Journal articles: 'Azeotropic point'

1

Wang, Xuehui, Tiannian Zhou, Qinpei Chen, Junjiang He, Zheng Zhang, and Jian Wang. "Experimental study on combustion characteristics of blended fuel pool fires." Journal of Fire Sciences 37, no. 3 (May 2019): 236–56. http://dx.doi.org/10.1177/0734904119839917.

Full text

Abstract:

Liquid–vapor phase equilibrium theories are used to analyze boiling processes of blended fuel pool fires, and the results show that there are two boiling mechanisms (azeotropism and non-azeotropism) for blended fuels compared with single-component fuels. A series of pool fire experiments were conducted to investigate the combustion characteristics of blended fuel pool fires. The experimental results showed that the two boiling mechanisms have different effects on the burning process of the fuel blends. The boiling temperature and composition varied for the non-azeotropic blends during the burning process and remained steady for azeotropic blends. Furthermore, the boiling temperature of azeotropic blends is lower than that of its components and ranges from a specific temperature to the boiling point of the less volatile component. The flame radiant fraction of the azeotropic blend was also relatively constant during the burning process, whereas that of the non-azeotropic blend varied in different stages of the burning process. Heskestad’s flame height model and flame axial temperature distribution model are applicable for pool fires of azeotropic and non-azeotropic blends.

APA, Harvard, Vancouver, ISO, and other styles

2

Mahdi, Taha, Arshad Ahmad, Mohamed M. Nasef, and Adnan Ripin. "Simulation and Analysis of Process Behavior of Ultrasonic Distillation System for Separation Azeotropic Mixtures." Applied Mechanics and Materials 625 (September 2014): 677–79. http://dx.doi.org/10.4028/www.scientific.net/amm.625.677.

Full text

Abstract:

The performance of an ultrasonic distillation (USD) system is evaluated in Aspen Plus simulation environment. To facilitate the flowsheet development, a mathematical model of a single stage USD developed using Aspen Custom Modeler software is exported to Aspen Plus process simulator. As a case study, the separation of ethanol-ethyl acetate mixture that is known to form azeotrope 55 mole % of ethyl acetate at minimum boiling point of 71.8oC is considered. Simulation results revealed the achievable purity of ethyl acetate of 99 mole % from azeotropic mixture, thus reinforcing the anticipated potentials of sonication phenomena in intensifying distillation process to overcome azeotropes.

APA, Harvard, Vancouver, ISO, and other styles

3

Kameshkov, Alexey V., Alexander A. Gaile, Vasily N. Klementyev, and Sofya D. Usanova. "FORMATION OF AZEOTROPIC MIXTURES OF N-METHYLPYRROLIDONE WITH HYDROCARBONS." Bulletin of the Saint Petersburg State Institute of Technology (Technical University) 56 (2021): 12–16. http://dx.doi.org/10.36807/1998-9849-2020-56-82-12-16.

Full text

Abstract:

Using the limiting activity coefficients of the components of binary systems of N-methylpyrrolidone with n-alkanes and the conditions for the formation of azeotropes, it is found that N-methylpyrrolidone forms azeotropic mixtures with n-alkanes С9 - С 15, with alkylbenzenes С 10 - С 12 and with naphthalene. The formation of azeotropes with saturated hydrocarbons with a boiling point of 230-270 ° C must be taken into account when developing a technological scheme for the N-methylpyrrolidone regeneration unit, and also not to use this extractant for extraction purification of raw materials with a boiling point below 230 ° C

APA, Harvard, Vancouver, ISO, and other styles

4

Fan, Zhi Dong, Xu Bin Zhang, Lu Yang Zhao, Wang Feng Cai, and Fu Min Wang. "Study on the Separation of Azeotrope of Tetrahydrofuran-Water Using a Combined Method of Extractive and General Distillation." Advanced Materials Research 803 (September 2013): 149–52. http://dx.doi.org/10.4028/www.scientific.net/amr.803.149.

Full text

Abstract:

As an important solvent, tetrahydrofuran has broad applications. Due to its process of production, water will be mixed into the product and should be removed. However, tetrahydrofuran will form a minimum boiling azeotrope with water, which has a boiling point of 63.4°C, so general distillation can not separate them. Common methods to solve this include extractive distillation, pressure swing distillation, azeotropic distillation, pervaporation and so on. In this experiment, we coupled extractive distillation and general distillation, selecting ethylene glycol as the extractant, and successfully dehydrated the azeotrope. The mass fraction of water is reduced from 18% to less than 500ppm,which matches the requirement.

APA, Harvard, Vancouver, ISO, and other styles

5

Yanyu, Liang. "Sufficient Conditions for Existence of the Azeotropic Point." University Chemistry 30, no. 1 (2015): 82–88. http://dx.doi.org/10.3866/pku.dxhx20150117.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Moad, G., DH Solomon, TH Spurling, and DJ Vearing. "Critical-Points (Azeotropic Compositions) in Multicomponent Copolymerization." Australian Journal of Chemistry 39, no. 11 (1986): 1877. http://dx.doi.org/10.1071/ch9861877.

Full text

Abstract:

The necessary and sufficient conditions for the existence of critical points ( azeotropic compositions) in multicomponent copolymerization are defined, and the preferred method for calculating critical points for a given set of reactivity ratios is provided. This method offers considerable advantages in both simplicity and computation speed over methods already in the literature. A computer program for performing the calculation on systems with up to 10 components is briefly described. Approximate probabilities for the existence of critical points in ternary and quaternary systems have been evaluated as a function of whether binary critical points exist for pairs of the monomers involved. These data show that, contrary to the widely held view, in systems of three or more components all rij > 1 or all rij < 1is neither a necessary nor a sufficient condition for the existence of a critical point. Those systems which always and those systems which never give rise to critical points are indicated.

APA, Harvard, Vancouver, ISO, and other styles

7

Faramarzi, Zohreh, Fatemeh Abbasitabar, Jalali Jahromi, and Maziar Noei. "New structure-based models for the prediction of normal boiling point temperature of ternary azeotropes." Journal of the Serbian Chemical Society 86, no. 7-8 (2021): 685–98. http://dx.doi.org/10.2298/jsc210218035f.

Full text

Abstract:

Recently, development of the QSPR models for mixtures has received much attention. The QSPR modelling of mixtures requires the use of the appropriate mixture descriptors. In this study, 12 mathematical equations were considered to compute mixture descriptors from the individual components for the prediction of normal boiling points of 78 ternary azeotropic mixtures. Multiple linear regression (MLR) was employed to build all QSPR models. Memorized_ ACO algorithm was employed for subset variable selection. An ensemble model was also constructed using averaging strategy to improve the predictability of the final QSAR model. The models have been validated by a test set comprised of 24 ternary azeotropes and by different statistical tests. The resulted ensemble QSPR model had R2 training, R2 test and q2 of 0.97, 0.95, and 0.96, respectively. The mean absolute error (MAE), as a good indicator of model performance, were found to be 3.06 and 3.52 for training and testing sets, respectively.

