A. Elias

EFFECT OF CHAIN LENGTH OF ALKANE-1-HYDROXY-1, 1′-METHYLDIPHOSPHONIC ACIDS ON THE IRON (III) LIQUID–LIQUID EXTRACTION

ABSTRACT (1-Hydroxy-1-phosphonohexadecyl) phosphonic acid (HPHPA) and (1-hydroxy-1-phosphonododecyl) phosphonic acid (HPDPA) were prepared by reaction of phosphorus trichloride with palmitic and lauric acids, respectively. After purification, these products were characterized by elemental microanalysis and by IR, 1H, 31P NMR spectroscopies. In this paper, we propose a tentative assignment for the shifts of those two ligands and their specific complexes with iron (III). A spectroscopic analysis has showed that coordination of iron (III) takes place via oxygen atoms. We also measured the extraction of Fe+3 by HPHPA and HPDPA from [CCl4-Octanol (v/v: 90%/10%)] solutions. The complexes formed in the organic phase may be Fe[C11 H23C(OH)(PO3H)2]Cl, 3H2O with HPDPA and Fe[C15H31C(OH) (PO3H)2]Cl, 3H2O with HPHPA, respectively. HPHPA as ligand exhibits a stronger extracting power for Fe3+ and has a more hydrophobic character than HPDPA.

SYNTHESIS OF MONO-AND DIALKYLPHOSPHATES BY THE REACTIONS OF HYDROXYCOMPOUNDS WITH THE PHOSPHORUS PENTAOXIDE UNDER MICROWAVE IRRADIATION

The reactions of phosphorus pentoxide with two alcohols and one phenol were performed in different conditions under microwave irradiation. The products (alkylphosphates and dialkylphosphates) were identical to those formed by classic heating and were obtained with better yields. The speed of the reaction was increased by a factor from 100 to 4000.

The Phase Stability in the Fe-B Binary System: Comparison between the Interstitial and Substitutional Models

In the present work, a thermodynamic study was carried out in order to analyze the thermodynamic stability of the and phases in equilibrium with the phase using the calculation of phase diagrams (Calphad) formalism. The two phases and are modelled as substitutional and interstitial solid solutions of boron. The expressions of the chemical potentials of B and Fe are derived in both phases to perform the thermodynamic calculations. A comparison is made between the results provided by the substitutional and interstitial models and good agreement is observed between these two models.

Liquid-Liquid Extraction of Uranium(VI) from Aqueous Solution using 1-Hydroxyalkylidene-1,1-diphosphonic Acids

The extraction of uranium(VI) from aqueous solutions has been investigated using 1-hydroxyhexadecylidene-1,1-diphosphonic acid (HHDPA) and 1-hydroxydodecylidene-1, 1-diphosphonic acid (HDDPA), which were synthesized and characterized by elemental analysis and by FT-IR, 1H NMR, 31P NMR spectroscopy. In this article, we propose a tentative assignment for the shifts of those two ligands and their specific complexes with uranium(VI). We carried out the extraction of uranium(VI) by HHDPA and HDDPA from [carbon tetrachloride + 2-octanol (v/v: 90%/10%)] solutions. Various factors such as contact time, pH, organic/aqueous phase ratio, and extractant concentration were considered. The optimum conditions obtained were: contact time = 20 min, organic/aqueous phase ratio = 1, pH value = 3.0, and extractant concentration = 0.3 M. The extraction yields are more significant in the case of the HHDPA which is equipped with a hydrocarbon chain, longer than that of the HDDPA. Logarithmic plots of the uranium(VI) distribution ratio vs. pHeq and the extractant concentration showed that the ratio of extractant to extracted uranium(VI) (ligand/metal) is 2:1. The formula of the complex of uranium(VI) with the HHDPA and the DHDPA is UO2(H3L)2 (HHDPA and DHDPA are denoted as H4L). A spectroscopic analysis showed that coordination of uranium(VI) takes place via oxygen atoms.

Modelling of the Growth of Fe2B Layers in AISI 1018 Steel

In this work, a simulation of the growth kinetics of layers on AISI 1018 steel was done by means of a kinetic model. This model considers a solid diffusion of boron into a semi-infinite medium where the boron solubility in the Fe phase depends on the process temperature. An expression of the parabolic growth constant was then obtained through an application of the mass balance equation at the (/substrate) interface. The present model was validated by the experimental data available in the reference work (I. Campos-Silva et al: Kovove Mater. Vol.47 (2009), p.1-9). A good concordance was observed between the experimental parabolic growth constants and the predicted ones by the model for an upper limit of boron in the phase equal to 8.91 wt.% ( as a fitting parameter of the model). In addition, the generated weight gain was estimated at the surface of the borided AISI 1018 steel as a function of the upper limit of boron in the phase and the temperature.