Oxidation Of Methyl Tert-butyl Ether Research Articles

Investigating the Protective Role of Biochaga Drug on Structural Changes of Bovine Serum Albumin in the Presence of Methyl tert-butyl Ether.

The health benefits of natural products have a long history. Chaga (Inonotus obliques) is used in traditional medicine and is an essential antioxidant for protecting the body from oxidants. Reactive oxygen species (ROS) are produced routinely due to metabolic processes. However, environmental pollution factors such as methyl tert-butyl ether (MTBE) can increase oxidative stress in the human body. MTBE is widely used as a fuel oxygenator that can harm health. The widespread use of MTBE has posed significant threats to the environment by polluting environmental resources, including groundwater. This compound can accumulate in the bloodstream by inhaling polluted air, with a strong affinity for blood proteins. The primary mechanism of MTBE's harmful effects is ROS production. The use of antioxidants may help reduce MTBE oxidation conditions. The present study proposes that biochaga, as an antioxidant, can reduce MTBE damage in the bovine serum albumin (BSA) structure. This study investigated the role of different concentrations of biochaga in the structural change of BSA in the presence of MTBE by biophysical methods such as UV-Vis, fluorescence, FTIR spectroscopy, DPPH radical inhibition method, aggregation test, and molecular docking. Research at the molecular level is critical to investigate the structural change of proteins by MTBE and the protective effect of the ideal dose (2.5µg/ml) of biochaga. the results of spectroscopic examinations showed that the concentration of 2.5µg/ml of biochaga has the least destructive effect on the structure of BSA in the presence and absence of MTBE, and it can play as an antioxidant.

Fenton-driven oxidation of contaminant-spent granular activated carbon (GAC): GAC selection and implications

Raw materials, activation methods, and post-activation treatment used in manufacturing granular activated carbon (GAC) results in a spectrum of physicochemical characteristics that potentially impact the adsorption oxidation treatment process. A comprehensive study is lacking that assesses the effect of GAC characteristics on adsorption oxidation treatment of contaminant spent-GAC. Consequently, it is inherently assumed the treatment process is GAC-independent. Here, GACs (n = 31) were characterized and used in the hydrogen peroxide (H2O2)-based adsorption oxidation treatment of 2-chlorophenol (2CP)-spent GAC. The GACs exhibited a range in surface area, pore volume distribution, metals content, surface functionality, and H2O2 reaction. Chloride recovery, the treatment metric for 2CP oxidation, indicated a wide range in oxidation (0–49.2%) where bituminous- and wood-based GAC performed best. A selected subset of GACs (n = 12), amended with iron, methyl tert-butyl ether (MTBE), and H2O2, exhibited a range in oxidative treatment (1.1–57.9%). Correlations were established between GAC surface functionality, H2O2 reactivity, adsorption, and MTBE oxidation indicating multiple parameters play a collective and compounding role. The order of GACs successfully used in the treatment process is bituminous-based coal > wood > coconut > peat. Results showed adsorption oxidation treatment is GAC-dependent, and therefore, GAC selection is a key factor in the success of this technology.

Intramolecular isotope effects during permanganate oxidation and acid hydrolysis of methyl tert-butyl ether

Stable isotopes have been widely used to monitor remediation of environmental contaminants over the last decades. This approach gives a good mechanistic description of natural or assisted degradation of organic pollutants, such as methyl tert-butyl ether (MTBE). Since abiotic degradation seems to be the most promising assisted attenuation method, the isotopic fractionation associated with oxidation and hydrolysis processes need to be further investigated in order to understand better these processes and make their monitoring more efficient. In this study, position-specific isotope effects (PSIEs) associated with permanganate oxidation and acid hydrolysis of MTBE were determined using isotope ratio monitoring by 13C Nuclear Magnetic Resonance Spectrometry (irm-13C NMR) combined with isotope ratio monitoring by Mass Spectrometry (irm-MS). The use of this Position-Specific Isotopic Analysis (PSIA) method makes it possible to observe a specific normal isotope effect (IE) associated with each of these two abiotic degradation mechanisms. The present work demonstrates that the 13C isotope pattern of the main degradation product, tert-butyl alcohol (TBA), depends on the chemical reaction by which it is produced. Furthermore, this study also demonstrates that PSIA at natural abundance can give new insights into reaction mechanisms and that this methodology is very promising for the future of modeling the remediation of organic contaminants.

