Surface tension alteration on calcite, induced by ion substitution

Hiroshi Sakuma; Martin Peter Andersson; Klaus Bechgaard; Susan Louise Svane Stipp

doi:10.1021/jp411151u

Surface tension alteration on calcite, induced by ion substitution

Hiroshi Sakuma^*, Martin Peter Andersson, Klaus Bechgaard, Susan Louise Svane Stipp

^*Corresponding author for this work

Department of Chemistry

50 Citations (Scopus)

Abstract

The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale, where particles are smaller than the smallest droplet? We investigated the energy required to exchange Mg²⁺ and SO₄ ^2- from aqueous solution into calcite {10.4} surfaces using density functional theory. Mg²⁺ substitution for Ca²⁺ is favored but only when SO₄ ^2- is also present and MgSO₄ incorporates preferentially as ion pairs at solution-calcite interfaces. Mg²⁺ incorporation weakens organic molecule adhesion while strengthening water adsorption so Mg²⁺ substitution renders calcite more water wet. When Mg²⁺ replaces 10% of surface Ca²⁺, the contact angle changes dramatically, by 40 to 70, converting a hydrophobic surface to a mixed wet surface or rendering a mixed wet surface hydrophilic. This increase in water wettability decreases affinity for organic compounds. An important outcome is that we can now explain why oil recovery from carbonate reservoirs is enhanced when both Mg²⁺ and SO₄ ^2- are present in the pore water. Incorporation of MgSO₄ into calcite, which is energetically favored, decreases surface tension and releases polar oil compounds.

Original language	English
Journal	Journal of Physical Chemistry C
Volume	118
Issue number	6
Pages (from-to)	3078-3087
Number of pages	10
ISSN	1932-7447
DOIs	https://doi.org/10.1021/jp411151u
Publication status	Published - 2014

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title = "Surface tension alteration on calcite, induced by ion substitution",

abstract = "The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale, where particles are smaller than the smallest droplet? We investigated the energy required to exchange Mg2+ and SO4 2- from aqueous solution into calcite {10.4} surfaces using density functional theory. Mg2+ substitution for Ca2+ is favored but only when SO4 2- is also present and MgSO4 incorporates preferentially as ion pairs at solution-calcite interfaces. Mg2+ incorporation weakens organic molecule adhesion while strengthening water adsorption so Mg2+ substitution renders calcite more water wet. When Mg2+ replaces 10% of surface Ca2+, the contact angle changes dramatically, by 40 to 70, converting a hydrophobic surface to a mixed wet surface or rendering a mixed wet surface hydrophilic. This increase in water wettability decreases affinity for organic compounds. An important outcome is that we can now explain why oil recovery from carbonate reservoirs is enhanced when both Mg2+ and SO4 2- are present in the pore water. Incorporation of MgSO4 into calcite, which is energetically favored, decreases surface tension and releases polar oil compounds.",

author = "Hiroshi Sakuma and Andersson, {Martin Peter} and Klaus Bechgaard and Stipp, {Susan Louise Svane}",

year = "2014",

doi = "10.1021/jp411151u",

language = "English",

volume = "118",

pages = "3078--3087",

journal = "The Journal of Physical Chemistry Part C",

issn = "1932-7447",

publisher = "American Chemical Society",

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TY - JOUR

T1 - Surface tension alteration on calcite, induced by ion substitution

AU - Sakuma, Hiroshi

AU - Andersson, Martin Peter

AU - Bechgaard, Klaus

AU - Stipp, Susan Louise Svane

PY - 2014

Y1 - 2014

N2 - The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale, where particles are smaller than the smallest droplet? We investigated the energy required to exchange Mg2+ and SO4 2- from aqueous solution into calcite {10.4} surfaces using density functional theory. Mg2+ substitution for Ca2+ is favored but only when SO4 2- is also present and MgSO4 incorporates preferentially as ion pairs at solution-calcite interfaces. Mg2+ incorporation weakens organic molecule adhesion while strengthening water adsorption so Mg2+ substitution renders calcite more water wet. When Mg2+ replaces 10% of surface Ca2+, the contact angle changes dramatically, by 40 to 70, converting a hydrophobic surface to a mixed wet surface or rendering a mixed wet surface hydrophilic. This increase in water wettability decreases affinity for organic compounds. An important outcome is that we can now explain why oil recovery from carbonate reservoirs is enhanced when both Mg2+ and SO4 2- are present in the pore water. Incorporation of MgSO4 into calcite, which is energetically favored, decreases surface tension and releases polar oil compounds.

AB - The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale, where particles are smaller than the smallest droplet? We investigated the energy required to exchange Mg2+ and SO4 2- from aqueous solution into calcite {10.4} surfaces using density functional theory. Mg2+ substitution for Ca2+ is favored but only when SO4 2- is also present and MgSO4 incorporates preferentially as ion pairs at solution-calcite interfaces. Mg2+ incorporation weakens organic molecule adhesion while strengthening water adsorption so Mg2+ substitution renders calcite more water wet. When Mg2+ replaces 10% of surface Ca2+, the contact angle changes dramatically, by 40 to 70, converting a hydrophobic surface to a mixed wet surface or rendering a mixed wet surface hydrophilic. This increase in water wettability decreases affinity for organic compounds. An important outcome is that we can now explain why oil recovery from carbonate reservoirs is enhanced when both Mg2+ and SO4 2- are present in the pore water. Incorporation of MgSO4 into calcite, which is energetically favored, decreases surface tension and releases polar oil compounds.

U2 - 10.1021/jp411151u

DO - 10.1021/jp411151u

M3 - Journal article

AN - SCOPUS:84894099553

SN - 1932-7447

VL - 118

SP - 3078

EP - 3087

JO - The Journal of Physical Chemistry Part C

JF - The Journal of Physical Chemistry Part C

IS - 6

ER -

Surface tension alteration on calcite, induced by ion substitution

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