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

Abstract

Adsorption of methylphosphonic acid (MPA) onto goethite (α- FeOOH) was studied as a function of pH and the concentration of MPA in 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 Γ, MPA was bound to the surface of goethite predominantly as a monodentate protonated species, while at high pH and low Γ 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.

Adsorption of Extracellular Polymeric Substances Derived from S. cerevisiae to Ceria Nanoparticles and the Effects on Their Colloidal Stability

“…The frequency values of the P=O and P-OX vibration are altered by the adsorption form. Barja and others reported that the adsorption form is constrained by the adsorption density, where bridging bidentate complexes can transform to protonated monodentate complexes with increasing the adsorption density [43]. Similarly, the broadening of the bands should be partly ascribed to the multiple adsorption forms at the CeNPs surface in the present experiments.…”

Soil Chemical Insights Provided through Vibrational Spectroscopy

“…Phosphate groups originating from phospholipids, DNA, LPS, and other extracellular biomolecules provide potential binding sites to initiate bacterial adhesion to metal oxide surfaces. The binding of phosphate with Fe oxide surfaces is well documented in numerous ATR-FTIR spectroscopic studies (Barja et al, 2001(Barja et al, , 1999Cagnasso et al, 2010;. used a combined ATR-FTIR spectroscopy and modeling approach to demonstrate the occurrence of P-O-Fe bonds (1037 cm −1 ) for extracted EPS reacted with goethite (α-FeOOH) (Figure 1.16).…”

“…Coordination of the phosphonate group with aqueous Fe was indicated by a broad and unresolved band from 1200 to 950 cm −1 where stretching vibrations of the PO 2 − and PO 3 − are observed in the free ligand, and the absence of P=O and P-OH at 1400-1200 cm −1 and 917 cm −1 , respectively (Barja and dos Santos Afonso, 1998). Barja et al (1999) employed methylphosophonic acid (MPA) as an adsorbate surrogate for glyphosate in adsorption studies with goethite. In situ CIR-FTIR spectra at low pH suggested that protonated MPA was bound through a monodentate complex between the phosphonate group and the goethite surface; whereas, a bridging bidentate complex was the proposed structure for MPA bonding at high pH.…”

Hybrid Organic-Inorganic Materials Based on Organophosphorus Derivatives

“…In the case of goethite, (g-AlOOH), it was found that methylphosphonic acid bound to the surface as a monodentate or a bidentate species depending on the pH and the concentration [163].…”