Methyl Mercaptan Gas Research Articles

Fate and emission of methyl mercaptan in a full-scale MBBR process by TOXCHEM simulation

Abstract The emission and fate of methyl mercaptan from the residential complex treatment plant (RCTP) moving bed bioreactor (MBBR) process in the city of Al-Hur in Karbala governorate in Iraq were studied using the TOXCHEM 4.1 model. The release of odorous sulfur compounds from treatment plants harms workers and the surrounding area. Methyl mercaptan, in particular, is responsible for odors similar to rotten cabbage. The sensitivity analysis for the methyl compounds in the MBBR system was conducted based on the following factors: a large thick biofilm layer, the specific surface area of media, media fill fraction, and aeration flowrate. The model was validated via RMSE and R, which showed the model outputs are representatives of real-world observations. Degradation and emission were shown to be the two most important processes in the system. During the summer (32 °C) and winter (12 °C), about 13 and 10%, 2 and 4%, 0.5 and 1%, and 85 and 85% were emitted into the atmosphere, discharged with effluent, sorbed into sludge, and biodegraded, respectively. The overall concentrations of CH4S emitted in summer and winter were 1.78 and 1.38 ppm, respectively. Operating the MBBR system with a thick biofilm layer, a large specific surface area of media, a greater media fill fraction, and a low aeration rate contributed significantly to the decomposition of methyl mercaptan and thus decreased emission into the atmosphere. Finally, the TOXCHEM simulation accurately predicts the fate of CH4S and the emissions inherent to the MBBR system. The manipulation of the operating factors led to the improvement of the system and the reduction of methyl mercaptan gas emissions without the need to add units and chemical additives.

Methyl mercaptan gas: mechanisms of toxicity and demonstration of the effectiveness of cobinamide as an antidote in mice and rabbits

Context Methyl mercaptan (CH3SH) is a colorless, toxic gas with potential for occupational exposure and used as a weapon of mass destruction. Inhalation at high concentrations can result in dyspnea, hypoventilation, seizures, and death. No specific methyl mercaptan antidote exists, highlighting a critical need for such an agent. Here, we investigated the mechanism of CH3SH toxicity, and rescue from CH3SH poisoning by the vitamin B12 analog cobinamide, in mammalian cells. We also developed lethal CH3SH inhalation models in mice and rabbits, and tested the efficacy of intramuscular injection of cobinamide as a CH3SH antidote. Results We found that cobinamide binds to CH3SH (K d = 84 µM), and improved growth of cells exposed to CH3SH. CH3SH reduced cellular oxygen consumption and intracellular ATP content and activated the stress protein c-Jun N-terminal kinase (JNK); cobinamide reversed these changes. A single intramuscular injection of cobinamide (20 mg/kg) rescued 6 of 6 mice exposed to a lethal dose of CH3SH gas, while all six saline-treated mice died (p = 0.0013). In rabbits exposed to CH3SH gas, 11 of 12 animals (92%) treated with two intramuscular injections of cobinamide (50 mg/kg each) survived, while only 2 of 12 animals (17%) treated with saline survived (p = 0.001). Conclusion We conclude that cobinamide could potentially serve as a CH3SH antidote.

Solvent‐Free Single‐Pot Mannich Reaction and Detoxification of Industrial Hazardous Waste Methyl Mercaptan Gas

AbstractEnvironment pollution is causing serious human health issues and forest deterioration. Methyl mercaptan is a malodorous gaseous pollutant, which is a by product of sewage treatment plants, pulp plants, petrochemical plants, agrochemicals, and some pharmaceutical products. A long term exposure to methyl mercaptan may lead to adverse effects on central nervous system and cardiovascular system. The pharmaceutical industries are devoting significant efforts to develop process by using green solvents like water, and develop solvent‐free reactions. This will help to develop green, sustainable methods for the synthesis of API and reduce the manufacturing cost. A ZnCl2 catalyzed solvent‐free, one‐pot process for the synthesis of ranitidine and quenching of hazardous waste methyl mercaptan gas to a useful product have been developed.

