Methyl Tert-butyl Ether Research Articles

Standard-Compliant Gasoline by Upgrading a DTG-Based Fuel through Hydroprocessing the Heavy-Ends and Blending of Oxygenates

Methanol-to-gasoline (MTG) and dimethyl ether-to-gasoline (DTG) fuels are rich in heavy aromatics such as 1,2,4,5-tetramethylbenzene, resulting in low volatilities due to a lack of light ends, increased emission tendencies and drivability problems due to crystallization. Approaches addressing these issues mainly focus on single aspects or are optimized for petroleum-based feedstocks. This research article introduces an upgrading strategy for MTG and DTG fuels through hydroprocessing (HP) heavy-ends and applying a sophisticated blending concept. Different product qualities were prepared by HP heavy gasoline (HG) and Fischer-Tropsch wax using commercially available Pt/HZSM-5 and Pt/SAPO-11 catalysts in a fixed-bed reactor. The products were used for blending experiments, focusing on gasoline volatility characteristics. Accordingly, methanol, ethanol, methyl tert-butyl ether (MTBE), and ethyl tert-butyl ether (ETBE) were evaluated in a second blending experiment. The results were finally considered for preparing blends meeting EN 228. HP of HG was found to improve the amount of light-ends and the vapor pressure of the DTG fuel with increasing reaction temperature without, however, satisfying EN 228. The front-end volatility was further improved by blending methanol due to the formation of near-azeotropic mixtures, while ethyl tert-butyl ether (ETBE) considerably supported the mid-range volatility. A final blend with an alcohol content of less than 3 vol.%, mostly meeting EN 228, could be provided, making it suitable even for older vehicles.

Threat and Risk Analysis-Based Neural Network for a Chemical Explosion (TRANCE) Model to Predict Hazards in Petroleum Refinery.

Risk analysis and prediction is a primary monitoring strategy to identify abnormal events occurring in chemical processes. The accidental release of toxic gases may result in severe problems for people and the environment. Risk analysis of hazardous chemicals using consequence modeling is essential to improve the process reliability and safety of the refineries. In petroleum refineries: toluene, hydrogen, isooctane, kerosene, methanol, and naphtha are key process plants with toxic and flammable chemicals. The major process plants considered for risk assessment in the refinery are the gasoline hydrotreatment unit, crude distillation, aromatic recovery, continuous catalytic reformer, methyl-tert-butyl-ether, and kerosene merox units. Additionally, we propose a threat and risk analysis neural network for the chemical explosion (TRANCE) model for refinery incident scenarios. Significantly, 160 attributes were collected for the modeling on the basis of the significance of failure and hazardous chemical leaks in the refinery. Hazard analysis shows that the leakages of hydrogen and gasoline at the gasoline hydrotreatment unit, kerosene at the kerosene merox plant, and crude oil at crude-distillation units were areas of profound concern. The developed TRANCE model predicted the chemical explosion distance with an R2 accuracy value of 0.9994 and MSE of 679.5343.

Impacts of COVID-19's restriction measures on personal exposure to VOCs and aldehydes in Taipei City

The Coronavirus Disease 2019 (COVID-19) pandemic provided an unprecedented natural experiment, that allowed us to investigate the impacts of different restrictive measures on personal exposure to specific volatile organic compounds (VOCs) and aldehydes and resulting health risks in the city. Ambient concentrations of the criteria air pollutants were also evaluated. Passive sampling for VOCs and aldehydes was conducted for graduate students and ambient air in Taipei, Taiwan, during the Level 3 warning (strict control measures) and Level 2 alert (loosened control measures) of the COVID-19 pandemic in 2021–2022. Information on the daily activities of participants and on-road vehicle counts nearby the stationary sampling site during the sampling campaigns were recorded. Generalized estimating equations (GEE) with adjusted meteorological and seasonal variables were used to estimate the effects of control measures on average personal exposures to the selected air pollutants. Our results showed that ambient CO and NO2 concentrations in relation to on-road transportation emissions were significantly reduced, which led to an increase in ambient O3 concentrations. Exposure to specific VOCs (benzene, methyl tert-butyl ether (MTBE), xylene, ethylbenzene, and 1,3-butadiene) associated with automobile emissions were remarkably decreased by ~40–80 % during the Level 3 warning, resulting in 42 % and 50 % reductions of total incremental lifetime cancer risk (ILCR) and hazard index (HI), respectively, compared with the Level 2 alert. In contrast, the exposure concentration and calculated health risks in the selected population for formaldehyde increased by ~25 % on average during the Level 3 warning. Our study improves knowledge of the influence of a series of anti-COVID-19 measures on personal exposure to specific VOCs and aldehydes and its mitigations.

