Tert-amyl Methyl Ether Research Articles

Effectiveness of ethynylcyclohexanol and methyl-tert-amyl ether in increasing the octane number of gasoline compositions

The purpose of this study is to systematically compare the octane-enhancing properties of the novel tertiary acetylenic alcohol (TAA) ethinylcyclohexanol (ECH) with the conventional ether methyl-tert-amyl ether (MTAE) as a gasoline additive. ECH was synthesized using a modified Favorsky reaction and blended with gasoline compositions containing varying ratios of straight-run, delayed coking, and catalytic reforming fractions. The octane number was measured using a SHATOX SX-100K octanometer. The results indicate that ECH provides significantly higher boosts in research and motor octane numbers compared to MTAE for all blend compositions tested, even at high reformate content where knock resistance becomes less sensitive to oxygenates. The comparison shows that ECH has a superior octane response compared to MTAE, indicating its potential as an alternative gasoline octane booster.

Toward a More Sustainable Sample Preparation in Phytochemistry: Case Studies in Four Subclasses of Alkaloids.

The fact that alkaloids are bases has been the most explored chemical feature of their extraction and purification procedures. The main drawback of these procedures is that they employ undesirable chemicals, with HCl and CH2Cl2 probably being the most commonly employed chemicals in their subsequent steps. This work tested the hypothesis that advantages in recovery efficiency support this common practice. Experiments were conducted in three laboratories, monitoring the alkaloids harmine (1), boldine (2), vincamine (3), and mescaline (4) extracted from Banisteriopsis caapi, Peumus boldus, Vinca minor, and Trichocereus macrogonus var. pachanoi, respectively. The research demonstrated that HCl could be replaced with citric acid (CA) without loss or even better extraction performance. The recommended EtOAc could completely replace CH2Cl2 in three out of four study cases and partially in the fourth case without harming the extraction efficiency. In addition, the alternative solvents tert-amyl methyl ether (TAME) and n-butyl acetate (BuOAc) could enhance the extraction of alkaloids. These results might incentivize natural products laboratories to consider sustainability more routinely, thus being closer to current practices in the pharmaceutical industry, which has been replacing solvents and processes with greener ones.

Operating windows for early evaluation of the applicability of advanced reactive distillation technologies

Advanced reactive distillation technologies (ARDT) are often overlooked during process synthesis due to their complexity. This work proposes the use of operating windows with additional features to identify suitable operating limits for ARDT. Data needed to construct the operating windows are thermodynamic properties, kinetic parameters, constraints of materials and experimental methods, and heuristics. In addition, two new concepts are proposed to represent complex features: representative components and a sliding window. Results include the identification of suitable operating limits for ARDT to help assess their feasibility early in process design. The proposed approach is demonstrated by case studies. Methyl acetate production can be carried out at low pressures (0.5–3.6 atm), while lactic acid purification requires vacuum conditions (0.3–0.8 atm) to avoid thermal degradation. Tert-amyl methyl ether production was evaluated in two scenarios where the effect of side reactions is evidenced in a reduction of the reaction window due temperature limits to favour the main reaction over side reaction. This study is the first to evaluate advanced reactive distillation technologies using a graphical representation in an operating window to aid process synthesis, where the results provide key selection insights.

Unraveling the Superior Role of Characterizing Methyl Ester of Isohexene as an Innovative High-Octane Gasoline Mixing Component

