A method was developed to determine the concentration of methyl tert-butyl ether(MTBE) in gasoline, diesel and heating oil by gas chromatography(GC) with mass spectrometry(GC-MS) or flame ionization detection(FID). Th...A method was developed to determine the concentration of methyl tert-butyl ether(MTBE) in gasoline, diesel and heating oil by gas chromatography(GC) with mass spectrometry(GC-MS) or flame ionization detection(FID). The diluted gasoline was directly injected into the GC, and the complete separation of MTBE from co-eluting hydrocarbons was not required. GC/MS or GC/FID method can be used to analyze MTBE in different concentration range and have good consistency.展开更多
The contamination of methyl ten-butyl ether （MTBE） in underground waters has become a widely concerned problem all over the world. In this study, a novel dosed culture system with oxygen supplied by H2O2 was introdu...The contamination of methyl ten-butyl ether （MTBE） in underground waters has become a widely concerned problem all over the world. In this study, a novel dosed culture system with oxygen supplied by H2O2 was introduced for MTBE aerobic biodegradation. After 7 d, almost all MTBE was degraded by a pure culture, a member of β-Proteobacteria named as PMI, in a closed system with oxygen supply, while only 40% MTBE was degraded in one without oxygen supply. Dissolved oxygen （DO） levels of the broth in closed systems respectively with and without H2O2 were about 5-6 and 4 mg/L. Higher DO may improve the activity of monooxygemase, which is the key enzyme of metabolic pathway from MTBE to tert-butyl alcohol and finally to CO2, and may result in the increase of the degrading activity of PM1 cell. The purge and trap GC-MS result of the broth in closed systems showed that tea-butyl alcohol, isopronol and acetone were the main intermediate products.展开更多
The toxicity of methyl tert-butyl ether （MTBE） to Chlorella ellipsoidea and Aphanizomenon flos-aquae was tested and assessed for a 15-d incubation with concentrations of MTBE from high （2.00×10^4 mg/L） to low...The toxicity of methyl tert-butyl ether （MTBE） to Chlorella ellipsoidea and Aphanizomenon flos-aquae was tested and assessed for a 15-d incubation with concentrations of MTBE from high （2.00×10^4 mg/L） to low （2 mg/L）. The results showed that the toxicity was low when the concentration of MTBE was in the range 1.00× 10^4-2.00× 10^4 mg/L （the greatest inhibition of growth-rate was 70%-71%, occurred during the day 1-5）. Low concentrations （2-500 rag/L） stimulated algal growth up to the greatest effect of 85%-200% when the concentration of MTBE was 50-100 mg/L during day 3-5. The toxicity of MTBE （72-120 h EC50） was 6.65×10^3-9.58×10^3 mg/L for C. ellipsoidea and that is 1.14× 10^4-2.00× 10^4 mg/L for A. floc-aquae. We found that the toxicity and ecological risk of MTBE for the algal community structure were low and the toxicity was influenced by the duration time of the test.展开更多
BACKGROUND The use of methyl-tertiary butyl ether(MTBE)to dissolve gallstones has been limited due to concerns over its toxicity and the widespread recognition of the safety of laparoscopic cholecystectomy.The adverse...BACKGROUND The use of methyl-tertiary butyl ether(MTBE)to dissolve gallstones has been limited due to concerns over its toxicity and the widespread recognition of the safety of laparoscopic cholecystectomy.The adverse effects of MTBE are largely attributed to its low boiling point,resulting in a tendency to evaporate.Therefore,if there is a material with a higher boiling point and similar or higher dissolubility than MTBE,it is expected to be an attractive alternative to MTBE.AIM To determine whether tert-amyl ethyl ether(TAEE),an MTBE analogue with a relatively higher boiling point(102°C),could be used as an alternative to MTBE in terms of gallstone dissolubility and toxicity.METHODS The in vitro dissolubility of MTBE and TAEE was determined by measuring the dry weights of human gallstones at predetermined time intervals after placing them in glass containers with either of the two solvents.The in vivo dissolubility was determined by comparing the weights of solvent-treated gallstones and control(dimethyl sulfoxide)-treated gallstones,after the direct infusion of each solvent into the gallbladder in both hamster models with cholesterol and pigmented gallstones.RESULTS The in vitro results demonstrated a 24 h TAEE-dissolubility of 76.7%,56.5%and 38.75%for cholesterol,mixed,and pigmented gallstones,respectively,which represented a 1.2-,1.4-,and 1.3-fold increase in dissolubility compared to that of MTBE.In the in vitro experiment,the 24 h-dissolubility of TAEE was 71.7%and 63.0%for cholesterol and pigmented gallstones,respectively,which represented a 1.4-and 1.9-fold increase in dissolubility compared to that of MTBE.In addition,the results of the cell viability assay and western blot analysis indicated that TAEE had a lower toxicity towards gallbladder epithelial cells than MTBE.CONCLUSION We demonstrated that TAEE has higher gallstone dissolubility properties and safety than those of MTBE.As such,TAEE could present an attractive alternative to MTBE if our findings regarding its efficacy and safety can be consistently reproduced in further subclinical and clinical studies.展开更多