A Fast and Robust Analytical Method Based on QuEChERS Technique using UPLC- PDA for Quantification of Carcinogenic Arylamines in Consumer Goods inclusive of Leather

Arylamines present in leather and textile products are reduced in vivo by cleavage of azo groups to form highly mutagenic and carcinogenic products that pose consumer’s health risk. The major textile and leather products that are offered to consumers need to be safe. In order to ensure safety as per the global regulations, the allowed limit of carcinogenic amines in textile and leather products cannot be more than 20 mg/kg. There are several methods that have been used for extracting the azo dyes and analyzing them in textile and leather products. Most of these methods are polluting from high solvent usage, time consuming, laborious, and have lower recovery rates. In the present study QuEChERS method, (dispersive solid phase extraction-dSPE) method was utilized for extraction of carcinogenic arylamines from dyed leather and textile products. The released arylamines are extracted into acetonitrile using QuEChERS salt and analyzed by Ultra Performance Liquid Chromatography-Photo Diode Array (UPLC-PDA). The extracted product was further confirmed by Gas Chromatography-Mass Spectrometer (GC-MS). The method proposed in this study is novel as it eliminates all significant concerns associated with the official ISO-17234-1 &14362-1 test methods, such as use of solvents like tert-butyl methyl ether (MTBE) and the long duration of analysis. The sample preparation time is minimized from 120 min to 20 min. The developed method is easy to adopt with efficient recovery rate of arylamines in comparison to the official ISO method.

Development of a solvent screening methodology for cannabinoid recovery from a wax by-product via recrystallization

Wax by-products from commercial Cannabis processing, containing between 41 and 46% (w/w) cannabinoids, are currently underutilized due to lack of research done, and significant value can be added through recovery of the cannabinoids. The cannabinoids are aimed to be recovered via a novel solvent-assisted recrystallization technology, and this study provides a robust solvent screening methodology for recovery of the cannabinoids for this technology. Solvents were screened based on their relative polarity, boiling point temperature, and safety of use. Further criteria such as reactivity toward wax compounds were implemented through evaluation of the Kamlet-Taft parameters of potential solvents. Solubility predictions of the wax in different solvents were done using the Hansen solubility parameters (HSP). The methodology was tested on a set of 73 commonly used solvents identifying five suitable solvents, which were 1,2-dimethoxyethane, 3-pentanone, ethyl acetate, methyl acetate, and methyl tert-butyl ether. The identified solvents were tested for use in recrystallization and were found to be suitable, validating the use of the developed methodology.Graphical

Determination of olverembatinib in human plasma and cerebrospinal fluid by an LC-MS/MS method: Validation and clinical application

A sensitive and robust LC-MS/MS method has been developed and validated for olverembatinib quantification in human plasma and cerebrospinal fluid (CSF). The method involved liquid-liquid extraction with methyl tertiary butyl ether for plasma pretreatment and precipitation enrichment with methanol for CSF pretreatment. Separation was achieved on the C18 column with gradient elutions of 10 mM ammonium formate in water and methanol-acetonitrile (50:50,v/v). Analyte detection was conducted by electrospray ionization (ESI) in a positive ion mode using multiple reaction monitoring (MRM). The m/z transitions were 533.4→433.2 for olverembatinib and m/z 502.4→394.2 for the internal standard (IS, Imatinib-d8). Calibration curves ranged from 0.500 to 50.0 ng/mL for plasma and from 0.0100 to 1.00 ng/mL for CSF. The intra- and inter-day precision and accuracy were < 15% for both plasma and CSF with four different quality control concentrations. The relative matrix effect was < 10% in plasma and artificial CSF. This method was successfully utilized for the measurement of olverembatinib concentrations in plasma and CSF from chronic myeloid leukemia patients.

