Search

The removal of methyl tertiary butyl ether (MTBE) from simulated water is going to be a critical environmental issue. The aims of the present study are to synthesise the Fe3O4/SiO2/TiO2 magnetic nanoparticles (MNPs) and evaluate its efficiency for the removal of MTBE by UV/O3/Fe3O4/SiO2/TiO2 combined process (CP) from water. The MNPs were synthesised via modified method and characterised using XRD, SEM and EDS. Then, the effects of initial ozone concentration, pH, MNP concentration, initial MTBE concentration (C0) and irradiation time were evaluated. The findings depicted that the performance of CP is better than separate processes. The optimum condition with initial ozone concentration of 150 mg/L, pH of 8, MNP concentration of 0.1 g/L and C0 of 10 mg/L at 60 min irradiation time results in maximum degradation of MTBE up to 91.65%. Also, the mineralisation rate of MTBE was achieved 68% removal at the same condition. Kinetic profile presented that the reduction of MTBE was fitted into second-order kinetics model for all the runs. The findings illustrate the capabilities of CP as a reliable technology to remove MTBE contained in water. [ABSTRACT FROM AUTHOR]

In this work, a new type of composite nanoparticles, 'pearl chain', was developed by linking titanium dioxide and silicon dioxide by polyacrylic acid polymer chains, and the prepared TiO2-PAA-SiO2 composite nanoparticles were analysed by SEM, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis, zeta potential, x-ray diffraction, etc. The success of this work was verified by the successful linking of TiO2-PAA-SiO2 composite nanoparticles.TiO2-PAA-SiO2 composite nanoparticles were analysed to verify the successful attachment of pearl chains. The obtained TiO2-PAA-SiO2 were subsequently blended in different ratios to prepare polyvinylidene fluoride (PVDF) ultrafiltration membranes. The membrane performance was tested by porosity and water contact angle measurements, scanning electron microscopy, as well as experiments using bovine serum proteins and MTBE interception. The results showed that when a certain amount of TiO2-PAA-SiO2 was added, the surface wettability, porosity and permeability of the prepared modified composite membranes were significantly improved, and the BSA adsorption rate was increased from 71.59% to 80.86%, and the retention rate of MTBE was increased by 77%, in addition to showing a better anti-pollution effect (FRR: 91.07%). It was finally concluded that the prepared membranes embedded with 1.0 wt.% TiO2-PAA-SiO2 nanofillers showed good overall filtration performance, better contamination resistance and remarkable durability. The present work successfully demonstrated the feasibility of using polyacrylic acid chemical chains to connect nanoparticles with different functions to prevent particle loss and substantially enhance membrane performance, which is valuable for bridging connection of composite nanoparticles and exploring the development of high-performance ultrafiltration membranes. [ABSTRACT FROM AUTHOR]

The extensive use of methyl tert-butyl ether (MTBE) as a gasoline additive has caused serious environmental problems that need to be addressed urgently. The feasibility of remediation of MTBE-contaminated groundwater by ZSM-5 zeolite with SiO2/Al2O3 ratio of 50/130/360 was explored. The SiO2/Al2O3 ratio had a great influence on the physicochemical properties and structure, as well as the adsorption and mass transfer of MTBE on ZSM-5. The adsorption of MTBE on zeolites with SiO2/Al2O3 ratios of 50 and 130/360 followed the Langmuir and Freundlich models, respectively, and was controlled by different mass transfer processes. The morphology and adsorption capacity of ZSM-5 (50) and ZSM-5 (130) differed significantly, while the differences between ZSM5-(130) and ZSM-5 (360) were less pronounced. ZSM-5 (360) had higher adsorption capacity and adsorption efficiency for MTBE, and the larger BET surface area, pore volume and stronger hydrophobicity were the key factors to promote MTBE adsorption. Compared to activated carbon (AC), ZSM-5 (360) was more effective for MTBE removal at low concentrations (<200 mg-L-1) and had the advantage of selective adsorption of MTBE with the addition of BTEX. In column adsorption, decreasing the concentration had opposite effects on MTBE removal by ZSM-5 and AC. At 5-10 mg-L-1, ZSM-5 (360) column reduced effluent concentration and improved bed utilization and removal efficiency. [ABSTRACT FROM AUTHOR]

The extensive use of methyl tert-butyl ether (MTBE) as a gasoline additive has caused serious environmental problems that need to be addressed urgently. The feasibility of remediation of MTBE-contaminated groundwater by ZSM-5 zeolite with SiO2/Al2O3 ratio of 50/130/360 was explored. The SiO2/Al2O3 ratio had a great influence on the physicochemical properties and structure, as well as the adsorption and mass transfer of MTBE on ZSM-5. The adsorption of MTBE on zeolites with SiO2/Al2O3 ratios of 50 and 130/360 followed the Langmuir and Freundlich models, respectively, and was controlled by different mass transfer processes. The morphology and adsorption capacity of ZSM-5 (50) and ZSM-5 (130) differed significantly, while the differences between ZSM5-(130) and ZSM-5 (360) were less pronounced. ZSM-5 (360) had higher adsorption capacity and adsorption efficiency for MTBE, and the larger BET surface area, pore volume and stronger hydrophobicity were the key factors to promote MTBE adsorption. Compared to activated carbon (AC), ZSM-5 (360) was more effective for MTBE removal at low concentrations (≤200 mg·L−1) and had the advantage of selective adsorption of MTBE with the addition of BTEX. In column adsorption, decreasing the concentration had opposite effects on MTBE removal by ZSM-5 and AC. At 5–10 mg·L−1, ZSM-5 (360) column reduced effluent concentration and improved bed utilization and removal efficiency.