APA, Harvard, Vancouver, ISO, and other styles

8

Hartanto, Dhoni, Prima Astuti Handayani, Akhmad Sutrisno, Viona Widya Anugrahani, Asalil Mustain, and Ianatul Khoiroh. "Isopropyl Alcohol Purification through Extractive Distillation using Glycerol as an Entrainer: Technical Performances Simulation and Design." Jurnal Bahan Alam Terbarukan 8, no. 2 (December 31, 2019): 133–43. http://dx.doi.org/10.15294/jbat.v8i2.23477.

Full text

Abstract:

Isopropyl alcohol is widely used as industrial chemical intermediates and common solvents in households, pharmaceuticals, food, cosmetics, and medical purposes. The high purity of isopropyl alcohol requires special separation from its impurity i.e. water due to isopropyl alcohol and water form an azeotropic point, which is difficult to separate using a conventional distillation method. The azeotropic point of this mixture is at isopropyl alcohol mole fraction of 0.68 and temperature of 353.4 K. One of the optimum methods to separate an azeotrope point is through the extractive distillation which use a third component as a solvent. Glycerol is one of the solvents which can be used as a potential entrainer in the extractive distillation. Glycerol is produced in the biodiesel production as a by-product. Moreover, glycerol is an eco-friendly chemical. In this work, the simulation of the extractive distillation of isopropyl alcohol/water system with glycerol as an entrainer was simulated using Aspen Plus. The Non-Random Two-Liquid (NRTL) model was used as thermodynamic model in the simulation. The effect of stage number, binary feed stage, entrainer feed stage, and reflux ratio to the purity of isopropyl alcohol, and reboiler-condenser duties were examined to achieve the optimum design for the extractive distillation column with less energy requirements. The simulation results showed that the optimum configurations in the extractive distillation column design are at 25 theoretical stages, binary feed stage (BFS) of 20, entrainer feed stage (EFS) of 2, and reflux ratio (RR) of 0.5 to produce isopropyl alcohol with the purity of 99.27%. The design and sizing of the extractive distillation column were also proposed in this work.

APA, Harvard, Vancouver, ISO, and other styles

9

Moad, G., DH Soloman, TH Spurling, and DJ Vearing. "Critical Points in Binary Copolymerization and the Penultimate Group Effect." Australian Journal of Chemistry 38, no. 9 (1985): 1287. http://dx.doi.org/10.1071/ch9851287.

Full text

Abstract:

In order to examine the influence that a penultimate group effect can have on the number and magnitude of critical points ( azeotropic compositions) in binary copolymerization an expression for the critical point(s) has been derived. Analysis of this relationship shows that in a situation where one critical point would have been expected on the basis of terminal-model kinetics (no penultimate group effect) a modest penultimate group effect can mean that zero, one or three critical points may exist, or, in systems where no critical points would have been predicted, two critical points may exist.

APA, Harvard, Vancouver, ISO, and other styles

10

Hiaki, Toshihiko, Katsumi Tochigi, and Kazuo Kojima. "Measurement of vapor-liquid equilibria and determination of azeotropic point." Fluid Phase Equilibria 26, no. 1 (January 1986): 83–102. http://dx.doi.org/10.1016/0378-3812(86)85006-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Mahdi, Taha, Arshad Ahmad, Adnan Ripin, and Mohamed M. Nasef. "Ultrasonic Enhancement of Separation Azeotropic Mixtures via Single Distillation Column." Advanced Materials Research 909 (March 2014): 83–87. http://dx.doi.org/10.4028/www.scientific.net/amr.909.83.

Full text

Abstract:

The separation of azeotropic mixtures is conventionally one of the most challenging tasks in industrial processes as their separation by a simple distillation is basically impossible. Vapor-liquid equilibrium (VLE) equations with ultrasonic technique was based on a number of assumptions need to be built model on MATLAB software and compared the results with experimental work to validity the model. As a case study, the influence of ultrasonic intensity and frequency on the VLE of ethanolethyl acetate mixture was investigated, and a combination of five ultrasonic intensities (from 100 and 500 W/cm2) and three frequencies (from 25 to 70 kHz) were used. It is noted that with increase the ultrasound intensity and decrease the frequency can be improved the azeotropic point and relative volatility of the mixture. The results revealed that ultrasonic waves had the potential to enhance separation of azeotropic mixtures in a distillation column.

APA, Harvard, Vancouver, ISO, and other styles

12

Shi, Xiu Min, and Min Wang. "Vapor-Liquid Equilibria for the Ternary System Ethyl Acetate-Acetonitrile-1-Octyl-3-Methylimidazolium Tetrafluoroborate." Advanced Materials Research 791-793 (September 2013): 141–44. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.141.

Full text

Abstract:

In order to research the possibility of separating the azeotrope of ethyl acetate + acetonitrile with ionic liquid as the extractant. Isobaric vapor-liquid equilibria for the ternary system ethyl acetate + acetonitrile + 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIBF4) were measured at 101.32 kPa using a recirculation still. The results showed that the VLE of the ternary system was different from that of the binary system. The ionic liquid (IL) studied showed a slight crossover salt effect, which changed the relative volatility of ethyl acetate to acetonitrile and eliminated the azeotropic point when the mole fraction of IL in the liquid phase was greater than 0.05. Therefore, [OMIBF4 can be used as the extractant of extractive distillation for ethyl acetate + acetonitrile system, the suitable mole fraction of [OMIBF4 is about 10%.

APA, Harvard, Vancouver, ISO, and other styles

13

Říčná, Květuše, Jaroslav Matouš, Josef P. Novák, and Vladimír Kubíček. "Liquid-liquid equilibrium in the water-ethanol-toluene system. Experimental results." Collection of Czechoslovak Chemical Communications 54, no. 3 (1989): 581–85. http://dx.doi.org/10.1135/cccc19890581.

Full text

Abstract:

Liquid-liquid equilibrium at 5, 25, and 50 °C was measured in the water-ethanol-toluene system. Special attention was paid to the determination of distribution coefficient of ethanol. Besides, the composition and boiling point of azeotropic mixture at normal pressure were determined.

