Complexation of Methylphosphonic Acid with the Surface of Goethite Particles in Aqueous Solution

BEATRIZ C. BARJA; M. ISABEL TEJEDOR-TEJEDOR; MARC A. ANDERSON

LANGMUIR

Año: 1999 vol. 15 p. 2316 - 2321

0743-7463

Adsorption of methylphosphonic acid (MPA) onto goethite (R- FeOOH) was studied as a function of pH and the concentration ofMPAin solution. In situ attenuated total reflectance-FTIR (ATR-FTIR) techniques were used to identify the type of surface complexes formed under each of the solution conditions used in the adsorption studies. Additionally, electrophoretic mobility measurements were performed in each of these systems. At low pH and high ¡, MPA was bound to the surface of goethite predominantly as a monodentate protonated species, while at high pH and low ¡ the prevailing structure was that of a bridging bidentate complex. The change in denticity of the surface MPA under different solution conditions may explain the charge reversals shown in the electrophoretic mobility curves.R- FeOOH) was studied as a function of pH and the concentration ofMPAin solution. In situ attenuated total reflectance-FTIR (ATR-FTIR) techniques were used to identify the type of surface complexes formed under each of the solution conditions used in the adsorption studies. Additionally, electrophoretic mobility measurements were performed in each of these systems. At low pH and high ¡, MPA was bound to the surface of goethite predominantly as a monodentate protonated species, while at high pH and low ¡ the prevailing structure was that of a bridging bidentate complex. The change in denticity of the surface MPA under different solution conditions may explain the charge reversals shown in the electrophoretic mobility curves.¡, MPA was bound to the surface of goethite predominantly as a monodentate protonated species, while at high pH and low ¡ the prevailing structure was that of a bridging bidentate complex. The change in denticity of the surface MPA under different solution conditions may explain the charge reversals shown in the electrophoretic mobility curves.¡ the prevailing structure was that of a bridging bidentate complex. The change in denticity of the surface MPA under different solution conditions may explain the charge reversals shown in the electrophoretic mobility curves.