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Cholesterol is an essential lipid molecule for several biological functions including the proper functioning of cell membranes, lipoproteins, and lipid rafts, as well as the synthesis of bile acids, vitamin D, and steroid hormones. Cholesterol can be extracted from liver tissue by multiple methods of lipid extraction. Subsequently, gas chromatography-mass spectrometry (GC-MS) can be used to obtain the highest level of sensitivity and selectivity in the analysis of cholesterol. This chapter describes two methods of lipid extraction for liver tissue, Bligh and Dyer and methyl tertiary butyl ether (MTBE), followed by an analysis with GC-MS., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

In Situ Chemical Oxidation (ISCO) based on the Fenton's process is a proven technology for the treatment of groundwater contaminated by organic compounds. Nevertheless, the application of this treatment process to methyl tert-butyl ether (MtBE) is questioned, as there are concerns about its capacity to achieve complete mineralization. Many existing studies have focused on water contaminated by MtBE and are thus not representative of in situ treatments since they do not consider the presence of soil. In this work, the effectiveness of a Fenton-like process for MtBE treatment was proven in soil column tests performed at operating conditions (i.e., oxidant and contaminant concentration and flow rates) resembling those typically used for in situ applications. No MtBE by-products were detected in any of the tested conditions, thus suggesting that the tert-butyl group of MtBE was completely degraded. A mass balance based on the CO 2 produced was used as evidence that most of the MtBE removed was actually mineralized. Finally, the obtained results show that preconditioning of soil with a chelating agent (EDTA) significantly enhanced MtBE oxidation. [ABSTRACT FROM AUTHOR]

The adsorption removal performance of DMDS from MTBE solution with various zeolites under the room conditions was studied. The results showed only ZSM-5 exhibited an excellent performance to remove DMDS from MTBE selectively for the strong competitive adsorption of MTBE, and yet other zeolites showed totally futile. The shape-selectivity should be responsible for the selective adsorption of ZSM-5. Effect of modification by transition metals loaded on ZSM-5 was studied. Only the adsorbent with Ag loading showed a positively enhanced capacity of selective sulfur adsorption among all adsorbents studied. The sulfur capacity was increased from 13.4 mg/g to 35.4 mg/g adsorbent in the simulation MTBE solution after modification by Ag. TGA-DSC analysis demonstrated the adsorption on the adsorbent occurred significantly via S—M bonds. [ABSTRACT FROM AUTHOR]

Oxygenated compounds (alcohols and ethers) have attracted attention as additives to gasoline to improve fuel specifications. These have a high octane number and contain oxygen. So, they decrease the knocking tendency and lead to the lowering of some exhaust emissions such as carbon monoxide (CO). In this study, methyl tertiary butyl ether (MTBE), a well-known oxygenate, was considered as a gasoline additive. The effects of MTBE-blended fuels with various blending rates (0, 5, 10, 20, and 30 vol.%) on engine performance and exhaust emissions were investigated using a Ricardo/Hydra, single cylinder, four-stroke spark ignition, fuel injection engine. The experiments were performed at engine speeds of 1500–5000 rpm with increments of 500 rpm at full load and a compression ratio of 10:1. The result of the engine tests indicated that engine torque was similar or close to unleaded gasoline (MTBE0) at MTBE percentages up to 10%. Moreover, MTBE blends improved brake thermal efficiency and decreased brake specific energy consumption. Regarding exhaust emissions, CO and HC emissions reduced with the increase of MTBE content in the blended fuel, but HC emissions did not decrease as much as CO emissions did. Furthermore, the concentration of NO increased for MTBE blends owing to oxygen enrichment. [ABSTRACT FROM AUTHOR]

In this study, biodiesel production under supercritical conditions among methanol, ethanol, and tert -butyl methyl ether (MTBE) was compared in order to elucidate the differences in their reaction behavior. A continuous reactor was employed, and experiments were conducted at various reaction temperatures (270–400 °C) and reaction times (3–30 min) and at a fixed pressure of 20 MPa and an oil-to-reactant molar ratio of 1:40. The results showed that under the same reaction conditions, the supercritical methanol method provided the highest yield of biodiesel. At 350 °C and 20 MPa, canola oil was completely converted to biodiesel after 10, 30, and 30 min in the case of – supercritical methanol, ethanol, and MTBE, respectively. The reaction kinetics of biodiesel production was also compared for supercritical methanol, ethanol, and MTBE. [ABSTRACT FROM AUTHOR]

Methyl tertiary-butyl ether (MTBE) is used to reduce carbon monoxide and ozone in urban air and to boost fuel octane. There is a lack of knowledge in the literature about the histomorphometric changes of the testis following exposure to MTBE. Therefore, this experimental study was performed to determine the effect of oral exposure to MTBE on histologic and histomorphometric changes of testis in adult rat. A total of 25 adult male Sprague-Dawley rats were randomly divided intofive equal experimental groups: control, almond oil and three treatment groups which received 400, 800 and 1600 mg/kg/day MTBE in almond oil by gavages for 30 consecutive days. Histomorphometric analysis showed no significant difference in absolute and relative testis weight, connective tissue thickness, germinal epithelium height, tunica albuginea thickness and Sertoli cell numbers between experimental groups (P>0.05). However, trend analysis showed that the seminiferous tubule diameter increased and interstitial cell numbers as well as spermatocyte and spermatid cell numbers decreased significantly in MTBE treated groups (P<0.05). It may be concluded that MTBE could exert adverse effects on spermatogenic cells in adult rat. Whether the observed changes in the present study are due to the direct effect of MTBE via passing blood-testis barrier or its indirect effect through another mechanism should be elucidated in future studies. [ABSTRACT FROM AUTHOR]