APA, Harvard, Vancouver, ISO, and other styles

14

Wei, Jia, Chanyeop Park, and Lukas Graber. "Breakdown characteristics of carbon dioxide–ethane azeotropic mixtures near the critical point." Physics of Fluids 32, no. 5 (May 1, 2020): 053305. http://dx.doi.org/10.1063/5.0004030.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Breen, C., and A. Deane. "The adsorption of 1,4-dioxan, tetrahydrofuran and tetrahydropyran from binary solution with methanol on Al3+ and Cr3+-exchanged montmorillonite." Clay Minerals 22, no. 2 (June 1987): 199–205. http://dx.doi.org/10.1180/claymin.1987.022.2.08.

Full text

Abstract:

AbstractSurface excess isotherms were determined for the adsorption of 1,4-dioxan (DIOX), tetrahydropyran (THP) and tetrahydrofuran (THF) from binary solution with methanol (MeOH) on Al3+- and Cr3+-exchanged, montmorillonite containing different amounts of pre-adsorbed water. The isotherm type is dominated by the binary mixture whereas the amplitude, which follows the sequence DIOX > THP > THF, is further influenced by the exchange cation, Al3+ > Cr3+, and the water content of the clay. The sorption of DIOX and THP from MeOH exhibit a type IV isotherm in the Schay-Nagy classification on both cation-exchanged forms, whilst that of THF from MeOH is of type I and THF is the preferred adsorbate. The azeotropic point for the type IV isotherms is close to a 1:1 mole ratio for the samples dried at 120°C but when the samples are rehydrated at 12% r.h. following thermal pretreatment at 120°C the azeotropic point shifts in favour of the cyclic ethers DIOX and THP, making them the preferred component over a substantial portion of the composition range.

APA, Harvard, Vancouver, ISO, and other styles

16

Handrian, Handrian, Wahyudi Budi Sediawan, and Aswati Mindaryani. "ADSORPSI AIR DARI CAMPURAN UAP ETANOL-AIR DENGAN ZEOLIT SINTETIS 4A DALAM PACKED BED DALAM RANGKA PRODUKSI FUEL GRADE ETHANOL." Jurnal Rekayasa Proses 11, no. 2 (January 23, 2018): 68. http://dx.doi.org/10.22146/jrekpros.30344.

Full text

Abstract:

Ethanol can be used as fuel if it has a purity of 99.5%, while ethanol distillation will stop at its azeotrop point, ie at 95.6%. Adsorption of molecular sieve is one of the methods to obtain ethanol with level above the azeotropic point. Adsorbent that serves as molecular sieve is synthetic zeolite 4A. The adsorbent has a pore diameter of 3.9 Ǻ, then water and ethanol each has a molecular diameter of 2.75 Ǻ and 4.4 Ǻ. Hence the adsorbent is selective against the ethanol-water mixture. The purpose of this research is to obtain ethanol above its azeotropic point and to study the relationship between the influence of flow rate (Vz) and temperature (T) to changes in the number of mass transfer coefficient (kc), radial diffusivity (Der) and henry constants (H') which can be used as parameters in the design of adsorption tools on a commercial scale.This experiment was conducting by weighing zeolite 4A as much as 100 grams, then compiled and measured the height on packed bed column adsorbent. The heating regulator is switched on and set to a constant temperature of 80, 85, 90, 95 and 1000C. Ethanol 95.61% with 250 ml volume is put into three-neck flask, then heat to evaporate. Turn on the cooling back and adjust the amount of formed vapor rate by adjusting the faucet opening and the degree of voltage in the heating mantle. The magnitude of the vapor flow rate is set at 2, 4 and 6 liters / minute. The products is accomodated and samples were taken every minute to analyze the ethanol content.This adsorption process gives the highest yield of ethanol with 99.40% content. The steam flow rate of 2 lpm and the temperature of 800C is the optimum combination in this research because much of the water vapor adsorbed on the 4A zeolite grain is 7.93 grams. The numerical calculation provides the result that the value of Der in this experiment is 1.59.10-3 cm2 / men, and the relation of kc are the function of reynolds and H' the function of temperature are as follows: kc = 7,95.10^-3.(Re)^0,1639 and H' = 4,47.10^-3.exp(2565,26/T)

APA, Harvard, Vancouver, ISO, and other styles

17

Istiqomah, Ana Ulfa, Fitria Rahmawati, and Khoirina Dwi Nugrahaningtyas. "REPLACING SODA ASH (NaOH) WITH KALIUM HYDROXYDE (KOH) IN DESTILATION OF BINARY ETHANOL-WATER MIXTURE." ALCHEMY Jurnal Penelitian Kimia 12, no. 2 (September 1, 2016): 179. http://dx.doi.org/10.20961/alchemy.12.2.1876.179-189.

Full text

Abstract:

Soda ash (NaOH) has been used in bioethanol production in the second step destillation to increase the purity up to 90%. The destillation process will produce waste water with a high sodium content. The soda ash itself serve as an electrolyte to modify the colligative properties of the water-ethanol mixture allowing the disappearance of azeotropic point. This research aims to study the replacement of NaOH with KOH, in which the kalium is a nutrient to maintain soil fertility. This research study the thermodynamics properties, vapor-liquid equilibrium, colligative properties and also its azeotropic point in the destillation of water-ethanol mixture when KOH and NaOH were used as the additive. A model of water-ethanol mixture at a various composition of 0-100 weight % of ethanol was used. The electrolyte addition was 0.1 mol electrolyte/total weight of ethanol-water. The result shows that the addition of electrolyte into ethanol-water mixture eliminate the azeotropic point and allows the ethanol molecules to separate from water. The enthalpy of mixing between water-ethanol is 239.601 kJ/mol. It becomes 259.796 kJ/mol and 264.793 kJ/mol after the addition of NaOH and KOH, respectively. It confirming the endothermic mixing process due to different polarity between water and ethanol. The presence of electrolyte even reduce more their molecular interaction. However, the change to irregularity result a high positive entropy values that result the negative Gibbs free energy. It confirms the spontaneity of mixing. The vaporization enthalpy, Hvap, of water-ethanol mixture is 76.229 kJ/mol and it becomes 235.366 kJ/mol and 126.189 kJ/mol after the addition of NaOH and KOH. It indicates that the presence of electrolyte inhibites vaporization of water as the major component and allowing ethanol molecules to vapor producing more high purity ethanol.

APA, Harvard, Vancouver, ISO, and other styles

18

Istiqomah, Ana Ulfa, Fitria Rahmawati, and Khoirina Dwi Nugrahaningtyas. "REPLACING SODA ASH (NaOH) WITH KALIUM HYDROXYDE (KOH) IN DESTILATION OF BINARY ETHANOL-WATER MIXTURE." ALCHEMY Jurnal Penelitian Kimia 12, no. 2 (September 1, 2016): 179. http://dx.doi.org/10.20961/alchemy.v12i2.1876.

