DOCSLIB.ORG

Evaluation of Azeotropic Dehydration for the Preservation of Shrimp. James Edward Rutledge Louisiana State University and Agricultural & Mechanical College

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Evaluation of Azeotropic Dehydration for the Preservation of Shrimp. James Edward Rutledge Louisiana State University and Agricultural & Mechanical College Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1969 Evaluation of Azeotropic Dehydration for the Preservation of Shrimp. James Edward Rutledge Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Rutledge, James Edward, "Evaluation of Azeotropic Dehydration for the Preservation of Shrimp." (1969). LSU Historical Dissertations and Theses. 1689. https://digitalcommons.lsu.edu/gradschool_disstheses/1689 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. This dissertation has been 70-9089 microfilmed exactly as received RUTLEDGE, James Edward, 1941- EVALUATION OF AZEOTROPIC DEHYDRATION FOR THE PRESERVATION OF SHRIMP. The Louisiana State University and Agricultural and Mechanical College, PhJD., 1969 Food Technology University Microfilms, Inc., Ann Arbor, Michigan Evaluation of Azeotropic Dehydration for the Preservation of Shrimp A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Food Science and Technology by James Edward Rutledge B.S., Texas A&M University, 1963 M.S., Texas A&M University, 1966 August, 1969 ACKNOWLEDGMENT The author wishes to express his sincere appreciation to his major professor, Dr, Fred H. Hoskins, for the guidance which he supplied not only in respect to this dissertation but also in regard to the author’s graduate career at Louisiana State University, Gratitude is also extended to Dr. Robert M. Grodner, who aided the author in securing a position at the NASA Mississippi Test Facility where several of the experiments were conducted, and to the other members of his committee: Dr0 J. A. Liuzzo, Dr. A. D. Larson, Dr. A. F. Novak, and Dr. J. H. Gholson. Thanks are also in order to the author's parents, Mr. and Mrs. Edward R, Rutledge, whose encouragement and support were never lacking. The author wishes to thank his wife, Carolyn, for her invaluable assistance in typing and manuscript preparation as well as her tireless motiva­ tion. TABLE OF CONTENTS PAGE ACKNOWLEDGMENT .................................... ii LIST OF T A B L E S .................................... iv ABSTRACT........................................... vi INTRODUCTION .......................................... 1 REVIEW OF LITERATURE............................... - 3 Azeotropic Freeze-drying................. e , 3 Azeotropic Distillation as a Separating Tool, ^ Solvent Recovery ..... ..................... 6 Problems Associated with Conventional Freeze- drying of Shrimp ...... 13 MATERIALS AND METHODS ............................... 19 Shrimp . „ . ...................... 29 Solvent . 0 . 0 .,..,,...,.., 19 Equipment 20 Experimental Method . 21 RESULTS AND DISCUSSION............................ 26 t SUMMARY AND CONCLUSIONS ....... ..... 33 LITERATURE CITED ............ ............ ^0 VITA ....... 0 o .. o ... .................. ^3 LIST OF TABLES TABLE PAGE I. Composition of ethyl alcohol-water azeo- trope at different pressures . ......... 7 II. Mutual solubilities of ethyl acetate and water at different temperatures ...... n III. Relative distribution of ethyl alcohol between two layers consisting of ethyl acetate and w a t e r .......................... 12 IV. Composition of ethyl alcohol-water azeotrope at different pressures ..... 13 V. Difference between boiling points of ethyl acetate and the azeotropic mixtures in agitated vessels •••..•• ......... 26 VI. Difference between boiling points of ethyl acetate and the azeotropic mixtures in unagitated vessels ............... 28 !VII. V/eight of azeotropic fractions collected at different temperature intervals ...... 30 VIII. Composition and boiling point of azeotropic mixtures of ethyl acetate, ethyl alcohol, and w a t e r ......................... 31 iv TABLE PAGE IX. The influence of extraction time on residual fat content of shrimp ...... 32 X. The influence of extraction time on moisture removal by solvent .................. 33 XI. The influence of extraction time on astacene pigment losses .......... 33 XII. Influence of temperature and pressure on processing t i m e s ............ 3^ XIII. Influence of processing temperature and pressure on residual moisture content of frozen and unfrozen shrimp processed by azeotropic distillation .......... 33 XIV. Influence of processing temperature and pressure on rehydration ratios of azeotropic dehydrated shrimp ...... ............. 35 XV. Influence of processing temperature and pressure on water-binding capacity of t azeotropic dehydrated shrimp •••«... 35 v ABSTRACT An investigation was conducted on solvent dehydra­ tion of shrimp. Aims of the study were threefold: an examination of the solvent system, including the discovery of parameters essential for end-point determination and the acquisition of data pertinent to solvent recovery; an investigation of necessity and kind of pretreatments facilitating dehydration; and employment of this data to delineate the general process of azeotropic dehydration of shrimp. Results of this investigation revealed certain advan­ tages inherent in the technique. One involved an accelera­ tion of the dehydration process as a whole* A second was adequate end-point determination of moisture levels and ease of monitoring, which has always been a problem in freeze-drying. Four chief drawbacks were encountered in the process. The first concerned the absence of a