The release of methyl tert-butyl-ether (MTBE) into the environment has increased the worldwide concern about the pollution of MTBE. In this paper, a microbial consortium was isolated from the soil sample near an oil station, which can degrade MTBE directly with a low biomass yield and MTBE degrading efficiency. Further research has indicated that this consortium can degrade MTBE efficiently when grown on n-octane as the cometabolic substrate. The results of 16S rDNA based on phylogenetic analysis of the selected operating taxonomic units (OTUs) involved in the consortium revealed that one OTU was related to Pseudomonas putida GPo1, which could cometabolically degrade MTBE on the growth of n-octane. This may help explain why n-octane could be the optimal cometabolic substrate of the consortium for MTBE degradation. Furthermore, the degradation of MTBE was observed along with the consumption of n-octane. Different K values for MTBE were observed for cells grown with or without n-octane, suggesting that different enzymes are responsible for the oxidation of MTBE in cells grown on n-octane or MTBE. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism. [ABSTRACT FROM AUTHOR]

This study was designed to examine the efficacy of UV-assisted nano material treatments to remove methyl tertiary butyl ether (MTBE) from contaminated water. The focus was to investigate the applicability of combining the degradation potential of nano TiO2photocatalysis and adsorption power of carbon nano tubes (CNTs). Effect of different combinations of two ultraviolet radiations (UVA and UVC) and three types of nano materials: TiO2, CNTs, and TiO2/CNTs on MTBE remediation was studied. Removal efficiency of different combinations varied significantly with highest removal (95%) achieved by UVC-TiO2, followed by UVC-CNTs (75%) and UVA-TiO2/CNTS(60%). However, additive effect of UV/TiO2/CNTs on MTBE removal from water was not observed. Major degradation byproducts formed were acetone, tertiary butyl formate, and tertiary butyl alcohol. [ABSTRACT FROM PUBLISHER]

Four methyl tert-butyl ether (MTBE)-degrading bacteria were isolated from a processing plant in Malaysia. Based on 16S rDNA sequences, the four isolates were identified as Exiguobacterium profundum P1M-2, Bacillus megaterium P1M-11, Alishewanella sp. P2A-12 and Pseudomonas mendocina P2M-8. Each of the isolates obtained optimum growth using a different source of nitrogen (0.1- 0.03 % yeast or peptone) and all four isolates were able to biodegrade 92.05-99.98 % of MTBE within seven days. Amongst the four isolates, the highest percentage of MTBE degradation was achieved using B. megaterium P1M-11. The highest growth on tert-butyl alcohol (TBA), tert-amyl alcohol (TAA) and 2-hydroxyisobutyric acid (2-HIBA) was also observed in B. megaterium P1M-11. This study suggests MTBE degradation by each of the bacteria can be enhanced by choosing the right nitrogen source. Furthermore, the ability of B. megaterium P1M-11 to grow on primary metabolites of MTBE and other structurally related ethers suggests the secretion of diverse degradative enzymes, making this isolate a good candidate to be applied in MTBE bioremediation strategies. [ABSTRACT FROM AUTHOR]

Methyl tert -butyl ether (MTBE) is used at significant percentages as an additive of unleaded gasoline. The physical–chemical properties of the substance (water solubility, soil organic carbon–water partition coefficient) cause high mobility and high concentrations in groundwater. Laboratory scale batch and column tests and mathematical modeling were performed to study the feasibility of a biobarrier (BB), that is an in situ permeable biological barrier with or without inoculation, for the remediation of MTBE and other gasoline-derived pollutants (benzene, toluene, ethylbenzene, o -xylene and m + p -xylenes, BTEXs) polluted groundwater and to estimate kinetic constants. The experimental results showed simultaneous biodegradation of MTBE and BTEXs, with similar removals in the uninoculated and the inoculated systems. Ranges for the first order kinetic removal were obtained for MTBE ((0.18 ± 0.02)/(0.28 ± 0.11 d −1 )), B ((0.39 ± 0.12)/(0.56 ± 0.12 d −1 )), T ((0.51 ± 0.03)/(0.78 ± 0.15 d −1 )), E ((0.46 ± 0.18)/(1.57 ± 0.21 d −1 )), o -X ((0.24 ± 0.08)/(0.64 ± 0.09 d −1 )) and m + p -X ((0.20 ± 0.04)/(1.21 ± 0.04 d −1 )). The results of the laboratory tests allowed to improve mathematical modeling in order to design a full-scale BB at a gasoline-contaminated site. [ABSTRACT FROM AUTHOR]

Bioethanol and fatty acid methyl esters are a regular part of the production of gasoline and diesel fuels, although in limited quantities. Introduction of bioethanol as part of automobile gasoline was associated with high production costs, technical and logistical problems. This article analyses changes of distillation curve of biobutanol and isobutanol as an alternative to bioethanol. Added alcohol to gasoline causes reduction of boiling point due to the formation of azeotrope. This phenomena of distillation curve are called Plato effect. Therefore, ethers (MTBE and ETBE) are added to fuel to affect the most central part of distillation curve. Especially, to decrease the distillation temperature oppose to gasoline without oxygenates of wide range of distilled volume. This article replaces simple universal models predicting properties of alcohol-gasoline mixtures. It was found that mixture of ETBE with bioethanol in gasoline the distillation curve summarise its effects. Butanol and MTBE influence distillation curve of gasoline only in values of its boiling points. Therefore, butanol is mixable with all listed fuel components without any additional addaptations. [ABSTRACT FROM AUTHOR]