Intramuscular cobinamide as an antidote to methyl mercaptan poisoning

Background Methyl mercaptan occurs naturally in the environment and is found in a variety of occupational settings, including the oil, paper, plastics, and pesticides industries. It is a toxic gas and deaths from methyl mercaptan exposure have occurred. The Department of Homeland Security considers it a high threat chemical agent that could be used by terrorists. Unfortunately, no specific treatment exists for methyl mercaptan poisoning. Methods We conducted a randomized trial in 12 swine comparing no treatment to intramuscular injection of the vitamin B12 analog cobinamide (2.0 mL, 12.5 mg/kg) following acute inhalation of methyl mercaptan gas. Physiological and laboratory parameters were similar in the control and cobinamide-treated groups at baseline and at the time of treatment. Results All six cobinamide-treated animals survived, whereas only one of six control animals lived (17% survival) (p = 0.0043). The cobinamide-treated animals returned to a normal breathing pattern by 3.8 ± 1.1 min after treatment (mean ± SD), while all but one animal in the control group had intermittent gasping, never regaining a normal breathing pattern. Blood pressure and arterial oxygen saturation returned to baseline values within 15 minutes of cobinamide-treatment. Plasma lactate concentration increased progressively until death (10.93 ± 6.02 mmol [mean ± SD]) in control animals, and decreased toward baseline (3.79 ± 2.93 mmol [mean ± SD]) by the end of the experiment in cobinamide-treated animals. Conclusion We conclude that intramuscular administration of cobinamide improves survival and clinical outcomes in a large animal model of acute, high dose methyl mercaptan poisoning.

A Quartz Crystal Microbalance Based Portable Gas Sensing Platform for On-Demand Human Breath Monitoring

The correlation between gas concentrations in human breath and diseases has been increasingly revealed in recent years, triggering the need for cheap and easy-to-use gas sensors that can detect diseases in their early stages. The gas sensors used in these clinical applications need to be portable and sensitive, and preferably provide on-demand measurements for prompt diagnosis. In this paper, we propose a portable and cost-effective sensor platform that can quickly identify gas concentrations in human breath. Specifically, we combined quartz crystal microbalance (QCM) sensors with a single board computer, Raspberry Pi, to enable real-time data processing and display of the sensor data. A web server was operated on the single board computer, and thus, on-demand visualization of the sensor data was possible using a web browser. A gas quantification protocol was also proposed based on Freundlich’s adsorption isotherm. We demonstrated the real-time monitoring of methyl mercaptan (MM) gas over the internet using the developed small sensor device, which can easily be handled in one hand. The limit of detection (LOD) for MM gas was 107 ppb when the sensors were operated for 20 minutes after gas injection. The developed gas sensing platform is unmatched in terms of size and cost compared with analytical devices though less sensitive. These advantages would allow for wide distribution of the developed device to hospitals and individuals in large quantities, leading for behavioral changes for preventive care.

Synthesis of single-phase Au nanorods in an anodic aluminum oxide template with an optimized process for a highly sensitive and non-enzyme methyl mercaptan gas detector

Single-phase Au nanorods were synthesized using an anodic alumina oxide (AAO) template for methyl mercaptan (CH3SH) gas detection. The Au nanorods were fabricated by pulse electrodeposition on a H2O2 modified template. A Au precursor solution was modified with dimethyl sulfoxide to improve the synthesis of Au nanorods. The deposition parameters of the duty cycle were modulated in multiple groups to produce high-quality Au nanorods. Scanning electron microscopy images illustrated the high regularity of the Au nanorods. X-ray diffraction and transmission electron microscopy images revealed the high composition of the (111) lattice interface. A Au nanorod gas sensor was fabricated after removal of the AAO template. The sensor utilized the self-assembled monolayer property between Au and CH3SH to alter the conductivity of the Au nanorod sensing layer. The sensor exhibited higher sensitivity and selectivity to CH3SH than to N2 and H2S. The sensor had a 0.88% current response under a 0.5 ppm concentration of CH3SH, which increased to 7.82% under 4 ppm CH3SH. The Au nanorods possessed a response 13 times higher than that of a Au thin-film structure.

Ultrasensitive Detection of Methylmercaptan Gas Using Layered Manganese Oxide Nanosheets with a Quartz Crystal Microbalance Sensor

Methylmercaptan (MM) is a marker of periodontal disease; however, the required sensitivity for MM is parts per billion, which has been challenging to realize with a simple sensor. Here, we report the capability to detect MM at concentrations as low as 20 ppb using layered manganese oxide nanosheets with a quartz crystal microbalance sensor. The sensing capabilities of the manganese oxide nanosheets are promoted by adsorbed water present on and between the nanosheets. The strong adsorption of MM to the sensor, which is necessary for the high sensitivity, leads to significant hysteresis in the response on cycling due to irreversible adsorption. However, the sensor can be readily reset by heating to 80 °C, which leads to highly reproducible response to MM vapor at low concentrations. A key aspect of this sensor design is the high selectivity toward MM in comparison to other compounds such as ethanol, ammonia, acetaldehyde, acetic acid, toluene, and pyridine. This layered nanosheets design for high-sensitivity sensors, demonstrated here for dilute MM, holds significant promise for addressing needs to identify sulfur compounds associated for environmental protection and medical diagnostics.