In recent years, magnesium oxide (MgO) has been considered by researchers as a new agent for the remediation of contaminated soils. In this paper, the effect of MgO and hydrated lime on the remediation of a clay soil contaminated with MTBE (Methyl Butyl Ether) was studied. The contaminated soil was made artificially by adding 2.25 g MTBE per kg of soil. MgO with different percentages (0.125, 0.25, 0.5, 5, 10, and 20%) and lime with 2.5, 5, and 10% percentages were added to the natural and contaminated soil. The results showed that by increasing the percentage of MgO or lime and curing time, the strength of natural and contaminated soil was improved. The results of the leaching tests showed that by adding 5, 10, or 20% MgO, all the existing MTBE in the soil samples were removed while for the smaller percentages of MgO (0.125, 0.25, and 0.5%) there was a decrease in the concentration of MTBE with time. The results of the leaching tests also revealed that the hydrated lime was effective in reducing the concentration of MTBE. The amount of reduction in the concentration of MTBE was dependent on the percentage of MgO or hydrated lime. The comparison of the results of the two binders showed that MgO was more effective than the hydrated lime in removing the MTBE from the soil. [ABSTRACT FROM AUTHOR]

The sulfur content of MTBE products from a certain company often exceeds the standard. Through laboratory analysis of the fiber membrane fouling sample in the product refining unit, and a comparative analysis of the forms of MTBE and amine sulfur, it was ultimately determined that the main reason was amine contamination of the alkaline solution and high oil phase sulfur content in the amine solution. The following measures have ben taken to address the above situation: the liquefied petroleum gas desulfurization tower has been transformed from upper limit control to lower limit control, increasing the static space for liquefied petroleum gas; In order to enhance the effect of mercaptan removal, GL deodorizing refining agent was used in the mercaptan removal system instead of sulfonated cobalt titanocyanine; The amine liquid regeneration is carried out using an amine liquid vacuum distillation purification unit, which can separate the oil from the amine liquid. By taking the above measures, the annual output of waste alkali in the product refining unit has decreased from 609. 5 tons to 346.7 tons, and the annual cost of hazardous waste treatment has been reduced by 578 000 yuan; After reducing the treatment load of the amine regeneration unit, the steam consumption of the reboiler decreased by 1. 5 t/h, and the annual steam consumption cost decreased by 2. 106 miilion yuan; In addition, the sulfur mass fraction of MTBE products has been reduced from 55 µg/g to 45 µg/g, meeting the indicator requirements. [ABSTRACT FROM AUTHOR]

In this paper, chemometric methods were used for exploratory analysis, categorization, and quantification of gasoline fuel using Fourier Transform Infrared Spectroscopy (FTIR) data. During exploratory analysis, Principal Component Analysis (PCA) was employed, and to categorise the gasoline samples, Support Vector Machine Classification (SVMC), Linear Discrimination Analysis (LDA), and Partial Least Squares Discriminant Analysis (PLS-DA) were used. The concentration of Benzene, Methyl Tert-butyl Ether (MTBE), and Public Distribution System (PDS) Kerosene were determined using the Partial Least Squares Regression (PLSR), Principal Component Regression (PCR), and Support Vector Machine Regression (SVMR). All of the chemometric models had 100% accuracy and high R-square and RMSEC significance values. The SVM classification techniques were identified as a suitable choice for both classifying oxygenated and adulterated samples among all approaches. Both PLSR and PCR can also be suitable choices for quantification when dealing with high dimensional data. As a result, the research reported in this study has the potential to become a significant tool for improving gasoline sample discrimination and as a resource for quality control in the petroleum industry.

In this study, the improvement of a clay soil contaminated with MTBE (methyl tert-butyl ether) using magnesium oxide and hydrated lime was studied. Soil contaminated with MTBE was prepared in the laboratory, then mixed with different percentages of magnesium oxide and hydrated lime. Natural soil was also mixed with the same percentages used with the desired additives. Atterberg limits, compaction, Unconfined compressive strength, and SEM tests were performed on all samples. To determine the strength, the samples were prepared by static method and tested after 7, 14, and 28 days of curing time. The results showed that magnesium oxide and lime both increase the strength and E50 and thus improve natural and contaminated soil, which is a function of the percentage of used additives and curing time. The Comparison of improvement results showed that the final strength in natural soil is higher than in contaminated soil. In addition, the comparison of the results showed that lime has less effect on soil improvement compared to magnesium oxide. The SEM results also showed that the increase in strength is due to the cement materials produced during the carbonation process, which makes the particles paste to each other and make a rigid body.

The degradation of the prevalent environmental contaminants benzene, toluene, ethylbenzene, and xylenes (BTEX) along with a common co-contaminant methyl tert-butyl ether (MTBE) by Rhodococcus rhodochrous ATCC Strain 21198 was investigated. The ability of 21198 to degrade these contaminants individually and in mixtures was evaluated with resting cells grown on isobutane, 1-butanol, and 2-butanol. Growth of 21198 in the presence of BTEX and MTBE was also studied to determine the growth substrate that best supports simultaneous microbial growth and contaminants degradation. Cells grown on isobutane, 1-butanol, and 2-butanol were all capable of degrading the contaminants, with isobutane grown cells exhibiting the most rapid degradation rates and 1-butanol grown cells exhibiting the slowest. However, in conditions where BTEX and MTBE were present during microbial growth, 1-butanol was determined to be an effective substrate for supporting concurrent growth and contaminant degradation. Contaminant degradation was found to be a combination of metabolic and cometabolic processes. Evidence for growth of 21198 on benzene and toluene is presented along with a possible transformation pathway. MTBE was cometabolically transformed to tertiary butyl alcohol, which was also observed to be transformed by 21198. This work demonstrates the possible utility of primary and secondary alcohols to support biodegradation of monoaromatic hydrocarbons and MTBE. Furthermore, the utility of 21198 for bioremediation applications has been expanded to include BTEX and MTBE. [ABSTRACT FROM AUTHOR]

In this study, the improvement a clay soil contaminated with MTBE (methyl tert-butyl ether) using magnesium oxide and hydrated lime was studied. Soil contaminated with MTBE was prepared in the laboratory, then mixed with different percentages of magnesium oxide and hydrated lime. Natural soil was also mixed with the same percentages used with the desired additives. Atterberg limits, compaction, Unconfined compressive strength, and SEM tests were performed on all samples. To determine the strength, the samples were prepared by static method and tested after 7, 14, and 28 days of curing time. The results showed that magnesium oxide and lime both increase the strength and E50 and thus improve the properties natural and contaminated soil, which are function of the percentage of used additives and curing time. The Comparison of improvement results showed that the final strength in natural soil is higher than in contaminated soil. In addition, the comparison of the results showed that lime has less effect on soil improvement compared to magnesium oxide. The SEM results also showed that the increase in strength is due to the cement materials produced during the carbonation process, which makes the particles paste to each other and causes a rigid body. [ABSTRACT FROM AUTHOR]

