Thermodynamic Modelling of Aqueous Sulfuric Acid

Hannu Sippola

Thermodynamic Modelling of Aqueous Sulfuric Acid

Julkaisun otsikon käännös: Rikkihappo-vesiliuoksen termodynaaminen mallinnus

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Rikkihappo on merkittävä kemikaali sekä teollisuuden että ympäristön suojelun kannalta, joten tarve yksinkertaiselle termodynaamiselle mallille on ilmeinen. Tämän väitöskirjan tavoitteena oli luoda rikkihapon vesiliuokselle termodynaaminen malli, jossa käytettävien malliparametrien lukumäärä on kohtuullinen. Merkittävä seikka rikkihapon vesiliuoksen mallintamisessa on toisen dissosioitumisvakion, K2, arvo. Tässä väitöskirjassa havaittiin, että rikkihapon vesiliuos voidaan mallittaa yhtä hyvin usealla eri dissosioitumisvakion yhtälöllä. Syyksi paljastui bisulfaatti- (HSO4[-]) ja sulfaatti- (SO4[2–]) ionien välinen tasapaino, joka lisää termodynaamiseen kuvaukseen sisäisen riippuvuuden. Dissosioitumisvakion yhtälö on siksi otettava mukaan parametrien sovitukseen. Rikkihapon vesiliuos mallinnettiin Pitzerin yhtälön avulla. Sekä K2 -yhtälö että Pitzerin parametrit sovitettiin yhtä aikaa. Vaihtelemalla sovitukseen mukaan otettuja kokeellisia tuloksia ja parametrien lämpötilariippuvuutta havaittiin, että rikkihapon vesiliuoksen termo-dynaamiseen kuvaukseen lämpötila-alueella 0–170°C tarvitaan vain neljä Pitzerin parametria, joissa on yhteensä kahdeksan sovitettavaa termiä. Mallilla lasketut termodynaamiset ominaisuudet ovat sopusoinnussa sekä kirjallisuudesta löytyneiden että muilla moni-mutkaisemmilla Pitzer malleilla laskettujen arvojen kanssa. Lisäksi tutkittiin äskettäin kehitetyn NPL Pitzer yhtälön soveltuvuutta ja havaittiin, että sen avulla voidaan kuvata sekä aktiivisuuskerroin että osmoottinen kerroin laajalla lämpötila-alueella vain viidellä parametrilla aina 80p% rikkihappoon asti.

Julkaisun otsikon käännös	Rikkihappo-vesiliuoksen termodynaaminen mallinnus
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Taskinen, Pekka, Vastuuprofessori Taskinen, Pekka, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-6150-4
Sähköinen ISBN	978-952-60-6151-1
Tila	Julkaistu - 2015
OKM-julkaisutyyppi	G5 Tohtorinväitöskirja (artikkeli)

Tutkimusalat

termodynaamiset ominaisuudet
Pitzerin yhtälö
aktiivisuuskerroin
osmoottinen kerroin
sähkökemiallinen kenno

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-6151-1Lisenssi: Määrittelemätön

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@phdthesis{238461f147b24f799597f25bb96f8aeb,

title = "Thermodynamic Modelling of Aqueous Sulfuric Acid",

abstract = "Aqueous sulfuric acid is an important chemical not only for the industry but also with respect to the environment. A need for a simple thermodynamic model is obvious. The purpose of this thesis was to create a thermodynamic model for aqueous sulfuric acid with a reasonable number of parameters. A key factor in modelling aqueous sulfuric acid is the correct value for the second dissociation constant, K2. In this thesis it was discovered that several equations describing K2, can model aqueous sulfuric acid equally well. The reason for this was identified as the equilibrium between sulfate (SO4[2-]) and bisulfate (HSO4[-]) ions which creates an internal redundancy in the thermodynamic description. Thus, the equation for K2 must be included in the assessment of aqueous sulfuric acid. The thermodynamic properties of aqueous sulfuric acid were modelled with the Pitzer equation. Both the second dissociation constant K2 for sulfuric acid and Pitzer parameters were fitted simultaneously. After variation of the experimental data used and the temperature dependencies of the Pitzer parameters, it was found that only four Pitzer parameters with eight fitted terms are required to cover the thermodynamic properties of aqueous sulfuric acid over a temperature range of 0–170°C. The obtained thermodynamic properties are in good agreement with literature values as well as with other Pitzer based and more complex thermodynamic models for aqueous sulfuric acid. The recent version of Pitzer equation, NPL Pitzer, was also tested. It was found to be capable of predicting activity and osmotic coefficient using only five parameters up to 80w% solution over a wide temperature range.",