Original hydrocarbon composition, volatility, compatibility with materials, calorific value and stability of the mixture in the presence of water are monitored usually. This paper deals with the stability of gasoline-biobutanol and gasoline-bioethanol mixtures in the presence of water. Biobutanol is better biofuel than bioethanol using the same raw materials. Different contents of alcohol and oxygenated cosolvents are evaluated. Experimental analysis are focused on the water solubility and phase stability. Solubility in water of butanol and ethanol mixtures is very similar. Butanol-gasoline mixture provides better phase stability upon contact with water or atmospheric moisture oppose to ethanol mixtures. Butanol also does not enter to the aqueous layer and fuel properties remain in phase separation preserved. Further, it was found that crystals occur at low temperatures after exclusion of water was seen. Moreover, the temperature of phase separation can affect the content of alcohol, water, hydrocarbon composition and cosolvents added. The only difference found between more beneficial butanol and less beneficial ethanol was ABE (Aceton-Butanol-Ethanol) fermentation with Clostridium Acetobutylicum allowing to ferment also saccharidic cellulose to biobutanol according to standard of second generation biofuels. [ABSTRACT FROM AUTHOR]

In addition to widely known species automotive fuels that are currently on the market, there are many other chemicals which are used or can be used as fuels or fuel components for current automotive internal combustion engines. Implementation of such ingredients car brings a number of technical problems. The vapour pressure is the pressure in the system in which they are at a certain temperature gaseous and liquid phases in equilibrium. The addition of alcohols such as gasoline constituents significantly affects the volatility of the resulting mixture. The article is focused on assessing the addition of biobutanol as n-butanol or isobutanol vapour pressure compared to the already commonly used in bioethanol. Also included is the possibility to use ethers for influencing the vapour pressure of the resulting mixture. Part of the experiment is to assess the influence of the quantity and type of oxygenates and composition of gasoline. Based on the measured data it is clear that addition of alcohol to gasoline create complications. Effect biobutanol as possible alternatives is different than bioethanol. It is therefore necessary to take into account the influence of alcohol, even at low concentrations corresponding to the limit according to standard EN 228. Biobutanol compared bioethanol can be used as 100% fuel. For the low vapour pressure of the fuel experiment also aims to increase its value using pentane. [ABSTRACT FROM AUTHOR]

This study was undertaken to support a remediation technique that will be applied to contaminated groundwater in the vicinity of Ghonan landfill, eastern Saudi Arabia. Preliminary field investigations involved hydrogeological characterization of the entire area. The improved understanding of the underlying geology and groundwater movement gained from the preliminary studies helped in determining a test site within the proximity of the landfill. One remediation well and five monitoring wells were constructed at the test site. Optimum pumping rate for the remediation well was determined to range from 2.642 through 7.926 gallons per minute (gpm) (0.01 m/min through 0.03 m/min) based on site-specific hydrogeological investigations and mathematical simulation. A concentration of 0.05 mg/L of methyl tertiary-butyl ether (MTBE) contaminated the aquifer in the test site. The simulated concentration of MTBE at the point of exposure after a period of 2 years was found to be higher than the maximum contaminant level of 0.005 mg/L set by the United States Environmental Protection Agency (U.S. EPA). The results of risk assessment conducted revealed that domestic use of groundwater in the study area through any of the exposure pathways (ingestion, dermal contact, and inhalation in the shower) may lead to development of health risks to human receptors. The landfill, which is being operated as a hazardous landfill and a dump site, may become a source of groundwater pollution in its vicinity in the near future. As a potential health risk, it should be controlled properly by remediating the aquifer and implementing environmental measures to the landfill users. [ABSTRACT FROM AUTHOR]

Highly hydrophobic titania, alumina and zirconia porous ceramic membranes were prepared by grafting of C 6 F 13 C 2 H 4 Si(OEt) 3 (C6) and C 12 F 25 C 2 H 4 Si(OEt) 3 (C12) molecules and subsequently applied in pervaporation (PV) process for removal of volatile organic compounds (methyl tert-butyl-ether/MTBE and ethyl acetate/EtAc) from binary aqueous solutions. Transport of pure water through pristine and hydrophobized membranes were compared. The transport and separation properties in PV process of investigated hydrophobic membranes were discussed. The influence of the membrane materials, pore size of the membranes as well as conditions of the grafting procedure (time and type of molecules) on the pervaporative properties was presented. All investigated membranes were selective toward organic compounds. The highest efficiency was found for the TiO 2 membranes, independently of the utilized system and applied grafting molecules. Better transport and selective properties were observed for membrane modified by C6 molecules than by C12 ones. TiO 2 and ZrO 2 membranes modified by C6 were characterized by high β separation factors 84 (TiO 2 ) and 56 (ZrO 2 ). The least effective membrane was alumina one. Additionally, the influence of contact of different solvents (water, EtAc and MTBE) with the hydrophobic layer was discussed. It was found that in the presence of organic compounds in the aqueous solution, the conformation of hydrophobic chains is changing from tangled to straight one. [ABSTRACT FROM AUTHOR]