Adverse effects of methyl tertiary-butyl ether (MTBE) have been noticed at different trophic levels by international researchers. However, there was unclear evidence about its effects on oxidative stress and DNA damage in earthworms. In this study, earthworms were cultivated in various doses of MTBE (0.0 mg/kg, 10.0 mg/kg, 30.0 mg/kg, and 60.0 mg/kg) contaminated agricultural soil for 7 days, 14 days, 21 days, and 28 days, respectively. The result showed that the reactive oxygen species (ROS) content of earthworms significantly increased in MTBE treatment groups compared to the control group. In MTBE treatment groups, the activities of superoxide dismutase, catalase, peroxidase, and glutathione S-transferase were significantly activated at the exposure of 7 days, which increased by 36.3–78.9%, 51.8–97.3%, 36.5–61.9%, and 12.0–54.8%, respectively. Then, the activities of these defense enzymes showed various changes following the changes in exposure times and MTBE concentrations. Especially in the 60.0 mg kg−1 group, both antioxidant enzymes and GST were still significantly activated at the exposure of 14 days and then significantly inhibited at the exposure of 28 days. The analysis of olive tail moment showed significant DNA damage in the 10.0 mg kg−1 group at the exposure of 28 days, and this damage in 30.0 mg/kg and 60.0 mg/kg groups was found at the exposure of 7 days. This result was consistent with the malondialdehyde accumulation in earthworms. Additionally, the analysis of IBRv2 showed the effects of MTBE treatments on earthworms in dose- and time-dependent manners. This study helps better to understand the effects of MTBE on soil invertebrate animals and provide theoretical support for soil protection in governing MTBE application. [ABSTRACT FROM AUTHOR]

• Co-removal feasibility of MTBE and Pb with PRB was assessed in column tests. • Column performance of mixed zeolite reactive media was evaluated. • Clinoptilolite granule and powder were used to examine the effect of particle size. • Removal capacity of clinoptilolite powder almost tripled granule (130.6 vs 45.3 mg/g). • The minimum thickness and longevity became higher with clinoptilolite powder. The co-contamination of metals and organic pollutants, such as Pb and methyl tert-butyl ether (MTBE), in groundwater, has become a common and major phenomenon in many contaminated sites. This study evaluated the feasibility of their simultaneous removal with permeable reactive barrier (PRB) packed with mixed zeolites (clinoptilolite and ZSM-5) using fixed-bed column tests and breakthrough curve modeling. The effect of grain size on the permeability of PRB and removal efficacy was also assessed by granular and power clinoptilolite. The replacement of granular clinoptilolite by powder clinoptilolite largely reduced the breakthrough time but increased the saturation time nearly fourfold. The column adsorption capacity of clinoptilolite powders almost tripled that of clinoptilolite granules (130.6 mg/g versus 45.3 mg/g) due to higher specific surface areas. The minimum thickness and corresponding longevity of PRB were calculated as 7.12 cm and 321.5 min when 5% of granular clinoptilolite was mixed with 5% ZSM-5 and 90% sand as mixed PRB reactive media compared with 10.86 cm and 1230.2 min for the application of powder clinoptilolite. This study is expected to provide theoretical support and guidance for the practical application of mixed adsorbents in PRBs. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

The search for suitable alternative for fossil fuel has been a challenge to the research community for the past two decades. So many alternatives have been identified and tested. However, a complete replacement cannot be provided without any penalties of cost, excess emission, poor operation, etc. The alcohols gave a new opportunity and a solution for that problem but had some setbacks of increased density and lower octane number. The present work focuses on striking a balance between advantages and disadvantages by using oxygenated additive with gasoline fuel. The additive CeO2 along with methyl tertiary butyl ether (MTBE) offers many advantages. The seven samples, namely M10, M15, M20, M25, M20 + 50 mg/l, M20+100 mg/l, M20+150 mg/l have been prepared and tested on spark ignition engine. Here, 10, 15, 20, and 25 denote the MTBE volume in blends and 50 mg/l, 100 mg/l, and 150 mg/l indicate the CeO2 in blends. The results have shown that only MTBE has caused an increase of 4% in brake thermal efficiency with M15 and then brake thermal efficiency has improved by 3% with M15 + 100 mg/l compared with pure gasoline. Fuel consumption has also been reduced upto 9% with M20 and 11% with M15+150 mg/l compared with pure gasoline. The maximum HC and CO reductions have also been observed from M20 and M20 + 150 mg/l. It was up to 19% and 22%, 23%, and 25% of HC and CO with M20, M20 + 150 mg/l. However, there has been an increase in CO2 emission level because of excessive unburned HC reduction. The MTBE with CeO2 has proved to be suited to all running conditions. The blends having more amounts of additive produce good combustion characteristics yet it should be restricted within 20 vol.% of MTBE and 150 mg/l of CeO2. [ABSTRACT FROM AUTHOR]

Developing methodologies for performing multi-omics with one sample has been challenging in zebrafish toxicology; however, related studies are lacking. A new strategy for the simultaneous analysis of metabolomics and lipidomics in zebrafish embryos was proposed and applied to explore the neurotoxicity mechanisms of perfluorooctanesulfonate (PFOS). Metabolite and lipid profiled simultaneously with methyl tert-butyl ether (MTBE) were compared with individual results from other extraction solvents. Behavioral alterations were measured after the zebrafish embryos were exposed to 0.1-20 μM PFOS for 5 days. The metabolite-lipid profiles of the MTBE-based strategy analyzed with optimized larval pooling size of 30 were comparable to those of other extraction solvents, indicating the feasibility and efficiency of MTBE-based multi-omics analysis. Many metabolites and lipids, which were enriched more than those previously reported, completed the toxicity pathways involved in energy metabolism and sphingolipids, improving our understanding of PFOS-induced neurotoxicity mechanism manifested by increased movement under dark conditions. Our novel MTBE-based strategy enabled the multi-omics analysis of one sample with minimal use of zebrafish embryos, thereby improving data reliability on changes in multi-layered biomolecules. This study will advance multi-omics technologies that are critical to elucidating the toxicity mechanisms of toxic chemicals including per- and polyfluoroalkyl substances., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

