophilic biotrickling filter for removal of Dimethyl Sulfide
    Chemical Engineering Journal, 2008
    Co-Authors: Munkhtsetseg Luvsanjamba, Bram Sercu, Julie Van Peteghem, Herman Van Langenhove
    Abstract:

    Abstract This study demonstrates the possibility of removal of Dimethyl Sulfide in a thermophilic biotrickling filter (BTF52) operated at 52 °C, using an enriched sludge inoculum. The efficiency and long-term performance of BTF52 were compared with a reactor operated in parallel at 22 °C (BTF22). After a start-up period of 17 and 25 days, maximum elimination capacity values of about 30 and 18 g m −3  h −1 were measured in BTF22 and BTF52, respectively. However, using tap water instead of deionized water as a matrix for the mineral medium caused a substantial improvement of maximum elimination capacity, increasing to 75 and 45 g m −3  h −1 in BTF22 and BTF52. CaCO 3 was found to be the crucial ingredient causing this performance increase. Also, the effect of variable operating conditions on the performance of both reactors was examined. At DMS loading rates of 6.5 g m −3  h −1 , the elimination capacities in both reactors recovered within 2 h after short-term (24 and 48 h) complete shut downs. Temperature changes to 21 and 59 °C decreased the removal efficiency of BTF52 by 90 and 30%, respectively. Finally, batch experiments showed that liquid-phase sulfate concentrations exceeding 2.2 g L −1 , decreased the removal rate by 50% at 52 °C.

  • inoculation and start up of a biotricking filter removing Dimethyl Sulfide
    Chemical Engineering Journal, 2005
    Co-Authors: Bram Sercu, Dariela Nunez, German Aroca, Nico Boon, Willy Verstraete, Herman Van Langenhove
    Abstract:

    Two Hyphomicrobium VS inoculation protocols were compared for start-up of a biotrickling filter removing Dimethyl Sulfide (DMS). One biotrickling filter (HBF 1) was filled with rings that were submerged in a nutrient medium containing Hyphomicrobium VS fed with DMS, another biotrickling filter (HBF 2) was similarly filled with rings that were submerged in nutrient medium, but continuously supplied with actively growing Hyphomicrobium VS and fed with methanol. Initially, about 40 times more Hyphomicrobium VS cells were attached to the rings in HBF 2. During the experiment, two to three times more Hyphomicrobium VS cells were still found to be present on the rings in HBF 2 compared to HBF 1. The maximal DMS elimination capacity at 90% removal efficiency of HBF 1 was 7.2 g m−3 h−1 after 30 days of operation. The elimination capacity decreased, however, when the inlet loading rate exceeded 15 g m−3 h−1 (200 ppmv inlet concentration). The performance of HBF 2 was much better, with an elimination capacity of 8.3 g m−3 h−1 (90% removal efficiency) after 2 days of operation, increasing to a maximum of 57 g m−3 h−1 at 92% removal efficiency. Microbial community analysis with denaturing gradient gel electrophoresis showed very different microbial communities in both biotrickling filters (Pearson correlation coefficient of 0%). Moreover, the decreased DMS elimination capacity of HBF 1 at higher influent loading rate corresponded with a drastic change of the microbial community on the rings. The latter observations suggest that the functional efficiency of the microbial community in a biotrickling filter can be related to its composition.

  • titanium dioxide mediated heterogeneous photocatalytic degradation of gaseous Dimethyl Sulfide parameter study and reaction pathways
    Applied Catalysis B-environmental, 2005
    Co-Authors: Kristof Demeestere, Jo Dewulf, Bavo De Witte, Herman Van Langenhove
    Abstract:

    Abstract This paper deals with the photocatalytic degradation of gaseous Dimethyl Sulfide (DMS) in a wide range of inlet concentrations (3 ppmv  in τ 2 Degussa P25 as a photocatalyst in a flat-plate photoreactor. DMS removal efficiencies increased with lower [DMS] in and higher τ , while the optimum RH was 22%. Although DMS removal efficiencies higher than 90% (peaks over 97%) could be obtained for at least 180 min at τ  = 55 s, RH  in in resulted into catalyst deactivation due to accumulation of reaction products on the TiO 2 surface. During photocatalytic DMS degradation at [DMS] in  ≥ 100 ppmv, Dimethyl diSulfide, carbon dioxide and sulfur dioxide were detected as gas-phase reaction products, while solid–liquid extraction revealed Dimethyl sulfoxide, Dimethyl sulfon, methane sulfonic acid and sulfate as reaction products adsorbed on the exposed catalyst. Consequently, detailed photocatalytic DMS degradation pathways were proposed, starting with TiO 2 (h + ) or OH mediated DMS oxidation and followed by C S bond cleavage, S-oxidation and C-oxidation. Carbon and sulfur mass balances were closed for 90–105% and 98 – 110%, respectively. [DMS] in did not have an important effect on product distribution, but interesting trends in DMS degradation products were observed as a function of RH.

Jianmin Chen - One of the best experts on this subject based on the ideXlab platform.

  • Dimethyl Sulfide photocatalytic degradation in a light emitting diode continuous reactor kinetic and mechanistic study
    Industrial & Engineering Chemistry Research, 2011
    Co-Authors: Zimeng Wang, Jing Liu, Yuancan Dai, Weiyang Dong, Shicheng Zhang, Jianmin Chen
    Abstract:

    This study investigated the feasibility, kinetics, and reaction pathways of the photocatalytic degradation of Dimethyl Sulfide (DMS) in a light-emitting-diode- (LED-) based continuous reactor. Four types of LEDs, with peak wavelengths at 365, 375, 385, and 402 nm, were used for comparison. The data were fitted with the Langmuir–Hinshelwood kinetic model, in which the rate constants for 365- and 375-nm LEDs were significantly larger than those for the 385- and 402-nm LEDs. The effect of wavelength on the reaction rate followed the TiO2 absorption spectrum. The effect of radiation intensity agreed with a nonlinear power law and was attributed to the TiO2 absorption of photon energy. For the 365- and 375-nm LEDs, the transition of the exponent values from first-order to one-half-order was estimated to occur at 0.5–1.0 mW·cm–2, whereas the 385- and 402-nm LEDs did not show a transition at this intensity. Dimethyl sulfoxide (DMSO), Dimethyl sulfone (DMSO2), Dimethyl diSulfide (DMDS), methanethiol (MT), methane...

  • Dimethyl Sulfide photocatalytic degradation in a light emitting diode continuous reactor kinetic and mechanistic study
    Industrial & Engineering Chemistry Research, 2011
    Co-Authors: Zimeng Wang, Jing Liu, Yuancan Dai, Weiyang Dong, Shicheng Zhang, Jianmin Chen
    Abstract:

    This study investigated the feasibility, kinetics, and reaction pathways of the photocatalytic degradation of Dimethyl Sulfide (DMS) in a light-emitting-diode- (LED-) based continuous reactor. Four...

Kei Toda - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of single column trapping separation and chemiluminescence detection for measurement of methanethiol and Dimethyl Sulfide from pig production
    Journal of Automated Methods & Management in Chemistry, 2012
    Co-Authors: Michael Jørgen Hansen, Kei Toda, Tomoaki Obata, Anders Peter S. Adamsen, Anders Feilberg
    Abstract:

    Reduced sulfur compounds are considered to be important odorants from pig production due to their low odor threshold values and low solubility in slurry. The objective of the present study was to investigate the use of a portable method with a single silica gel column for trapping/separation coupled with chemiluminescence detection (SCTS-CL) for measurement of methanethiol and Dimethyl Sulfide in sample air from pig production. Proton-transfer-reaction mass spectrometry (PTR-MS) was used to evaluate the trapping/separation. The silica gel column used for the SCTS-CL efficiently collected hydrogen Sulfide, methanethiol and Dimethyl Sulfide. The measurement of methanethiol by SCTS-CL was clearly interfered by the high concentration of hydrogen Sulfide found in pig production, and a removal of hydrogen Sulfide was necessary to obtain reliable results. Air samples taken from a facility with growing-finishing pigs were analyzed by SCTS-CL, PTR-MS, and a gas chromatograph with sulfur chemiluminescence detection (GC-SCD) to evaluate the SCTS-CL. The difference between the concentrations of methanethiol and Dimethyl Sulfide measured with SCTS-CL, PTR-MS, and GC-SCD was below 10%. In conclusion, the SCTS-CL is a portable and low-cost alternative to the commercial methods that can be used to measure methanethiol and Dimethyl Sulfide in sample air from pig production.