simple and economical means of solvent recovery. Another involved inherent pigment leaching. A third v:as poor rehydration ability coupled with inadequate water-binding, indicative of protein denaturation. However, the temperature of the process was low when compared to other dehydration techniques. Probably a large portion of the denaturation was due to solvent effects, rather than temperature. A final disadvantage was incomplete solvent removal, traces of which would be vi objectionable to consumers. The process has limited usefulness for commercial dehydration of shrimp until these problems are overcome. INTRODUCTION Traditionally, shrimp have been preserved by freezing; however, within the last five years freeze-drying has been introduced on a limited scale. The primary restriction in­ volved in both methods is inherent high cost; storage costs and the cost of equipment and capacity being most limiting. Consequently, there was a need for a method of preserving shrimp which combined the attributes of low cost, convenience, and quality. Recently Byron B. Bohrer developed, and the Sun Oil Company patented, a process which held promise for extend­ ing the range of foodstuffs adaptable to drying from a physical as well as economic viewpoint. The major benefit of the process is its ability to combine solvent extraction and azeotropic distillation for separation of water and oil from the product. Using ethyl acetate, the extrac­ tion and azeotropic distillation steps occur at tempera­ tures low enough to retain full nutritive value. Ethyl acetate combines with water in the sample to form an azeo- trope. With the aid of a vacuum .the azeotrope is distilled, leaving a dehydrated product. After residual solvent and s odors are removed, the resultant product appears as though it were freeze-dried. The need for a commercially feasible method for processing such a product was apparent in view of increasing public demand for preprocessed foods. The aims of this study were threefold: an examination of the solvent system, including study of parameters essen­ tial for end-point determination and acquisition of data pertinent to solvent recovery; an investigation of the necessity and kind of pretreatments facilitating later dehydration; and employment of these data to delineate the general process of azeotropic dehydration of shrimp* REVIEW OP LITERATURE Azeotropic Freeze-Drying The process of solvent dehydration by azeotropic dis­ tillation is described in U.S. patent 3*298,109 issued to the Sun Oil Company on January 17, 1967* The process com­ prises placing an unfrozen or frozen material with an agent which forms an azeotrope with water. By adjusting pressure and temperature to levels at. which the azeotropic mixture will continuously boil, the material is dehydrated. The azeotrope-forming agent should be biologically degradable, and both it and its decomposition products should be harm­ less to humans since the materials will later be consumed. In addition, the azeotrope must have a boiling point lower than that of water. This enables easy removal of the agent after drying is completed. Moreover, the agent should have at least a partial miscibility with water, since this property enables the process to be adapted to drying large chunks or whole foodstuffs. Agents described in the U.S. patent 3*298,109 which have been found suitable include n-propyl alcohol, n-propyl acetate, ethyl alcohol, and ethyl acetate0 The preferred agents, however, are ethyl t alcohol and ethyl acetate. Either frozen or unfrozen material is placed in a vessel containing the agent and attached to a vacuum source through a condenser, A vacuum is applied, and the vessel heated to a temperature suf­ ficient
Load more

Recommended publications
  • The Separation of Three Azeotropes by Extractive Distillation by An-I Yeh A
    The separation of three azeotropes by extractive distillation by An-I Yeh A thesis submitted in partial fulfillment of the requirement for the degree of Master of Science in Chemical Engineering Montana State University © Copyright by An-I Yeh (1983) Abstract: Several different kinds of extractive distillation agents were investigated to affect the separation of three binary liquid mixtures, isopropyl ether - acetone, methyl acetate - methanol, and isopropyl ether - methyl ethyl ketone. Because of the small size of the extractive distillation column, relative volatilities were assumed constant and the Fenske equation was used to calculate the relative volatilities and the number of minimum theoretical plates. Dimethyl sulfoxide was found to be a good extractive distillation agent. Extractive distillation when employing a proper agent not only negated the azeotropes of the above mixtures, but also improved the efficiency of separation. This process could reverse the relative volatility of isopropyl ether and acetone. This reversion was also found in the system of methyl acetate and methanol when nitrobenzene was the agent. However, normal distillation curves were obtained for the system of isopropyl ether and methyl ethyl ketone undergoing extractive distillation. In the system of methyl acetate and methanol, the relative volatility decreased as the agents' carbon number increased when glycols were used as the agents. In addition, the oxygen number and the locations of hydroxyl groups in the glycols used were believed to affect the values of relative volatility. An appreciable amount of agent must be maintained in the column to affect separation. When dimethyl sulfoxide was an agent for the three systems studied, the relative volatility increased as the addition rate increased.