High concentrations of isoolefinic hydrocarbons can adversely affect the physical, chemical, mechanical, and ecological characteristics of gasoline fuels. One of the solutions to reduce olefin contents is the utilization of the methoxylation process. The current paper declares a perspective toward a gasoline-component-first technique, revealing an innovative high-octane additive on the basis of isoolefinic components, like isohexene. The olefin content of isohexene was 94% volumetrically. This affected the chemical oxidation under atmospheric conditions. Several gasoline fuels and experimental facilities that match European and Russian requirements were used to execute the recent work. The objective of the methoxylation process is to enhance the chemical oxidation fuels to raise the portion of aliphatic hydrocarbon isomers, to decrease unwanted olefin content, as well as to generate high-octane motor ethers as gasoline octane boosters. The product can be defined as methyl ester of isohexene (MEIH). Various MEIH blends have been measured with other gasoline octane boosters and refinery products. The results proved that antidetonation properties of MEIH were higher than those of base gasolines, tertiary amyl methyl ether (TAME), and isohexene and approximately equal to that of methyl tertiary butyl ether (MTBE). Additionally, the results of the calculated MEIH mixing octane rating were from 104.3 to 131.5 for the research method and from 87.5 to 120.0 for the motor method. Likewise, the olefin content of MEIH was 74.2% when the methoxylation process was applied for isohexene. The oxygen content of MEIH was 3.3 wt %, with no oxygen content in the sample of isohexene. Those have been done thanks to the utilization of the methoxylation process of isohexene. Finally, MEIH provided an individual perspective as a liquid transportation fuel with merits over isohexene, in terms of antidetonation properties, olefin contents, as well as a distillation characteristic range.

FORENSIC INVESTIGATION OF OXYGENATES IN MOTOR TYPES OF GASOLINE

The main types of oxygenates, which are used in the manufacture of motor types of gasoline, are considered. Oxygenates (oxygen-containing compounds) is the general name for lower alcohols and ethers used as high-octane components of motor fuels. For the manufacture of motor types of gasoline, a low-octane base is used to which high-octane components are added. In many cases, lower alcohols (methanol, ethanol, etc.) and ethers (methyl tert-butyl ether, tert-amyl methyl ether, etc.) are used as high-octane components of motor types of gasoline. Straight-run gasoline and stable gasoline are often used as the low-octane gasoline base for mixed motor types of gasoline. Methanol (CH3OH) is the simplest monohydric alcohol. Methyl alcohol is now produced synthetically from carbon monoxide (CO) and hydrogen (H2). Ethanol (ethyl alcohol) is a representative of monohydric alcohols with the formula C2H5OH. The production of ethyl alcohol is possible in several ways: biochemical, hydrolysis, synthetic, or ethylene hydration. For the manufacture of motor types of gasoline, dehydrated ethyl alcohol (bioethanol, an alternative universal component of motor fuel (KMPU), etc.) is used. Bioethanol is produced according to DSTU 7166: 2010 “Bioethanol. Technical mind”. According to DSTU 7166: 2010, bioethanol is dehydrated ethyl alcohol made from biomass or from raw ethyl alcohol for use as biofuel. As a technological and denaturing additive, gasoline (petroleum products) is introduced into bioethanol in an amount of up to 1.5 % by volume. KMPU is produced in accordance with TU U 20.5-00372536-001: 2013 “Component of firing motor alternative universal (KMPU). Technical conditions”. An alternative universal motor fuel component is dehydrated ethyl alcohol with a complex of additives, which is used for the manufacture of mixed motor types of gasoline and alternative types of motor types of gasoline. Compositionally, KMPU is similar to bioethanol but differs from it in the presence of another high-octane component – methyl tert-butyl ether (MTBE). Methyl tert-butyl ether, formula CH3-O-C (CH3)3 is a product that can be obtained in large quantities by reacting isobutylene with methanol. The advantage of MTBE is its good solubility in gasoline, and, at the same time, it is not washed out of it with water. MTBE does not impair the physical and chemical stability of gasoline; it is characterized by stable anti-knock properties during storage and operation. The article discusses the results of the study of the listed oxygenates by gasliquid chromatography. This method makes it possible to establish the qualitative and quantitative composition of oxygenates and motor types of gasoline based on them. It is shown that from readily available petroleum components (stable gas gasoline) without the use of complex technological equipment by mixing with oxygenates, it is possible to obtain a gasoline mixture with a high detonation resistance, which is fake gasoline in composition. When mixing in certain proportions a low-octane gasoline base, for example, stable gas gasoline and oxygenates (lower alcohols, ethers), which have appropriate performance characteristics, it is possible to obtain commercial gasoline that will meet the requirements of regulatory documents (DSTU) for motor types of gasoline. The considered technology also allows, when mixing in the calculated proportions of commercial gasoline A-92 (A-95) with oxygenates and stable gasoline, to improve the operational characteristics (knock resistance) of the obtained gasoline mixture or to increase the volume of the resulting gasoline mixture without improving its operational characteristics. Key words: blended types of gasoline, alternative types of gasoline, oxygenates, lower alcohols, ethers, bioethanol, alternative motor fuel component universal.