Bioremediation of groundwater contaminated with methyl tert -butyl ether (MTBE) has been widely described since their cost/efficient ratios are lower than other physic-chemical methodologies. The present study focused on the isolation and selection of MTBE degrading microorganisms from contaminated soil and groundwater samples based on results from growth on mineral media amended with MTBE and BTEX, presence or absence of the monooxygenase genes and specific ability to degrade MTBE. Three bacterial strains were selected and identified as Rhodococcus ruber , strains EE1 (CECT 8555), EE6 (CECT 8612) and A5 (CECT 8556), showing the ability to degrade 60.0, 36.0 and 10.0 mg l −1 MTBE, respectively. Moreover, all the R. ruber strains showed the presence of genes encoding MTBE-degrading enzymes. One isolated strain was identified as Paenibacillus sp. SH7 (CECT 8558) and demonstrated the greatest MTBE degradation value (100 mg l −1 ), but together with the last strain selected and identified as Agrobacterium sp. MS2 (CECT 8557) did not result in positive amplification of any of the monooxygenase primers tested. The lowest toxicity (as EC 50 ) was observed after 4-days growth of R. ruber EE6 on MTBE-supplemented mineral medium. The potential application of these strains in bioremediation processes is discussed. [ABSTRACT FROM AUTHOR]

Methyl tert-butyl ether (MTBE) is an organic compound toxic and very soluble in water. When MTBE-contaminated water is available, it requires some method of decontamination. The Fenton method is used in environmental remediation and water treatment with low contaminant concentrations. In the search to extend the field of application of this methodology, they were begun to use catalysts in solid phase, particularly, metallic Fe nanoparticles (ZVI). In our laboratory we have prepared and characterized a supported catalyst (ZVI on a natural zeolite) that was studied for benzene degradation in experiences in batch and in fixed bed (continuous system) with interesting results. A similar set up was designed for the experiences described in this paper where aqueous solutions of MTBE with different concentrations were employed. The pH was regulated at 3.5 with a buffer. Bubble detachment was observed from the catalyst located in the bottom of the erlenmeyer demonstrating an important MTBE mineralization degree. Secondary products of degradation were detected and characterized. For experiences in batch, the MTBE removal was 45% approximately in 24 hours. MTBE degradation in columns after the first hour is higher than the observed in the batch system although it raises a degradation degree in the order of 52% during the entire run. [ABSTRACT FROM AUTHOR]

Surface water and air volatile organic compound ( VOC) data from 10 U.S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water ( C w s) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m- & p-xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long-term method detection levels ( LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one-half the LTMDL in water. Six compounds (chloroform, p-isopropyltoluene, methylene chloride, perchloroethene, 1,1,1-trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m- & p-xylene, methyl tert-butyl ether ( MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere. [ABSTRACT FROM AUTHOR]

A method of producing MTBE product with low sulfur content and recovering bisulfides (RSSR) was discussed. Based on the boiling point differences of the components and sulfides in the mixed C4 fraction, mixed C4 fraction were sent to a fractionator to separate the light C4 fraction and heavy C4 fraction. The top products were routed to MTBE unit as light C4 fraction, while the heavy C4 fraction were drawn as side product, which mainly contained C5, cis butylene, ethanethiol, iso-propanethiol, etc. The heavy C4 fraction account for about 8%-15% of the total mixed C4 fraction ration. A RSSR recycling feedback line was set on just beneath the lowest side-draw tray of the fractionator mainly to solve the problem of bottom level control due to the small amount of RSSR. The bottom products(mainly RSSR) were sent to a RSSR fractionator, which was specially designed and operated batchwise. Dimethyl-bisulfides and diethyl-bisulfides were separated in the fractionator and used as chemical raw materials or chemical products. The treated light C4 fraction contains no heavy sulfides such as C5 or ethanethiol, so that the total sulfur content of the MTBE produced by the treated light C4 fraction was decreased to below 10 mg/kg. The method has advantages of simple process, no need of outside adsorbents or absorbents, and no additional waste emissions. [ABSTRACT FROM AUTHOR]

Endocrine-related endpoints in animals have been reported to respond to high doses of methyl tertiary-butyl ether (MTBE), however, a systematic and transparent evaluation of endocrine potential has not been published. Resolving whether MTBE exhibits endocrine activity is important given regulatory and public interest in endocrine disrupting substances and their potential for causing adverse effects in humans or wildlife. A weight-of-evidence (WoE) analysis was conducted, focusing on hypotheses related to the potential for MTBE to interact with estrogen, androgen, and thyroid pathways, and steroidogenesis. To reach scientifically justified conclusions based on the totality of evidence, this WoE procedure involved a semi-quantitative relevance weighting of each endpoint for each hypothesis and systematic consideration of each endpoint in various study designs. This procedure maximized use of an extensive body of relevant and reliable literature on MTBE with evidence supporting or opposing a given mode of action hypothesis. Evaluating the strength and consistency of observations from many MTBE studies also provided a way to assess whether high doses used in experiments with MTBE confound identification of direct endocrine system responses. Based on results of studies using mammalian and fish models and in vitro screening assays, this WoE assessment reveals that MTBE lacks direct endocrine activity. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports about a pilot-scale feasibility study of In-Situ Chemical Oxidation (ISCO) application based on the use of stabilized hydrogen peroxide catalyzed by naturally occurring iron minerals (Fenton-like process) to a site formerly used for fuel storage and contaminated by MtBE. The stratigraphy of the site consists of a 2–3meter backfill layer followed by a 3–4meter low permeability layer, that confines the main aquifer, affected by a widespread MtBE groundwater contamination with concentrations up to 4000μg/L, also with the presence of petroleum hydrocarbons. The design of the pilot-scale treatment was based on the integration of the results obtained from experimental and numerical modeling accounting for the technological and regulatory constraints existing in the site to be remediated. In particular, lab-scale batch tests allowed the selection of the most suitable operating conditions. Then, this information was implemented in a numerical software that allowed to define the injection and monitoring layout and to predict the propagation of hydrogen peroxide in groundwater. The pilot-scale field results confirmed the effective propagation of hydrogen peroxide in nearly all the target area (around 75m2 using 3 injection wells). As far as the MtBE removal is concerned, the ISCO application allowed us to meet the clean-up goals in an area of 60m2. Besides, the concentration of TBA, i.e. a potential by-product of MtBE oxidation, was actually reduced after the ISCO treatment. The results of the pilot-scale test suggest that ISCO may be a suitable option for the remediation of the groundwater plume contaminated by MtBE, providing the background data for the design and cost-estimate of the full-scale treatment. [Copyright &y& Elsevier]