Deodorant activity of phthalocyanine complex nanofiber

Unpleasant odor is a problem in the modern lifestyle. In order to prevent malodor, we fabricated phthalocyanine combined with nanofibers to prevent unpleasant odor for the first time. Cu-coordinated phthalocyanine was used as an odor preventing agent and methyl mercaptan gas was selected as a model malodorant. This study was conducted with two different polymers, poly(vinyl alcohol) (PVA) and silk. A total of 4 wt% of phthalocyanine was incorporated in the solutions of both polymers, resulting in the successful fabrication of nanofibers. It is notable that the deodorant activity test clearly showed a reduction of methyl mercaptan gas in both phthalocyanine incorporated PVA and silk nanofibers. In addition, the phthalocyanine/silk nanofibers exhibited better deodorant performance in comparison to the phthalocyanine/PVA nanofiber.

Silver Ion Polyelectrolyte Container as a Sensitive Quartz Crystal Microbalance Gas Detector.

A polyelectrolyte film containing metastable silver ions was applied as a quartz crystal microbalance (QCM) gas detector. The polyelectrolyte film was obtained by immersing a polyelectrolyte with numerous amine groups in a metal ion solution. The QCM detector with silver ions responded to a very low methylmercaptan gas concentration (20 ppb) but did not respond to ammonia, volatile amines, aromatic compounds, or alcohols. The response speed of the QCM detector increased gradually with increasing methylmercaptan concentrations. The highly sensitive and selective response is promoted by a ligand substitution reaction caused by the formation of coordinative bonds between a metastable silver ion and amine groups in the polyelectrolyte film. To the best of our knowledge, this system has the highest sensitivity among reported QCM gas detectors. Such high-sensitivity among reported QCM gas detectors. Such high-sensitivity gas detectors for volatile sulfur compounds have wide ranging applications in areas such as volcanic eruption prediction, food inspection, environmental analysis, and medical diagnostics.

A potential development of breathing gas sensor using an open path fibre technique

This paper describes a potential development of methyl mercaptan or bad breathing gas measurement in the 200nm–250nm region. Methyl mercaptan shows a potential peak selection at 204nm and the absorption cross section spectrum display a similar pattern with the theory. A cross sensitivity analysis is also reported and it shows that there are no discernible interference effects between the methyl mercaptan gas with other breathing gases such as carbon dioxide, oxygen and water vapor at 204nm.

Alternative Use of Light Emitting Diodes in an Activated Charcoal-Supported Photocatalyst Reactor for the Control of Volatile Organic Compounds

The applicability of ultraviolet-light emitting diodes (LEDs) as a light source for photocatalysis using granular activated charcoal (GAC) impregnated with transition metal-enhanced photocatalysts for the control of volatile organic compounds (VOCs) was investigated. Two target compounds (toluene and methyl mercaptan) were selected to evaluate the removal activities of the TiO 2 /GAC composites. The photocatalysts were prepared by a sol-gel method. Methyl trimethoxy silane was added as a precursor sol solution to bind the photocatalyst with the GAC. Metal (Zn 2+ , Fe 3+ , Ag + , and Cu 2+ ) enhanced TiO 2 /GAC composites were prepared and tested for their photocatalytic activities under 400 nm LED irradiation. The specific surface area (SSA) and the surface chemical composition of the prepared composites were investigated. The SSAs of all the impregnated composites were similar to those of pure GAC. Both field emission-scanning electron microscopy and energy dispersive spectroscopic analysis confirmed that titanium and the impregnated metals were deposited on the surface of the adsorbent. The breakthrough time for GAC toward toluene or methyl mercaptan gas increased upon photocatalytic impregnation and LED illumination. Using different binders affected the breakthrough time of the TiO 2 /GAC composite and the addition of zinc oxide to TiO 2 increased the VOC removal capacity of the GAC composite. UV wavelength light emitting diodes were used for the adsorption photocatalytic removal of volatile organic compounds and of granular activated charcoal (GAC) that was impregnated with a TiO 2 photocatalyst or with TiO 2 /co-catalysts, which resulted in enhanced removal efficiency.