  • single column trapping separation and chemiluminescence detection for on site measurement of methyl mercaptan and Dimethyl Sulfide
    Analytical Chemistry, 2006
    Co-Authors: Abul Kalam Azad, Shin Ichi Ohira, Kei Toda
    Abstract:

    A simple, automated method for the measurement of methyl mercaptan (CH3SH) and Dimethyl Sulfide (DMS) has been investigated. These two sulfur gases have strong and unpleasant odors. The collection and separation are performed in sequence with a single short column packed with silica gel powder. CH3SH and DMS are separated according to their desorption temperatures and introduced into a chemiluminescence cell in this order. These two gases emit strong chemiluminescence by reaction with ozone. The calibration curves obtained are linear, which is superior to flame photometric detection of these substances. The whole system, including a small cylinder for the carrier nitrogen, can be set in a portable box. The instrument is applicable to breath odor analysis, and automated measurement of room air can also be performed. In toilet air analysis, it was observed that levels of the sulfur gases increased after dark. With this instrument, sulfur gases at a ppbv level are successfully measured by a simple procedure ...

Andrey S Kudryavtsev - One of the best experts on this subject based on the ideXlab platform.

Yiquan Yang - One of the best experts on this subject based on the ideXlab platform.

  • thiolation of Dimethyl Sulfide to methanethiol over wo3 zro2 catalysts
    Journal of Molecular Catalysis A-chemical, 2012
    Co-Authors: Shiping Chen, Weiming Wang, Yuanhua Zhang, Yucai Wei, Weiping Fang, Yiquan Yang
    Abstract:

    Abstract The thiolation of Dimethyl Sulfide with H 2 S over a variety of tungsten–zirconia (WO 3 /ZrO 2 ) catalysts with different contents of WO 3 was studied. The maximum yield of methanethiol was obtained at the reaction temperature of 633 K in the presence of 10 wt.%WO 3 /ZrO 2 catalyst. XRD, BET and TPD characterization results reveal that supporting WO 3 species on ZrO 2 gives rise to the improvement of both in structure stability and surface acidity. The MT yield increased first and then decreased with the increase of reaction temperature for all of the catalysts due to the decomposition of methanethiol and Dimethyl Sulfide. The optimum loading of WO 3 was found to be 5–10 wt.% (with a surface density of 3.5–4.5 w-atom nm −2 ). Furthermore, the WO 3 /ZrO 2 catalyst exhibits high resistance to water.

  • study on methanethiol synthesis from h2s and Dimethyl Sulfide over al2o3 catalysts promoted with phosphorus
    Applied Catalysis A-general, 2012
    Co-Authors: Shiping Chen, Yuanhua Zhang, Weiping Fang, Yiquan Yang
    Abstract:

    Abstract A series of P-promoted alumina catalysts with phosphorous contents varying in the range of 1–5% for the reaction of hydrogen Sulfide (H2S) and Dimethyl Sulfide (DMS) to produce methanethiol (MT) were prepared and characterized by using XRD, SEM, BET, FT-IR and NMR techniques. The activity assay results showed that at the reaction temperature of 593 K, the P-promoted alumina catalyst exhibits as high as 100% selectivity toward MT; the DMS conversion ranges from 44.7% to 51.4% depending on the loading of phosphorus. The characterization results showed that introducing a small amount of phosphorus into γ-Al2O3 increases the specific surface area, pore volume and the amount of Lewis acid sites. The increase of the Lewis acid sites enhances the capacity of the catalyst to break the C S bond of Dimethyl Sulfide to methylthiolate (CH3S−) and CH3+, and H2S adsorbed on alumina to SH− and H+, both of CH3+ and H+ then interact further with lattice oxygen O2− of the catalyst to form methoxyl (CH3O−) and OH−, respectively, subsequent combination of CH3S− with OH− or CH3O− with SH− leads to the formation of methanethiol.