A one-pot synthesis procedure is designed for preparing three α-aminophosphonates (R-H, R-COOH, and R-NH 2 ); through the reaction of amine precursors (aniline, anthranilic or o-phenylene diamine, respectively) with salicylaldehyde and triphenylphosphite, under controlled conditions. These materials are first characterized by elemental analysis, FTIR, 1 H NMR, 31 P NMR, BET, DLS, pH zpc , TGA and titration. In a second step, the sorption properties are compared for U(VI) recovery from mildly acidic solutions. At the optimum pH (i.e., pH 4) the sorbents can be ranked according the series: R-H (1.057 mmol U g − 1 ) > R-NH 2 (0.746 mmol U g − 1 ) > R-COOH (0.533 mmol U g − 1 ). The isotherms are fitted by the Langmuir equation. Uranium uptake is relatively fast: under selected experimental conditions, the equilibrium is reached within 90 min of contact. The kinetic profiles are indistinctly fitted by the model of resistance to intraparticle diffusion and the pseudo-first order rate equation.The study of sorption thermodynamics shows substantial changes between the sorbents: uranyl uptake is endothermic with R-H and R-NH 2 sorbents, while the reaction is exothermic with R-COOH sorbent. The diversity in functional groups and the speciation of uranyl in sulfuric acid solutions induce metal-binding through a combination of chelation and anion-exchange mechanisms (in function of pH). Sodium bicarbonate solutions achieve complete desorption of uranium from loaded-sorbents; the resins can be recycled for a minimum of 4-5 cycles with limited loss in efficiencies. The successful application of these resins for uranium recovery from acidic ore leachates demonstrates their promising properties for valorization of low-grade ores.
α-aminophosphonate (α-AP) is used as a novel corrosion inhibitor for carbon steel. The aggressive media applied in this study are HCl and H2SO4 acid solutions. The findings indicate that the morphology of the α-AP compound is cubic, with particles ranging in size from 17 to 23 μm. FT-IR, 1HNMR, 31PNMR, and 13CNMR analysis confirmed the synthesis of the α-AP molecule. It has been discovered that the compound α-AP plays an important role in inhibiting the corrosion of carbon steel in both HCl and H2SO4 acids. This was identifiably inferred from the fact that the addition of α-AP compound decreased the corrosion rate. It is important to report that the maximum inhibition efficiency (92.4% for HCl and 95.7% for H2SO4) was obtained at 180 ppm. The primary factor affecting the rate at which steel specimens corrode in acidic electrolytes is the tendency of α-AP compounds to adsorb on the surface of steel through their heteroatoms (O, N, and P). This was verified by SEM/EDX results. The adsorption actually occurs through physical and chemical mechanisms via different active centers which are matched with the calculated quantum parameters. In addition, the adsorption of α-AP follows the Langmuir isotherm.
Different metal catalysts have been tested for the one-pot transformation of carbonyl compounds, amines and phosphites to α-aminophosphonates. The influence of catalyst type, amount, solvent and the substrate electronic factor have been investigated. The results revealed that the carbonyl compounds could be smoothly converted into α-aminophosphonates at room temperature in good to excellent yields, with or without solvent in a reasonable reaction time. These results suggested that among others, lithium perchlorate and metal triflates were proven to be effective catalysts in 10 moles % catalysts. Polar aprotic solvents proved to be the best for the synthesis of α-aminophosphonates. The synthesized compounds' structure characterizations were elucidated by different spectroscopic tools and showed results consistent with the expected structures.
Pollution is one of the main threats possessing a potential risk for man and animals, especially the potentially toxic elements (PTE) which are considered non-biodegradable and can persist in soils for years. Clay minerals are thought to be among the main factors immobilizing PTE in soils and; therefore, these minerals control their bioaccessibility. Thus, the current research aims at determining the mechanisms by which the potentially toxic element Pb beside of the metalloid B are retained in a clayey non-calcareous soil and a clayey calcareous one under different pH values i.e. 5, 7 and 9. The clayey non-calcareous soil is characterized by a clay content of 58.25% and CaCO 3 content of 24.8 g kg -1 while the clayey calcareous one is characterized mainly by a clay content of 40.75% and CaCO 3 content of 289.9 g kg -1 . The clay fraction of the investigated soils was separated and identified of the types of the clay minerals dominating in these soils using X-ray diffraction analyses. Montmorillonite was the dominant clay mineral in the non-calcareous clayey soil, whereas kaolinite and palyorskite were the dominant ones in the calcareous clayey one. Adsorption of Pb and B on soils and clay minerals increased gradually with increasing the initial concentration of these ions in the equilibrium systems, especially with increasing the pH of theses systems from 5 to 9. In this concern, adsorption of the investigated ions by the clay minerals exhibited much higher values than those occurred on the investigated soils. Freundlich isotherm was the most efficient model fitting Pb sorption on both soils and clay minerals, whereas, Langmuir isotherm model seemed to be more appropriate for fitting the sorption data of B on the investigated soils and separated clay minerals. In conclusion, adsorption of Pb and B on clay minerals seemed to be the dominant mechanism controlling their mobility in soils even at pH 9. The actual sorption capacities and affinities in soils remained much lower than that occurred by the separated clay minerals. To what extent can clay minerals retain PTE versus a clayey and a calcareous clayey soils was a matter of concern in this study.
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