Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (alpha-FeOOH) nanoparticles

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Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (alpha-FeOOH) nanoparticles. / Persson, Per; Andersson, Tove; Nelson, Hanna; Sjoberg, Staffan; Giesler, Reiner; Lovgren, Lars.

In: Journal of Colloid and Interface Science, Vol. 386, 2012, p. 350-358.

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Persson, Per ; Andersson, Tove ; Nelson, Hanna ; Sjoberg, Staffan ; Giesler, Reiner ; Lovgren, Lars. / Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (alpha-FeOOH) nanoparticles. In: Journal of Colloid and Interface Science. 2012 ; Vol. 386. pp. 350-358.

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TY - JOUR

T1 - Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (alpha-FeOOH) nanoparticles

AU - Persson, Per

AU - Andersson, Tove

AU - Nelson, Hanna

AU - Sjoberg, Staffan

AU - Giesler, Reiner

AU - Lovgren, Lars

PY - 2012

Y1 - 2012

N2 - Typically, a significant fraction of phosphorus in soils is composed of organic phosphates, and this fraction thus plays an important role in the global phosphorus cycle. Here we have studied adsorption of monomethyl phosphate (MMP) to goethite (alpha-FeOOH) as a model system in order to better understand the mechanisms behind adsorption of organic phosphates to soil minerals, and how adsorption affects the stability of these molecules. The adsorption reactions and stability of MMP on goethite were studied at room temperature as a function of pH, time and total concentration of MMP by means of quantitative batch experiments, potentiometry and infrared spectroscopy. MMP was found to be stable at the watergoethite interface within the pH region 3-9 and over extended periods of time, as well as in solution. The infrared spectra indicated that MMP formed three predominating pH-dependent surface complexes on goethite, and that these interacted monodentately with surface Fe. The complexes differed in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The presented surface complexation model was based on the collective spectroscopic and macroscopic results, using the Basic Stern approach to describe the interfacial region. The model consisted of three monodentate inner sphere surface complexes where the MMP complexes were stabilized by hydrogen bonding to a neighboring surface site. The three complexes, which had equal proton content and thus could be defined as surface isomers, were distinguished by the distribution of charge over the O-plane and beta-plane. In the high pH-range, MMP acted as a hydrogen bond acceptor whereas it was a hydrogen bond donor at low pH. (C) 2012 Elsevier Inc. All rights reserved.

AB - Typically, a significant fraction of phosphorus in soils is composed of organic phosphates, and this fraction thus plays an important role in the global phosphorus cycle. Here we have studied adsorption of monomethyl phosphate (MMP) to goethite (alpha-FeOOH) as a model system in order to better understand the mechanisms behind adsorption of organic phosphates to soil minerals, and how adsorption affects the stability of these molecules. The adsorption reactions and stability of MMP on goethite were studied at room temperature as a function of pH, time and total concentration of MMP by means of quantitative batch experiments, potentiometry and infrared spectroscopy. MMP was found to be stable at the watergoethite interface within the pH region 3-9 and over extended periods of time, as well as in solution. The infrared spectra indicated that MMP formed three predominating pH-dependent surface complexes on goethite, and that these interacted monodentately with surface Fe. The complexes differed in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The presented surface complexation model was based on the collective spectroscopic and macroscopic results, using the Basic Stern approach to describe the interfacial region. The model consisted of three monodentate inner sphere surface complexes where the MMP complexes were stabilized by hydrogen bonding to a neighboring surface site. The three complexes, which had equal proton content and thus could be defined as surface isomers, were distinguished by the distribution of charge over the O-plane and beta-plane. In the high pH-range, MMP acted as a hydrogen bond acceptor whereas it was a hydrogen bond donor at low pH. (C) 2012 Elsevier Inc. All rights reserved.

U2 - 10.1016/j.jcis.2012.07.042

DO - 10.1016/j.jcis.2012.07.042

M3 - Article

VL - 386

SP - 350

EP - 358

JO - Journal of Colloid and Interface Science

T2 - Journal of Colloid and Interface Science

JF - Journal of Colloid and Interface Science

SN - 0021-9797

ER -