A general review on the application of adsorption and oxidation combined processes on methyl tert-butyl ether removal

A general review on the application of adsorption and oxidation combined processes on methyl tert-butyl ether removal

Hydrogen bonding guest-water interactions in pinacolone, tert-butyl amine, and tert-butylmethyl ether: a theoretical study on energetics, structure, and topological +

In guest-host interactions, guest molecules used for hydrogen bonding potential of clathrate hydrate cages are involved as "promoters" for hydrogen or methane storage. Among the promoter molecules, there are pinacolone and tert-butylmethyl ether containing oxygen atom, and tert-butyl amine among those containing nitrogen atom. The dimer and trimer interactions of these molecules with the water clusters were investigated. The cooperativity effect, which is a measure of the hydrogen bonding of these oxygen and nitrogen-containing complexes, was calculated and these complexes were analyzed. Moreover, molecular electrostatic potential (MEP) analysis was performed to determine intermolecular interactions. Clusters of several molecules may seem like a non-significant state of matter; however, in systematic studies with small clusters, important results can be obtained. Therefore, it is very useful to work with clusters to understand the properties of the dense phase, and this study aimed to examine the properties of structures, energies, infrared vibration frequencies, and topological parameters, which develop as a result of the interaction of structures in different clusters with water molecules. The MP2 level was performed using aug-cc-pVDZ basis set calculations for this study. Tight converting criteria were used in the optimization step. Harmonic vibrational modes were calculated at the MP2/aug-cc-pVDZ level. Each minima obtained from the MP2 level was subjected to single-point energy calculations using CCSD(T) levels with the aug-cc-pVDZ basis set by the Gaussian16 package program suite. Thetopological analyseswere performed withnon-covalent interaction (NCI). MEP surface of the complex was also composed by Gaussian program using the optimized geometry at a MP2/aug-cc-pvdz level.

Separation of methanol and ethanol from azeotropic MTBE mixtures using choline chloride-based deep eutectic solvents

In this study, the performance of five different choline chloride – based deep eutectic solvents (DESs), including ChCl – urea, ChCl – ethylene glycol, ChCl – glycerol, ChCl – 1,2- propanediol, and ChCl – glucose, has been experimentally and computationally investigated for the purpose of liquid – liquid extraction at 298.15 K and 1 atm. In this regard, the effect of them on the extraction efficiency to separate methanol and ethanol from azeotropic systems, methyl tert-butyl ether (MTBE) + ethanol and MTBE + methanol, is studied. To synthesize these DESs, chlorine chloride as a hydrogen bond acceptor (HBA) is blended with urea, ethylene glycol, glycerol, 1,2- propanediol, and glucose as hydrogen bond donors (HBDs). Through the investigation, it is revealed that all the studied DESs deliver a distribution coefficient, β, that is higher than unity (β > 1). Similarly, the measured selectivities for these DESs have presented values that are far greater than unity (S ≫ 1). This is advantageous as it demonstrates their industrial applications. Furthermore, to have a better view of how effective they are in terms of the extraction capacity, the experimental data have been compared to the performance of ionic liquids used for the liquid – liquid extraction of MTBE + methanol. The reliability of the tie-line compositions was checked by applying the Othmer–Tobias equation. Additionally, to show the consistency, UNIQUAC Functional-group Activity Coefficients (UNIFAC) as a thermodynamic model has been employed to predict the equilibrium tie-lines. The predicted data is compared with the experimentally measured data through the calculation of the root-mean-square deviation (RMSD), showing that both predicted and experimental data are in a good agreement together.

Glutaminase 1 isoform up-regulation associated with lipid metabolism disorder induced by methyl tertiary-butyl ether in male rats

Methyl tertiary-butyl ether (MTBE) is a new unleaded gasoline additive, which is considered to be associated with abnormal lipid metabolism in many studies, but the metabolic characteristics and mechanism are still unclear. To observe the characteristics of lipid metabolism induced by MTBE and possible pathways, 21 male Wistar rats got intragastric administration for 24 weeks. The serum lipid metabolism indexes and metabolites were analyzed separately by a biochemical analyzer and untargeted metabolomics. And found that serum high-density lipoprotein cholesterol (HDL-C) levels in the exposure group were significantly reduced, and serum very low-density lipoprotein (VLDL) levels were significantly increased. In untargeted metabolomics, 190 differential metabolites were obtained. Among them, 23 metabolites were found to show the same trend in MTBE exposure groups, which might play a key role in systemic energy metabolism. Further metabolic pathways analysis showed that D-Glutamine, D-glutamate metabolism, and the other three pathways were affected by MTBE significantly. Therefore, we evaluated serum glutamine and glutamate levels and found that MTBE exposure significantly reduced glutamine levels and increased glutamate levels in rat serum and L-02 cells. Further, the key regulatory gene of glutamine metabolism, glutaminase 1 isoform (GLS1), was significantly up-regulated in rat liver and L-02 cells exposed to MTBE. While the effect of glutamine and glutamate metabolism induced by MTBE could be weakened by BPTES, an antagonist of GLS1. In conclusion, our results indicated that MTBE exposure could change the level of glutamine metabolism by promoting GLS1 expression and ultimately lead to abnormal lipid metabolism.

