Additive Methyl Tertiary Butyl Ether Research Articles

Eco-friendly removal of methyl tert-butyl ether from contaminated water using steam and CO2-activated carbons

AbstractPetrol frequently contains the additive methyl tertiary butyl ether (MTBE). Because of its significant health risks, MTBE pollution of surface and ground water is a severe concern for the environment. Highly porous physically activated carbons, particularly CO2-activated carbon (CO2-AC) and steam-activated carbon (Steam-AC), were obtained from date stones as potential eco-friendly adsorbents for MTBE from contaminated water. The chemical composition, microstructure, textural, and structural characteristics of adsorbents were characterised by elemental analysis, SEM, N2 sorption, XRD, and FTIR. The adsorption process evaluation based on the initial MTBE concentration, liquid-to-solid ratio, and equilibrium contact time. CO2-AC and steam-AC adsorbents have high surface areas of 819.5 m2/g, and 567.7 m2/g, respectively. At 40 °C, CO2-AC has an adsorption capability of 181.36 mg/g. The adsorption result was best fitted by the Freundlich model. The two-step intraparticle diffusion process prevailed the adsorption process, and the pseudo-second-order model presented an optimal fit for the adsorption kinetics models. Spontaneous physical adsorption was endothermic when CO2-AC adsorbs at 40 °C because ∆G was − 6.34 kJ/mol. Finally, the water quality improved and the salt content, the alkalinity, and the hardness decreased with the use of CO2-AC as an environmentally friendly adsorbent for removing MTBE from the polluted water.

Impact Effect of Methyl Tertiary-Butyl Ether "Twelve Months Vapor Inhalation Study in Rats".

Simple SummaryThe detection of major blood-based markers for cancer requires expensive blood tests. Therefore, finding simple and effective blood-based markers is of great interest. The present results suggested that CA II, CA I, and peroxiredoxin2 could be utilized as potential biomarkers for the early detection of tracheal and lung cancer.We investigated the early risk of developing cancer by inhalation of low doses (60 µL/day) of methyl tertiary butyl ether (MTBE) vapors using protein SDS-PAGE and LC-MS/MS analysis of rat sera. Furthermore, histological alterations were assessed in the trachea and lungs of 60 adult male Wistar rats. SDS-PAGE of blood sera showed three protein bands corresponding to 29, 28, and 21 kDa. Mass spectroscopy was used to identify these three bands. The upper and middle protein bands showed homology to carbonic anhydrase 2 (CA II), whereas the lower protein band showed homology with peroxiredoxin 2. We found that exposure to MTBE resulted in histopathological alterations in the trachea and the lungs. The histological anomalies of trachea and lung showed that the lumen of trachea, bronchi, and air alveoli packed with free and necrotic epithelial cells (epithelialization). The tracheal lamina propria of lung demonstrated aggregation of lymphoid cells, lymphoid hyperplasia, hemorrhage, adenomas, fibroid degeneration, steatosis, foam cells, severe inflammatory cells with monocytic infiltration, edema, hemorrhage. Occluded, congested, and hypertrophied lung arteries in addition, degenerated thyroid follicles, were observed. The hyaline cartilage displayed degeneration, deformation, and abnormal protrusion. In conclusion, our results suggest that inhalation of very low concentrations of the gasoline additive MTBE could induce an increase in protein levels and resulted in histopathological alterations of the trachea and the lungs.

Applications of the Poly-K Statistical Test to Life-Time Cancer Bioassay Studies

ABSTRACT The statistical analysis of cancer bioassay data has historically depended on the pathological determination of the experimental animal's cause of death. The poly-k statistical test has provided a method of statistical analysis of animal bioassay data without the need for cause of death information. The test has been shown to have good statistical properties in the typical 2-year cancer bioassay. However, while the poly-k test has been applied to chronic lifetime animal studies, it has not been formally evaluated with respect to the operating characteristics of this statistical test when applied to such studies. Thus, our objective is to assess the performance of the poly-k test for lifetime studies and to make comparisons with other tests. We observed in one recent lifetime study of the gasoline additive methyl tertiary butyl ether (MTBE) that the application of the poly-k test was not statistically robust. Simulation studies were subsequently conducted for a limited number of scenarios of lifetime cancer bioassays. These simulations showed that the poly-k test is not statistically robust for testing effect of increasing dose in some lifetime cancer studies.