Biochars generated at various temperatures might show significant differences in sorption for organic contaminants. In this study, a series of biochars, generated from pyrolyzing maize straws at different temperatures, were systematically characterized. The characterization results showed that with increasing pyrolysis temperature, the surface areas, micropore areas and aromaticity of biochars were enhanced. Batch experiments were conducted to study methyl tert-butyl ether (MTBE) and benzene sorption to biochars. The results indicated that the sorption capacity of benzene to biochars was higher than that of MTBE. The higher pyrolyzed temperature of biochars resulted in a stronger sorption affinity for target compounds, and the dominant sorption mechanisms varied for biochars pyrolyzed at different temperatures. The sorption to biochars pyrolyzed at 700 and 800 °C performed a high adsorption capacity, which indicated that they might be a promising sorbent to remove MTBE and benzene from water. Biochar pyrolyzed at 400 °C showed transitional sorption mechanisms from partition to adsorption for MTBE and benzene. Pore-filling was a possible sorption mechanism to biochars pyrolyzed at high temperature. [ABSTRACT FROM AUTHOR]

Abstract: This activated carbon research appraised how pore size and empty-bed contact time influenced the removal of methyl tert-butyl ether (MTBE) at part-per-billion (ppb) concentrations when MTBE was the sole organic impurity. The study compared six granular activated carbons (GACs) from three parent sources; these GACs contained a range of pore volume distributions and had uniform slurry pHs of 9.7–10.4 (i.e. the carbons' bulk surface chemistries were basic). Several of these activated carbons had been specifically tailored for enhanced sorption of trace organic compounds. In these tests, MTBE was spiked into deionized-distilled water (∼pH 7); MTBE loading was measured by isotherms and by rapid small-scale column tests (RSSCTs) that simulated full-scale empty-bed contact times of 7, 14, and 28 min. The results showed that both ultra-fine micropores and small-diameter mesopores were important for MTBE adsorption. Specifically, full MTBE loading during RSSCTs bore a strong correlation (R 2 = 0.94) to the product (mL/g × mL/g) of pore volume ≤4.06 Å wide and pore volume between ∼22 Å and ∼59 Å wide. This correlation was greater than for the product of any other pore volume combinations. Also, this product exhibited a stronger correlation than for just one or the other of these two pore ranges. This multiplicative relationship implied that both of these pore sizes were important for the optimum GAC performance of these six carbons (i.e. favorable mass transfer coupled with favorable sorption). The authors also compared MTBE mass loading during RSSCTs (μg MTBE/g GAC) to isotherm capacity (μg MTBE/g GAC). This RSSCT loading “efficiency” ranged from 28% to 96% for the six GACs; this efficiency correlated most strongly to pores that were 14–200 Å wide (R 2 = 0.94). This correlation indicated that only those carbons with a sufficient volume of 14–200 Å pores could adsorb MTBE to the extent that would be predicted from isotherm data. [Copyright &y& Elsevier]

Abstract: Methyl tertiary-butyl ether (MTBE) is a solvent and fuel additive included in reformulated gasoline to increase combustion efficiency. While widespread use in motor fuels in the U.S. was discontinued after MTBE was detected in surface and ground waters due to concerns about environmental persistence and water quality, it is still manufactured in the U.S. for export. Questions concerning the etiology of rat Leydig cell and mouse liver tumors identified in extremely high dose cancer studies have led to an interest in evaluating potential hormonal imbalances and endocrine system involvement. To address the possibility that MTBE or its metabolite, tert-butanol (TBA), are interacting with components of the endocrine system that are involved in steroidogenesis a number of targeted experiments were performed focusing mostly on the primary gonadal steroids, estradiol and testosterone. The goal of the experiments was to gain a better understanding of potential interactions with the steroidogenic pathway, including effects specifically on aromatase, the P450 enzyme that converts testosterone to estradiol. In three GLP-compliant in vitro guideline studies, MTBE and TBA were classified as non-binders to the androgen receptor, were classified negative for effects on testosterone and estradiol in the steroidogenesis assay, and were classified as non-inhibitors of aromatase activity. In three 14-day in vivo experiments involving gavaging of male Sprague-Dawley rats with doses of MTBE ranging from 400 to 1500mg/kg bw/day, the lack of definitive and consistent supporting statistically significant findings in steroid hormone measurements and aromatase activity and mRNA measured in liver and testis microsomes further suggested that it is unlikely that MTBE is interacting with the endocrine system directly. Evidence of other underlying systemic effects were also seen, including reduced body weight gain, increased adrenal weights, and elevated corticosterone suggestive of a more general stress response. Taken together, the results from these studies suggest that MTBE and TBA do not directly impact the steroidogenic pathways involved in estrogen and androgen production. [Copyright &y& Elsevier]