In this work, a new type of composite nanoparticles, 'pearl chain', was developed by linking titanium dioxide and silicon dioxide by polyacrylic acid polymer chains, and the prepared TiO 2 -PAA-SiO 2 composite nanoparticles were analysed by SEM, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis, zeta potential, x-ray diffraction, etc. The success of this work was verified by the successful linking of TiO 2 -PAA-SiO 2 composite nanoparticles.TiO 2 -PAA-SiO 2 composite nanoparticles were analysed to verify the successful attachment of pearl chains. The obtained TiO 2 -PAA-SiO 2 were subsequently blended in different ratios to prepare polyvinylidene fluoride (PVDF) ultrafiltration membranes. The membrane performance was tested by porosity and water contact angle measurements, scanning electron microscopy, as well as experiments using bovine serum proteins and MTBE interception. The results showed that when a certain amount of TiO 2 -PAA-SiO 2 was added, the surface wettability, porosity and permeability of the prepared modified composite membranes were significantly improved, and the BSA adsorption rate was increased from 71.59% to 80.86%, and the retention rate of MTBE was increased by 77%, in addition to showing a better anti-pollution effect (FRR: 91.07%). It was finally concluded that the prepared membranes embedded with 1.0 wt.% TiO 2 -PAA-SiO 2 nanofillers showed good overall filtration performance, better contamination resistance and remarkable durability. The present work successfully demonstrated the feasibility of using polyacrylic acid chemical chains to connect nanoparticles with different functions to prevent particle loss and substantially enhance membrane performance, which is valuable for bridging connection of composite nanoparticles and exploring the development of high-performance ultrafiltration membranes.

MTBE is an aliphatic matter successfully removed from contaminated water by an advanced oxidation process. Additionally, arsenic is a toxic metalloid that is detected in some water supplies, such as in Iran. Concerning the oxidation potential of arsenic in an aqueous solution, it is expected that its interference in the photocatalytic removal of organic matter includes MTBE. Nevertheless, there is a lack of observation of this effect. In this study, the effect of arsenic on the photocatalytic removal of MTBE using an Fe2O3/MgO catalyst under UV radiation was investigated. Using an experimental design, modeling, and optimizing operational parameters, such as the arsenic and MTBE concentrations, catalyst dosage, pH, and reaction time, were studied. The synthesized nanocatalyst had a uniform and spherical morphological structure and contained 33.06% Fe2O3 and 45.06% MgO. The results indicate that the best model is related to the quadratic (p-value < 0.0001, R2 = 0.97) and that the effect of the MTBE concentration is greater than the others. The highest removal efficiency was taken in an initial concentration of 37.5 mg/L MTBE, 1.58 mg/L Fe2O3/MgO, pH 5, and a reaction time of 21.41 min without any As. The removal efficiency was negatively correlated with the initial MTBE concentration and pH, but it was positively associated with the Fe2O3/MgO dosage and reaction time. Finally, the presence of arsenic decreased the removal efficiency remarkably (90.90% As = 0.25 μg/L and 61% As = 500 μg/L). Consequently, MTBE was removed by the photocatalytic process caused by Fe2O3/MgO, but the presence of arsenic was introduced as a limiting factor. Therefore, pretreatment for the removal of arsenic and more details of this interference effect are suggested. [ABSTRACT FROM AUTHOR]

Methyl-tert-butyl ether (MTBE) is a fuel oxygenate used in non-United States geographies. Multiple health reviews conclude that MTBE is not a human-relevant carcinogen, and this review provides updated mode of action (MOA), exposure, dosimetry and risk perspectives supporting those conclusions. MTBE is non-genotoxic and has large margins of exposure between blood concentrations at the overall rat 400 ppm inhalation NOAEL and blood concentrations in typical workplace or general population exposures. Non-cancer and threshold cancer hazard quotients range from a high of 0.046 for fuel-pump gasoline station attendants and are 100–1,000-fold lower for general population exposures. Cancer risks conservatively assuming genotoxicity for these same scenarios are all less than 1 × 10−6. The onset of MTBE nonlinear toxicokinetics (TK) in rats at inhalation exposures less than 3,000 ppm, a dose that is also not practically achievable in fuel-use scenarios, indicates that high-dose specific male rat kidney and testes (3,000 and 8,000 ppm) and female mouse liver tumors (8000 ppm) are not quantitatively relevant to humans. Mode of action analyses also indicate MTBE male rat kidney tumors, and lesser so female mouse liver tumors, are not qualitatively relevant to humans. Thus, an integrated analysis of the toxicology, exposure/dosimetry, TK, and MOA data indicates that MTBE presents minimal human cancer and non-cancer risks. [ABSTRACT FROM AUTHOR]

Methyl tertiary butyl ether (MTBE) is used as a gasoline additive formed by the reaction of isobutylene and methanol. Due to its high water solubility and low soil adsorption coefficient, leakages from storage facilities cause immediate groundwater contamination. The aim is to use alternative adsorbent for the removal of MTBE that causes various environmental and health problems. Mesoporous magnesia (MgO) that was synthesized via template-free hydrothermal method and commercial adsorbent Sepabeads-207 (SP-207) were used in this study. MTBE adsorption experiments were carried out at room temperature with a fixed sorbent/liquid ratio (0.1 g sorbent/10 mL aqueous solution) and 100–500 mg/L MTBE initial concentrations. Batch adsorption experiments showed that MgO and SP-207 have high MTBE adsorption capacity with a maximum adsorption amount of 333 and 233 mg MTBE/g adsorbent. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models of adsorption isotherms were used to investigate the adsorption behavior and the Langmuir isotherm model showed a better fit. Adsorption kinetic studies were also performed, and the pseudo-second-order kinetics fitted well with experimental data. Gibbs free energy changes of adsorption were obtained as −48.4 and −60.3 kJ/mol for MgO and SP-207, respectively. Methanol was used to regenerate the used adsorbents, and the re-use of MgO demonstrated good performance. [ABSTRACT FROM AUTHOR]

Hollow TiO2/g-C3N4 nanocomposite was prepared using solvothermal method. Two-dimensional g-C3N4 nanosheets were coupled with TiO2 hollow spheres at different ratios to investigate the charge-carrier interactions with the aim of enhancing the photocatalytic properties of the nanocomposite. This coupling was systematically examined by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence, X-ray photoelectron spectroscopy, and UV diffuse reflectance spectroscopy. The prepared nanocomposite was used for the photodegradation of the volatile organic carbons methyl tetra-butyl ether and toluene present in aqueous solution. Elemental analysis and X-ray diffraction revealed a high-purity sample, while the UV diffuse reflectance spectroscopy demonstrated the presence of a well-defined anatase crystal phase for the TiO2 hollow sphere; and the photoluminescence measurements showed an enhancement in visible-light absorbance, with a good reduction in the electron-hole recombination rate. The performance of the nanocomposites in the photocatalytic degradation of toluene under irradiation with visible-light was evaluated. The 20/80% TiO2/g-C3N4 nanocomposite materials showed highest photocatalytic activity for toluene and methyl tetra-butyl ether, achieving a degradation of more than 90%; this is attributed to the interaction between the two surfaces in the TiO2/g-C3N4 nanocomposite, resulting in a higher performance than the individual components. [ABSTRACT FROM AUTHOR]

