Thermodynamics, Experimental, and Modelling of Aqueous Electrolyte and Amino Acid Solutions

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Thermodynamics, Experimental, and Modelling of Aqueous Electrolyte and Amino Acid
Solutions
Breil, Martin Peter
Publication date:
2001
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Citation (APA):
Breil, M. P. (2001). Thermodynamics, Experimental, and Modelling of Aqueous Electrolyte and Amino Acid
Solutions.

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Thermodynamics, Experimental, and
Modelling of Aqueous Electrolyte and
Amino Acid Solutions
Martin P. Breil
2001
IVC-SEP
Department of Chemical Engineering
Technical University of Denmark
DK-2800 Kongens Lyngby, Denmark

Preface iii
Preface
This thesis is submitted as a partial fulfilment of the Ph.D. degree at the Technical University
ofDenmark.
The project, granted by the IVC-SEP, has been carried out from October 1998 to September
2001attheDepartmentofChemicalEngineering, TechnicalUniversityof Denmarkunderthe
supervisionofJørgenMollerup. Iwishtothank mysupervisorforhis guidance,hisideas, and
hisabilitytoencourageme.
I would also like to thank Kaj Thomsen for our many discussions on matters of electrolytes
andforlettingmeborrowarticlesfromhisextensivelibrarywhennecessary.
My thanks also extend to the people that I met during my sabbatical at the Kluyver
Laboratoryfor Biotechnology, Delft Universityof Technologyin the Netherlands. Especially,
Luuk van der Wielen and Marcel Ottens who made the stay possible, and Susanne Rudolph
whowasmysupervisor.
Finally, I wish to thank the staff of the IVC-SEP and of the Kluyver Laboratory for making
thepastthree yearssosuccessful.
MartinPeterBreil
KongensLyngby,September2001
Preface iv
Summary v
Summary
The thesis addresses the thermodynamics involved when describing the properties of
solutions of amino acids and dipeptides. Furthermore, it presents the solubilitymeasurements
of two dipeptides (glycylglycine and glycyl-L-alanine) in aqueous salt solutions and electrode
potentialmeasurementsofthesametwodipeptidesinaqueousNaClsolutions.
Chapter 1 is an introduction to the chemistry of amino acids and dipeptides. It presents the
principles of the Bjerrum diagram and the isoelectric point of a polyvalent compound. The
industrialandmedicaluseofaminoacidsisbrieflytouched.
Chapter 2 is the main thermodynamic chapter where most of the required properties are
presented and defined. The schism of defining the activity coefficient at infinite dilution in a
non-binarymixtureispointedoutaswellasthealternativetypesofconcentrationscales.
In Chapter 3 the four most common types for experimental methods for determination of
solvent or solute activity are described by using the thermodynamic properties of the
proceedingchapter.
Chapter 4 focuses on the thermodynamics of electrochemistry and is based on the principles
of Chapter 2. As an example experimental data obtained on a so-called Harned cell is
presented.
Chapter 5 presents the results of the experimental work carried out during the sabbatical,
namely the solubility of glycylglycine and glycyl-L-alanine in aqueous NaCl, Na2SO4, and
(NH ) SO solutions - and electrode potential measurements with ISE's of solutions
4 2 4
containingNaClandthetwodipeptidesmentionedabove.
Chapter 6 presents the basis for the so-called McMillan-Mayer framework in relation to
statisticalthermodynamicsandinrelationtotheusual(Lewis-Randall)framework.
InChapter7,theosmoticequilibriumandlimitationsofthevan'tHoffequationareexamined.
In Chapter 8, the continuum concept is described and related to the McMillan-Mayer
framework. Different types of electrolyte models are presented: Debye-Hückel, extended
UNIQUAC,andHS-MSA.Theusuallyapproachtomodelsolubilitydataispresented.
Summary vi
In Chapter 9, the modelling results of the extended UNIQUAC model on binary and ternary
aqueous solutions containing amino acid are presented. The solubility prediction of the
extendedUNIQUACmodelcommented.Furthermore,ananalysisofthe behaviouroftheHS-
MSAmodelinelectrolytesolutionsiscarriedoutandcommented.
Chapter10isgivinganoverviewoftheextentofthedatabasecreatedduringthisproject.
Chapter11isaconclusion,summarisingtheresultsachievedduringthisproject.
Three appendices are included: one on Euler's theorem, one on equilibrium, and one on
electrostatics.
Resumépådansk vii
Resumé på dansk
Afhandlingen omhandler den termodynamik, der er involveret, når man skal beskrive
egenskaberne af opløsninger af aminosyrer og dipeptider. Ydermere præsenteres opløse-
lighedsmålinger af to dipeptider (glycylglycin og glycyl-L-alanin) i vandige salt-opløsninger
ogmålingerafelektrode-potentialerafdesammetodipeptiderivandigNaClopløsninger.
Kapitel 1 er en introduktion til aminosyrer og dipeptiders kemi. Det præsenterer principperne
ved Bjerrum-diagrammerne og det isoelektriske punkt af et fler-valent stof. Den industrielle
ogmedicinalebrugafaminosyrererkortberørt.
Kapitel 2 er det centrale termodynamiske kapitel, hvor de fleste af de krævede egenskaber er
præsenteret og defineret. Skismaet ved definitionen af aktivitetskoefficienten ved uendelig
fortyndingienikke-binærblandingerbelyst,ligeledessomalternativekoncentrationsskalaer.
I Kapitel 3 er de fire mest almindelige typer af eksperimentelle metoder til bestemmelse af
aktiviteten af opløsningsmidlet eller det opløste stof beskrevet af hjælp af de termodynamiske
egenskaberfradetforegåendekapitel.
Kapitel 4 fokuserer på termodynamikken i elektrokemien og er baseret på principperne fra
Kapitel2. SometeksempelereksperimentelledatafraensåkaldtHarned-cellepræsenteret.
Kapitel 5 præsenterer resultaterne af det eksperimentelle arbejde, som er udført under det
eksterne forskningsophold, nemlig opløseligheden af glycylglycin og glycyl-L-alanin i vandig