Highlights: [•] A pseudo first order reaction model could describe the decomposition kinetics. [•] MTBE molecules are more resistant to ozone than ETBE and TAEE molecules. [•] The removal kinetics by photocatalytic ozonation in water and wastewater were similar. [•] The adsorption level on the catalyst surface was as follows: MTBE>ETBE>TAEE. [•] Photocatalysis increased the ozonation rates of MTBE, ETBE and TAEE significantly. [Copyright &y& Elsevier]

Abstract: Ethanol and methyl-tertiary butyl ether (MTBE) were close substitutes in the gasoline additives market until MTBE was banned due to the concerns about groundwater contamination, leading to a sudden and dramatic substitution toward ethanol as an alternative oxygenate and octane-booster. We use variation in the timing of MTBE bans across states to identify their effects on gasoline prices. We find that state bans increased reformulated gasoline prices by 3–6 cents in non-Midwestern states for which the bans were binding, with larger impacts during times of high ethanol prices relative to MTBE and crude oil. We find qualitatively similar, yet smaller effects for conventional gasoline. We argue on the basis of a simple conceptual model and supporting empirical evidence that these bans functioned as implicit ethanol blending mandates in areas that were previously using MTBE to comply with strict environmental constraints. Overall, our results are consistent with the theoretical prediction that mandating a minimum market share for a more costly alternative fuel—either directly, or implicitly through a ban on the preferred conventional fuel—will inevitably increase fuel prices in a competitive market. [Copyright &y& Elsevier]

Abstract: Wide use of methyl tert-butyl ether (MTBE) as fuel oxygenates leads to worldwide environment contamination with this compound basically due to fuel leaks from storage or pipelines. Presence of MTBE in drinking water is of high environmental and social concern. Existing methods for MTBE removal from water have a number of limitations which can be possibly overcome in the future with use of emerging technologies. This work aims to provide an updated overview of recent developments in technologies for MTBE removal from water. [Copyright &y& Elsevier]

A field-scale fixed bed bioreactor was used to successfully treat an MTBE-contaminated aquifer in North Hollywood, CA without requiring inoculation with introduced bacteria. Native bacteria from the MTBE-impacted aquifer rapidly colonized the bioreactor, entering the bioreactor in the contaminated groundwater pumped from the site, and biodegraded MTBE with greater than 99 % removal efficiency. DNA sequencing of the 16S rRNA gene identified MTBE-degrading bacteria Methylibium petroleiphilum in the bioreactor. Quantitative PCR showed M. petroleiphilum enriched by three orders of magnitude in the bioreactor above densities pre-existing in the groundwater. Because treatment was carried out by indigenous rather than introduced organisms, regulatory approval was obtained for implementation of a full-scale bioreactor to continue treatment of the aquifer. In addition, after confirmation of MTBE removal in the bioreactor to below maximum contaminant limit levels (MCL; MTBE = 5 μg L), treated water was approved for reinjection back into the aquifer rather than requiring discharge to a water treatment system. This is the first treatment system in California to be approved for reinjection of biologically treated effluent into a drinking water aquifer. This study demonstrated the potential for using native microbial communities already present in the aquifer as an inoculum for ex-situ bioreactors, circumventing the need to establish non-native, non-acclimated and potentially costly inoculants. Understanding and harnessing the metabolic potential of native organisms circumvents some of the issues associated with introducing non-native organisms into drinking water aquifers, and can provide a low-cost and efficient remediation technology that can streamline future bioremediation approval processes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phase equilibrium and surface tension of the binary system methyl-tert-butyl ether+2,5-dimethylfuran. [•] Experimental vapor–liquid equilibrium data for methyl-tert-butyl ether+2,5-dimethylfuran at 50, 75 and 94kPa. [•] Experimental surface tension data for methyl-tert-butyl ether+2,5-dimethylfuran 298.15K. [•] Theoretical modeling of phase equilibrium and interfacial properties by PR EoS, MHV mixing rule and square gradient theory. [Copyright &y& Elsevier]

Highlights: [•] New multi-element isotope modeling approach based on position-specific isotopologues. [•] The method mechanistically tracks contaminant transformation via different pathways. [•] 2D and 3D isotope modeling applications: toluene, MTBE and nitrobenzene degradation. [ABSTRACT FROM AUTHOR]

This study was undertaken to develop a methodology suitable for the direct removal and degradation of methyltertiarybutyl ether (MTBE) in water using different nano-catalysts supported laser based photo-oxidation process. For this purpose, nano-structured WO3catalyst was synthesized in our laboratory and its photocatalytic activity for the demineralization of MTBE in water was compared with different catalysts such as ZnO, TiO2, Fe2O3and NiO using 355 nm laser radiations generated by the third harmonic of Nd: YAG laser. The effect of laser irradiation time, amount of catalysts and pH were also investigated for the optimization of MTBE removal process. For 60 min of laser exposure time, the overall percentage of MTBE degradation was found to be 93%, 89%, 82%, 80% and 71% for WO3, ZnO, Fe2O3,NiO and TiO2,respectively. In addition the photonic efficiencies of different nano-structured catalysts toward degradation of MTBE were estimated, and they were found to follow the trend of WO3> ZnO > Fe2O3> NiO > TiO2. [ABSTRACT FROM AUTHOR]