A study of the variations of oxidation-reduction potential, pH and dissolved oxygen during photo-Fenton oxidation of methyl tert-butyl ether in the presence of nanosized zero-valent iron particle, hydrogen peroxide, and ultraviolate radiation

A study of the variations of oxidation-reduction potential, pH and dissolved oxygen during photo-Fenton oxidation of methyl tert-butyl ether in the presence of nanosized zero-valent iron particle, hydrogen peroxide, and ultraviolate radiation

Photocatalytic Oxidation of Methyl Tert-Butyl Ether in Presence of Various Phase Compositions of TiO2

MTBE (methyl tert-butyl ether) represents a rising threat to the environment, especially drinking water, and its effective removal (with all by-products) is necessary. Even a very low concentration of MTBE makes the water undrinkable; therefore, an effective treatment has to be developed. This work is focused on MTBE photocatalytic oxidation in presence of various TiO2 photocatalysts with different phase composition prepared by different methods. It was confirmed the phase composition of TiO2 had the most significant influence on the photocatalytic degradation of MTBE. The rutile phase more easily reduces adsorbed oxygen by photogenerated electrons to superoxide radical, supporting separation of charge carriers. The presence and concentrations of by-products have to be taken into account as well. The conversion of total organic carbon (TOC) was used for the comparison, 40% of TOC was removed after 1 h of irradiation in presence of TiO2–ISOP–C/800 photocatalyst composed of anatase and rutile phase.

Hydroperoxide Formation and Thermal Oxidation of Methyl tert-Butyl Ether Oxidation at Low Temperature

In this work, we investigated the thermal oxidation of methyl tert-butyl ether (MTBE) using a customer-designed mini-closed-pressure vessel test and quantitatively analyzed the hydroperoxides produ...

VUV/Fe(II)/H2O2 as a novel integrated process for advanced oxidation of methyl tert-butyl ether (MTBE) in water at neutral pH: Process intensification and mechanistic aspects

Vacuum UV (VUV) technologies have recently attracted high interest due to their high efficacy in generating reactive oxygen species (ROS). To date, no systematic study of the modes of action of the integrated VUV/Fe(II)/H2O2 process against contaminants elimination exists; the present study reports the oxidation of MTBE in a new light-assisted Fenton-process, by employing either narrowband UVC (254 nm) or VUV (185 and 254 nm) irradiation, in a comparative evaluation. The processes under investigation were the UVC- or VUV/Fe(II)/H2O2 sensitized ones and their constituents, i.e. Fe(II)/H2O2, VUV, VUV/Fe(II), VUV/H2O2, VUV/Fe(II)/H2O2, as well as the UVC, UVC/H2O2 and UVC/Fe(II)/H2O2. We scrutinize the operational parameters of the VUV-assisted process, its enhancements and synergies, comparison with the UVC-based ones, as well as their inflicted pathways towards MTBE degradation. Complete degradation and 87.8% mineralization of 50 mg/L MTBE was achieved in the VUV/Fe(II)/H2O2 process (0.9 mM Fe(II) and 3 mM H2O2), at near-neutral pH (reaction times: ∼30 and 60 min, respectively). Irradiation with VUV light was found to act synergistically and in high kinetic rates enhancement compared to the UVC source, sensitizing the Fenton process for effective oxidation of MTBE in the aqueous solution. A scavenger study and degradation by-products investigation has been performed, leading to a mechanistic pathway proposition, elucidating MTBE degradation. The VUV/Fe(II)/H2O2 process demonstrated potential applicability in the field since it could efficiently treat (100% degradation and 86.4% mineralization) groundwater spiked with MTBE, operated either under batch or continuous-flow mode. The findings clearly indicates the VUV-assisted Fenton as an emerging and viable technology for field application to treat the MTBE-contaminated effluents or waters.

Correlation of Rh Particle Size with CO Chemisorption: Effect on the Catalytic Oxidation of MTBE

This study was conducted to identify the correlation between the CO chemisorption (linear interaction and gem dicarbonyl) and the specific size of rhodium particles, and further to determine the influence of this relationship on the catalytic oxidation reaction of methyl tert-butyl ether (MTBE). During the synthesis, first, TiO2 was developed by the sol-gel method under acidic conditions. Second, Rh was deposited (1 wt %) by the incipient wetness impregnation method. Later, with the aim of controlling the particle size, the Rh/TiO2 materials were crystallized at different reduction conditions during 3 h heat treatment. The results obtained by TEM micrographs indicated that the average particle size varies between 1.0 and 8.1 nm, depending on the conditions of heat treatment. From the histogram analysis of each TEM micrograph, two correlations were made: (i) the gem-dicarbonyl interaction was typical of Rh particles ≤ 1.5 nm, and (ii) a linear interaction, bridged interaction and dentate interaction were observed in particles ≥ 1.6 nm. The gem-dicarbonyl interaction (particle size ≤ 1.5 nm) was the most active in the oxidation reaction of MTBE.

Water remediation contaminated with MTBE using a catalytic oxidation process in batch reactor: influence of the cerium loading on the activity and CO2 selectivity.

Destruction of methyl tert-butyl ether (MTBE) in liquid phase and in a batch reactor was studied using ruthenium catalysts over alumina support, modified with different cerium loadings. Ce loading increment causes an increase in the particle size from 1.26 nm to 2.3 nm, enhancing the MTBE oxidation (at 150 °C), and the selectivity toward CO2. The high catalytic activity of Ru/ACe10 is attributed to the species Ce4+-O2--M that could favor the oxygen transfer between the catalyst surface and the adsorbed species by a redox mechanism. Thus, CeOx plays an important role in both enhancing the affinity between MTBE and catalyst during MTBE adsorption and promoting the catalytic activity for MTBE oxidation.

Heterogeneous persulfate oxidation of BTEX and MTBE using Fe3O4−CB magnetite composites and the cytotoxicity of degradation products

Groundwater contamination by organic aromatic compounds such as gasoline fuel is a serious worldwide problem because of their carcinogenic and mutagenic potential. This study evaluated the use of Fe3O4−carbon black (CB) composites for persulfate (PS) oxidation of benzene, toluene, ethylene, and xylene (BTEX) and methyl tert-butyl ether (MTBE) compounds from the aqueous solution. The characterization results of environmental scanning electron microscopy coupled with energy-dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and a superconducting quantum interference device magnetometry evidenced the successful synthesis of Fe3O4−CB composites. In addition, the in vitro cytotoxic activity and apoptotic response of these composites were investigated before and after the Fe3O4−CB/PS processes test of the BTEX and MTBE samples was performed. The effects of various operating parameters were evaluated to optimize the oxidation process, including the PS concentration, initial pH, and Fe3O4−CB amount. The results showed that increasing PS and Fe3O4−CB dosage could accelerate BTEX and MTBE oxidation when PS and Fe3O4−CB concentrations increased to 15 g L−1 and 1.0 g L−1, respectively, at a pH of 3.0. The degradation rate of BTEX and MTBE was strongly pH-dependent. Methyl thiazolyl tetrazolium assay was employed to perform a cytotoxicity study after Fe3O4−CB/PS processing treatment of BTEX and MTBE degradation products on the zebrafish (Danio rerio) embryonic cell line (ZF4), which revealed that a weak effect and apoptosis in cell viability ultimately leads to cell death. The results suggested that Fe3O4−CB assisted persulfate oxidation without elevating the temperature is a suitable and economic alternative for the ex-situ treatment of BTEX- and MTBE-contaminated aquatic environments.

Silver nanoparticles supported on zirconia–ceria for the catalytic wet air oxidation of methyl tert-butyl ether

In this work Ag nanoparticles supported on ZrO2–CeO2 promoted with different amounts of CeO2 were synthesized by deposition–precipitation method in order to test the Catalytic Wet Air Oxidation (CWAO) of Methyl Tert-Butyl Ether (MTBE).

Dosing of ozone in oxidation of methyl tert-butyl ether while minimizing hexavalent chromium formation in groundwater

Co-oxidation of trivalent chromium (Cr(III)) to hexavalent chromium (Cr(VI)) during ozonation of organic pollutants represents a common problem facing the implementation of in situ chemical oxidation (ISCO) for environmental remediation. A laboratory study was conducted by using groundwater and saturated soil samples from a field site in Sacramento, California, to determine optimal O3 dosage to achieve satisfactory remediation of MTBE while minimizing co-oxidation of Cr(III) to Cr(VI). Total oxidant demand was determined (28.33mg O3 L−1) and used as the benchmark to establish a range of ozone dosages for the study. Concentration changes in MTBE and chromium were monitored at O3 dosages less than and greater than the benchmark. The results indicate that MTBE is preferentially oxidized by ozone at and below the indicated benchmark dosage prior to the oxidation of Cr(III) to Cr(VI). The resultant O3 dosage of 28.33mgL−1 was applied in the field implementation, verifying that the O3 can be applied in a controlled manner to remediate MTBE while minimizing the formation of Cr(VI).

The fate of MtBE during Fenton-like treatments through laboratory scale column tests

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 CO2 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.

Cometabolism of methyl tert-butyl ether by a new microbial consortium ERS.

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 s 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.

Expression of an alkane monooxygenase (alkB) gene and methyl tert-butyl ether co-metabolic oxidation in Pseudomonas citronellolis.

Pseudomonas citronellolis UAM-Ps1 co-metabolically transforms methyl tert-butyl ether (MTBE) to tert-butyl alcohol with n-pentane (2.6mM), n-octane (1.5mM) or dicyclopropylketone (DCPK) (4.4mM), a gratuitous inducer of alkane hydroxylase (AlkB) activity. The reverse transcription quantitative real-time PCR was used to quantify the alkane monooxygenase (alkB) gene expression. The alkB gene was expressed in the presence of n-alkanes and DCPK and MTBE oxidation occurred only in cultures when alkB was transcribed. A correlation between the number of alkB transcripts and MTBE consumption was found (ΜΤΒΕ consumption in μmol=1.44e(-13) x DNA copies, R(2)=0.99) when MTBE (0.84mM) was added. Furthermore, alkB was cloned and expressed into Escherichia coli and the recombinant AlkB had a molecular weight of 42kDa. This is the first report where the expression of alkB is related to the co-metabolic oxidation of MTBE.

Impact of activation methods on persulfate oxidation of methyl tert-butyl ether

To provide guidance on the selection of proper persulfate processes for the remediation of MTBE contaminated groundwater, MTBE aqueous solutions were treated with three common field persulfate processes including heat activated persulfate, Fe(III)-EDTA activated persulfate and alkaline persulfate, respectively. The results were compared with MTBE oxidation by Fenton's reagent and persulfate alone at 25°C. The impact of the activating conditions on the fate of MTBE and its daughter products was investigated. Heat activation at 40°C offered the most rapid removal of MTBE and its daughter products, while Fe(III)-EDTA activation showed higher efficiency of MTBE removal but low removal efficiency of its daughter products. On the other hand, alkaline persulfate showed slower kinetics for the removal of MTBE and less accumulation of the daughter products. Furthermore, tert-butyl alcohol and acetone were observed as the main purgeable daughter products along with a small amount of tert-butyl formate in persulfate oxidation of MTBE, while tert-butyl formate, tert-butyl alcohol and acetone were the main products in Fenton oxidation. Mechanistic analysis suggests that degradation of MTBE by persulfate most likely happens via non-oxygen demand pathways, different from the dominant oxygen demand degradation pathways observed in Fenton oxidation.