Full text

Abstract:

Soda ash (NaOH) has been used in bioethanol production in the second step destillation to increase the purity up to 90%. The destillation process will produce waste water with a high sodium content. The soda ash itself serve as an electrolyte to modify the colligative properties of the water-ethanol mixture allowing the disappearance of azeotropic point. This research aims to study the replacement of NaOH with KOH, in which the kalium is a nutrient to maintain soil fertility. This research study the thermodynamics properties, vapor-liquid equilibrium, colligative properties and also its azeotropic point in the destillation of water-ethanol mixture when KOH and NaOH were used as the additive. A model of water-ethanol mixture at a various composition of 0-100 weight % of ethanol was used. The electrolyte addition was 0.1 mol electrolyte/total weight of ethanol-water. The result shows that the addition of electrolyte into ethanol-water mixture eliminate the azeotropic point and allows the ethanol molecules to separate from water. The enthalpy of mixing between water-ethanol is 239.601 kJ/mol. It becomes 259.796 kJ/mol and 264.793 kJ/mol after the addition of NaOH and KOH, respectively. It confirming the endothermic mixing process due to different polarity between water and ethanol. The presence of electrolyte even reduce more their molecular interaction. However, the change to irregularity result a high positive entropy values that result the negative Gibbs free energy. It confirms the spontaneity of mixing. The vaporization enthalpy, Hvap, of water-ethanol mixture is 76.229 kJ/mol and it becomes 235.366 kJ/mol and 126.189 kJ/mol after the addition of NaOH and KOH. It indicates that the presence of electrolyte inhibites vaporization of water as the major component and allowing ethanol molecules to vapor producing more high purity ethanol.

APA, Harvard, Vancouver, ISO, and other styles

19

Saengsikhiao, Piyanut, and Juntakan Taweekun. "The Data Mining Technique Using RapidMiner Software for New Zeotropic Refrigerant." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, no. 1 (June 3, 2021): 70–90. http://dx.doi.org/10.37934/arfmts.83.1.7090.

Full text

Abstract:

This research presents the development of environmentally-friendly and energy efficient refrigerant for medium temperature refrigeration systems that new azeotropic refrigerant mixture of hydrofluorocarbons and hydrocarbon that can retrofit in the refrigeration system using R404A. The medium back pressure refrigeration testing standard that follow CAN/ANSI/AHRI540 standard air-conditioning, heating, and refrigeration institute (AHRI) and The properties of refrigerants and refrigeration simulation system that used national institute of standards and technology (NIST) reference fluid thermodynamic and transport properties database (REFPROP) software and NIST vapor compression cycle model accounting for refrigerant thermodynamic and transport properties (CYCLE_D-HX) software. The methodology uses decision tree function in datamining by rapid minor software that first of KDnuggets annual software poll that showed new azeotropic refrigerant mixture had cooling capacity, refrigerant effect, GWP and boiling point were lower than R404A but work and pressure for medium temperature refrigeration system of azeotropic refrigerant mixture were higher than R404A. The artificial intelligence (AI) by data mining technic can predictive environmentally-friendly and energy efficient refrigerant for medium temperature refrigeration. The result of refrigerant mixed by R134A, R32, R125 and R1270 and is consistent with the evolution of fourth-generation refrigerants that contain a mixture of HFCs and HCs which are required to produce a low-GWP, zero-ozone-depletion-potential (ODP), high-capacity, low-operating-pressure, and nontoxic refrigerant.

APA, Harvard, Vancouver, ISO, and other styles

20

Bagani, Maria, Efthymios Balomenos, and Dimitrios Panias. "Nepheline Syenite as an Alternative Source for Aluminum Production." Minerals 11, no. 7 (July 6, 2021): 734. http://dx.doi.org/10.3390/min11070734.

Full text

Abstract:

The increasing demand for aluminum in conjunction with the limited available bauxite deposits in Europe results in the dire need for the evaluation of alternative raw materials for the whole value chain of alumina production. The present paper focuses on the possible use of nepheline syenite, originated as a mine byproduct, in alumina production through leaching with an azeotropic HCl solution. Previous work on nepheline syenite dissolution focused more on the extraction of potassium and sodium values. In this work, emphasis is given at the characteristics and leachability of aluminum content phases by applying a high temperature HCl leaching in untreated material. From this point of view, leaching experiments were conducted on nepheline syenite, at a temperature range of 90 °C to 150 °C and with aqueous azeotropic HCl solution. Leaching, in the aforementioned conditions, is a process, characterized by medium aluminum dissolution. The results show that the aluminum-bearing phases that withstand the dissolution process are mainly the ones of sodium and potassium feldspars.

APA, Harvard, Vancouver, ISO, and other styles

21

Rouhandeh, Hosein, and Shahram Ghanbari Pakdehi. "Measurement and Correlation of Isobaric Vapor-Liquid Equilibrium Data for Water + 2-Azido-N,N-Dimethylethanamine System at 4 kPa." Chemistry & Chemical Technology 15, no. 2 (May 15, 2021): 226–32. http://dx.doi.org/10.23939/chcht15.02.226.

Full text

Abstract:

Isobaric vapor-liquid equilibrium (VLE) data for binary system of water + 2-azido-N,N-dimethylethanamine (DMAZ) was measured at 4 kPa. The results showed an azeotropic point at x1 = 0.985 and T = 302.17 K. The data was correlated with nonrandom two-liquid (NRTL), Wilson and universal quasi-chemical activity coefficient (UNIQUAC) models for the liquid phase. A comparison of the model performances was made using of the criterion of the average absolute deviation, standard deviation and mean standard deviation in boiling-point temperature. The results indicated that the NRTL activity coefficient model satisfactorily correlated the VLE data.

APA, Harvard, Vancouver, ISO, and other styles

22

Novák, Josef P., Jaroslav Matouš, and Petr Voňka. "Vapour-liquid equilibrium. The effect of temperature on the equilibrium vapour phase composition and on the azeotropic point composition." Collection of Czechoslovak Chemical Communications 56, no. 4 (1991): 745–49. http://dx.doi.org/10.1135/cccc19910745.

Full text

Abstract:

On the basis of analysis of calorimetric data, it is shown that the tert-butyl alcohol(1)-water(2) system exhibits the non-monotonous dependence of the equilibrium vapour phase composition on temperature which is reflected in the non-monotonous dependence of azeotropic composition on temperature. This behaviour is conditioned primarily by the fact that the molar heats of vaporization of both the substances have the same value at the temperature of 57°C. From the values of heats of vaporization of C3 and C4 alcohols and water it is evident that the analogous behaviour occurs also in aqueous systems of these alcohols at common temperatures.