Highlights: [•] Achromobacter xylosoxidans MCM2/2/1 was reported to degrade Ethyl tert butyl ether (ETBE) and Methyl tert butyl ether (MTBE). [•] Presence of putative cytochrome P450 was identified in A. xylosoxidans MCM2/2/1 through PCR. [•] Expression of the putative cytochrome P450 gene was altered in the presence of MTBE and TBA. [•] Full length cytochrome P450 gene was identified. [ABSTRACT FROM AUTHOR]

Methyl tertiary butyl ether (MTBE) is known as a promising substitute for tetra ethyl lead (TEL) in order to increase the octane number of gasoline. MTBE process, as many other processes, has two distinguished section, namely reaction section and separation section. In this paper we focus only on synthesis and optimization of separation section of this process. In order to achieve this objective, many possible flowsheets have been considered, among which, two alternatives are pointed out as optimum candidates. The second step involves determination of dominant design variables and their range of variation. Both selected flowsheets have been cost analyzed in their corresponding ranges of dominant design variables to determine plots of total annual cost (TAC). Knowing feed specifications at the entrance of separation section, the designer will be able to choose appropriate flowsheet and optimum conditions using the plots presented in this paper.

• New RON and MON measurements of pure components and gasolines blended with MTBE. • The RON and MON of MTBE/gasoline blends are mostly non-linear. • Octane predictive models of MTBE blended with gasoline fuels were developed. • The models consist of linear and non-linear terms that depend on base fuel properties. • The models can be integrated in the process of designing MTBE/gasoline surrogates. Despite the wide utilization of MTBE as an octane booster for market gasoline fuels, the blending characteristics of methyl tert -butyl ether (MTBE) with gasoline fuels are not fully understood. This arises from the lack of octane number measurement of MTBE/gasoline blends, along with lack of detailed analyses of MTBE blending characteristics. In an attempt to address the knowledge gap in MTBE blending, this study provides new research octane number (RON) and motor octane number (MON) measurements of MTBE blended with various pure components and gasoline fuels. The first set of blends were binary mixtures of pure components blended with MTBE. The pure components we chosen to represent PIONA (paraffins, iso -paraffins, olefins, naphthenes and aromatics) molecular classes. The second set of blends were Fuels for Advanced Combustion Engines (FACE) and market gasoline fuels with MTBE. It was observed that the addition of MTBE to n-paraffins, iso -paraffins and olefins results in synergistic octane number effect while linear-by-volume and antagonistic blending was observed for MTBE blends with naphthenes and aromatics, respectively. The octane numbers and response of gasoline/MTBE blends are also dependent on the composition of the base gasoline fuel. These new measurements along with literature dataset were utilized to develop octane predictive models for MTBE blended with gasoline fuels. Various blending rules such as linear-by-volume (LBV), octane sensitivity (OS) and PIONA based models were developed in this work. The most accurate model was the linear-by-volume with the iso -paraffins and aromatics terms where more than 80% of the predictions are within the experimental reproducibility limits. The model can be used to predict and quantify the characteristics of octane boost caused by MTBE addition to gasoline fuels. It can also be used to optimize the octane boost due to the addition of MTBE by changing the composition of the base gasoline fuel. [ABSTRACT FROM AUTHOR]

Abstract: Methyl tert-butyl ether (MTBE) was removed from aqueous solution by photochemical reaction catalyzed by nanocrystalline TiO2 and UV radiation as a treatment strategy. The experiments were conducted at high concentration of MTBE (10,570μL−1) in a recirculating batch reactor. The optimum loading of TiO2 was found experimentally. The concentrations of MTBE and its by products were measured using a purge-and-trap gas chromatography and ion chromatography methods. Additionally, in order to explore the degradation mechanism of MTBE, by-products of MTBE oxidation were identified by using a Head space gas chromatograph–mass spectrometer (HS/GC/MS) as tert-butyl formate (TBF), tert-butyl alcohol (TBA), acetone, 2-methyl-1-propene and isopropanoic acid, all are readily degraded photocatalytically. Nearly complete removal of MTBE (>99.9%) was achieved after 2h of reaction and a pseudo first order rate constant for the degradation of MTBE was estimated to be 6.4×10−2 min−1. Moreover TBF degradation rate was slower and proceeded with a first-order rate constant of 2.8×10−2 min−1. Finally, the percent of photocatalytic degradation of MTBE was studied in the presence of carbonate ion. Mass balance calculations have shown that MTBE is virtually completely mineralized. This study offers a potential remediation technique for treating MTBE-contaminated groundwater. [Copyright &y& Elsevier]