Liquid–liquid equilibrium for ternary methyl tert-amyl ether + phenol + water system at 283.15, 298.15, and 313.15 K

ABSTRACT Liquid–liquid equilibrium data have been measured for the ternary MTAE + phenol + water system at 283.15, 298.15, and 313.15 K. Experimental results show that the temperature increase leads to a decrease in phenol distribution coefficient. At a temperature of 298.15 K, the maximum achieved value of distribution coefficient is 46.5. The NRTL model was applied to correlate the experimental data. The obtained experimental data were compared with the literature data for the same ternary systems with the use of methyl isobutyl ketone, butyl acetate, and methyl tert-butyl ether as extractants.

ПЕРЕПРОФИЛИРОВАНИЕ УСТАНОВКИ ПРОИЗВОДСТВА МЕТИЛ-ТРЕТ-БУТИЛОВОГО ЭФИРА НА ПОЛУЧЕНИЕ НОВОЙ ПРОДУКЦИИ

The possibility of converting the existing plant for the production of methyl tert-butyl ether to the production of oxygenates of another type, for example, methyl tert-amyl ether, was considered

Exposure Profile to Traffic Related Pollution in Pediatric Age: A Biomonitoring Study.

The aim of this study was to trace an exposure profile to traffic-derived pollution during pediatric age. For this purpose, two biomonitoring campaigns for the determination of urinary (u-) methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether (DIPE) were carried out in two different periods of the year (summer 2017 and winter 2018), among a large sample of healthy children (n = 736; 5–11 years old) living in rural and urban areas in central Italy. The quantification of u-MTBE, u-ETBE, u-TAME, and u-DIPE was performed by HS-SPME-GC/MS technique and information on participants was collected by a questionnaire. u-DIPE concentrations resulted always under the LOQ. u-TAME mean levels were similar in both seasons (18.7 ng L−1 in summer vs. 18.9 ng L−1 in winter), while u-MTBE and u-ETBE levels were, respectively, 69.9 and 423.5 ng L−1 (summer) and 53.3 and 66.2 ng L−1 (winter). Main predictors of urinary excretion resulted the time spent in motor vehicles, being male and younger.

Biodegradation of diisopropyl ether, ethyl tert-butyl ether, and other fuel oxygenates by Mycolicibacterium sp. strain CH28

Growing use of recalcitrant fuel oxygenates like methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether (DIPE) poses serious threat to aquatic environments and drinking water sources. Mycolicibacterium sp. strain CH28 was isolated earlier as a potential degrader of DIPE. Optimal culture conditions for strain CH28 were determined to be 32 °C and pH 5.00–6.00. Substrate utilization tests revealed that several n-alkanes, aromatic compounds, short-chain alcohols and acids were metabolized by strain CH28. In resting cell assays, strain CH28 was able to mineralize DIPE with a degradation rate of 1.63 ± 0.03 nmol min−1 mg biomass−1. Complete mineralization of 75 mg l−1 DIPE occurred within 42 hours in microcosm systems using groundwater samples inoculated with strain CH28. 2-propanol, acetone, and acetate were identified as intermediates of DIPE degradation with GC-MS, and a degradation pathway was proposed. Mixed cultures of strain CH28 and Hydrogenophaga sp. strain T4 were able to fully mineralize 200 mg l−1 ETBE in 60 hours. Moreover, strain CH28 could co-oxidize MTBE and TAME in the presence of DIPE as the growth substrate. Our results indicate that strain CH28 holds great potential in the bioremediation of sites contaminated with gasoline ether oxygenates.

Cleaner Process and Entrainer Screening for Bioethanol Dehydration by Heterogeneous Azeotropic Distillation

Greenhouse gas footprint of fuels is due to both the burning fuel and its production process. Bioethanol is a sustainable biofuel but it is obtained diluted in water and its dehydration consumes large amounts of energy. Heterogeneous azeotropic distillation is a well-known suitable option for dehydration of bioethanol (separation of ethanol from water). Many entrainers for this process are studied in literature but unfortunately, there is no critical comparison in terms of the corresponding process efficiency. The distillation efficiency assessment is necessary as it has a great impact on the energy consumption and sustainability of bioethanol production. The process scheme and entrainer are screened following a fast-to-rigorous procedure: feasibility checking using the infinite/infinite analysis, screening based on the Distillation Sequence Efficiency (DSE) method and rigorous simulation using AspenPlus®. Different process schemes are assessed taking into account also that some gasoline additives, used as entrainers, could remain in bioethanol, which is to be included in the gasoline formulation. Some examples of commonly used ethers as gasoline additives are methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), diisopropyl ether (DIPE) and tert-amyl methyl ether (TAME). The study shows that when the entrainer is a gasoline additive, collecting the distillation product as a mixture of ethanol and additive consumes 27 % less energy than collecting pure ethanol. Performing the ethanol dehydration and gasoline additive mixing together in the same process leads to a 27 % decreasing of CO2 emissions.

Evolutionary Algorithms for Controller Tuning of Tert-Amyl-Methyl-Ether Reactive Distillation

Efficient tuning of the coefficients used by proportional-integral-derivative (PID) controllers enhances their performance. For highly non-linear systems, optimization algorithms are required to make the PID controllers more responsive to disturbances. The production of tert-amyl-methyl-ether (TAME), an essential additive for gasoline, in reactive distillation columns integrates highly non-linear reaction and separation processes. On the other hand, TAME distillation is an azeotrope distillation process, therefore non-linearity of this process is more complex than that of conventional distillation. PID-controller tuning methods applying a genetic algorithm (GA) and a particle swarm optimization (PSO) algorithm are compared using a dynamic simulation that integrates the optimization algorithms with the HYSYS process simulator. The PID controller response trends are analyzed following the introduction of a significant disturbance to the TAME reactive distillation column (i.e., a ten percent change in the methanol feed temperature). The PSO PID controller tuning method that minimizes the integral of the absolute error (IAE) as its objective function significantly outperforms the GA tuning method. The novel PID-tuning methodology developed has more extensive application potential.

Optimization of Pressure-Swing Distillation for iC5-Methanol Azeotropic Mixture Purification

Typical industrial technologies to produce tert-amyl methyl ether (TAME), a gasoline oxygenated additive, require some advanced purification process for methanol recovery from the reactor effluent, due to the presence of the iC5-methanol minimum boiling point azeotrope. Pressure-swing distillation (PSD) is widely used as an efficient method for separating pressure-sensitive azeotropic mixtures in industrial processes. However, it is well known that distillation units are responsible for the highest energy consumption in chemical separation facilities, reaching in some cases to 95% of the total energy cost. Thus, the objective of this work was to perform an optimization methodology of the main design and operational variables of the PSD process applied to the separation of the azeotropic iC5-methanol mixture, considering minimizing the objective function of total annual cost (TAC). For this purpose, Honeywell’s UniSim Design® Suite software was used to simulate the process flowchart and Matlab® was used to perform TAC optimization. The optimized PSD design revealed potential for saving of up to 12% per year in terms of TAC when compared to the non-optimized process, thus proving the feasibility of the optimization methodology for this specific process. Furthermore, it reinforces the main objective of the optimization technique that is to make chemical processes more economically competitive in the industrial sector.

Optimization and heat integration of hybrid R–HIDiC–PV process with the series–parallel arrangement of PV modules and recycle streams for TAME production

Tert–amyl methyl ether (TAME) production process is consisted of a reactor, a reactive distillation (RD) column and the methanol recovery section. The bottom product of the RD column is TAME while the distillate is consisted of the azeotropic mixture of methanol and isopentane (i-pentane) that can be separated by either the pervaporation (PV) membrane or conventional pressure swing distillation (PSD) and extractive distillation (ED) methods. The PV process allows the use of both series and parallel arrangements. The series arrangement has a lower membrane area compared to the parallel arrangement, while the parallel arrangement has a lower energy cost. A series–parallel arrangement with recycle streams was used in the present study to take advantage of both the series and parallel arrangements. The HIDiC method was used for reducing energy consumption in the RD column. Moreover, heat integration between PV streams and internal flows in the RD column was used to reduce PV energy consumption. The number of modules in each row, the recycle stream, the heat exchange ratio between the rectifying and stripping sections in the RD column and the heat exchange ratio between PV streams and internal RD streams were obtained by a hybrid GA–PSO algorithm. Furthermore, all RD and PV parameters were considered optimization variables and most importantly, all process variables were optimized simultaneously. According to the results, the proposed process reduced the total annual cost (TAC) by 52% and led to a 57% energetic gain compared to the conventional hybrid RD–PSD process. The proposed process also reduced TAC by 48% and led to a 40% energetic gain in comparison with the hybrid RD–PV process. This can be related to the reduced membrane area compared to the series and parallel arrangements as well as reduced energy costs of PV heaters through heat integration between PV steams and internal flows of the column.