APA, Harvard, Vancouver, ISO, and other styles

23

Novák, Josef P., Jaroslav Matouš, Květuše Říčná, and Vladimír Kubíček. "Liquid-liquid equilibrium in the water-ethanol-toluene system. Correlation of equilibrium data." Collection of Czechoslovak Chemical Communications 54, no. 3 (1989): 586–601. http://dx.doi.org/10.1135/cccc19890586.

Full text

Abstract:

Liquid-liquid equilibrium data in the water-ethanol-toluene system were correlated by the superposition of the Wilson and Redlich-Kister equations with a ternary term. The correlation of both homogeneous binary systems was taken from the literature. The ternary liquid-liquid equilibrium data were at all temperatures satisfactorily described on using only three ternary parameters determined from the equilibrium data at 50 °C. The parameters obtained by the correlation yield also a good estimate of boiling point and composition of homogeneous azeotropic mixture.

APA, Harvard, Vancouver, ISO, and other styles

24

XU, Yingjie, Jia YAO, Ping YAO, Haoran LI, and Shijun HAN. "Prediction of Vapor-Liquid Equilibria of Alcohol-Hydrocarbon Systems by 1H NMR and Azeotropic Point." Chinese Journal of Chemical Engineering 18, no. 3 (January 2010): 455–61. http://dx.doi.org/10.1016/s1004-9541(10)60243-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Susial, Pedro, José Rodríguez-Henríquez, José Apolinario, Victor Castillo, and Esteban Estupiñan. "Vapour pressures and vapour-liquid equilibria of propyl acetate and isobutyl acetate with ethanol or 2-propanol at 0.15 MPa. Binary systems." Journal of the Serbian Chemical Society 77, no. 9 (2012): 1243–57. http://dx.doi.org/10.2298/jsc111213025s.

Full text

Abstract:

Vapour pressures of propyl acetate, isobutyl acetate and 2-propanol from 0.004 to 1.6 MPa absolute pressure and VLE data for the binary systems propyl acetate+ethanol, propyl acetate+2-propanol, isobutyl acetate+ethanol and isobutyl acetate+2-propanol at 0.15 MPa have been determined. The experimental VLE data were verified with the test of van Ness and the Fredenslund criterion. The propyl acetate+ethanol or +2-propanol binary systems have an azeotropic point at 0.15 MPa. The different versions of the UNIFAC and ASOG group contribution models were applied.

APA, Harvard, Vancouver, ISO, and other styles

26

Li, Weisong, Lei Zhong, Yongchao He, Jihong Meng, Fanglian Yao, Yusheng Guo, and Chunjian Xu. "Multiple Steady-States Analysis and Unstable Operating Point Stabilization in Homogeneous Azeotropic Distillation with Intermediate Entrainer." Industrial & Engineering Chemistry Research 54, no. 31 (July 29, 2015): 7668–86. http://dx.doi.org/10.1021/acs.iecr.5b00572.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Li, Ying-Feng, Yang-Xin Yu, Yuan-Xiang Zheng, and Ji-Ding Li. "Shift of the azeotropic point of binary Lennard–Jones mixtures confined in a slit-like pore." Fluid Phase Equilibria 292, no. 1-2 (May 2010): 110–16. http://dx.doi.org/10.1016/j.fluid.2010.02.008.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Lešek, František, Josef Eichler, and Miroslav Balcar. "Liquid-liquid equilibrium of ternary systems water-glycol-aromatic hydrocarbon." Collection of Czechoslovak Chemical Communications 50, no. 1 (1985): 153–66. http://dx.doi.org/10.1135/cccc19850153.

Full text

Abstract:

By using the method of determining cloud point, the liquid-liquid equilibria of the systems water-1,2-propanediol-toluene, water-1,2-propanediol-xylene, water-1,3-butanediol-toluene and water-1,3-butanediol-xylene were measured within the range of 40 °C up to azeotropic points at atmospheric pressure. The solubility of the hydrocarbons w3 in the glycols has increased with temperature t according to the relation w3 = (A-Bt)-1, where A and B have been functions of water content in the glycols. The solubility of the water(l)-glycol(2) binary system in the hydrocarbons has increased with temperature according to the relation (w1 + w2) = C exp (Dt). The decrease of mutual solubilities of toluene or xylene in aqueous 1,2-propanediol or 1,3-butanediol was found experimentally to be proportional to the increasing content of water in glycols.

APA, Harvard, Vancouver, ISO, and other styles

29

Song, Bingyi, Na Xu, Wenlong Jiang, Bin Yang, Xiumin Chen, Baoqiang Xu, Lingxin Kong, Dachun Liu, and Yongnian Dai. "Study on azeotropic point of Pb–Sb alloys by ab-initio molecular dynamic simulation and vacuum distillation." Vacuum 125 (March 2016): 209–14. http://dx.doi.org/10.1016/j.vacuum.2016.01.004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Fiorelli, F. A. S., and O. M. Silvares. "EXPERIMENTAL VALIDATION OF A CAPPILARY TUBE SIMULATION MODEL WITH REFRIGERANT MIXTURES FLOW." Revista de Engenharia Térmica 3, no. 1 (June 30, 2004): 15. http://dx.doi.org/10.5380/reterm.v3i1.3485.

Full text

Abstract:

This paper presents the experimental validation of a simulation model for refrigerant mixtures flow through capillary tubes. To perform such validation it was built an experimental apparatus using a blow-down process. It was carried out preliminary tests for characterization of experimental parameters: actual capillary tube diameters; relative roughness; and the heat losses in subcooling/quality control system. It was obtained almost 200 experimental points for R-407C (a zeotropic mixture) and R-410A (a near azeotropic mixture). Complete data set for each point consists of the measured pressure and temperature profiles, mass flow rate and mixture composition, as well as subcooling/quality control system inlet and outlet temperatures and heater electric power consumption for tests with two-phase flow capillary tube inlet conditions. Comparison of simulation and experimental data show a good agreement. Main deviations are connected with the delay of vaporization phenomenon occurrence, experimentally verified by the authors.

APA, Harvard, Vancouver, ISO, and other styles

31

Martinez Riascos, Carlos Arturo, and Libardo Estupiñan Perez. "Conceptual analysis of single-feed heterogeneous distillation columns." Ingeniería e Investigación 35, no. 2 (August 5, 2015): 36–42. http://dx.doi.org/10.15446/ing.investig.v35n2.49247.