    [Show full text]
  • Development of a Process for N-Butanol Recovery from Abe
    937 A publication of CHEMICAL ENGINEERING TRANSACTIONS VOL. 74, 2019 The Italian Association of Chemical Engineering Online at www.cetjournal.it Guest Editors: Sauro Pierucci, Jiří Jaromír Klemeš, Laura Piazza Copyright © 2019, AIDIC Servizi S.r.l. ISBN 978-88-95608-71-6; ISSN 2283-9216 DOI: 10.3303/CET1974157 Development of a Process for N-Butanol Recovery from Abe Wastewater Streams by Membrane Technology * Marco Stoller , Marco Bravi, Paola Russo, Roberto Bubbico, Barbara Mazzarotta Sapienza University of Rome, Dept. of Chemical Materials Environmental Engineering, Via Eudossiana 18, 00184 Rome, Italy [email protected] The aceton-butyl-ethanolic fermentation process (ABE) is a biotechnological process that leads to the production of acetone, n-butanol and ethanol (ABE compounds) from glucose sources and amides by use of certain biomasses. The process was developed initially during the middle of the last century and suffers from decline due to the greater petrochemical production of products and the lowering of the costs of the sector. Nowadays, the ABE process is regaining great interest because the fraction with the highest concentration, i.e. n-butanol, is an excellent constituent for biofuels. The ABE process has been optimized over time to obtain maximum yields of n-butanol, but the problem of separating and concentrating the butanol in the outlet stream of the ABE process persists. To allow an adequate use, often distillation by use of more columns is required. Moreover, the contained biomasses and suspended solids, in high quantity, must be eliminated, leading to overall high treatment costs. This work will report the main idea and some preliminary experimental results for the development and application of a process based on membrane technologies, to separate and concentrate the butanol from ABE process streams to sensibly reduce the difficulty to perform a final distillation.
    [Show full text]
  • Assessment of End-Of-Life Opportunities for Reverse Osmosis
    Assessment of End-of-Life Opportunities for Reverse Osmosis Membranes Will Lawler A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy School of Chemical Engineering Faculty of Engineering March 2015 i. Abstract Reverse osmosis (RO) membranes are now core to modern desalination processes and are widely used around the world. Based on the increasing number of desalination plants, and the finite lifespan of the membranes, the resulting number of used RO modules to be discarded is becoming a critical challenge. The overall aim of this study is to identify, develop and assess alternative end-of-life options for used RO elements and investigate the associated technical readiness, environmental impact, financial considerations and legislative challenges. The assessed end-of-life alternatives include, direct reuse of the old membranes within lower throughput systems; chemical conversion into porous, ultrafiltration (UF) like filters; direct reuse or recycling of the various module components; various energy recovery techniques, and landfill disposal. The results show that direct reuse is a promising application that can be utilised with minimal additional treatment or infrastructure; however, module storage techniques are a critical consideration, particularly as membrane drying has a significant and irreversible impact on membrane performance due to pore collapse in the polysulfone support layer. The method for chemical conversion with controlled exposure to NaOCl has been optimised, resulting in promising organic and virus removal properties, comparable to commercially available 10 – 30 kDa molecular weight cut off UF membranes; however, there was significant variation in hydraulic performance, ranging from 8 – 400 L.m-2.h-1.bar-1.