Physiologically Based Pharmacokinetic Model of Methyl Tertiary Butyl Ether and Tertiary Butyl Alcohol Dosimetry in Male Rats Based on Binding to α2u-Globulin

Current physiologically based pharmacokinetic (PBPK) models for the fuel additive methyl tertiary butyl ether (MTBE) and its metabolite tertiary butyl alcohol (TBA) have not included a mechanism for chemical binding to the male rat-specific protein alpha2u-globulin, which has been postulated to be responsible for renal effects in male rats observed in toxicity and carcinogenicity studies with MTBE. The objective of this work was to expand the previously published models for MTBE to include binding to alpha2u-globulin in the kidney of male rats. In the model, metabolism of MTBE was assumed to occur only in the liver via two saturable pathways. TBA metabolism was assumed to occur only in the liver via one saturable, low-affinity pathway and to be inducible following repeated exposures. The binding of MTBE and TBA to alpha2u-globulin was modeled as saturable and competitive and was assumed to only affect the rate of hydrolysis of alpha2u-globulin in the kidney. The developed model characterized the differences in kidney concentrations of MTBE and TBA in male versus female rats from inhalation exposures to MTBE, as well as the observed changes in blood and tissue concentrations from repeated exposure to TBA. The model-predicted binding affinity of MTBE to alpha2u-globulin was greater than TBA, and the hydrolysis rate of chemically bound alpha2u-globulin was approximately 30% of the unbound protein. This PBPK model supports the role of MTBE and TBA binding to the male rat-specific protein alpha2u-globulin as essential for predicting concentrations of these chemicals in the kidney following exposure.

How to Assess the Risks of Nanotechnology: Learning from Past Experience

Nanotechnology may yield a plethora of beneficial applications, but it can also be expected to present risks. The challenge is to anticipate and reduce environmental and health risks or, at a minimum, identify and deal with such threats once they begin to become evident. Past experience, particularly with the fuel additive MTBE (methyl tertiary butyl ether), provides valuable guidance on how to assess the potential risks of nanotechnology using a comprehensive environmental assessment approach, which combines a product life-cycle perspective with the risk assessment paradigm. This systematic approach can serve not only to guide the development of a research strategy for assessing the risks of nanotechnology but possibly even help avert unintended consequences of nanotechnology.

Systematic Approach to Evaluating Trade‐Offs among Fuel Options

The fuel additive methyl tertiary butyl ether (MTBE) has been used in an effort to improve air quality in the United States, but other undesirable effects, particularly the contamination of water resources, were eventually judged to outweigh any air quality benefits it may have offered. The experience with MTBE offers many lessons, including the need to evaluate potential positive and negative environmental impacts associated with fuel choices using a comprehensive approach that combines a product life-cycle perspective with the risk assessment paradigm. Such an approach, referred to as "comprehensive environmental assessment" (CEA), is illustrated here by highlighting some of the issues that might be considered in evaluating reformulated gasoline (RFG) produced with MTBE, ethanol, or no oxygenate.

Persistence Pays Off in MTBE tussle

Utilities often feel that time and resource constraints limit their ability to mount effective advocacy campaigns. This case study demonstrates how to achieve success even on a small budget. In August 2005, President George W. Bush signed national energy legislation without a provision that would have granted gasoline makers immunity from water contaminated by the gasoline additive methyl tertiary butyl ether (MTBE). The exclusion of this provision was largely the result of the AWWA‐led advocacy discussed in this article. The AWWA MTBE campaign demonstrated the power of a disciplined advocacy and effective media campaign, showing the importance of framing the issue, staying on message, providing the best information, building partnerships, and mobilizing grassroots support. Utility managers will be able to apply the lessons learned from this campaign to face their own public affairs challenges and create more effective public campaigns.

Much Ado: How Big Is the Problem of Hydrolysis of Methyl Tertiary Butyl Ether (MtBE) to Form Tertiary Butyl Alcohol (tBA)?