Nowadays, Producing and using chemical compounds in different industrials has caused environmental pollution. One of these compounds that can bring a widespread pollution in natural resources is Methyl Tert-Butyl Ether (MTBE). This organic compound that is produced in petrochemical industries is used as a substitute to produce lead free gasoline in all over the world. Human exposure to MTBE may cause dizziness, coughing, fever, headaches, vomiting, muscular aches, sleepiness and skin and eye irritation. Concerning the destructive consequences of MTBE on the environment, and human health, clearing polluted resources are vital. The main objective of this study is dedicated to treat MTBE-contaminated waters through adsorption process in the presence of granular activated carbon (GAC). In this study, the effect of pH as well as exposure time on the removal of MTBE from aqueous solution have been examined and finally the efficacies of the process is assessed in terms of organic compounds removal and GAC reusability. According to the results, the adsorption capacity of used activated carbon depends considerably on the PH and reaction time. In this study, after 45 minutes of reaction time at PH of 8 the maximum COD removal efficiency of 62% was achieved. In this research both the Langmuir and Freundlich isotherm model best represented the MTBE adsorption behavior of GAC, having R2 of 92.2% and 84.6%, respectively. Moreover, maximum capacity of adsorption, in optimized condition, was estimated to be 67 mg of COD per each gr of GAC.

Background & aim: Methyl-tertiary butyl ether (MTBE) is one of the fuel oxygenated additive that is used to reduce the environmental pollution resulting from engine combustion. The present study was conducted to evaluate the acute (1 day) and sub chronic (30 days) effects of MTBE on some fertility indices in male rats. Methods: In the present experimental study conducted in 2019, 40 male rats with an approximate weight of 180-200 grams entered the study. The mice were then classified in two separate experiments into two acute groups (one day of treatment) and sub chronic (30 consecutive days of treatment) (15 heads in the acute group and 25 heads in the chronic group). In each acute and chronic group, the animals were randomly divided into 5 subgroups of control, oil (sham), 400, 800, and 1600 mg/kg body weight and placed in individual cages. At the end of each experiment, selected parameters related to sperm quality (sperm motility percentage, live sperm mania percentage and total sperm count) were examined. Data were analyzed using analysis of variance and linear regression. Results: The results of the present study indicated that in a sub chronic experiment, peanut oil as a solvent of MTBE had a significant effect on sperm motility percentage (p

Methyl tert-butyl ether (MTBE) is a widely used gasoline additive. It is considered an endocrine-disrupting chemical. Whether MTBE affects the development of Leydig cells in late puberty of males and its underlying mechanism remains unclear. Twenty-four male Sprague-Dawley rats (35 days old) were randomly allocated into four groups and were orally given MTBE (0, 300, 600, and 1200 mg/kg/day) from postnatal day (PND) 35–56. MTBE markedly reduced serum testosterone levels at 300 mg/kg and higher doses without altering the serum levels of luteinizing hormone and follicle-stimulating hormone. It mainly inhibited cell proliferation, induced mitochondrial autophagy and apoptosis, and indirectly stimulated Sertoli cells to secrete anti-Müllerian hormones, thereby significantly reducing the number of Leydig cells at 1200 mg/kg. MTBE also markedly down-regulated the expression of mature Leydig cell biomarker Cyp11a1 and Hsd3b1 and their proteins, while up-regulating the expression of immature Leydig cell biomarker Akr1c14 and its protein at 600 mg/kg and higher. MTBE significantly down-regulated the expression of cell cycle gene Ccnd1, antioxidant gene Gpx1, and anti-apoptotic gene Bcl2, while increasing pro-apoptotic gene Bax level at 1200 mg/kg. In vitro study further confirmed that MTBE can inhibit testosterone synthesis by inducing reactive oxygen species (ROS) generation, mitophagy, and apoptosis at 200 and 300 mM. In conclusion, exposure to MTBE compromises the development of Leydig cells in late puberty in male rats.

Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes. Our results indicate that gene mdpC is involved in the induction of both mdpA and mdpJ in response to MTBE and tert-butyl alcohol (TBA) exposure in PM1. An additional independent mechanism may be involved in the induction of mdpJ in the presence of TBA.

In this work, layer by layer (LbL) thin film nanocomposite (TFN) membranes were prepared and used as pervaporation membranes to separate methyl tertiary butyl ether (MTBE)/methanol (MeOH) mixture. TFN membranes, comprising of carbon nanotubes (CNT), were prepared by interfacial polymerization (IP) of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers on the porous polyethersulfone/polyethylene glycol (PES/PEG) sublayer. Carbon nanotubes were functionalized by ethylenediamine (EDA) and incorporated into the polyamide (PA) layer at 0.01–0.04 wt.% loadings. After that, the surface roughness, surface hydrophilicity, and morphology of the resulting membranes were characterized. Also, the effect of the sequence of reactants deposition and concentrations of the nanotubes on the membrane performance were investigated using pervaporation of MTBE/MeOH under feed temperature and feed flow rate of 30 °C and 4 L.h-1, respectively. The pressure of permeate-side was about 100 mbar. Obtained results showed that both separation factor and permeation flux of LbL TFN membranes increased by adding CNT into the PA layer up to 0.02 wt.%. By increasing CNT loading to 0.04 wt.%, the separation factor decreased from 106 to 77.6, while permeation flux increased from 0.56 to 0.81 kg.m-2.h-1. It should be noted that, in the single-layer membrane, the separation factor decreased from 73.2 for TFC membrane to 56.4 for TFN membrane with increasing the CNT loading from the beginning. According to these results, LbL TFC and TFN membranes are expected to be the next generation of high-performance PV membranes. [ABSTRACT FROM AUTHOR]

El trabajo fue realizado en el Laboratorio de Combustibles y Lubricantes del Instituto Nacional de Tecnología, Normalización y Metrología – INTN, en el marco del proyecto 14-INV-193, financiado por el CONACYT y el INTN. Este proyecto tuvo como objetivos monitorear los niveles de benceno, hidrocarburos aromáticos y compuestos oxigenados (éteres y alcoholes) en muestras de gasolinas importadas en el país, mediante técnicas normalizadas por la ASTM y establecidas como métodos de referencia por el Ministerio de Industria y Comercio. El periodo de estudio abarca desde febrero de 2016 a julio de 2017. Los resultados obtenidos en promedio, se encontraron dentro de los límites establecidos en la legislación vigente, aunque se observaron casos puntuales donde excedieron los límites permitidos. Estos datos son importantes para tener un diagnóstico de la situación en cuanto a niveles de compuestos nocivos para el medioambiente y la salud humana, así como para la toma de decisiones de entes reguladores