메칠멜캅탄 가스센서용 TiO2/전해질폴리머 박막 제조

메칠멜캅탄(<TEX>$CH_3SH$</TEX>) 가스를 검출하는 수정진동자(QCM) 가스센서를 QCM의 전극에 <TEX>$TiO_2$</TEX> 나노입자와 전해질 폴리머를 증착하여 제조하였다. LBL-SA법에 의해 제조된 <TEX>$TiO_2$</TEX>/PSS 박막은 높은 비표면적을 나타내었고, 가스센서의 감도를 증가시켰다. 1.0 ppm의 농도를 갖는 메칠멜캅탄에 노출된 TEA 혹은 <TEX>$TiO_2$</TEX>/PSS 막이 증착된 QCM의 주파수 변이는 각각 약 9 Hz, 2 Hz 였다. (<TEX>$TiO_2$</TEX>/PSS) 박막의 증착수가 늘어남에 따라 제조된 박막의 비표면적이 증가하게 되어 QCM 센서의 주파수 변이도 점차적으로 증가하였다. 추가적으로 메칠멜캅탄 가스의 농도가 0.5 ppm에서 2.0 ppm으로 높아짐에 따라 QCM 센서의 주파수 변화도 증가되었다. 본 연구에서는, (<TEX>$TiO_2$</TEX>/PSS) 박막이 증착된 QCM 센서의 표면구조의 변화와 센서 특성을 측정하였다. Quartz crystal microbalance (QCM) gas sensor to detect methyl mercaptan (<TEX>$CH_3SH$</TEX>) gas was fabricated by depositing <TEX>$TiO_2$</TEX> nanoparticles and polyelectrolyte on the electrode of QCM. The <TEX>$TiO_2$</TEX>/poly(sodium 4-styrenesulfonate) (PSS) thin film fabricated by a layer-by-layer self-assembly (LBL-SA) method showed a high surface area and increased the sensitivity of gas sensor. When the QCM sensors coated with triethanolamine (TEA) or (<TEX>$TiO_2$</TEX>/PSS) were exposed to methyl mercaptan gas (1.0 ppm), the frequency shifts of QCM with TEA casting film and <TEX>$TiO_2$</TEX>/PSS thin film were ca. 9 Hz and ca. 24 Hz, respectively. As the bilayer number of (<TEX>$TiO_2$</TEX>/PSS) increased, the frequency shift of QCM sensor with (<TEX>$TiO_2$</TEX>/PSS) thin film was gradually increased. In addition, the frequency shift of QCM sensor was gradually increased as the concentration of methyl mercaptan gas increased from 0.5 ppm to 2.0 ppm. In this study, the surface morphology and sensor property of QCM sensor coated with (<TEX>$TiO_2$</TEX>/PSS) thin film were measured.

Purification and characterization of methyl mercaptan oxidase fromThiobacillus thioparus for mercaptan detection

Methyl mercaptan oxidase was successfully induced inThiobacillus thioparus TK-m using methyl mercaptan gas, and was purified for the detection of mercaptans. The purification procedure involved a DEAE (diethylaminoethyl)-Sephacel, or Superose 12, column chromatography, with recovery yields of 47.5 and 48.5%, and specific activities of 374 and 1240.8 units/mg-protein, respectively. The molecular weight of the purified methyl mercaptan oxidase was 66.1kDa, as determined by SDS-PAGE. The extract, from gel filtration chromatography, oxidizes methyl mercaptan, producing formaldehyde, which can be easily detected by the purpald-coloring method. The optimized temperature for activity was found to be at 55°C. This enzyme was inhibited by both NH4Cl and (NH4)2SO4, but was unaffected by either KCl or NaCl at less than 200 mM. With K2SO4, the activity decreased at 20 mM, but recovered at 150 mM. In the presence of methanol, full activity was maintained, but decreased in the presence of glycerin, ethanol and acetone 43, 78 and 75%, respectively.

Isolation and purification of methyl mercaptan oxidase fromRhodococcus rhodochrous for mercaptan detection

Methyl mercaptan oxidase was successfully induced fromRhodococcus rhodochrous IGTS8 using methyl mercaptan gas and purified to homogeneity for the detection of mecrcaptans. The purification procedure involved DEAE-Sephacel and Superose 12 column chromatography with recovery yields of 85.8 and 83.3%, and a specific activity of 92.7 and 303.4 units/mg-protein, respectively. The molecular weight of purified methyl mercaptan, oxidase was determined to be 64.5 kDa by SDS-PAGE. The extract from gel filtration chromatography oxidizes methyl mercaptan to produce formaldehyde, which can be easily detected by the purpald-coloring method. Optimum temperature for activity was achieved at 60°C. This enzyme was inhibited by both K2SO4 and NaCl at concentration of less than 100 mM and recovered to original activity at concentration of 200 mM. In the presence of methanol, the activity decreased by 33%.