From Hamamelitannin Synthesis to the Study of Enzymatic Acylations of D-Hamamelose.

The bioactive natural substance, hamamelitannin, was effectively synthesized in two ways. The chemical acylation of 2,3-O-isopropylidene-α,β-D-hamamelofuranose promoted by Bu2SnO using 3,4,5-tri-O-acetylgalloyl chloride, followed by the deprotection provided hamamelitannin in 79%. Pilot enzymatic benzoylation of D-hamamelose using vinyl benzoate (4 equiv.) and Lipozyme TL IM as a biocatalyst in t-butyl methyl ether (t-BuMeO) gave mainly benzoylated furanoses (89%), of which tribenzoates reached (52%). Enzymatic galloylation of 2,3-O-isopropylidene-α,β-D-hamamelofuranose with vinyl gallate under the catalysis of Lipozyme TL IM in t-butyl alcohol (t-BuOH) or t-BuMeO provided only the 5-O-galloylated product. The reaction in t-BuMeO proceeded in a shorter reaction time (61 h) and higher yield (82%). The more hydrophobic vinyl 3,4,5-tri-O-acetylgallate in the same reactions gave large amounts of acetylated products. Vinyl gallate and triacetylgallate in the enzymatic acylation of D-hamamelose with Lipozyme TL IM in t-BuMeO yielded 2',5-diacylated hamamelofuranoses in a yield below 20%. The use of other vinyl gallates hydrophobized by methylation or benzylation provided 2',5-diacylated hamamelofuranoses in good yields (65-84%). The reaction with silylated vinyl gallate did not proceed. The best results were obtained with vinyl 2,3,5-tri-O-benzyl gallate, and the only product, 2',5-diacylated hamamelofuranoside precipitated from the reaction mixture (84% in 96 h). After debenzylation, hamamelitannin was obtained an 82% yield from hamamelose in two steps. This synthesis is preparatively undemanding and opens the way to multigram preparations of bioactive hamamelitannin and its analogues.

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.

A Validated Chiral LC–MS/MS Method for the Enantioselective Determination of (S)-(+)- and (R)-(-)-Ibuprofen in Dog Plasma: Its Application to a Pharmacokinetic Study

The purpose of this study was to develop a method for simultaneously separating ibuprofen enantiomers using electrospray ionization (ESI) liquid chromatography with tandem mass spectrometry (LC-MS/MS). LC-MS/MS was operated with negative ionization and multiple reaction monitoring modes; transitions were monitored at m/z of 205.1 > 160.9 for ibuprofen enantiomers, 208.1 > 163.9 for (S)-(+)-ibuprofen-d3 [internal standard 1 (IS1)], and 253.1 > 208.9 for (S)-(+)-ketoprofen (IS2), respectively. In a one-step liquid-liquid extraction, 10 μL plasma was extracted with ethyl acetate:methyl tertiary-butyl ether of 7:3. Enantiomer chromatographic separation was carried out with an isocratic mobile phase consisting of 0.008% formic acid in water-methanol (v/v) at a flow rate of 0.4 mL/min on a CHIRALCEL® OJ-3R column (150 × 4.6 mm, 3 µm). This method was fully validated for each enantiomer and results were in compliance with the regulatory guidelines of the U.S. Food and Drug Administration and the Korea Ministry of Food and Drug Safety. The validated assay was executed for nonclinical pharmacokinetic studies after oral and intravenous administration of racemic ibuprofen and dexibuprofen in beagle dogs.

Global methyl tertiary butyl ether market to register a CAGR of over 4% during 2022–2032

Global methyl tertiary butyl ether market to register a CAGR of over 4% during 2022–2032

Synthesis, Crystal Structure, and Conductivity of a Weakly Coordinating Anion/Cation Salt for Electrolyte Application in Next-Generation Batteries.