Due to the importance and widespread applications of oil products as well as their threats to surface water bodies in Iran, it is inevitable to apply suitable simulation models to develop management plans, actions, and appropriate scenarios . There are two modified versions of CE-QUAL-W2 and both can be used for simulations of emergency pills of toxic waste in transpotation roadways. In this research, both modified versions were employed to simulate the fate of Methyl tert-butyl ether (MTBE) (a gasoline oxygenated addetive) during an emergency spill. As a case study, the application of both models was used to evaluate the MTBE emergy spill that occurred on March 2003 near Khalifeh Torkhan river. Several remediation techniques including artificial turbulent, mixing, and aeration were used during the simulation study. Results showed that the modified version of the model (CE-QUAL-W2) depicted a better temporal and spatial distribution of MTBE pollution in reservoir compared compared to the first version of the model. Multiple scenarios were simulated in this study under various meteorological, hydrological, and MTBE loading for Gheshlagh reservoir. The simulation results showed that lower air temperature and higher wind speed are among the factors that reduces the reservoir recovery time. In addition,, another parameter that found to decrease the recovery time of Gheshlagh reservoir is an increase in reservoir inflow and/or outflow rate.

• Over 70 catalysts were screened for etherification of glycerol with isobutene. • Desired ether selectivity enhanced with decreasing acid capacity in ion exchange resins. • High desired ether selectivity was obtained with high acid strength zeolites and heteropolyacids. • Results present a comprehensive guideline for catalyst selection. We compared the performance of more than 70 solid acid catalysts with Brønsted acid function for the etherification of glycerol with isobutene under identical reaction conditions of 75 °C, 10 bar, 6 h and with an isobutene/glycerol molar ratio of 3/1. The catalysts were selected from a wide range of solid acid catalysts including ion exchange resins, zeolites, silica, and heteropolyacids, and their counterparts modified by simple treatments, with more than half of them being investigated for the first time for this reaction. For the modified commercial acid catalysts, the desired glycerol tertiary butyl ether (DTBGE and TTBGE) selectivity improved from 75 to 87 wt% upon partial cation exchange of the sulfonic acid protons in Amberlyst™ type ion exchange resins with Na+ cations; from 66 to 85 wt% by hydrothermal steam treatment of zeolite H-Y (SiO 2 /Al 2 O 3 = 80); and from 75 to 80 wt% with partial La+-exchange of zeolite H-Beta (SiO 2 /Al 2 O 3 = 300), all at high (90–100%) glycerol conversion. Impregnation of the heteropolyacids, tungstosilicic acid (TSA) and tungstophosphoric acid (TPA), on silica at a loading of 50 wt% provided a glycerol conversion of higher than 65 wt% and with a desired ether selectivity in the range of 62 to 76 wt%. In general, total ether selectivity increased with decreasing acid capacity for ion exchange resins, while the desired ether selectivity was enhanced with increasing acid strength for zeolites and supported heteropolyacids on mesoporous silica. Data present a detailed guideline for the selection of solid acid catalysts for the etherification of glycerol with isobutene. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the efficiency of a simple and cheap catalytic oxidation process for removal of MTBE in high concentration by H2O2/CuO process. The effects of H2O2, CuO and initial MTBE concentration, pH and reaction time on the catalytic oxidation were investigated. The study was performed using Design-Expert. According to statistical analyses, 2FI model has been introduced as the best model that was statistically valid. Based on the experimental design model, the most effective factors were initial MTBE concentration and CuO, respectively. The highest removal efficiency (79%) was obtained at the following condition: CuO concentrations; 19 mgCuO/Lwater, pH 7.25, reaction time 16.30 min, H2O2 12.5 mL/L and initial MTBE concentration 225 mg/L. The higher the MTBE and CuO concentration, the less the removal efficiency. Optimization conditions were initial MTBE concentration 225 mg/L, reaction time 16.5 min, H2O2 13.4 mL/L, pH 7.5, CuO 19 mg/L. Removal efficiency in the laboratory condition was obtained to be 72%. The best kinetic model for removal of MTBE was pseudo-second order (R² = 0.99, RMSE = 0.21). Therefore, the adsorption of MTBE on CuO catalyst was the predominant process. This is the first time that the CuO/H2O2 has been used as a cost-benefit, simple and effective method as well as kinetic model for removal of high concentration of MTBE during a short period of time. [ABSTRACT FROM AUTHOR]

Groundwater flow and transport modeling conducted for court litigation at Plateau Plaza, Rocky Mount, VA, USA. In October 1999 about 6,500 to 7,500 liters of petroleum released to the subsurface. Many residential and commercial water supply wells impacted by dissolved phase MTBE. The study objective is to evaluate travel time of dissolved phase MTBE from site to individual properties of supply wells, MS-7 and MS-9. Groundwater flow and dissolved phase transport models were constructed using MODFLOW and MT3D. The two-layered model was conceptualized and constructed using historical drilling data, groundwater gauging, sampling, slug-testing, and geophysical studies. Flow and transport models calibrated to historical groundwater levels and concentrations. Sensitivity analysis conducted to evaluate uncertainty in hydraulic conductivity, dispersivity, and source concentration. The conclusions based on geologic, hydrogeologic, geophysical and dissolved concentration data spanning over eight years that portray actual field conditions. The specific dates of dissolved MTBE movement and to approach the boundaries of individual properties based on modeling and professional expertise. The model is sensitive to change in any parameter that would affect the plume speed. Any changes to those parameters, including changes that would slow the migration of the simulated plume were detrimental to the calibration of the model. It is appraised that the dissolved MTBE entered the property of Well No. MS-7 in the deep and upper zones in December 31, 2001, and February 24, 2002, respectively. The plume in the property of Well No. MS-9 entered in deeper and upper zones in September 11, 2002, and October 13, 2002. [ABSTRACT FROM AUTHOR]