NaCl, Na SO og (NH ) SO opløsninger - og målinger af elektrode-potentialer med
2 4 4 2 4
ionselektiveelektroderiopløsningerindeholdendeNaClogdetoovennævntedipeptider.
Kapitel 6 præsenterer grundlaget for det såkaldte McMillan-Mayer framework i relation til
statistisktermodynamikogirelationtildetsædvanlige(Lewis-Randall)framework.
IKapitel7forklaresdenosmotiskeligevægtogbegrænsningerneafvan'tHoff-ligningen.
I Kapitel 8 beskrives kontinuum-konceptet og relateres til McMillan-Mayer framework'et.
Forskellige typer af elektrolyt-modeller er præsenterede: Debye-Hückel, udvidet UNIQUAC
ogHS-MSA.Densædvanligemåde,hvorpåopløselighedsdatamodelleres,erpræsenteret.
I Kapitel 9 præsenteres modelleringsresultaterne fra den udvidede UNIQUAC-model på
binære og ternære vandige opløsninger indeholdende aminosyre. Den udvidede UNIQUAC-
Resumépådansk viii
models forudsagte opløseligheder er kommenteret. Ydermere er der udført en analyse af
forløbetafHS-MSA-modellenielektrolyt-opløsningerogkommenteret.
Kapitel10giveretoverblikoveromfangetafdendatabase,somerskabtiløbetafprojektet.
Kapitel11erenkonklusion,deropsummererdeopnåederesultater.
Treappendiceserinkluderede:étomEuler'stheorem,étomligevægtogétomelektrostatik.
TableofContents ix
Table of Contents
Preface................................................................................................................................... i
Summary............................................................................................................................... iii
Resumépådansk................................................................................................................... v
TableofContents.................................................................................................................. vii
1.IntroductiontotheChemistryofAminoAcids................................................................. 1
1.1Structureofaminoacids.................................................................................................................. 1
1.2Stereochemistry............................................................................................................................... 2
1.3TheinfluenceofpH......................................................................................................................... 2
1.4Theisoelectricpoint......................................................................................................................... 6
1.5Theuseofaminoacids.................................................................................................................... 9
2.BasicThermodynamics..................................................................................................... 13
2.1States................................................................................................................................................ 13
2.2TheresidualpropertyoftheGibbsenergy....................................................................................... 14
2.3Purephase........................................................................................................................................ 14
2.4Theonespeciesinthepurephase.................................................................................................... 14
2.5Mixture............................................................................................................................................ 16
2.6Speciesinthemixture...................................................................................................................... 17
2.7Referencestate................................................................................................................................. 18
2.8Idealsolution................................................................................................................................... 19
2.9Definitionoftheactivitycoefficient................................................................................................ 19
2.10TheexcesspropertyoftheGibbsenergy....................................................................................... 19
2.11Thereferencestatefortheasymmetricactivitycoefficient........................................................... 21
2.12Thereferencestateforthemolalityactivitycoefficient................................................................ 23
2.13Thereferencestateforthemolarityactivitycoefficient................................................................ 24
3.ThermodynamicsofExperimentalMethods..................................................................... 27
3.1Thethermodynamicsofvapourpressuremeasurements................................................................. 27
3.2Simplificationsonthevapourpressuremeasurements.................................................................... 29
3.3Thethermodynamicsoffreezingpointdepressionmeasurements.................................................. 29
3.4Simplificationsonfreezingpointdepressionmethods.................................................................... 31
3.5Boilingpointelevationmeasurements............................................................................................. 32
3.6Thethermodynamicsofisopiesticmeasurements............................................................................ 32
4.Electrochemistry................................................................................................................ 35
4.1Electrochemicalequilibrium............................................................................................................ 35
4.2Equilibriumofanelectrochemicalcell............................................................................................ 37