ConspectusResearch at historically black colleges and universities (HBCUs) started with humble beginnings by G. W. Carver at Tuskegee Institute AL, the nation's first HBCU. He is now remembered as the man who transformed one crop, peanuts to more than 300 useful products such as food, beverages, medicines, cosmetics, and chemicals. However, research was not the focus of most of the newly founded HBCUs to provide, primarily, liberal arts education and training in agriculture for the black minority. HBCUs remained segregated, lacking facilities such as libraries and scientific/research equipment comparable to those at traditionally white institutions. While the Civil Rights Act of 1964 heralded the dawn of "equal opportunity" and progressive desegregation in the South, many public HBCUs had to close or merge with white institutions due to loss of funding and/or students. In order to remain competitive in enrollment and financial support of the best talents, HBCUs have been expanding their research and federal contracts by working in collaboration with research-intensive institutions and/or minority-serving institutions (MSIs). Albany State University (ASU), an HBCU with a great tradition of in-house and extramural undergraduate research, has partnered with the laboratory of Dr. John Miller at Brookhaven National Laboratory (BNL) to offer the best training and mentorship to our undergraduates. Students synthesized and performed conductivity measurements on a new generation of ion-pair salts. One of these constitutes, potentially, a nonaqueous electrolyte for the next generation of high-energy-density batteries owing to its electrochemical properties.The quest for rechargeable batteries with greater energy density and capable of shorter recharge time at the "pump" for electrical vehicles (EVs) is leading the development of electrolytes with higher ionic mobility and greater limiting conductivity. In order to achieve high energy density, it is vital for an electrolyte to be electrochemically stable while operating at high voltages.The development of a weakly coordinating anion/cation electrolyte for energy storage applications offers a challenge of technological significance. This class of electrolytes is advantageous for the investigation of electrode processes in low-polarity solvents. The improvement arises from the optimization of both ionic conductivity and solubility of the ion pair formed between a substituted tetra-arylphosphonium (TAPR) cation and tetrakis-fluoroarylborate (TFAB), a weakly coordinating anion. The chemical "push-pull" between cation and anion affords a highly conducting ion pair in low-polarity solvents such as tetrahydrofuran (THF) and tert-butyl methyl ether (TBME). The limiting conductivity value of the salt, namely, tetra-p-methoxy-phenylphosphonium-tetrakis(pentafluorophenyl)borate or TAPR/TFAB (R = p-OCH3), is in the range of lithium hexafluorophosphate (LiPF6) used in lithium-ion batteries (LIBs). This TAPR/TFAB salt can improve the efficiency and stability of batteries over those of existing and commonly used electrolytes by optimizing the conductivity tailored to the redox-active molecules. LiPF6 dissolved in carbonate solvents is unstable with high-voltage electrodes that are required to achieve greater energy density. In contrast, the TAPOMe/TFAB salt is stable and has a good solubility profile in low-polarity solvents given its relatively great size. And it constitutes a low-cost supporting electrolyte capable of bringing nonaqueous energy storage devices to compete with existing technologies.

Enhanced Methyl Tert-Butyl Ether Removal by Mixed Consortium: Performance and Adaptability

Methyl tert-butyl ether (MTBE) is widely used as a gasoline additive with toxicity and carcinogenicity, and has caused environmental pollution worldwide. Biodegradation is a promising method for the removal of MTBE from contaminated sites. In this paper, three strains with high adaptability and different degrading characteristics to MTBE were cultured. The kinetic models were established to systematically simulate the biodegradation of MTBE by various strains at different concentrations. Moreover, the removal of MTBE in a synergistic system containing a mixture of three pure strains was studied. The mixed consortium enhanced MTBE removal at high concentrations (30–50 mg/L), and the degradation efficiency was increased by about 20% compared to pure strains at a concentration of 30 mg/L. Further, the mixed consortium degraded MTBE nearly three times faster than any of the individual, indicating that the co-cultures of three pure cultures improved both efficiency and the rate of MTBE biodegradation. In addition, it was found that the mixed consortium effectively removed MTBE in the presence of other gasoline components, and exhibited stronger adaptability, especially at low or high temperatures. This study supports the cultivation of a mixed consortium to remediate MTBE-contaminated environments, either as a single substrate or in environments containing other gasoline components.