Hydrocarbon contamination of water resources is a global issue. These compounds are generated and discharged into the environment in industrial areas from chemical and petrochemical plants, oil refineries, power plants, and so forth. Fuel hydrocarbons, namely, BTEX (benzene, toluene, ethylbenzene, and xylenes) and MTBE (methyl tert-butyl ether), are commonly found in groundwater, posing environmental and health risks to humans and ecosystems. Nature-based technologies represent an alternative solution, providing high efficiency, an environmentally friendly character, simple operation, and cost efficiency, which are characteristics particularly desired by the international petroleum industry. This article discusses the use of the green technology of constructed wetlands to remediate water polluted with hydrocarbons. Although the number of related international experiences and studies is limited, the article presents the latest developments of wetland technology for the removal of MTBE and benzene-BTEX. The discussion includes the overall efficiency of the different wetland types that have been tested and used, the main transformation and removal processes that regulate the fate of BTEX and MTBE in constructed wetlands, and the potential for future investigations. [ABSTRACT FROM AUTHOR]

The preparation of high-performance polycrystalline MOF membranes for MeOH/MTBE separation poses a challenge. In this study, intact 400 nm thick UiO-66 membranes with well-controlled structures were successfully fabricated using a novel formulation. The high ligand/metal ratios and the new zirconium sources provide ideas for designing UiO-66 membranes with effective pore structures. Consequently, the membranes exhibited an exceptional pervaporation performance, achieving a flux of 5.68 kg m−2 h−1 and a separation factor of 28000 for MeOH/MTBE (5/95 wt/wt.%) at 40 °C. Further, the UiO-66 membranes have excellent temperature and concentration resistance and remain stable during 120 h of operation. The high pervaporation performance, along with this stability, demonstrates that this UiO-66 membrane is a competitive candidate for MeOH/MTBE separation. [Display omitted] • The UiO-66 membranes exhibited unprecedented performance for MeOH/MTBE separation. • The membrane structures were controlled using trace Zr(n -OPr) 4 as sole metal source. • The membranes manifested good stability. [ABSTRACT FROM AUTHOR]

The utilisation of internal combustion engines is one of the main causes of particle emissions in urban areas. As the interest for the utilisation of biofuels increases, it is important to understand their effect on particle number emissions. In this paper, the particle size distribution and the particle number emissions from a gasoline-optimised direct-injected spark-ignited (DISI) engine are investigated. The effects of five different biofuel alternatives on these emissions were evaluated and compared to gasoline. The utilisation of the high-resolution, high-temperature ELPI+ enabled undiluted measurements of the particle size distribution down to 6 nm, without extensive cooling of the engine exhaust. Contrary to other studies, the results show that the particle number emissions for the three measured cut-off sizes (23, 10 and 7 nm) increased with the utilisation of oxygenated biofuels. The results indicate that the decreased volatility and energy density of the alcohols has a more significant impact on the particle formation in a DISI engine than the increased oxygen content of these fuels.

Widespread contamination of groundwater by methyl tertiary butyl ether (MTBE) has triggered the exploration of different technologies for in situ removal of the pollutant, including biostimulation of naturally occurring microbial communities or bioaugmentation with specific microbial strains known to biodegrade the oxygenate. After laboratory studies revealed that bacterial strain PM1 rapidly and completely biodegraded MTBE in groundwater sediments, the organism was tested in an in situ field study at Port Hueneme Naval Construction Battalion Center in Oxnard, California. Two pilot test plots (A and B) in groundwater located down-gradient from an MTBE source were intermittently sparged with pure oxygen. Plot B was also inoculated with strain PM1. MTBE concentrations up-gradient from plots A and B initially varied temporally from 1.5 to 6 mg MTBE/L. Six months after treatment began, MTBE concentrations in monitoring wells down-gradient from the injection bed decreased substantially in the shallow zone of the groundwater in plots A and B, thus even in the absence of the inoculated strain PM1. In the deeper zone, downstream MTBE concentrations also decreased in plot A and to a lesser extent in plot B. Difficulties in delivery of oxygen to the deeper zone of plot B, evidenced by low dissolved oxygen concentrations, were likely responsible for low rates of MTBE removal at that location. We measured the survival and movement of strain PM1 in groundwater samples using two methods for detection of DNA sequences specific to strain PM1: TaqMan quantitative polymerase chain reaction, and internal transcribed spacer region analysis. A naturally occurring bacterial strain with > 99% 16S rDNA sequence similarity to strain PM1 was detected in groundwater collected at various locations at Port Hueneme, including outside the plots where the organism was inoculated. Addition of oxygen to naturally occurring microbial populations was sufficient to stimulate MTBE removal at this site. In some cases, however, inoculation with an MTBE-degrading culture may be warranted.

Gastrointestinal stromal tumour has already been well explored at the genome level; however, little is known about metabolic processes occurring in the sarcoma. Sample preparation is a crucial step in untargeted metabolomics workflow, highly affecting the metabolome coverage and the quality of the results. In this study, four liquid-liquid extraction methods for the isolation of endogenous compounds from gastrointestinal stromal tumours were compared and evaluated. The protocols covered two-step or stepwise extraction with methyl-tert-butyl ether (MTBE) or dichloromethane. The extracts were subjected to LC-MS analysis by the application of reversed-phase and hydrophilic interaction liquid chromatography to enable the separation and detection of both polar and nonpolar analytes. The extraction methods were compared in terms of efficiency (total number of detected metabolites) and reproducibility. The method was based on the stepwise extraction with MTBE, methanol, and water proved to be the most reproducible, and thus, its robustness to fluctuations in experimental conditions was assessed employing Plackett–Burman design and hierarchical modelling. While most studied factors had no effect on the metabolite abundance, the highest coefficient value was observed for the volume of MTBE added during extraction. Herein, we demonstrate the application and the feasibility of the selected protocol for the analysis of gastrointestinal stromal tumour samples. The method selected could be considered as a reference for the best characterization of underlying molecular changes associated with complex tissue extracts of GIST.

A bench-scale study was designed for removal of Methyl Tertio Butyl Ether (MTBE) and benzene from south of Tehran groundwater. The experiments were implemented on a one-dimensional soil column with similar chemical and physical conditions of the region. Fenton’s chemical oxidation with stabilized nano zero-valent iron particles (S-NZVI) as catalyst was used. For treatment of groundwater polluted with 2 mg L-1 MTBE and 1 mg L-1 benzene, optimum concentrations of H2O2 and S-NZVI were 1500 and 300 mg L-1, respectively. The optimum concentrations led to 78 % elimination of MTBE and 87 % of benzene. Hazardous by-products (acetone and tertio-butyl alcohol) concentrations were less than 0.1 mg L-1, which were considered to be negligible. The soil permeability was reduced to 30 % after removal process. To increase the system efficiency and reduce the consumption of iron, the reaction environment was acidified down to pH = 3.2 led to removal efficiency of 90 % and 96 % for MTBE and benzene, respectively. The scavengers (ions) reduced the system efficiency up to 15 %. This study indicates that theoretically the MTBE and benzene could be removed from groundwater using Fenton’s chemical oxidation with S-NZVI.