    [Show full text]
  • Flash Column Chromatography Guide
    8.9 - Flash Column Chromatography Guide Overview: Flash column chromatography is a quick and (usually) easy way to separate complex mixtures of compounds. We will be performing relatively large scale separations in 5.301, around 1.0 g of compound. Columns are often smaller in scale than this and some of you will experience these once you move into the research lab. Column chromatography uses the same principles discussed in the TLC Handout, but can be used on a preparative scale. We are running flash columns since we will use compressed air to push the solvent through the column. This not only helps provide better separation, but also cuts down the amount of time required to run a column. Reading: For an excellent description, see LLP pages 205 - 214. Preparing and Running a Flash Column: 1) Determine the dry, solvent-free weight of the mixture that you want to separate. 2) Determine the solvent system for the column by using TLC (see TLC Handout). You should aim for Rf values between 0.2 and 0.3. If your mixture is complicated then this may not be possible. In complex cases, you will probably have to resort to gradient elution. This simply means that you increase the polarity of the solvent running through the column (eluent) throughout the course of the purification. This technique will be described in more detail later in the handout, but for the TLC analysis you should determine which solvent systems put the different spots in the 0.2 to 0.3 Rf range. 3) Determine the method of application to the column.
    [Show full text]
  • FUGACITY It Is Simply a Measure of Molar Gibbs Energy of a Real Gas
    FUGACITY It is simply a measure of molar Gibbs energy of a real gas . Modifying the simple equation for the chemical potential of an ideal gas by introducing the concept of a fugacity (f). The fugacity is an “ effective pressure” which forces the equation below to be true for real gases: θθθ f µµµ ,p( T) === µµµ (T) +++ RT ln where pθ = 1 atm pθθθ A plot of the chemical potential for an ideal and real gas is shown as a function of the pressure at constant temperature. The fugacity has the units of pressure. As the pressure approaches zero, the real gas approach the ideal gas behavior and f approaches the pressure. 1 If fugacity is an “effective pressure” i.e, the pressure that gives the right value for the chemical potential of a real gas. So, the only way we can get a value for it and hence for µµµ is from the gas pressure. Thus we must find the relation between the effective pressure f and the measured pressure p. let f = φ p φ is defined as the fugacity coefficient. φφφ is the “fudge factor” that modifies the actual measured pressure to give the true chemical potential of the real gas. By introducing φ we have just put off finding f directly. Thus, now we have to find φ. Substituting for φφφ in the above equation gives: p µ=µ+(p,T)θ (T) RT ln + RT ln φ=µ (ideal gas) + RT ln φ pθ µµµ(p,T) −−− µµµ(ideal gas ) === RT ln φφφ This equation shows that the difference in chemical potential between the real and ideal gas lies in the term RT ln φφφ.φ This is the term due to molecular interaction effects.
    [Show full text]
  • Settling-Thickening Tanks
    Chapter 6 Settling-Thickening Tanks Pierre-Henri Dodane and Magalie Bassan Technology Learning Objectives • Understand in what contexts settling-thickening tanks are an appropriate treatment technology. • Understand the fundamental mechanisms of how settling-thickening tanks function. • Have an overiew of potential advantages and disadvantages of operating a settling-thickening tank. • Know the appropriate level of operations, maintenance and monitoring necessary to achieve solids-liquid separation in settling-thickening tanks. • Be able to design a settling-thickening tank to achieve the desired treatment goal. 6.1 INTRODUCTION Settling-thickening tanks are used to achieve separation of the liquid and solid fractions of faecal sludge (FS). They were fi rst developed for primary wastewater treatment, and for clarifi cation following secondary wastewater treatment, and it is the same mechanism for solids-liquid separation as that employed in septic tanks. Settling-thickening tanks for FS treatment are rectangular tanks, where FS is discharged into an inlet at the top of one side and the supernatant exits through an outlet situated at the opposite side, while settled solids are retained at the bottom of the tank, and scum fl oats on the surface (Figure 6.1). During the retention time, the heavier particles settle out and thicken at the bottom of the tank as a result of gravitational forces. Lighter particles, such as fats, oils and grease, fl oat to the top of the tank. As solids are collected at the bottom of the tank, the liquid supernatant is discharged through the outlet. Quiescent hydraulic fl ows are required, as the designed rates of settling, thickening and fl otation will not occur with turbulent fl ows.