Degradation of methyl tert-butyl ether by catalytic wet air oxidation over Rh/TiO2–CeO2 catalysts

The catalytic wet air oxidation of methyl tert-butyl ether was carried on Rh/TiO2 and Rh/TiO2–CeO2 catalysts. The TiO2–CeO2 (1, 3, 5, 10, and 20wt% CeO2) mixed oxides were prepared by the sol–gel method. The catalysts were characterized by different techniques: surface adsorption–desorption of N2 (BET surface area), X-ray diffraction (XRD), Fourier transform infrared of CO adsorption (FTIR-CO), Fourier transformed infrared of pyridine adsorption (FTIR-pyridine), temperature programmed reduction of H2 (H2-TPR), total organic compound (TOC) and transmission electron microscopy (TEM). A higher specific surface area BET and Lewis acidity sites were obtained on catalysts containing cerium oxide. Small Rh particles <1.8nm were obtained in all catalysts. The Rh catalysts containing cerium oxide showed higher activity than the reference Rh/TiO2 and a maximum in activity at 5wt% loading of CeO2. It is assumed that the acid sites are acting as a tramp for the MTBE molecule increasing the conversion on the Rh particles joined to an additional oxygen supply by cerium oxide redox process. The presence of cerium oxide inhibits the deposit of carbon on the catalyst; the higher cerium oxide concentration, the lower carbon deposited on the Rh surface. The addition of HCl on the initial reaction solution increases the CWAO activity.

Persulfate oxidation of MTBE- and chloroform-spent granular activated carbon

Activated persulfate (Na 2S 2O 8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H 2O 2–persulfate binary mixtures. H 2O 2 may serve multiple roles in oxidation mechanisms including Fenton-driven oxidation, and indirect activation of persulfate through thermal or ferrous iron activation mechanisms. More frequent, lower volume applications of persulfate solution (i.e., the persulfate loading rate), higher solid/solution ratio (g GAC mL −1 solution), and higher persulfate concentration (mass loading) resulted in greater MTBE oxidation and removal. Chloroform oxidation was more effective in URV GAC compared to F400 GAC. This study provides baseline conditions that can be used to optimize pilot-scale persulfate-driven regeneration of contaminant-spent GAC.

Electrochemical removal of MTBE from water using the iridium dioxide coated electrode

Methyl tert-butyl ether (MTBE) is always the most likely found compound at the front of a gasoline plume due to its chemical characteristics. In this study, an iridium dioxide (IrO 2) coated electrode was utilized to perform electrochemical removal of MTBE in a lab-scale bath electrolyzer. Depending on the constant-potential controls, electrochemical removal of MTBE can be conducted either through direct oxidation, water electrolysis competition, or indirect oxidation. Direct oxidation mechanism performed MTBE removal up to 39% as electrolyzing below 1.2 V, and the occurrence of water electrolysis competition dropped MTBE removal as increasing the operative potential up to 2.0 V. The continual increase of operative potential above 2.0 V brought about indirect oxidation of MTBE through the chain reactions of the redox mediator S 2O 8 2−/SO 4 2−. The matrix effect of iron enhances electrochemical oxidation of MTBE to provide about 2 times improvement on MTBE removal. The products of MTBE degradation were identified as tert-butyl alcohol (TBA), acetone, and CO 2 by GC/MS, and the distributions of carbon atoms in TBA, acetone, CO 2, and MTBE were found 18, 12, 62, and 8% through the optimum control of electrochemical oxidation.

Catalytic Combustion of Methyl Tert-Butyl Ether on Rh/γ-Al2O3 and Rh/γ-Al2O3–CeO2 Catalysts: Effects of Thermal Treatments, Cerium Oxide and Particle Size

The effects of activation pretreatments, Rh particle size and content of cerium oxide on Rh/γ-Al2O3 catalysts for the oxidation of methyl tert-butyl ether (MTBE) were investigated. Three different conditions were used for the activation of the catalysts: (1) with air flow, (2) using a mixture of air and MTBE, and (3) by hydrogen reduction followed by oxidation with air. On Rh/γ-Al2O3 catalyst the thermal pretreatments are of great importance for the MTBE oxidation. However, on Rh/γ-Al2O3–Ce1 catalyst, the total combustion of MTBE was reached at a temperature of 200 °C lower than that obtained with the Rh/γ-Al2O3 catalyst at whatever thermal treatment applied. A Rho/Rhδ+ and Ce3+/Ce4+ species were identified by XPS suggesting that they are the responsible of the high activity showed by the Rh/γ-Al2O3–Ce1 catalyst. A particle size effect for MTBE oxidation was observed on Rh/γ-Al2O3 catalysts, large Rh particles are more active than the small ones.