Methanethiol Removal Research Articles

Development of a Suitable Method for the Synthesis of New Thiadiazoles Using Hydrazonoyl Halides

Background: Hydrazonoyl halides and methylhydrazinecarbodithioate have been generally utilized in the synthesis of heterocycles. Methods: This study describes a new and simple method to prepare new thiadiazoles from the reaction of N-(naphthalen-1-yl)-2-oxopropanehydrazonoyl chloride or ethyl 2-chloro-2-(2-(naphthalen-1-yl)hydrazono)acetate with methylhydrazinecarbodithioate in the presence of basic medium under reflux. In this study, the synthetic schemes are designed to show the chemical reactions. Elements analysis, Fourier Transform Infrared Spectroscopy (FT-IR), Mass Spectrom-etry (MS), and Nuclear Magnetic Resonance (NMR) are used to identify and characterize the final compounds. Results: There are two ways to synthesize the final thiadiazoles molecules. The first can be through nucleophile substitution of thiolate of methylhydrazonecarbodithioate to the chlorinated carbon of hydrazonoyl. Hydrochloric acid is then removed to provide an S-alkylated intermediate. Methanethiol is eliminated from this intermediate by an in situ intra-molecular cyclocondensation process to give the final products. The subsequent [3+2] cy-cloaddition involving 1,3-dipolar cycloadditions of nitrilimines to C=S is succeeded by the re-moval of methanethiol. Conclusion: This approach utilizes affordable, readily accessible reagents and simple reaction conditions to produce new thiadiazole derivatives with satisfactory yields.

Methanethiol removal from biogas by biological conversion in an anaerobic biotrickling filter

In this study, methanethiol(MT)-degradation bacteria were cultivated by using MT, methanol and trimethylamine as carbon sources under anaerobic conditions. It was found that the batch bacteria used MT and methanol as carbon sources grew faster than those used trimethylamine. The enriched bacteria used MT and methanol as the carbon sources were respectively inoculated in different biotrickling filters. The biological conversion performance of MT under anaerobic conditions was investigated in biotrickling filters. The results showed that the performance of the biotrickling filter inoculated with the bacteria enriched using MT was better than that inoculated with the bacteria enriched using methanol. When the inlet concentration of MT was 0.005vol%(50,ppm), the empty bed residence time was 50 s, pH value was 8.0, and the flow rate of the nutrient solution was 10 L/h, the removal efficiency of MT reached 95.3%. Adding methanol stimulated the growth of the biomass and the degradation of MT, but caused that some bacteria only degrading methanol outcompeted the bacteria only degrading MT. The concentration of sodium bicarbonate in the nutrient solution needed to be controlled lower than 30 g/L, otherwise, it would be harmful to the degradation of MT.

Modeling removal of volatile sulfur compounds in a full‐scale biological air filter

AbstractBACKGROUNDH2S and methanethiol, which are important odorants from pig facilities, were unsatisfactorily removed in field biological air filters with short residence time. For a better understanding of the process, this study established a dynamic model for simulation of H2S and methanethiol removal in a three‐stage biological air filter (two stages of biotrickling filter and one stage of biofilter), based on experimental determined mass transfer coefficients and partition coefficients from previous studies.RESULTSThe maximum biodegradation rates for both H2S and methaetniol were estimated to be relatively low, with differences observed for different stages. Further, H2S removal was also observed to be limited by mass transfer, while other parameters such as active water content, biofilm thickness and diffusion coefficient were also shown to affect model performance, indicating the relevance of proper estimation of these parameters. For methanethiol, on the other hand, the model is mainly limited by maximum biodegradation rate.CONCLUSIONOverall, the established model can properly simulate the performance of the field biological air filter for the removal of volatile sulfur compounds. Calibration of model parameters in field conditions may further improve the model precision and robustness for predicting performance of the field biological air filter. © 2015 Society of Chemical Industry

Biological removal of methanethiol from gas and water streams by using Thiobacillus thioparus: investigation of biodegradability and optimization of sulphur production

The present work mainly deals with biological oxidation, which was tested using the bacterium Thiobacillus thioparus in semi-batch bioreactor systems to evaluate the removal efficiencies and optimal conditions for the biodegradation of methanethiol (MT) in order to treat the natural gas and refinery output streams. The efficiency of this method is analysed by evaluating the concentration of MT in a bioreactor. The effect of operational parameters, such as initial concentration of MT, pH, temperature, dissolved oxygen (DO), initial concentration of bacteria and reaction time on the degradation of MT, were studied. In this process, MT is converted into elemental sulphur particles as an intermediate in the oxidation process of MT to sulphate. The obtained results showed that the highest degradation rate occurred during the first 300 minutes of reaction time. The optimal conditions of the different initial MT concentrations with 0.3–0.6 bacteria OD, DO of 0.5 ppm, acidic pH value of 6.2 and temperature of 30°C are obtained. Acidic pH and oxygen-limiting conditions were applied to obtain 80–85% selectivity for elemental sulphur formation in products. Under the optimal conditions, and for the highest (8.51 mM) and the lowest (0.53 mM) concentration of MT, the biological removal was about 89% and 94%, respectively.

REMOVAL OF METHANETHIOL BY SEPIOLITE AND VARIOUS SEPIOLITE-METAL COMPOUND COMPLEXES IN AMBIENT AIR

In ambient air having 60% relative humidity (RH) at 25°C, the adsorption of methanethiol by sepiolite was studied by comparison with that by coconut-shell active carbon. The amount of methanethiol adsorbed by sepiolite was as small as 0.12 μmol/g in the air with 1 ppm methanethiol, while, the amount by active carbon was as large as > 1.1 μmol/g in the air with ≤ 0.03 ppm methanethiol. Methanethiol was converted into dimethyldisulfide on active carbon. In ambient air having 60% RH at 25°C, the removal of methanethiol by the sepiolite-metal complexes was also studied by comparison with that by the corresponding metal compounds

Removal of methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide from contaminated air by Thiobacillus thioparus TK-m.

Methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide were efficiently removed from contaminated air by Thiobacillus thioparus TK-m and oxidized to sulfate stoichiometrically. More than 99.99% of dimethyl sulfide was removed when the load was less than 4.0 g of dimethyl sulfide per g (dry cell weight) per day.