Recently, pervaporation separation processes have gained much attention in the separation of azeotropic and close boiling point organic-organic mixtures due to its high separation efficiency, economy, safety, and energy saving potentials. In this work, the effects of experimental factors such as feed composition and operating temperature on the performance of a commercial poly vinyl alcohol membrane in the separation of methanol/methyl tertiary butyl ether (MTBE) mixtures at low permeate side pressures (1-20 mmHg) were evaluated. Separation factor and methanol flux significantly increased by decreasing permeate side pressure, especially to less than 5 mmHg. Therefore, the reduction of pressure from 20 to 1 mmHg at 45 °C at a feed methanol concentration of 5 wt.% increased methanol flux and separation factor from 248 to 412 g/hm2 and 73 to 211 respectively. In addition, the results indicate that by increasing feed temperature and methanol concentration in the feed, methanol flux is increased, while separation factor dropped.

El Metil tert-butíl Éter (MTBE) es un combustible oxigenado ampliamente utilizado en Paraguay, así como en muchos países de América del Sur como elevadores del octanaje para reemplazar los aditivos tóxicos prohibidos en la gasolina. En varios países europeos se encontró en aguas subterráneas debido a la fuga de tanques de gasolina. Se realizó la validación del método analítico para MTBE y sus sub-productos de degradación como Tert-butil Alcohol (TBA) y Tert-butil Formiato (TBF) mediante micro extracción en fase sólida y cromatografía de gases acoplada con espectrometría de masas (SPME-GC/MS), utilizando procedimientos estandarizados de validación. Este método está todavía en desarrollo incluyendo el enfriamiento de la fibra de extracción. En este estudio, la temperatura de la fibra fue de 21-25oC. Otros parámetros evaluados fueron: especificidad, linealidad, sensibilidad, límite de detección, exactitud, incluyendo una evaluación de la veracidad y precisión. El volumen de muestra fue de 5mL con el agregado de 1,8 gramos de NaCl como modificador de matriz, la muestra es extraída a temperatura constante de 35ºC con agitación constante por exposición de la fibra en el Headspace durante 30 minutos bajo una temperatura entre 21 a 25oC. Se trazó una curva de calibración lineal en el intervalo de 0-200 μg/L para MTBE. El r2 del método fue 0,9991 -0,9925 y 0,9992 para MTBE, TBA y TBF respectivamente, con desviación estándar relativa de 0,5 a 6,6%. Los Lımites de Detección Inferiores obtenidos fueron de 0,009 μg/L para MTBE; 0,029 μg/L para TBA y 0,010 μg/L de TBF. La exactitud se evaluó con veracidad y precisión en condiciones de repetibilidad y reproducibilidad, obteniendo recuperaciones entre 100,4 y 106,8% con desviación estándar relativa hasta 6,4%. Este método cumple con los criterios de validación dentro de los niveles de concentración, ofrece alta sensibilidad y selectividad suficiente para la investigación bioanalítica y por lo tanto es adecuado para el uso rutinario en el análisis de estas moléculas orgánicas en agua potable y subterránea.

Since groundwaters are a major source of drinking water, their pollution with organic contaminants such as methyl tertiary-butyl ether (MTBE) is a very significant issue. Hence, this research investigated the photocatalytic degradation of MTBE in an aqueous solution of TiO2-ZnO-CoO nanoparticle under UV irradiation. In order to optimize photocatalytic degradation, response surface methodology was applied to assess the effects of experimental variables such as catalyst loading, initial concentration of MTBE and pH on the dye removal efficiency. The optimal condition to achieve the best degradation for the initial concentration of 30.58 mg/L of MTBE was found at a pH of 7.68 and a catalyst concentration of 1.68 g/L after 60 min.

Widespread contamination of groundwater by MTBE has triggered the exploration of different technologies for in situ removal of the pollutant. After laboratory studies revealed that bacterial strain PMl is capable of rapid and complete MTBE biodegradation, the organism was tested in an in-situ bioaugmentation field study at Port Hueneme Naval Base, Oxnard, CA. Two small pilot test plots (A and B) located down gradient from an MTBE source were injected with pure oxygen at two depths. One plot (B) was also inoculated with Strain PMl. MTBE concentrations upstream from plots A and B initially varied temporally from 1.5 to 6 mg per L. By six months after treatment began, MTBE concentrations wells downstream from the injection bed substantially decreased in the shallow zone of the groundwater in both plots, even in the absence of Strain PM 1. In the deeper zone, downstream MTBE concentrations also decreased substantially in Plot A and to lesser extent in Plot B. Difficulties in delivery of oxygen to the deep zone of Plot B, evidenced by low dissolved oxygen concentrations, are likely responsible for low rates of MTBE removal at that location. We measured the survival and movement of PMl in groundwater using three different methods for detection of PMl rDNA sequences: TaqMan quantitative peR, Denaturing Gradient Gel Electrophoresis (DGGE), and Intergenic Spacer Region (ITS) analysis. A naturally occurring organism with >99% rDNA sequence similarity to Strain PMl was detected in groundwater collected outside the test plots. Changes in the groundwater microbial community were also monitored over time using ITS, a PCR-based DNA fingerprinting method. The largest differences in the microbial community profiles were observed between the shallow and deep groundwater samples, regardless of whether they were from plot A or B.

Sphingolipids, including sphingosine and sphinganine, are one of the major classes of lipids. They serve as constituents of cell membranes and lipid rafts and aid in the performance of cell-cell communication and adhesion. Abnormal levels of sphingolipids in the aqueous humor can indicate impaired sphingolipid metabolism and associated ocular pathologies. Sphingolipids can be extracted from the aqueous humor by the methyl-tert-butyl ether (MTBE) lipid extraction method and subsequently analyzed by liquid chromatography-mass spectrometry (LC-MS). This chapter describes a modified protocol for an MTBE lipid extraction from the aqueous humor, followed by analysis with ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS)., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)