Comparison of Oxalate, Citrate and Tartrate Ions Adsorption in the Hydroxyapatite/Aqueous Electrolyte Solution System

The kinetics of adsorption/desorption of oxalate, citrate and tartrate anions was investigated using hydroxyapatite from solutions at the initial concentrations of 0.000001 and 0.001 mol/dm3 anions. The adsorption process from a solution with a concentration of 0.001 mol/dm3 takes place in three stages and is well described by the multiexponential equation of adsorption kinetics. The process of tartrate and citrate ion desorption after increasing the pH to 10 is irreversible, while the oxalate ions undergo significant desorption with the increasing pH. The adsorption of oxalate ions decreases with the increasing pH. This effect is weaker in the adsorption of citrate and tartrate ions. Ion adsorption studies were supplemented with the measurements of zeta potential, FTIR and particle distribution of hydroxyapatite particles.

Corrosion inhibition of aluminum by oxalate self-assembling monolayer

Purpose This paper aims to evaluate the inhibition efficiency (IE) of oxalate ions in controlling corrosion of aluminum at pH 10. Design/methodology/approach The IE has been determined by the classical weight loss method. The corrosion behavior of aluminum was investigated by using potentiodynamic polarization and electrochemical impedance measurements. Ultra violet (UV)-visible and Fluorescence spectra have been used to analyze the film formed on the aluminum surface after immersion. Findings The maximum IE was 88 per cent, which was offered by a mixture of 250 ppm oxalate ions and 50 ppm [Zn2+]. Potentiodynamic polarization data revealed that the protective film was formed on the metal surface. UV-visible and Fluorescence spectra indicated the presence of Al3+−oxalate complex in the protective film formed on aluminum substrate after immersion in [OX]/[Zn2+] solution. Originality/value The findings of this work shed more light on the corrosion inhibition of aluminum by oxalate self-assembling monolayers.

Crystal structure of bis(diisopropylammonium) cis-diiodidobis(oxolato-κ2 O 1,O 2)stannate(IV)

In the title compound, (iPr2NH2)2[SnI2(C2O4)2], which was prepared by reacting ( i Pr2NH2 +)2·C2O4 2− with SnI4 in a 2:1 molar ratio in a mixed ethanol–acetonitrile solvent, the Sn atom is coordinated by two chelating oxalate ions and two iodide ions, with the latter in a cis configuration. In the crystal, the cations are linked to the anions by N—H...O and bifurcated N—H...(O,O) hydrogen bonds, generating [10-1] chains.

Naloxegol hydrogen oxalate displaying a hydrogen-bonded layer structure

In the salt (5α,6α)-6-[(2,5,8,11,14,17,20-heptaoxadocosan-22-yl)oxy]-3,14-dihydroxy-17-(prop-2-en-1-yl)-4,5-epoxymorphinan-17-ium hydrogen oxalate, C34H54NO11 +·C2HO4 − the polyether unit of the naloxegol cation adopts the shape of a squashed open letter `O'. In the crystal, the hydrogen oxalate anions are linked into a chain by O—H...O hydrogen bonds. Each naloxegol unit is hydrogen bonded to three hydrogen oxalate ions via two O—H...O and one N—H...O interactions. The resulting hydrogen-bonded two-dimensional layer structure is 3,5-connected and has the 3,5 L50 topology.

Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers

Copper(II) oxalate grown on carboxy-terminated self-assembled monolayers (SAM) using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II) acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II) oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS). Helium ion microscopy (HIM) reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS) confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor.