Density functional theory studies on the formation of CaCO3 depositions on cristobalite, diamond, and titanium carbide surfaces

Eini Puhakka, Markus Riihimäki, Tiina M. Pääkkönen, Riitta L. Keiski

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)

Abstract

Fouling caused by inversely soluble salts, like CaCO3, is a general problem on heat transfer surfaces. Carbonate depositions are typically cleanable with acids, but costs of energy losses, operation, and maintenance are significant. In this study, formation of CaCO3 depositions was investigated on cristobalite, diamond, and titanium carbide surfaces. The aim of the study was to clarify the detailed mechanisms of crystallization fouling during the initiation on crystalline phases existing in materials used as coatings (SiOx, TiCN, diamond-like carbon [DLC]), and to compare the results to the fouling mechanism of stainless steel (Cr2O3). In experimental studies of fouling, detailed mechanisms and description of sterical and electrostatic factors of surfaces are often very much simplified. In this work, molecular modeling was used to describe surface structures and to investigate the effect of process fluid (water) on the structures. The adsorption of water can be molecular or dissociative. During the dissociative adsorption, hydroxylated surface structures are formed. The existence of hydroxyl groups on the surfaces has an effect on the fouling mechanism. First, the dissociation probability of water on different surfaces was determined according to the adsorption mechanism and energies, and then the attachment of CaCO3 onto optimized and hydroxylated surfaces was investigated. As a result, the formation mechanism with detailed intermediate steps of CaCO3 deposition was obtained. The fouling takes place via hydrogen carbonate intermediates, but the final deposition structure was found to vary between surfaces.
Original languageEnglish
Pages (from-to)282-290
JournalHeat Transfer Engineering
Volume32
Issue number3-4
DOIs
Publication statusPublished - 2011
MoE publication typeA1 Journal article-refereed

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titanium carbides
Titanium carbide
Diamond
Silicon Dioxide
carbides
Density functional theory
Fouling
Diamonds
fouling
diamonds
density functional theory
Adsorption
Surface structure
Water
Carbonates
adsorption
carbonates
Molecular modeling
Stainless Steel
water

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Puhakka, Eini ; Riihimäki, Markus ; Pääkkönen, Tiina M. ; Keiski, Riitta L. / Density functional theory studies on the formation of CaCO3 depositions on cristobalite, diamond, and titanium carbide surfaces. In: Heat Transfer Engineering. 2011 ; Vol. 32, No. 3-4. pp. 282-290.
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abstract = "Fouling caused by inversely soluble salts, like CaCO3, is a general problem on heat transfer surfaces. Carbonate depositions are typically cleanable with acids, but costs of energy losses, operation, and maintenance are significant. In this study, formation of CaCO3 depositions was investigated on cristobalite, diamond, and titanium carbide surfaces. The aim of the study was to clarify the detailed mechanisms of crystallization fouling during the initiation on crystalline phases existing in materials used as coatings (SiOx, TiCN, diamond-like carbon [DLC]), and to compare the results to the fouling mechanism of stainless steel (Cr2O3). In experimental studies of fouling, detailed mechanisms and description of sterical and electrostatic factors of surfaces are often very much simplified. In this work, molecular modeling was used to describe surface structures and to investigate the effect of process fluid (water) on the structures. The adsorption of water can be molecular or dissociative. During the dissociative adsorption, hydroxylated surface structures are formed. The existence of hydroxyl groups on the surfaces has an effect on the fouling mechanism. First, the dissociation probability of water on different surfaces was determined according to the adsorption mechanism and energies, and then the attachment of CaCO3 onto optimized and hydroxylated surfaces was investigated. As a result, the formation mechanism with detailed intermediate steps of CaCO3 deposition was obtained. The fouling takes place via hydrogen carbonate intermediates, but the final deposition structure was found to vary between surfaces.",
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Density functional theory studies on the formation of CaCO3 depositions on cristobalite, diamond, and titanium carbide surfaces. / Puhakka, Eini; Riihimäki, Markus; Pääkkönen, Tiina M.; Keiski, Riitta L.

In: Heat Transfer Engineering, Vol. 32, No. 3-4, 2011, p. 282-290.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Density functional theory studies on the formation of CaCO3 depositions on cristobalite, diamond, and titanium carbide surfaces

AU - Puhakka, Eini

AU - Riihimäki, Markus

AU - Pääkkönen, Tiina M.

AU - Keiski, Riitta L.

N1 - Project code: 8991

PY - 2011

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N2 - Fouling caused by inversely soluble salts, like CaCO3, is a general problem on heat transfer surfaces. Carbonate depositions are typically cleanable with acids, but costs of energy losses, operation, and maintenance are significant. In this study, formation of CaCO3 depositions was investigated on cristobalite, diamond, and titanium carbide surfaces. The aim of the study was to clarify the detailed mechanisms of crystallization fouling during the initiation on crystalline phases existing in materials used as coatings (SiOx, TiCN, diamond-like carbon [DLC]), and to compare the results to the fouling mechanism of stainless steel (Cr2O3). In experimental studies of fouling, detailed mechanisms and description of sterical and electrostatic factors of surfaces are often very much simplified. In this work, molecular modeling was used to describe surface structures and to investigate the effect of process fluid (water) on the structures. The adsorption of water can be molecular or dissociative. During the dissociative adsorption, hydroxylated surface structures are formed. The existence of hydroxyl groups on the surfaces has an effect on the fouling mechanism. First, the dissociation probability of water on different surfaces was determined according to the adsorption mechanism and energies, and then the attachment of CaCO3 onto optimized and hydroxylated surfaces was investigated. As a result, the formation mechanism with detailed intermediate steps of CaCO3 deposition was obtained. The fouling takes place via hydrogen carbonate intermediates, but the final deposition structure was found to vary between surfaces.

AB - Fouling caused by inversely soluble salts, like CaCO3, is a general problem on heat transfer surfaces. Carbonate depositions are typically cleanable with acids, but costs of energy losses, operation, and maintenance are significant. In this study, formation of CaCO3 depositions was investigated on cristobalite, diamond, and titanium carbide surfaces. The aim of the study was to clarify the detailed mechanisms of crystallization fouling during the initiation on crystalline phases existing in materials used as coatings (SiOx, TiCN, diamond-like carbon [DLC]), and to compare the results to the fouling mechanism of stainless steel (Cr2O3). In experimental studies of fouling, detailed mechanisms and description of sterical and electrostatic factors of surfaces are often very much simplified. In this work, molecular modeling was used to describe surface structures and to investigate the effect of process fluid (water) on the structures. The adsorption of water can be molecular or dissociative. During the dissociative adsorption, hydroxylated surface structures are formed. The existence of hydroxyl groups on the surfaces has an effect on the fouling mechanism. First, the dissociation probability of water on different surfaces was determined according to the adsorption mechanism and energies, and then the attachment of CaCO3 onto optimized and hydroxylated surfaces was investigated. As a result, the formation mechanism with detailed intermediate steps of CaCO3 deposition was obtained. The fouling takes place via hydrogen carbonate intermediates, but the final deposition structure was found to vary between surfaces.

U2 - 10.1080/01457632.2010.495626

DO - 10.1080/01457632.2010.495626

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JO - Heat Transfer Engineering

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