Groundwater contaminated by the gasoline additive methyl tertiary butyl ether (MtBE) is also frequently impacted by tertiary butyl alcohol (tBA). The USEPA recently sponsored a study that discusses the possibility of hydrolysis of MtBE to form tBA during analytical procedures. This finding is important because it suggests that existing tBA data may not accurately depict tBA or MtBE concentrations in groundwater. This article discusses the mechanism and kinetics of MtBE hydrolysis, then presents three case studies of analytical results from sites in California, USA. Although these case studies are limited in scope, the data do not support the occurrence of the hydrolysis of MtBE to form tBA due to acid preservation of groundwater samples. At a minimum, this suggests that MtBE hydrolysis may not be as pervasive a problem as suggested in USEPA's study; therefore, concerns about the validity of historical tBA data may not be warranted. The reason for this result may be simple: there are two necessary factors that promote hydrolysis: low pH and high temperature (above 40°C). Although the static headspace analysis method used to obtain the data in the White et al. study may require heating to achieve adequate sensitivity, many laboratories perform purge-and-trap analyses without heating. Under those conditions, hydrolysis may not occur. However, it may be prudent to preserve samples with alkaline preservatives, to eschew high temperatures during the analysis of groundwater samples, or to neutralize the sample pH before heating.

Emission and Fate Assessment of Methyl Tertiary Butyl Ether in the Boston Area Airshed Using a Simple Multimedia Box Model: Comparison with Urban Air Measurements

Expected urban air concentrations of the gasoline additive methyl tertiary butyl ether (MTBE) were calculated using volatile emissions estimates and screening transport models, and these predictions were compared with Boston, MA, area urban air measurements. The total volatile flux of MTBE into the Boston primary metropolitan statistical area (PMSA) airshed was calculated based on estimated automobile nontailpipe emissions and the Universal Quasi-Chemical Functional-Group Activity Coefficient computed abundance of MTBE in gasoline vapor. The fate of MTBE in the Boston PMSA was assessed using both the European Union System for the Evaluation of Substances, which is a steady-state multimedia box model, and a simple airshed box model. Both models were parameterized based on the meteorological conditions observed during air sampling in the Boston area. Measured average urban air concentrations of 0.1 and 1 [H9262]g/m3 MTBE during February and September of 2000, respectively, were comparable to corresponding model predictions of 0.3 and 1 μg/m3 and could be essentially explained from estimated temperature-dependent volatile emissions rates, observed average wind speed (the airshed flushing rate), and reaction with ambient tropospheric hydroxyl radical (.OH), within model uncertainty. These findings support the proposition that one can estimate gasoline component source fluxes and use simple multimedia models to screen the potential impact of future proposed gasoline additives on urban airsheds.

Stable carbon isotopic composition of gasolines determined by isotope ratio monitoring gas chromatography mass spectrometry

A large number of underground gasoline storage facilities in the United States continuously leak gasoline into the subsurface, which makes gasoline a major groundwater contaminant. Gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) are used currently to characterize contaminated groundwater and soils. Correlations of contaminants with suspected source(s) are extremely difficult by these techniques because many gasolines have similar hydrocarbon distributions. The present study applied the technique of isotope ratio monitoring gas chromatography–mass spectrometry (irmGC–MS) to 19 gasoline samples from different areas of the USA. This allows a much better correlation of gasoline contaminants to source. Data obtained indicate a wide range of δ13C values for 16 ubiquitous compounds in the gasolines The majority of samples could be distinguished from each other on the basis of δ13C hydrocarbon composition. The oxygenated additive methyl tertiary butyl ether (MTBE) was present in ten of the gasolines analyzed, and had a relatively narrow range of δ13C values (−30.4 to −28.3‰). Preliminary investigations were also made to determine the extent of carbon isotopic fractionation after simple water washing and evaporation experiments. Results indicate that the majority of compounds did not undergo significant carbon isotopic fractionation as a result of these processes.

Health Risk Assessment of the Migration of Unleaded Gasoline – A Model for Petroleum Products

Unleaded gasoline consists of over 100 chemicals. The risk assessment strategy proposed identifies benzene, toluene, ethylbenzene, (o-, m-, p-) xylenes, n-hexane and methyl-tertiary-butyl ether (MTBE) as the major components of health concern for humans from the migration of unleaded gasoline to groundwater and/or other potential drinking water sources. The mixtures model for human exposure to drinking water contaminated with unleaded gasoline proposed indicates that the greatest proportion of the total health risk is due to cancer risk from the benzene component. The extensive migration of the unleaded gasoline additive MTBE in groundwater indicates that human exposure guidelines are needed to protect human health. This paper proposes a maximum level of 0.2 mg MTBE/L in groundwater/drinking water to protect from potential central nervous system (CNS) depressant and other toxicity. More limited human exposure to contaminated air due to gasoline releases may occur. A mixtures model based upon limited dose-response data for expected predominant air components is also proposed.