Alternating Current Electrophoretic Deposition of Hydroxyapatite Composite Coating on Mg-0.8wt.%Ca-3%wt.%Zn alloy

The present work investigates the AC electrophoretic deposition of nano-sized  HAP composite coating on Mg-0.8wt.%Ca-3%wt.%Zn alloy.  Nano HAP powder was prepared using hydrothermal microwave assisted technique. HAP coating is deposited electrophoretically from dispersing medium (ETELAC) forming composite coating on the alloy surface.  Electrophoretic deposition experiments were conducted as single run (S), double run (D) and multirun (M). The properties of HAP coating regarding adhesion, morphology and corrosion behavior were thoroughly investigated.Results show that the best coating regarding the weight gain as well as the morphology was obtained from multi run (M) experiments of  5%HAP and 5% ETELAC at 200 V under 150 rpm stirring.  Electrochemical Impedance (EIS) investigation show that HAP composite coating posses a high corrosion resistance compared to the substrate alloy.  The mechanism of HAP/ETELAC coating formation was thoroughly discussed

Studies on the Recovery of Cu (II) and U (VI) on Highly Adsorptive Modified Magnetic Amine Resins from Dolostone Leachate Solution

Magnetic chelating resin containing amine moiety was obtained by polymerization of chloromethyl styrene with both 5 % and 10% divinylbenzene as a crosslinking agent in the presence of Fe3O4 as magnetite particles, the yield was treated with malononitrile followed by reaction with hydrazine hydrate in the presence of absolute ethanol to get hydrazenyl amine polymer. The obtained resins were investigated by FT-IR, elemental analysis and SEM. The use of magnetite particles was used for increasing the surface of chelating active sites and easy collection from solution. The obtained resins were evaluated toward the uptake of Cu (II) and U (VI) from their aqueous synthetic solutions followed by application on acid leachate of dolostone ore materials from southwestern Sinai. Contact time, pH and initial concentration of the metal ions were investigated as factors affecting the uptake behavior. The modified resins display higher uptake capacity compared to the metal oxide-free resin also high regenerated efficiency

Controlled Synthesis of NiO and Co₃O₄ Nanoparticles from Different Coordinated Precursors: Impact of Precursor’s Geometry on the Nanoparticles Characteristics

Metal oxide nanoparticles are of great technological relevance because of their wide applications in catalysis and photonics. Herein, we report a one-pot method to synthesize transition metal oxide nanoparticles such as NiO and Co₃O₄ via solid state thermal decomposition of their analogue coordinated metal precursors without stirring and washing. The significance of the reported method is represented in its purity without washing and the systematic production. The impact of precursor structure on the characteristics of the nanoparticles was investigated. Variation of the precursor geometry affected the morphology of the nanoparticles from spherical to pyramidal upon changing the geometry from octahedral to square-pyramidal, respectively. The synthesized nanoparticles were characterized by XRD, XPS, N₂ sorpometry, UV–vis, and SEM. The photocatalytic activity of the prepared nanoparticles was assessed toward the photodegradation of methylene blue dye as a model pollutant. The nanoparticles exhibited superior photocatalytic efficiency in the trend of NiO > Co₃O₄. The morphology–photoefficiency relationship was investigated. The reported method herein would provide a potential facile route for fabricating other metal oxides with controllable morphology

Fabrication of Mesoporous NaZrP Cation-Exchanger for U(VI) Ions Separation from Uranyl Leach Liquors

As the demand for uranium production-based energy worldwide has been increasing in the last decades to maintain nuclear growth for electricity production, there are great efforts towards developing an easy and inexpensive method for uranium extraction and separation from its ores. For this purpose, mesoporous inorganic cation exchangers provide an efficient separation technology that can help streamline production and lower overall cost. This study describes the development of nano-structured mesoporous sodium zirconium phosphate (NaZrP-CEX) for separation and extraction of uranyl ions from real samples. The fabricated NaZrP-CEX was well characterized by various techniques such as X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), N2 adsorption/desorption, Dynamic light scattering (DLS) and zeta potential). The kinetics/thermodynamic behaviors of uranyl ion adsorption into NaZrP-CEX from an aqueous solution were minutely studied. The kinetic studies showed that the pseudo-second order model gave a better description for the uptake process. The negative value of ΔG indicate high feasibility and spontaneity of adsorption. Finally, mesoporous NaZrP-CEX can be regenerated using both of HNO3 (0.05 M) or HCl (1 M) up to seven cycles of operation

Grafting of arginine and glutamic acid onto cellulose for enhanced uranyl sorption

International audienceThe grafting of arginine and glutamic acid on cellulose (through an intermediary step of chlorination) allows improving uranyl sorption of the biopolymer. The sorbents (Arg-Cell and Glu-Cell) were characterized by elemental analysis, FTIR spectrometry, XRD, SEM-EDX analysis and TGA. The sorption efficiency increases with pH; this can be attributed to the deprotonation of carboxylic acid and amine groups and to the formation of polynuclear hydrolyzed uranyl species. Sorption isotherms (fitted by the Langmuir equation) show sorption capacities at saturation of the monolayer of 147 and 168 mg U g(-1) for Arg-Cell and Glu-Cell, respectively (compared to 78 mg U g(-1) for raw cellulose); maximum sorption capacities at equilibrium (experimental values) reach 138, 160 and 73.4 for Arg-Cell, Glu-Cell and cellulose, respectively. Uranyl sorption is endothermic and is spontaneous for amino acid derivatives of cellulose (contrary to exothermic for cellulose). Uptake kinetics for the different sorbents are fitted by the pseudo-second-order rate equation. Uranium can be desorbed using sulfuric acid solutions, and the sorbents can be recycled for a minimum of five cycles of sorption/desorption: the decrease in sorption capacities at the fifth cycle does not exceed 13%