As an additive of gasoline,methyl tert-butyl ether(MTBE)has a higher solubility in water,which is about 20 times as high as that of benzene.This characteristic results in MTBE dissolving out of the gasoline into the s...As an additive of gasoline,methyl tert-butyl ether(MTBE)has a higher solubility in water,which is about 20 times as high as that of benzene.This characteristic results in MTBE dissolving out of the gasoline into the soil and groundwater.Due to relative unique physicochemical behavior of MTBE it would be an ideal candidate for use in environmental forensic investigations.In order to study the transport and distribution of MTBE in saturated zone of ground water,a two-dimensional experimental cell was setup to simulate the real environment of the groundwater flow.The effects of soil and groundwater flow velocity on the MTBE transport were investigated.The results show that the mobile distance of MTBE in vertical direction was smaller than that in horizontal direction paralleling with the groundwater flow.Because the main dynamics of groundwater flow direction was convection and dispersion,the movement of MTBE is also diffusion in the vertical direction.In addition,the transport of MTBE was more quick in high permeability porous media,and the increase of groundwater flow velocity can accelerate the MTBE plume de-velopment,but the irregularity and randomness of the plume are enhanced synchronously.These research results can give some helps for the investigation of MTBE movement in the groundwater,also can make some references for other petroleum contamination behavior.展开更多
Several pervaporation membranes,cellulose acetate(CA),polyvinylbutyral(PVB),poly(MMA-co-AA),MMA-AA-BA,CA/PVB blend and CA/poly(MMA-co-AA)blend,were prepared,and their pervporation proper-ties were evaluated by separat...Several pervaporation membranes,cellulose acetate(CA),polyvinylbutyral(PVB),poly(MMA-co-AA),MMA-AA-BA,CA/PVB blend and CA/poly(MMA-co-AA)blend,were prepared,and their pervporation proper-ties were evaluated by separation of methanol/C5 or methanol/MTBE(methyl tert-butyl ether),The results shows that the CA composite membrane has a high separation performance (flux Jmethanol=35g.m^-2.h^-1 and separa-tion factor α>400)for methanol /C5 mixtures ,and the pervaporation characteristics of MMA-AA-BA copolymer membranes changes with the ratio of copolymer,For CA/poly(MMA-co-AA) blend membrane,the pervapora-tion performance is improved in comparison with CA or poly(MMA-co-AA) membrane,From the experiment of CA/PVB blend membranes for methanol/MTBE mixture,it is found that the compatibility of blends may affect the separation features of blend membrane.展开更多
文摘A method was developed to determine the concentration of methyl tert-butyl ether(MTBE) in gasoline, diesel and heating oil by gas chromatography(GC) with mass spectrometry(GC-MS) or flame ionization detection(FID). The diluted gasoline was directly injected into the GC, and the complete separation of MTBE from co-eluting hydrocarbons was not required. GC/MS or GC/FID method can be used to analyze MTBE in different concentration range and have good consistency.
基金Project supported by the National Natural Science Foundation of China (No. 20476099) Zhejiang Provincial Natural Science Foundation (No. Y504272).
文摘The contamination of methyl ten-butyl ether （MTBE） in underground waters has become a widely concerned problem all over the world. In this study, a novel dosed culture system with oxygen supplied by H2O2 was introduced for MTBE aerobic biodegradation. After 7 d, almost all MTBE was degraded by a pure culture, a member of β-Proteobacteria named as PMI, in a closed system with oxygen supply, while only 40% MTBE was degraded in one without oxygen supply. Dissolved oxygen （DO） levels of the broth in closed systems respectively with and without H2O2 were about 5-6 and 4 mg/L. Higher DO may improve the activity of monooxygemase, which is the key enzyme of metabolic pathway from MTBE to tert-butyl alcohol and finally to CO2, and may result in the increase of the degrading activity of PM1 cell. The purge and trap GC-MS result of the broth in closed systems showed that tea-butyl alcohol, isopronol and acetone were the main intermediate products.