keywords = "thermodynamic properties, Pitzer model, activity coefficient, osmotic coefficient, electrochemical cell, termodynaamiset ominaisuudet, Pitzerin yht{\"a}l{\"o}, aktiivisuuskerroin, osmoottinen kerroin, s{\"a}hk{\"o}kemiallinen kenno, thermodynamic properties, Pitzer model, activity coefficient, osmotic coefficient, electrochemical cell",

author = "Hannu Sippola",

year = "2015",

language = "English",

isbn = "978-952-60-6150-4",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "44",

address = "Finland",

school = "Aalto University",

}

TY - THES

T1 - Thermodynamic Modelling of Aqueous Sulfuric Acid

AU - Sippola, Hannu

PY - 2015

Y1 - 2015

N2 - Aqueous sulfuric acid is an important chemical not only for the industry but also with respect to the environment. A need for a simple thermodynamic model is obvious. The purpose of this thesis was to create a thermodynamic model for aqueous sulfuric acid with a reasonable number of parameters. A key factor in modelling aqueous sulfuric acid is the correct value for the second dissociation constant, K2. In this thesis it was discovered that several equations describing K2, can model aqueous sulfuric acid equally well. The reason for this was identified as the equilibrium between sulfate (SO4[2-]) and bisulfate (HSO4[-]) ions which creates an internal redundancy in the thermodynamic description. Thus, the equation for K2 must be included in the assessment of aqueous sulfuric acid. The thermodynamic properties of aqueous sulfuric acid were modelled with the Pitzer equation. Both the second dissociation constant K2 for sulfuric acid and Pitzer parameters were fitted simultaneously. After variation of the experimental data used and the temperature dependencies of the Pitzer parameters, it was found that only four Pitzer parameters with eight fitted terms are required to cover the thermodynamic properties of aqueous sulfuric acid over a temperature range of 0–170°C. The obtained thermodynamic properties are in good agreement with literature values as well as with other Pitzer based and more complex thermodynamic models for aqueous sulfuric acid. The recent version of Pitzer equation, NPL Pitzer, was also tested. It was found to be capable of predicting activity and osmotic coefficient using only five parameters up to 80w% solution over a wide temperature range.

AB - Aqueous sulfuric acid is an important chemical not only for the industry but also with respect to the environment. A need for a simple thermodynamic model is obvious. The purpose of this thesis was to create a thermodynamic model for aqueous sulfuric acid with a reasonable number of parameters. A key factor in modelling aqueous sulfuric acid is the correct value for the second dissociation constant, K2. In this thesis it was discovered that several equations describing K2, can model aqueous sulfuric acid equally well. The reason for this was identified as the equilibrium between sulfate (SO4[2-]) and bisulfate (HSO4[-]) ions which creates an internal redundancy in the thermodynamic description. Thus, the equation for K2 must be included in the assessment of aqueous sulfuric acid. The thermodynamic properties of aqueous sulfuric acid were modelled with the Pitzer equation. Both the second dissociation constant K2 for sulfuric acid and Pitzer parameters were fitted simultaneously. After variation of the experimental data used and the temperature dependencies of the Pitzer parameters, it was found that only four Pitzer parameters with eight fitted terms are required to cover the thermodynamic properties of aqueous sulfuric acid over a temperature range of 0–170°C. The obtained thermodynamic properties are in good agreement with literature values as well as with other Pitzer based and more complex thermodynamic models for aqueous sulfuric acid. The recent version of Pitzer equation, NPL Pitzer, was also tested. It was found to be capable of predicting activity and osmotic coefficient using only five parameters up to 80w% solution over a wide temperature range.

KW - thermodynamic properties

KW - Pitzer model

KW - activity coefficient

KW - osmotic coefficient

KW - electrochemical cell

KW - termodynaamiset ominaisuudet

KW - Pitzerin yhtälö

KW - aktiivisuuskerroin

KW - osmoottinen kerroin

KW - sähkökemiallinen kenno

KW - thermodynamic properties

KW - Pitzer model

KW - activity coefficient

KW - osmotic coefficient

KW - electrochemical cell

M3 - Doctoral Thesis

SN - 978-952-60-6150-4

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Thermodynamic Modelling of Aqueous Sulfuric Acid

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