The role of low-lying conformers and pressure effect in kinetic modeling of hydrogen abstraction of tertiary amyl methyl ether by OH radicals

In this short communication, the kinetic discrepancy between calculation and experiment for the hydrogen abstraction reaction of t-amyl methyl ether by OH radicals is resolved by combining (i) an accurate potential energy surface, including the newly found lowest-lying structures of the reactant and transition states, explored at the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ level and (ii) a rigorous master equation/Rice–Ramsperger–Kassel–Marcus (ME/RRKM) rate model, which includes the corrections of the hindered internal rotation and tunneling effects, to account for pressure and temperature effects.

A New control structure for tert-amyl methyl ether production using reactive distillation

The aim of this paper is to introduce new control structures in both centralized and decentralized scheme for tert-amyl methyl ether (TAME) production unit using reactive distillation which developed as a benchmark by Luyben (2005). Steady state and dynamic simulation was performed based on the case study data using Aspen® simulator. Dynamic simulation shows that control performance of the plant has oscillatory behavior using conventional PI controllers. Hence, a proper modification on the process flow sheet was carried out in order to remove oscillatory behavior of the process. Although, the new structure has better dynamic performance than the previous one using PI controller, it is not capable of eliminating the oscillations completely. Non-minimal state space with proportional integral plus controller (NMSS–PIP) controller was applied to dynamic model of the modified process. In this way, the system identification was carried out using refined instrumental variable (RIV) method and state matrices was obtained as left matrix fraction description (LMFD). The control performance of the PI and PIP controller for the modified structure revealed that the NMSS–PIP, completely eliminates the process oscillations while it has smoother responses with better settling time than the PI configuration. Furthermore, comparison of the ITAE criterion between main case and modified process indicates that the ITAE for PI and PIP control decreased by about 20% and 88%, respectively.

Contaminants migrating from crossed-linked polyethylene pipes and their effect on drinking water odour

The formation potential of contaminants diffusing from cross-linked polyethylene (PE-X) pipes and their impact on the odour of drinking water was determined. Three types of PE-X material, Pe-Xa, PE-Xb and PE-Xc, were extensively assessed by performing migration tests following EN 1420 and EN 12873–1. Migration waters were analysed for their threshold odour number (TON). The same samples were investigated by two gas chromatography-mass spectrometry methods: screening and olfactometry. Most of the PE-X materials failed the German regulation of TON <2 for cold water and TON ≤4 for warm water. PE-Xb material caused the strongest odour and also released the highest amount of contaminants. Metilox, 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, 3,5-di-tert-butyl-4-hydroxybenzaldehyde and 2,6-di-tert-butyl-p-benzoquinone (2,6-DtBQ) were the most often detected substances leaching from the tested plastic materials. However, no odour was perceived for most of these substances. Methyl tert-butyl ether (MtBE) and 2-tert-butylphenol are believed to contribute to the sensory problem in the migration water among other substances such as tert-amyl methyl ether, 2,2,2,5-tetramethyltetrahydrofuran, toluene or xylene. In total ten specific descriptions characterized the odour of the individual contaminants: ethereal, fresh, solvent, sweet, fruity, floral, unsavoury, pungent, aromatic and chemical.

Optimally designed reactive distillation processes for eco‐efficient production of ethyl levulinate

AbstractBACKGROUNDEthyl levulinate (EL) is an important chemical that can be used as a bio‐based replacement of fuel additives such as methyl tert‐butyl ether (MTBE) and tert‐amyl methyl ether (TAME). EL production from lactic acid and ethanol is a viable option, as both precursors can be obtained from biomass. However, the problem of EL production by esterification is that this reaction is hindered by the chemical equilibrium limitations and the boiling points ranking, which is not the most favorable.RESULTSThis study provides novel optimally designed reactive distillation (RD) processes for the production of EL, taking into account costs, environmental impact and safety. The thermally coupled RD process is the most appealing, with the lowest energy use (1.667 MJ kg−1 EL), minimal investment cost, major energy savings (up to 54.3% lower than other RD processes), reduced environmental impact (up to 51% lower ECO99 index value) and similar safety as other RD processes considered (less than 2% differences in the individual risk (IR) indicator).CONCLUSIONThe multi‐objective optimization approach used here showed its robustness, practicality and flexibility to provide multiple optimal designs of intensified processes that are economically attractive, environmentally friendly and inherently safe. © 2019 The Authors. Journal of Chemical Technology &amp; Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry.

Atmospheric oxidation of tertiary amyl methyl and ethyl ethers. A quantum chemistry study

In this work, a systematic investigation on the mechanism and kinetics of the reactions of t-amyl methyl ether (TAME) and t-amyl ethyl ether (TAEE) with OH radicals in the gas phase has been performed within the Density Functional Theory (DFT) framework. The potential energy surfaces were obtained at the M06-2X/6-311++G(d,p) level. Kinetic data for the initial step in the oxidative degradation of TAME and TAEE were obtained, as well as branching ratios between the possible reaction channels. The calculated total rate constants are 3.9 × 10−11 cm3 molecules−1 s−1 and 1.3 × 10−12 cm3 molecules−1 s−1, for TAME and TAEE, respectively. Contrary to what occurs in the case of the MTBE and ETBE oxidation initiated by OH radicals, for TAME and TAEE the H-abstraction from α methoxy or ethoxy groups is not favored. For both molecules, the contribution of the reaction channels involving H-abstraction from the t-amyl group amounts to about 70% of the total rate coefficients. Using our calculated rate constants and a chosen OH tropospheric concentration of 1 × 106 molecule cm−3, lifetimes of ∼43 and ∼128 min were obtained for TAME and TAEE, respectively.

Thermophysical Study of Binary Systems of tert-Amyl Methyl Ether with n-Hexane and m-Xylene

This work presents the experimentally determined density (ρ), viscosity (η), speed of sound (u), and surface tension (σ) data for tert-amyl methyl ether (TAME) + n-hexane and TAME + m-xylene systems at several temperatures (298.15, 308.15, 318.15, 323.15, and 328.15 K). These experimentally determined thermophysical data are utilized to compute various excess/deviation parameters such as molar volume (VE), isentropic compressibility (κsE), speed of sound (uE), deviation in viscosity (Δ ln η), isobaric thermal expansion coefficient (αPE), and surface tension (σE). The inspection of parameters response may interpret the existing specific molecular interactions as well as the mixing behavior of solutions. The critical analysis of observed parametric behavior have unveiled the strong and weak molecular interactions in TAME with m-xylene and TAME with n-hexane systems, respectively.

Intensification of Reactive Distillation for TAME Synthesis Based on the Analysis of Multiple Steady-State Conditions

Our previous study reported that operation in multiple steady states contributes to an improvement in reaction conversion, making it possible to reduce the energy consumption of the reactive distillation process for tert-amyl methyl ether (TAME) synthesis. This study clarified the factors responsible for an improvement in the reaction conversion for operation in the multiple steady states of the reactive distillation column used in TAME synthesis. The column profiles for those conditions, in which multiple steady states existed and those in which they did not exist, were compared. The vapor and liquid flow rates with the multiple steady states were larger than those when the multiple steady states did not exist. The effect of the duty of the intermediate condenser, which was introduced at the top of the reactive section, on the liquid flow rate for a reflux ratio of 1 was examined. The amount of TAME production increased from 55.2 to 72.1 kmol/h when the intermediate condenser was operated at 0 to −5 MW. Furthermore, the effect of the intermediate reboiler duty on the reaction performance was evaluated. The results revealed that the liquid and vapor flow rates influenced the reaction and separation performances, respectively.