Abstract: Vertical flow systems filled with porous medium have been shown to efficiently remove volatile organic contaminants (VOCs) from contaminated groundwater. To apply this semi-natural remediation strategy it is however necessary to distinguish between removal due to biodegradation and due to volatile losses to the atmosphere. Especially for (potentially) toxic VOCs, the latter needs to be minimized to limit atmospheric emissions. In this study, numerical simulation was used to investigate quantitatively the removal of volatile organic compounds in two pilot-scale water treatment systems: an unplanted vertical flow filter and a planted one, which could also be called a vertical flow constructed wetland, both used for the treatment of contaminated groundwater. These systems were intermittently loaded with contaminated water containing benzene and MTBE as main VOCs. The highly dynamic but permanently unsaturated conditions in the porous medium facilitated aerobic biodegradation but could lead to volatile emissions of the contaminants. Experimental data from porous material analyses, flow rate measurements, solute tracer and gas tracer test, as well as contaminant concentration measurements at the boundaries of the systems were used to constrain a numerical reactive transport modeling approach. Numerical simulations considered unsaturated water flow, transport of species in the aqueous and the gas phase as well as aerobic degradation processes, which made it possible to quantify the rates of biodegradation and volatile emissions and calculating their contribution to total contaminant removal. A range of degradation rates was determined using experimental results of both systems under two operation modes and validated by field data obtained at different operation modes applied to the filters. For both filters, simulations and experimental data point to high biodegradation rates, if the flow filters have had time to build up their removal capacity. For this case volatile emissions are negligible and total removal can be attributed to biodegradation, only. The simulation study thus supports the use of both of these vertical flow systems for the treatment of groundwater contaminated with VOCs and the use of reactive transport modeling for the assessment of VOCs removal and operation modes in these high performance treatment systems. [Copyright &y& Elsevier]

Methyl tert-butyl ether (MTBE) is a common gasoline additive; it has become a worldwide groundwater pollutant. Granular activated carbon (GAC) adsorption treatment is not cost effective for removing MTBE because it is not well adsorbed. Bioaugmentation of enriched MTBE degraders originated from the soil sample of a gasoline station enhanced the performance of the column filled with the MTBE degrader containing spent GAC of the La Mirada remediation site, and made it an effective biological activated carbon (BAC) system producing a high quality effluent that will meet the US EPA's recommended <20 μg/L for source of drinking water. The carbon samples of this system were successfully employed to start up several highly efficient BAC columns in 30 days producing stable effluents under variable treatment conditions with long term effluent MTBE concentration mostly <10 μg/L, more than 99% reduction of 1-1.3 mg /L in the influent. On the basis of the similarity of 16 s rDNA sequence of the PCR-DGGE procedures, five major bacterial species of stable biochemical properties were found in the BAC effluent samples; one of the five was Bacterium RS58G, whereas the other four were uncultured bacteria. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 512-523, 2013 [ABSTRACT FROM AUTHOR]

Methyl Tert-Butyl Ether (MTBE) is an oxygenated organic compound extensively substituted for lead in gasoline worldwide. MTBE can affect human and environment. In this research, biodegradation capability of MTBE by identified indigenousBacillus cereusstrainRJ1was studied. Obtained results showed that biological removal of MTBE with 200 mg/L samples in 28°C is 27.5% while in 37°C within 120 days reaches to 34%. In addition, biodegradation ofBacillus cereus RJ1in 500 mg/L and 1,000 mg/L is 28% and 23.9% in 28°C, respectively. Therefore, this bacterium could clean up MTBE from the environment. [ABSTRACT FROM PUBLISHER]

In the chemical and petrochemical industries, dehydrogenating of hydrocarbons to olefins as raw materials for the manufacture of various chemical products is an important economic issue. So, here, the redispersion and regeneration of a commercial Pt-Sn/γ-Al2O3 catalyst utilized for the conversion of isobutane to isobutene was studied. First, in order to regenerate the deactivated commercial catalyst unloaded from a commercial reactor, coke burning under controlled conditions was carried out. Then, to redisperse the platinum on the surface of the catalyst, a HCl solution (injected through a syringe pump) and Cl2 were passed over the catalytic bed at specific flow rates and temperatures. Evaluation tests carried out over the regenerated catalyst prove that the regenerated catalyst has similar conversion, selectivity, and structural characteristics as compared to the fresh one. [ABSTRACT FROM AUTHOR]

Highlights: [•] Low-pressure laminar premixed flames of PRF90/ethanol and PRF90/MTBE were realized. [•] A detailed mechanism for the low-pressure oxidation of the blends was developed. [•] The effect of ethanol and MTBE on high temperature oxidation of PRF90 was analyzed. [Copyright &y& Elsevier]

Highlights: [•] Two novel adsorbents: nano-PFOALG and nano-PFOALB were used as sorbents. [•] Experimental and modeling analysis of MTBE/TBA adsorption in single and binary systems. [•] Effect of the single-component isotherm equation on the binary isotherm predictions. [•] Binary adsorption kinetics of the MTBE and TBA were comprehensively studied. [•] The adsorbents exhibited good adsorption behavior for MTBE and TBA. [ABSTRACT FROM AUTHOR]

Two deep frozen persons, a female and a male, were found dead in a car. There had been an explosive fire inside the car which had extinguished itself. On the floor inside the car were large pools of liquid which smelled of gasoline. The autopsy findings and routine toxicological analyses could not explain the cause of death. Carboxyhemoglobin levels in the blood samples were <10%. Analysis with a headspace gas chromatography revealed methyl tert-butyl ether ( MTBE) concentrations of 185 mg/L (female victim) and 115 mg/L (male victim) in peripheral blood. The urine MTBE concentrations were 150 mg/L and 256 mg/L, respectively. MTBE is a synthetic chemical which is added to gasoline as a fuel oxygenate. Gasoline poisoning is likely to be the cause of the death in these two cases, and MTBE can be a suitable marker of gasoline exposure, when other volatile components have vaporized. [ABSTRACT FROM AUTHOR]