Bioethanol production from banana peels

Banana varieties have a significant effect on the reducing sugar content in the peel. In recent years, potential efforts have been directed towards the utilization of cheap renewable agricultural resources, such as banana peel waste as alternative substrate for ethanol production. Various conversion pathways are compared from technical, economic, and environmental points of view. This study also deals mainly with the yield of ethanol from molasses with respect to the dilution ratio and the amount of yeast used for fermentation keeping the temperature and fermentation duration constant. This fuel energy is also a safer substitute to methyl tertiary-butyl ether (MTBE), a common additive used in gasoline for clean combustion.

Mechanism analysis and liquid-liquid equilibrium of methyl tert-butyl ether separation from petroleum wastewater azeotrope by green mixed solvent

Petroleum wastewater contains large amounts of methyl tert-butyl ether (MTBE) and ethanol azeotropes. Efficiently and cleanly separating these azeotropes while conserving energy and reducing the emission of petroleum wastewater is an urgent problem that needs to be solved. In this work, the process of extracting MTBE from petroleum wastewater with water and ionic liquids (ILs) mixed extractant was clarified, and a complete method of evaluating the extraction performance based on the COSMO-SAC model, liquid-liquid extraction measurement, and micro-scale analysis mechanism is proposed. The COSMO-SAC model was used to determine organic solvents and ILs with the best extraction performance from among more than 250 ILs. A mixed solvent of water and the IL 1-ethyl-2,3-dimethylimidazolium ethylsulfate ([EMMIM][EtSO4]) at different molar ratios was selected for the liquid-liquid extraction experiment. It was found that the distribution coefficients and selectivity were maximum when the molar ratio of [EMMIM][EtSO4] to water was 1:2. Combined with molecular dynamics simulations and quantum chemical calculations, the interaction mechanisms of different solvents with MTBE and ethanol were revealed on the micro-level. This work provides a prototype for the high-efficiency extraction of MTBE from petroleum wastewater using a new mixed solvent of ILs and water, and it provides an application prospect for the efficient and green recycling of MTBE.

Chiral Separation of Cannabichromene, Cannabicyclol, and Their Acidic Analogs on Polysaccharide Chiral Stationary Phases.

Until recently, chirality has not been a major focus in the study of cannabinoids, as most cannabinoids of interest, such as cannabidiol and tetrahydrocannabinol, exist as a single isomer from natural sources. However, this is changing as more cannabinoids are identified, and compounds such as cannabichromene and cannabicyclol are emerging as potential investigatory candidates for varying indications. Because these molecules are chiral, the separation and study of the individual enantiomers' biological and physiological effects should therefore be of interest. The purpose of this study was to identify analytical separation conditions and then adapt those conditions to preparative separation. This was accomplished with a column-screening approach on Daicel's immobilized polysaccharide chiral stationary phases using non-traditional mobile phases, which included dichloromethane, ethyl acetate, and methyl tert-butyl ether under high-performance liquid chromatography conditions. CHIRALPAK® IK was found to separate all four compounds well with mobile phases containing hexane-dichloromethane (with or without an acidic additive). From these methods, the separation productivities were calculated to better visualize the separation scalability, which shows that the kilogram-scale separations of each are feasible.

Growing nearly vertically aligned ZnO nanorod arrays on porous α-Al2O3 membranes to enhance the separation of MTBE from aqueous solution

The separation of methyl tertiary butyl ether (MTBE) from aqueous solution by pervaporation-based membrane technology has attracted much attention recently. The present work proposed a novel strategy to enhance the MTBE/water separation performance of porous α-Al2O3 membranes. ZnO seeds were planted on the surface of α-Al2O3 membranes by the deposition and decomposition of zinc acetate, followed by growing ZnO nanorod arrays (ZNA) on the seeded α-Al2O3 membranes by hydrothermal reaction in the mixed hydrated zinc nitrate (HZN) and hexamethylenetetramine (HMTA) solution. Finally, the membranes were hydrophobized by grafting fluoroalkylsilane (FAS) onto their surface. The results show that the MTBE/water separation factor has been dramatically promoted from 7.7 for the α-Al2O3 membranes to 55.7 for the ZNA-covered α-Al2O3 membranes. The promotion may be attributed to the nearly vertically aligned ZnO nanorod arrays, which provide much surface area to load more fluorocarbon groups that are amiable to MTBE molecules and supply a superhydrophobic surface. The MTBE in the permeate mixture has been concentrated to as high as 72.9 wt%, in striking contrast to 4.6 wt% in the feed solution. The obtained membranes are highly stable upon long-term operation.