The density functional theory and cluster model methods have been employed to investigate the interactions between methanethiol, dimethyl sulfide and zeolites. The molecular complexes formed by adsorption of methaneth...The density functional theory and cluster model methods have been employed to investigate the interactions between methanethiol, dimethyl sulfide and zeolites. The molecular complexes formed by adsorption of methanethiol or dimethyl sulfide on silanol H3SiOSi（OH）2OSiH3 with five coordination forms or four coordination forms, and complexes formed by interactions of BrSnsted acid sites of bridging hydroxyl H3Si（OH）AI（OH）2OSiH3 with methanethiol or dimethyl sulfide have been investigated. Full optimization and frequency analysis of all cluster models have been carried out using the B3LYP hybrid method at 6-31＋G （d,p） basis set level for hydrogen, silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms between methanethiol and H3Si（OH）Al（OH）2OSiH3, dimethyl sulfide and H3Si（OH）Al（OH）2OSiH3, methanethiol and H3SiOSi（OH）2OSiH3, dimethyl sulfide and H3SiOSi（OH）2OSiH3 complexes have been comparatively studied. The calculated results showed the nature of interactions that led to the formation of all complexes was van der Waals force confirmed by an insignificant change of geometric structures and properties. The conclusions that methanethiol and dimethyl sulfide molecules were adsorbed on bridging hydroxyl group prior to silanol group were obtained on the basis of adsorption heat, the most stable adsorption models of a 6 ring structure for interaction between bridging hydroxyl and methanethiol, and a 7 ring structure for interaction between bridging hydroxyl and dimethyl sulfide.展开更多
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 metha- nol...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 metha- nol 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 ot 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 en- riched using methanol. When the inlet concentration of MT was 0.005vo1% （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.展开更多
In preventing and combating the chemical terrorist activities,in addition to those concerned highly toxic and huge harmful chemicals,some of mass destruction,widely affecting and poisoning of concealment volatile chem...In preventing and combating the chemical terrorist activities,in addition to those concerned highly toxic and huge harmful chemicals,some of mass destruction,widely affecting and poisoning of concealment volatile chemicals should also be concerned,such as hydrocyanic acid,hydrogen sulfide and methanethiol.Improvement of the identification and prevention awareness of such chemicals would be more effective in fighting against terrorist crimes.This article introduced the physical and chemical property and the toxicity of methanethiol,and the analysis method of the chemical in blood sample by GC-MS.展开更多
The preconcentration effect of alumina,silica gel,activated carbon and Chromsorb G-HP as adsorbents for ppb/v hydrosulfide and methanethio in ambient air was investigated by gas chromatography with FPD.Some factors in...The preconcentration effect of alumina,silica gel,activated carbon and Chromsorb G-HP as adsorbents for ppb/v hydrosulfide and methanethio in ambient air was investigated by gas chromatography with FPD.Some factors including absorbent temperature,desorbing temperature and sampling flow rate were studied.The experimental results indicated that silica gel had maximum preconcentration efficiency.adsorbing rates for hydrosulfide and methanethio are 74%、84% respectively,and enrichment rate can reach 500 fold for 5 L sample.The selected adsorbent was used for pretreatment of practical determination of analytes,and the average recovery rate was 95.5%、97.0%,RSD(n=5) was 5.3%、6.7% respectively.展开更多
文摘The density functional theory and cluster model methods have been employed to investigate the interactions between methanethiol, dimethyl sulfide and zeolites. The molecular complexes formed by adsorption of methanethiol or dimethyl sulfide on silanol H3SiOSi（OH）2OSiH3 with five coordination forms or four coordination forms, and complexes formed by interactions of BrSnsted acid sites of bridging hydroxyl H3Si（OH）AI（OH）2OSiH3 with methanethiol or dimethyl sulfide have been investigated. Full optimization and frequency analysis of all cluster models have been carried out using the B3LYP hybrid method at 6-31＋G （d,p） basis set level for hydrogen, silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms between methanethiol and H3Si（OH）Al（OH）2OSiH3, dimethyl sulfide and H3Si（OH）Al（OH）2OSiH3, methanethiol and H3SiOSi（OH）2OSiH3, dimethyl sulfide and H3SiOSi（OH）2OSiH3 complexes have been comparatively studied. The calculated results showed the nature of interactions that led to the formation of all complexes was van der Waals force confirmed by an insignificant change of geometric structures and properties. The conclusions that methanethiol and dimethyl sulfide molecules were adsorbed on bridging hydroxyl group prior to silanol group were obtained on the basis of adsorption heat, the most stable adsorption models of a 6 ring structure for interaction between bridging hydroxyl and methanethiol, and a 7 ring structure for interaction between bridging hydroxyl and dimethyl sulfide.
基金Supported by the National Natural Science Foundation of China(No.21106098)
文摘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 metha- nol 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 ot 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 en- riched using methanol. When the inlet concentration of MT was 0.005vo1% （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.
文摘In preventing and combating the chemical terrorist activities,in addition to those concerned highly toxic and huge harmful chemicals,some of mass destruction,widely affecting and poisoning of concealment volatile chemicals should also be concerned,such as hydrocyanic acid,hydrogen sulfide and methanethiol.Improvement of the identification and prevention awareness of such chemicals would be more effective in fighting against terrorist crimes.This article introduced the physical and chemical property and the toxicity of methanethiol,and the analysis method of the chemical in blood sample by GC-MS.
基金supported by the National Natural Science Foundation of China(20903075,21273172)Program of Introducing Talents of Discipline to Universities,China(111 Project)(B08040)Northwestern Polytechnical University Foundation for Fundamental Research,China(JC20100226)~~
文摘The preconcentration effect of alumina,silica gel,activated carbon and Chromsorb G-HP as adsorbents for ppb/v hydrosulfide and methanethio in ambient air was investigated by gas chromatography with FPD.Some factors including absorbent temperature,desorbing temperature and sampling flow rate were studied.The experimental results indicated that silica gel had maximum preconcentration efficiency.adsorbing rates for hydrosulfide and methanethio are 74%、84% respectively,and enrichment rate can reach 500 fold for 5 L sample.The selected adsorbent was used for pretreatment of practical determination of analytes,and the average recovery rate was 95.5%、97.0%,RSD(n=5) was 5.3%、6.7% respectively.