Full text

Abstract:

Separation in heterogeneous distillation columns is attained by interaction of two liquid and one vapor phases, interaction of three phases involves complexities due to the determination of vapor-liquid-liquid equilibrium and hence, in the design of separation units. Nevertheless, the liquid-liquid equilibrium allows developing separations that may be unfeasible by vapor-liquid equilibrium. In this way, heterogeneous azeotropic distillation is a useful operation for the separation of azeotropic and close-boiling mixtures. In this work, a new methodology for evaluating the feasibility of this process is developed. This methodology is an extension of that proposed by Castillo et al. (1998) for homogeneous systems. Operation leaves for heterogeneous systems are calculated using the concept of pinch point curves in order to establish the process feasibility. Heterogeneous columns with external decanter are considered as the only heterogeneous stage (OHED: only heterogeneous external decanter). The initialization process for the column calculation requires the selection of the distillate composition using thermodynamic criteria in order to guarantee homogeneous phases within the column. A system with industrial and academic relevance was considered as case study: water-acetic acid-amyl acetate. Results show that the developed shortcut method allows evaluating process feasibility and estimating design parameters, without the use of trial and error procedures implemented, with the aid of simulation tools.<div> </div>

APA, Harvard, Vancouver, ISO, and other styles

32

da Cunha, Sergio, Horng-Jang Liaw, and Vincent Gerbaud. "On the relation between azeotropic behavior and minimum / maximum flash point occurrences in binary mixtures of flammable compounds." Fluid Phase Equilibria 452 (November 2017): 113–34. http://dx.doi.org/10.1016/j.fluid.2017.08.019.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Patil, M. B., M. K. Amshumali, and S. N. M. Mathad. "POLY(VINYL ALCOHOL) AND MCM-41 MIXED MATRIX MEMBRANES FOR PERVAPORATION DEHYDRATION OF ISOPROPANOL AT THEIR AZEOTROPIC POINT." ACTA CHEMICA IASI 28, no. 1 (2020): 47–62. http://dx.doi.org/10.2478/achi-2020-0004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Said Solaiman, Obadah, and Ishak Hashim. "Efficacy of Optimal Methods for Nonlinear Equations with Chemical Engineering Applications." Mathematical Problems in Engineering 2019 (July 14, 2019): 1–11. http://dx.doi.org/10.1155/2019/1728965.

Full text

Abstract:

In this study, we propose a modified predictor-corrector Newton-Halley (MPCNH) method for solving nonlinear equations. The proposed sixteenth-order MPCNH is free of second derivatives and has a high efficiency index. The convergence analysis of the modified method is discussed. Different problems were tested to demonstrate the applicability of the proposed method. Some are real life problems such as a chemical equilibrium problem (conversion in a chemical reactor), azeotropic point of a binary solution, and volume from van der Waals equation. Several comparisons with other optimal and nonoptimal iterative techniques of equal order are presented to show the efficiency of the modified method and to clarify the question, are the optimal methods always good for solving nonlinear equations?

APA, Harvard, Vancouver, ISO, and other styles

35

Tang, Hong Bo, and Min Qing Zhang. "Thermodynamic Model for Vapor-Liquid Phase Equilibrium in an Exerted Magnetic Field." Advanced Materials Research 550-553 (July 2012): 2704–11. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2704.

Full text

Abstract:

Many researchers have shown a great deal of interest in the effects that magnetic fields have when applied in chemical reactions, crystallization, magnetic separation of materials, magnetic levitation, materials processing, and wastewater treatment. However, surprisingly little research has been done on the effects of magnetic fields on the vapor-liquid equilibrium and the thermodynamic model for vapor-liquid phase equilibrium. The influence of magnetic fields on vapor-liquid equilibrium of binary heterogeneous azeotrope was investigated with ethanol-water in this paper. It was found that the vapor-liquid equilibrium of an ethanol-water system is influenced by the external magnetic field, but that the azeotropic point of the ethanol-water system is not changed by the magnetic field when the magnetic intensity reaches 0.8 T. Rather, the exerted magnetic field reduces the equilibrium temperature and shortens the distance between T-x curve and T-y curve in T-x-y diagram of the vapor-liquid equilibrium of the ethanol-water system. A thermodynamic model for vapor-liquid phase equilibrium in the exerted magnetic field was derived theoretically, based on the fundamental thermodynamic theory. The results show that the logarithm value of the ratio of the composition of the certain component in a magnetic field to that without the magnetic field is proportional to the magnetic susceptibility of the solution, and to the square of magnetic field intensity. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

APA, Harvard, Vancouver, ISO, and other styles

36

Li, Zhen Yu, Hong Yan Tao, and Run Ze Yang. "Preparation of Isoamyl Acetate by Reaction-Distillation Using Ionic Liquid as Catalyst." Advanced Materials Research 550-553 (July 2012): 164–69. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.164.

Full text

Abstract:

In this thesis, isoamyl acetate was synthesized by reaction-distillation , using acetic acid and isoamyl alcohol as starting materials, using acid ion-liquid as catalyst and extracting agent.These are some factors were investigated, including different catalysts, ratio between acid and alcohol, amount of Ion-Liquid, and reflux ratio. Technology to prepare iso-pentyl acetate was optimized with single factor experiments. Results showed that acid ion-liquids are good catalysts and extracting agents, which increased the purity and yield of iso-pentyl acetate, as well as diminished the azeotropic point of iso-pentyl acetate and acetic acid.The optimal technological conditions are as following: ratio of acid:alcohol 2:1 (mol), dosage of ion-liquid V = 2 mL, reflux ratio R = 2.5. Under this condition, purity of obtained iso-pentyl acetate is 99%, and the yield is 85%.

APA, Harvard, Vancouver, ISO, and other styles

37

B. Patil, Mallikarjunagouda. "Hybrid Nanocomposite Membranes of Poly(vinyl alcohol) and Cerium Oxide for Pervaporation Dehydration of Ethanol at their Azeotropic Point." International Journal of Advanced Science and Engineering 06, no. 04 (March 27, 2020): 1472–75. http://dx.doi.org/10.29294/ijase.6.4.2020.1472-1475.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Song, Bingyi, Wenlong Jiang, Bin Yang, Xiumin Chen, Baoqiang Xu, Lingxin Kong, Dachun Liu, and Yongnian Dai. "Study on Exploration of Azeotropic Point of Pb-Sb Alloys by Vacuum Distillation and Ab Initio Molecular Dynamic Simulation." Metallurgical and Materials Transactions A 47, no. 10 (July 25, 2016): 5214–22. http://dx.doi.org/10.1007/s11661-016-3663-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Demirel, Yaşar. "Estimation of the entropy of vaporization at the normal boiling point for azeotropic mixtures containing water, alcohol or acetic acid." Thermochimica Acta 339, no. 1-2 (November 1999): 79–85. http://dx.doi.org/10.1016/s0040-6031(99)00211-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Kandlikar, S. G. "Boiling Heat Transfer With Binary Mixtures: Part II—Flow Boiling in Plain Tubes." Journal of Heat Transfer 120, no. 2 (May 1, 1998): 388–94. http://dx.doi.org/10.1115/1.2824262.