    [Show full text]
  • Stormwater Total Suspended Solids Removal Using a Coalescing Plate
    Stormwater Total Suspended Solids Removal using a Coalescing Plate Separator Prepared for Jensen Precast and Mohr Separations Research, Inc. by Portland State University Table of Contents Abstract .....................................................................................................................2 Background ............................................................................................................... 2 Problem Statement and Objectives .......................................................................... 3 Experimental Testing Procedure .............................................................................. 4 Results .......................................................................................................................5 Conclusion ................................................................................................................ 9 References ............................................................................................................... 10 Appendix ................................................................................................................. 11 List of Figures Figure 1. Box plots for influent/effluent TSS concentrations ................................. 3 Figure 2. Photograph of setup ................................................................................. 4 Figure 3. Schematic drawing of setup ..................................................................... 4 Figure 4. Typical particle size distribution for U.S Silica
    [Show full text]
  • By a 965% ATT'ys
    July 19, 1960 A. WATZL ETAL 2,945,788 PROCESS FOR THE PURIFICATION OF DIMETHYLTEREPHTHALATE Filed Nov. 19, l956 AZEOTROPE DISTILLATE CONDENSER CONDENSED WACUUM DISTILLATE DRY DISTILLATION MXTURE N2 COLUMN MPURE - SOD WACUUMFILTER ETHYLENE DMETHYL DMETHYL GLYCOL TEREPHTHALATE TEREPHTHALATE ETHYLENE GLYCOL INVENTORS: ANTON WATZL by aERHARD 965% SIGGEL ATT'YS 2,945,788 Patented July 19, 1960 2 phthalate is immediately suitable for reesterification or Subsequent polycondensation to polyethylene terephthal 2,945,788 ate. There are gained polycondensates of high degree of PROCESS FOR THE PURIFICATION OF viscosity with K values from 50 to 57. DMETHYLTEREPHTHALATE The best mode contemplated for practicing the inven Anton Watz, Kleinwallstadt (Ufr), and Erhard Siggel, tion involves the use of ethylene glycol as the aliphatic Laudenbach (Main), Germany, assignors to Vereinigte glycol. The following is a specific illustration thereof. Glanzstoff-Fabriken A.G., Wuppertal-Elberfeld, Ger Example many Thirty grams of crude dimethylterephthalate are mixed Filed Nov.19, 1956, Ser. No. 622,778 in a flask with 270 grams of ethylene glycol and azeo tropically distilled with the introduction of dry nitrogen 4 Claims. (C. 202-42) in a column of 30 cm. at about 44 Torr (1 Torr equals 1 mm. Hg). The azeotrope goes over at about 120° C. i This invention, in general, relates to production of into a cooled condenser. The dimethylterephthalate dimethylterephthalate and more particularly to the puri 5 separated from the glycol by vacuum filtering can be fication thereof. used immediately for reesterification or for polyconden The purification of dimethylterephthalate can be car sation. This process is illustrated in the flow sheet of ried out either by distillation or by recrystallization from the accompanying drawing.
    [Show full text]
  • SEPARATION PROCESS DRYING Part 1
    SEPARATION PROCESS DRYING Part 1 by Zulkifly bin Jemaat Faculty of Chemical and Natural Resources Engineering email: [email protected] Introduction • Drying – removal of relatively small amounts of water (or organic liquid) from material – water is removed as a vapor by air • Evaporation – removal of relatively large amounts of water from material – water is removed as vapor at its boiling point • Water also can be removed mechanically from solid materials by means of presses, centrifuging and other methods • Drying is usually the final processing step before packaging and makes many material more suitable for handling (i.e. soap powder, dye, etc.) • Drying or dehydration of biological materials (especially food) is used as a preservation techniques. • Microorganisms are not active when the water content is less than 10%, normally foods are dried less than 5% water content to preserve flavor and nutrition. • Freeze-dried for biological & pharmaceuticals materials which may not be heated for ordinary drying 2 Methods of Drying • Based on operation – Batch - material is inserted into the drying equipment and drying proceeds for given period of time. – Continuous - material is continuously added to the dryer and dried material continuously removed. • Based on physical conditions used to add heat or remove water vapor – Direct contact with heated air at atmospheric pressure, and water vapor formed is removed by the air. – Vacuum drying – evaporation is enhanced by lowering the pressure over the wet material and heat may be added by direct contact with a metal tray holding the wet material or by radiation (IR). – Freeze drying – Low pressures and temperatures are employed to cause the water to sublime from a solid state (ice).