基金supported by the National Natural Science Foundation of China (No. 20476099)
文摘The toxicity of methyl tert-butyl ether （MTBE） to Chlorella ellipsoidea and Aphanizomenon flos-aquae was tested and assessed for a 15-d incubation with concentrations of MTBE from high （2.00×10^4 mg/L） to low （2 mg/L）. The results showed that the toxicity was low when the concentration of MTBE was in the range 1.00× 10^4-2.00× 10^4 mg/L （the greatest inhibition of growth-rate was 70%-71%, occurred during the day 1-5）. Low concentrations （2-500 rag/L） stimulated algal growth up to the greatest effect of 85%-200% when the concentration of MTBE was 50-100 mg/L during day 3-5. The toxicity of MTBE （72-120 h EC50） was 6.65×10^3-9.58×10^3 mg/L for C. ellipsoidea and that is 1.14× 10^4-2.00× 10^4 mg/L for A. floc-aquae. We found that the toxicity and ecological risk of MTBE for the algal community structure were low and the toxicity was influenced by the duration time of the test.
文摘BACKGROUND The use of methyl-tertiary butyl ether(MTBE)to dissolve gallstones has been limited due to concerns over its toxicity and the widespread recognition of the safety of laparoscopic cholecystectomy.The adverse effects of MTBE are largely attributed to its low boiling point,resulting in a tendency to evaporate.Therefore,if there is a material with a higher boiling point and similar or higher dissolubility than MTBE,it is expected to be an attractive alternative to MTBE.AIM To determine whether tert-amyl ethyl ether(TAEE),an MTBE analogue with a relatively higher boiling point(102°C),could be used as an alternative to MTBE in terms of gallstone dissolubility and toxicity.METHODS The in vitro dissolubility of MTBE and TAEE was determined by measuring the dry weights of human gallstones at predetermined time intervals after placing them in glass containers with either of the two solvents.The in vivo dissolubility was determined by comparing the weights of solvent-treated gallstones and control(dimethyl sulfoxide)-treated gallstones,after the direct infusion of each solvent into the gallbladder in both hamster models with cholesterol and pigmented gallstones.RESULTS The in vitro results demonstrated a 24 h TAEE-dissolubility of 76.7%,56.5%and 38.75%for cholesterol,mixed,and pigmented gallstones,respectively,which represented a 1.2-,1.4-,and 1.3-fold increase in dissolubility compared to that of MTBE.In the in vitro experiment,the 24 h-dissolubility of TAEE was 71.7%and 63.0%for cholesterol and pigmented gallstones,respectively,which represented a 1.4-and 1.9-fold increase in dissolubility compared to that of MTBE.In addition,the results of the cell viability assay and western blot analysis indicated that TAEE had a lower toxicity towards gallbladder epithelial cells than MTBE.CONCLUSION We demonstrated that TAEE has higher gallstone dissolubility properties and safety than those of MTBE.As such,TAEE could present an attractive alternative to MTBE if our findings regarding its efficacy and safety can be consistently reproduced in further subclinical and clinical studies.
基金Under the auspices of the National Natural Science Foundation of China(No.20276048)the Municipal Natural Science Foundation of Tianjin(No.06YFJMJC06800)
文摘As an additive of gasoline,methyl tert-butyl ether(MTBE)has a higher solubility in water,which is about 20 times as high as that of benzene.This characteristic results in MTBE dissolving out of the gasoline into the soil and groundwater.Due to relative unique physicochemical behavior of MTBE it would be an ideal candidate for use in environmental forensic investigations.In order to study the transport and distribution of MTBE in saturated zone of ground water,a two-dimensional experimental cell was setup to simulate the real environment of the groundwater flow.The effects of soil and groundwater flow velocity on the MTBE transport were investigated.The results show that the mobile distance of MTBE in vertical direction was smaller than that in horizontal direction paralleling with the groundwater flow.Because the main dynamics of groundwater flow direction was convection and dispersion,the movement of MTBE is also diffusion in the vertical direction.In addition,the transport of MTBE was more quick in high permeability porous media,and the increase of groundwater flow velocity can accelerate the MTBE plume de-velopment,but the irregularity and randomness of the plume are enhanced synchronously.These research results can give some helps for the investigation of MTBE movement in the groundwater,also can make some references for other petroleum contamination behavior.
基金Supported by the National NaturM Science Foundation of China(No.29836160).
文摘Several pervaporation membranes,cellulose acetate(CA),polyvinylbutyral(PVB),poly(MMA-co-AA),MMA-AA-BA,CA/PVB blend and CA/poly(MMA-co-AA)blend,were prepared,and their pervporation proper-ties were evaluated by separation of methanol/C5 or methanol/MTBE(methyl tert-butyl ether),The results shows that the CA composite membrane has a high separation performance (flux Jmethanol=35g.m^-2.h^-1 and separa-tion factor α>400)for methanol /C5 mixtures ,and the pervaporation characteristics of MMA-AA-BA copolymer membranes changes with the ratio of copolymer,For CA/poly(MMA-co-AA) blend membrane,the pervapora-tion performance is improved in comparison with CA or poly(MMA-co-AA) membrane,From the experiment of CA/PVB blend membranes for methanol/MTBE mixture,it is found that the compatibility of blends may affect the separation features of blend membrane.