Full text

Abstract:

Flow boiling heat transfer with pure fluids comprises convective and nucleate boiling components. In flow boiling of binary mixtures, in addition to the suppression effects present in pool boiling, the presence of flow further modifies the nucleate boiling characteristics. In the present work, the flow boiling correlation by Kandlikar (1990, 1991b) for pure fluids is used as the starting point, and the mixture effects derived in Part I (Kandlikar, 1998) of this paper are incorporated. Three regions are defined on the basis of a volatility parameter, V1 = (cp/ΔhLG)(k/D12)1/2|(y1 − x1)dT/dx1|. They are: region I—near azeotropic, region II—moderate diffusion-induced suppression, and region III—severe diffusion-induced suppression. The resulting correlation is able to correlate over 2500 data points within 8.3 to 13.3 percent mean deviation for each data set. Furthermore, the α–x trend is represented well for R-12/R-22, R-22/R-114, R-22/R-152a, R-500, and R-132a/R-123 systems. Electrically heated stainless steel test sections as well as fluid-heated copper test sections are both covered under this correlation.

APA, Harvard, Vancouver, ISO, and other styles

41

Gao, Qinglin, Zongchang Zhao, Peng Jia, and Xiaodong Zhang. "Effect of Ionic Liquids on the Isobaric Vapor-Liquid Equilibrium Behavior of Acetone-Chloroform." Applied Sciences 8, no. 9 (September 1, 2018): 1519. http://dx.doi.org/10.3390/app8091519.

Full text

Abstract:

Isobaric vapor-liquid equilibrium (VLE) data of the ternary system acetone + chloroform + 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) or 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) were obtained at 101.3 kPa. Results indicated that the addition of [MMIM][DMP] or [EMIM][DEP] could eliminate the azeotropic point of the binary system of acetone + chloroform when the mole fraction of ionic liquids (ILs) was above 0.15. Besides, the experimental data could be well correlated by the nonrandom two-liquid (NRTL) model. The structures as well as interactions between molecular solvents (acetone, chloroform) and the ion pairs ([MMIM][DMP], [EMIM][DEP]) were studied by quantum chemical calculations. The result indicated that the interaction energies (ΔE) follow the order of ΔE(acetone + [EMIM][DEP]) > ΔE(acetone + [MMIM][DMP]) > ΔE(chloroform + [EMIM][DEP]) ≈ ΔE(chloroform + [MMIM][DMP]), and chloroform had stronger affinity to ionic liquids than acetone.

APA, Harvard, Vancouver, ISO, and other styles

42

Schehlmann, M. S., E. Wiedemann, and R. N. Lichtenthaler. "Pervaporation and vapor permeation at the azeotropic point or in the vicinity of the LLE boundary phases of organic/aqueous mixtures." Journal of Membrane Science 107, no. 3 (November 1995): 277–82. http://dx.doi.org/10.1016/0376-7388(95)00142-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Zhang, Zongqi, Siquan Xu, Yuanfeng Wu, Shengbin Shi, and Guomin Xiao. "Recent Advances of Pervaporation Separation in DMF/H2O Solutions: A Review." Membranes 11, no. 6 (June 20, 2021): 455. http://dx.doi.org/10.3390/membranes11060455.

Full text

Abstract:

N,N-dimethylformamide (DMF) is a commonly-used solvent in industry and pharmaceutics for extracting acetylene and fabricating polyacrylonitrile fibers. It is also a starting material for a variety of intermediates such as esters, pyrimidines or chlordimeforms. However, after being used, DMF can be form 5%–25% spent liquors (mass fraction) that are difficult to recycle with distillation. From the point of view of energy-efficiency and environment-friendliness, an emergent separation technology, pervaporation, is broadly applied in separation of azeotropic mixtures and organic–organic mixtures, dehydration of aqueous–organic mixtures and removal of trace volatile organic compounds from aqueous solutions. Since the advances in membrane technologies to separate N,N-dimethylformamide solutions have been rarely reviewed before, hence this review mainly discusses the research progress about various membranes in separating N,N-dimethylformamide aqueous solutions. The current state of available membranes in industry and academia, and their potential advantages, limitations and applications are also reviewed.

APA, Harvard, Vancouver, ISO, and other styles

44

Banat, Fawzi A., Fahmi Abu Al-Rub, Rami Jumah, and Mohammad Shannag. "Theoretical investigation of membrane distillation role in breaking the formic acid-water azeotropic point: Comparison between Fickian and Stefan-Maxwell-based models." International Communications in Heat and Mass Transfer 26, no. 6 (August 1999): 879–88. http://dx.doi.org/10.1016/s0735-1933(99)00076-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Invernizzi, Costante, Marco Binotti, Paola Bombarda, Gioele Di Marcoberardino, Paolo Iora, and Giampaolo Manzolini. "Water Mixtures as Working Fluids in Organic Rankine Cycles." Energies 12, no. 13 (July 8, 2019): 2629. http://dx.doi.org/10.3390/en12132629.

Full text

Abstract:

This work explores the possibility to adopt in organic Rankine cycle (ORC) plants mixtures of water (acting as solvent) plus an organic compound (acting as solute) as the working fluid. Initially an evaluation of the thermodynamic properties of the mixtures is performed, in order to assess their properties, and to point out the molar fractions which entail a near-azeotropic behaviour. Four species from three different classes of chemical compounds are investigated: 2,2,2-trifluoroethanol and n-butanol for alcohols, where the first is fluorinated, acetonitrile for nitrile class and 2-methylpyrazine as a heterocyclic aromatic compound. Simultaneously, the thermal stability of the pure substances considered as the possible solute for the mixtures is experimentally investigated in order to estimate the temperature applicability range. The ORC plant performance, from a low-enthalpy geothermal heat source (hot water stream from 100 to 200 °C), adopting the selected mixtures as the working fluid is finally evaluated, and the analysis includes a preliminary discussion on the turbine design; results are compared with respect to the reference case of a hypothetical plant adopting water as the working fluid.

APA, Harvard, Vancouver, ISO, and other styles

46

Matsuda, Hiroyuki, Mitsuaki Negishi, Shinya Iino, Dana Constantinescu, Kiyofumi Kurihara, Katsumi Tochigi, Kenji Ochi, and Jürgen Gmehling. "Isothermal vapor–liquid equilibria at 383.15–413.15 K for the binary system methanol + dimethyl carbonate and the pressure dependency of the azeotropic point." Fluid Phase Equilibria 492 (July 2019): 101–9. http://dx.doi.org/10.1016/j.fluid.2019.03.019.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Del Col, D., A. Cavallini, and J. R. Thome. "Condensation of Zeotropic Mixtures in Horizontal Tubes: New Simplified Heat Transfer Model Based on Flow Regimes." Journal of Heat Transfer 127, no. 3 (March 1, 2005): 221–30. http://dx.doi.org/10.1115/1.1857951.