    [Show full text]
  • Heterogeneous Azeotropic Distillation
    PROSIMPLUS APPLICATION EXAMPLE HETEROGENEOUS AZEOTROPIC DISTILLATION EXAMPLE PURPOSE This example illustrates a high purity separation process of an azeotropic mixture (ethanol-water) through heterogeneous azeotropic distillation. This process includes distillation columns. Additionally these rigorous multi- stage separation modules are part of a recycling stream, demonstrating the efficiency of ProSimPlus convergence methods. Specifications are set on output streams in order to insure the required purity. This example illustrates the way to set "non-standard" specifications in the multi-stage separation modules. Three phase calculations (vapor-liquid- liquid) are done with the taken into account of possible liquid phase splitting. ACCESS Free-Internet Restricted to ProSim clients Restricted Confidential CORRESPONDING PROSIMPLUS FILE PSPS_EX_EN-Heterogeneous-Azeotropic-Distillation.pmp3 . Reader is reminded that this use case is only an example and should not be used for other purposes. Although this example is based on actual case it may not be considered as typical nor are the data used always the most accurate available. ProSim shall have no responsibility or liability for damages arising out of or related to the use of the results of calculations based on this example. Copyright © 2009 ProSim, Labège, France - All rights reserved www.prosim.net Heterogeneous azeotropic distillation Version: March, 2009 Page: 2 / 12 TABLE OF CONTENTS 1. PROCESS MODELING 3 1.1. Process description 3 1.2. Process flowsheet 5 1.3. Specifications 6 1.4. Components 6 1.5. Thermodynamic model 7 1.6. Operating conditions 7 1.7. "Hints and Tips" 9 2. RESULTS 9 2.1. Comments on results 9 2.2. Mass and energy balances 10 2.3.
    [Show full text]
  • Method 3520C: Continuous Liquid-Liquid Extraction, Part of Test
    METHOD 3520C CONTINUOUS LIQUID-LIQUID EXTRACTION 1.0 SCOPE AND APPLICATION 1.1 This method describes a procedure for isolating organic compounds from aqueous samples. The method also describes concentration techniques suitable for preparing the extract for the appropriate determinative steps described in Sec. 4.3 of Chapter Four. 1.2 This method is applicable to the isolation and concentration of water-insoluble and slightly soluble organics in preparation for a variety of chromatographic procedures. 1.3 Method 3520 is designed for extraction solvents with greater density than the sample. Continuous extraction devices are available for extraction solvents that are less dense than the sample. The analyst must demonstrate the effectiveness of any such automatic extraction device before employing it in sample extraction. 1.4 This method is restricted to use by or under the supervision of trained analysts. Each analyst must demonstrate the ability to generate acceptable results with this method. 2.0 SUMMARY OF METHOD 2.1 A measured volume of sample, usually 1 liter, is placed into a continuous liquid-liquid extractor, adjusted, if necessary, to a specific pH (see Table 1), and extracted with organic solvent for 18 - 24 hours. 2.2 The extract is dried, concentrated (if necessary), and, as necessary, exchanged into a solvent compatible with the cleanup or determinative method being employed (see Table 1 for appropriate exchange solvents). 3.0 INTERFERENCES 3.1 Refer to Method 3500. 3.2 The decomposition of some analytes has been demonstrated under basic extraction conditions required to separate analytes. Organochlorine pesticides may dechlorinate, phthalate esters may exchange, and phenols may react to form tannates.
    [Show full text]
  • Enhanced Distillation • Use of Triangular Graphs
    Lecture 15. Enhanced Distillation and Supercritical Extraction (1) [Ch. 11] • Enhanced Distillation • Use of Triangular Graphs - Zeotropic mixture -Mixture forming one minimum-boiling azeotrope - Mixture forming two minimum-boiling azeotropes • Residue-Curve Maps • Distillation-Curve Maps • Product-Composition Regions at Total Reflux Enhanced Distillation • Cases when ordinary distillation is not economical - Boiling point difference between components is less than 50℃ - Relative volatility is less than 1.10 - Mixture forms an azeotrope • Enhanced distillation - Extractive distillation : adding a large amount of solvent - Salt distillation : adding a soluble , ionic salt - Pressure-swing distillation : operating at two different pressures - Homogeneous azeotropic distillation : adding an entrainer - Heterogeneous azeotropic distillation : adding an entrainer - Reactive distillation : adding a separating agent to react selectively and reversibly with feed component(s) Zeotropic vs. Azeotropic Systems Binary zeotropic system Binary azeotropic system P = constant AtAzeotrope C T-y T-x Pure B xA, yA Pure A Use of Triangular Graphs • Triangular vapor-liquid diagram for ternary mixture - Too complex to understand • Plot with only equilibr ium liquid composition fofoatenayr a ternary mixture - Easy to understand -Convenient to use - Provide useful information in distillation of ternary components . Residue curve . Distill ati on curve Distillation Curves for Ternary Systems Each curve in each diagram is the locus of possible equilibrium liquid-phase
    [Show full text]