Full text

Abstract:

The need for optimal design of heat exchangers with in-tube condensation of zeotropic refrigerant mixtures has pushed the research of predictive methods in the last years. Some procedures have been developed, based on the Colburn and Drew (1937, Trans. AIChemE 33, pp. 197–215) analysis, that require significant numerical effort and the diffusivity properties of the mixture to calculate the mass transfer resistance in the process and, hence, are rarely used for heat exchanger design. Proposing a modified version of the well-known simplified approach of Silver (1947, Trans. Inst. Chem. Eng. 25, pp. 30–42) and Bell and Ghaly (1973, AIChE Symp. Ser. 69, pp. 72–79) to include the effects of interfacial roughness and nonequilibrium effects, the present study extends the flow-pattern-based model of Thome, El Hajal, and Cavallini (2003, Int. J. Heat Mass Transfer 46, pp. 3365–3387) for condensation of pure fluids and azeotropic mixtures to zeotropic mixtures. By implementing this within the above flow-pattern-based heat transfer model, it leads to an improved method for accurately predicting local mixture heat transfer coefficients, maintaining a clear relationship between flow regime and heat transfer, and achieving both the goals of higher prediction accuracy and low calculation effort. The method has been verified for refrigerant mixtures (both halogenated and hydrocarbon) having temperature glides of 3.5–22°C, that is temperature differences between the dew point and bubble point temperatures (at a fixed pressure and bulk composition).

APA, Harvard, Vancouver, ISO, and other styles

48

Msahel, Asma, Francesco Galiano, Martina Pilloni, Francesca Russo, Amor Hafiane, Roberto Castro-Muñoz, Vijay Bhooshan Kumar, et al. "Exploring the Effect of Iron Metal-Organic Framework Particles in Polylactic Acid Membranes for the Azeotropic Separation of Organic/Organic Mixtures by Pervaporation." Membranes 11, no. 1 (January 18, 2021): 65. http://dx.doi.org/10.3390/membranes11010065.

Full text

Abstract:

A microporous carboxylate metal-organic framework MIL-100 Fe was prepared as submicron particles by microwave-assisted hydrothermal synthesis (Fe-MOF-MW). This product was explored, for the first time, for the preparation of polylactic acid (PLA) mixed matrix membranes. The produced MOF was characterised by powder X-ray diffraction (PXRD), environmental scanning electron microscopy (ESEM) as well as by thermogravimetric analysis (TGA) and nitrogen adsorption/desorption. The effect of different Fe-MOF-MW concentrations (0.1 and 0.5 wt%) on the membrane properties and performance were evaluated. These membranes were used in the pervaporation process for the separation of methanol/methyl tert-butyl-ether mixtures at the azeotropic point. The influence of the feed temperature and vacuum pressure on the membrane performance was evaluated and the results were compared with PLA pristine membranes. Moreover, the produced membranes have been characterised in terms of morphology, MOF dispersion in the polymeric membrane matrix, wettability, thickness, mechanical resistance and swelling propensity. The presence of Fe-MOF-MW was found to have a beneficial effect in improving the selectivity of mixed matrix membranes towards methanol at both concentrations. The highest selectivity was obtained for the PLA membranes embedded with 0.5 wt% of Fe-MOF-MW and tested at the temperature of 25 °C and vacuum pressure of 0.09 mbar.

APA, Harvard, Vancouver, ISO, and other styles

49

Scheepers, Fabian, Andrea Stähler, Markus Stähler, Marcelo Carmo, Werner Lehnert, and Detlef Stolten. "Layer Formation from Polymer Carbon-Black Dispersions." Coatings 8, no. 12 (December 7, 2018): 450. http://dx.doi.org/10.3390/coatings8120450.

Full text

Abstract:

It has been well-established that effects such as cracking are observable when wet layers are dried. In particular, the layer thickness, as well as the surface tension of the liquid, is responsible for this behavior. The layer formation of polymer electrolyte fuel cells and electrolyzer electrodes, however, has not yet been analyzed in relation to these issues, even though the effect of cracks on cell performance and durability has been frequently discussed. In this paper, water propanol polymer-containing carbon-black dispersions are analyzed in situ with regard to their composition during drying. We demonstrate that crack behavior can be steered by slight variations in the initial dispersion when the solvent mixture is near the dynamic azeotropic point. This minor adjustment may strongly affect the drying behavior, leading to either propanol or water-enriched liquid phases at the end of the drying process. If the evaporation of the solvent results in propanol enrichment, the critical layer thickness at which cracks occur will be increased by about 30% due to a decrease in the capillary pressure. Microscopic images indicate that the crack area ratio and width depend on the wet layer thickness and initial liquid phase composition. These results are of much value for future electrode fabrication, as cracks affect electrode properties.

APA, Harvard, Vancouver, ISO, and other styles

50

Megawati, Dewi Selvia Fardhyanti, Radenrara Dewi Artanti Putri, Oki Fianti, Agustin Fitrianingsi Simalango, and Afiati Estrina Akhir. "Synthesis of Silica Powder from Sugar Cane Bagasse Ash and Its Application as Adsorbent in Adsorptive-distillation of Ethanol-water Solution." MATEC Web of Conferences 237 (2018): 02002. http://dx.doi.org/10.1051/matecconf/201823702002.

Full text

Abstract:

In this study, sugarcane bagasse ash (SCBA) as waste from sugarcane factory was extracted into silica powder. This powder was then used as adsorbent for ethanol purification. Prior to used, the SCBA was washed using HCl solution. The silica extraction was conducted using various NaOH concentrations (0.5; 1; 1.5 and 2 mol/L) as well as extraction times (30, 60 and 90 minutes). After that the mixture was precipitated using HCl solution. The solution was filtrated through a paper filter and its solid particle was dried until its weight was constant. The particle was grounded and sieved using 18 mesh sieves. The silica powder obtained was analysed using FTIR and its result showed that the powder has silica functional groups. The silica yield increases with increasing of concentration of NaOH solution as well as extraction time. The highest silica yield (45.5% w/w) was achieved at 2 mol/L NaOH solution at 90 min. The surface area, pore diameter, and pore volume of silica powder were measured to be 407 m2/g, 3.81Å, and 2.76 dm3/g, respectively. From application of silica powder as adsorbent in adsorptive-distillation, ethanol concentration can reach 99.3% w/w which indicates azeotropic point can be passed.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Azeotropic point'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles