Elaboration of Impregnated Composite for Sorption of Europium and Neodymium Ions from Aqueous Solutions (original) (raw)
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Journal of Radioanalytical and Nuclear Chemistry, 1997
Extraction chromatographic supports (XAD-7) impregnated with binary mixtures of cobalt dicar and one of the two phosphororganic extractants (dibutyl-N,N-diethylcarbamoyhnethyl phosphonate, DBDECMP, or octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide, (CMt~) were prepared using methanofic solutions of the extractants and subsequent evaporation of methanol at room temperature. The molar ratios (x) in isomolar series of the two extractants were 0, 0.25, 0.5, 0.75, and 1. The sorbents were used for investigating Eu capture from 0.I and 1M HNO 3 solutions under static s-9 s conditions (24 hours shaking, 2 cm 3 aqueous phase with 0.2 g orbent, Eu initial concentrations 3.10 ,0.0001, 0.001, 0.01 and 0.1M). The orbents containing mixtures of extractants corresponding to the interpolale.A value x = 0.45 (phosphororg./dicarb.) exhibited the highest values of the distribution ratios of Eu. A synergic effect of three orders of magnitude for low concentrations of Eu was observed. A tentative determination is given of the nature and the equilibrium constants of the chemical reactions assumed.
Journal of Environmental Chemical Engineering, 2018
New titanium phosphates were synthesized and tested as potential sorbents of europium from aqueous solutions. The experiments were undertaken in the concentration region 50-2000 mg. L-1 at pH 5 without and with background electrolyte. The uptake data were determined by γ-spectroscopy with 152 Eu as tracer and fitted by the Langmuir, Freundlich and Temkin models. The new materials showed high sorption capacities (up to 259.6 mg. g-1) as derived from the Langmuir equation. Investigation of the sorption kinetics took place at 293, 303, 313 and 323 K. It was demonstrated that Eu-sorption proceeds very fast and described by pseudo-second-order kinetics while the rate constant and activation energy were calculated. Infrared and Raman spectroscopy, scanning electron microscopy and X-ray diffraction were applied for the sorbents characterization. Leaching tests were performed to assess the environmental compatibility of the loaded sorbent as well as desorption tests. The obtained data indicated that the interaction of the synthesized titanium phosphates with the Eusolutions is a complex phenomenon based on ion exchange and formation of inner-sphere complexes.
Magnesium-cadmium hydroxyapatite [(Mg-Cd)HAP] and novel multi-wall carbon nanotubes Mg-Cd hydroxyapatite (CNTs/(Mg-Cd)HAP) composites were synthesized by a co-precipitation method. The synthesized sorbents were characterized using BET surface area measurements, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). They have possessed specifi c surface area of 34.85 and 60.41 m 2 g-1 for (Mg-Cd)HAP and CNTs/(Mg-Cd)HAP, respectively. Furthermore, the synthesized sorbents were applied in removal of Eu(III) ions from aqueous solutions. Sorption performance of the synthesized sorbents towards Eu(III) ions was studied under different sorption parameters such as equilibration time, sample mass, solution pH and ionic strength. Sorption of europium reached equilibrium within 6 h at pH 2.5. The maximum sorption capacity (Q max) was 137.31 and 151.47 mg g-1 for sorption of Eu(III) onto (Mg-Cd)HAP and CNTs/(Mg-Cd) HAP, respectively. Kinetically, the sorption process followed the pseudo-second-order model and both fi lm and pore diffusions participated in ruling the diffusion of Eu(III) ions. Equilibrium sorption data of Eu(III) were analyzed using Freundlich and Langmuir isotherm models. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for sorption of Eu(III) onto the synthesized sorbents were determined and the reaction is found to be feasible, spontaneous and endothermic process.
A new sorbent for europium nitrate extraction: phosphonic acid grafted on polystyrene resin
Journal of Radioanalytical and Nuclear Chemistry, 2011
A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid-solid extraction of europium(III). The results indicated that phosphonic resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH value of 6.5. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and ionic strength were investigated. The maximum uptake capacity of Eu(III) ions was 122.6 mg/g grafted resin at ambient temperature, at an initial pH value of 6.50. The overall adsorption process was best described by pseudo first-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, Eu(III) could be eluted by using 1.0 mol/L H 2 SO 4 solution and the grafted resin could be regenerated and reused.
Russian Journal of Applied Chemistry, 2018
Magnesium-cadmium hydroxyapatite [(Mg-Cd)HAP] and novel multi-wall carbon nanotubes Mg-Cd hydroxyapatite (CNTs/(Mg-Cd)HAP) composites were synthesized by a co-precipitation method. The synthesized sorbents were characterized using BET surface area measurements, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). They have possessed specifi c surface area of 34.85 and 60.41 m 2 g-1 for (Mg-Cd)HAP and CNTs/(Mg-Cd)HAP, respectively. Furthermore, the synthesized sorbents were applied in removal of Eu(III) ions from aqueous solutions. Sorption performance of the synthesized sorbents towards Eu(III) ions was studied under different sorption parameters such as equilibration time, sample mass, solution pH and ionic strength. Sorption of europium reached equilibrium within 6 h at pH 2.5. The maximum sorption capacity (Q max) was 137.31 and 151.47 mg g-1 for sorption of Eu(III) onto (Mg-Cd)HAP and CNTs/(Mg-Cd) HAP, respectively. Kinetically, the sorption process followed the pseudo-second-order model and both fi lm and pore diffusions participated in ruling the diffusion of Eu(III) ions. Equilibrium sorption data of Eu(III) were analyzed using Freundlich and Langmuir isotherm models. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for sorption of Eu(III) onto the synthesized sorbents were determined and the reaction is found to be feasible, spontaneous and endothermic process.
Europium removal with a mineral mixtre
Journal of Radioanalytical and Nuclear Chemistry, 1992
Natural mixture containing mostly minerals of iron, sillicon, magnesium, aluminium and calcium was exploited for the decontamination study of europium radionuclides from aqueous radioactive waste solutions. The physicochemical conditions, such as shaking and equilibration time, nature of hydrogen ions, pH, temperature, concentrations of adsorbate and adsorbent were experimentally determined. This study showed quantitative adsorption beyond pH 7 and under optimized conditions, up to 33 g of the adsorbate can be rapidly removed from radioactive effluents using only 1 kg of the mineral mixture (MM). Desorption study of the solidified radioactive waste product reveals no significant loss (< 0.01% month), indicating MM as an effective material for removal of radioactive europium and storing it in solid form over a long period of time.
Sorption of europium on TiO2 and cement at high Ph in the presence of organic ligands
Journal of Radioanalytical and Nuclear Chemistry, 2006
Organic substances present in radioactive waste lower the sorption of metal ions at the high pH in cement matrices and, hence, enhance their possible migration. The aim of this study was to develop a method to compare organic substances or their degradation products with respect to what extent they affect metal sorption. Batch sorption studies were performed with cement or TiO 2 as solid phase and Eu(III) as a model element for trivalent lanthanides and actinides at pH 12.5 (representative of a cement waste matrix during the first approximately 100,000 years). Different kinds of ligands were studied in a broad concentration range, e.g., organic acids, cement additives, cleaning agents and degradation products from ion-exchange resin.
The feasibility of using a macroporous strongly acidic cation exchange resin (SQS-6) as an adsorbent for lanthanum(III) and neodymium(III) from phosphoric acid medium, >4.0 M, was administered using batch and column techniques. Diff erent parameters aff ecting the sorption of these metal ions such as v/m ratio, acid concentration and the metal ion concentration were separately investigated. The results indicated that the sorption process is relatively fast, reaching equilibrium state within 10 min. Infl uence of temperature on the equilibrium distribution values was also studied to evaluate the changes in standard thermodynamic quantities where the results indicated that the sorption is endothermic and the process is spontaneous associated with increasing the randomness of the system. The adsorption results of the studied metal ions were found to obey Langmuir isotherm model over the entire studied concentration range. The recovery of La(III) and Nd(III) from the loaded resin was performed with 1.0 M citric acid at pH 4.0. The breakthrough capacity of La(III) and Nd(III) was found to be 33.55 and 17.30 mg/g, respectively. The experimental data resulting from column technique were followed Thomas and Yoon-Nelson models.
Factors affecting the sorption of Eu(III) on modified silica gel
8-Hydroxyquinoline in benzene, xylene, chloroform and toluene diluents was used to modify silica gel as a solid phase extractant (SPE) for the sorption of Eu(III) in batch extraction techniques. Influences of solid/liquid ratio, pH, metal ion concentration, particle size and temperature were studied. The optimum initial pH is 4.2, while the maximum sorption capacities for the prepared impregnated resins in benzene, xylene, chloroform and toluene diluents are 18.52, 14.98, 14.79 and 5.94 mg. g-1 , respectively. The sorption process was found to be affected by both metal ion concentration and particle size of the impregnated resin. Thermodynamic parameters for the sorption of Eu(III) were determined and the reaction is found to be exothermic and spontaneous with enthalpy −14.23 and −23.71 kJ. mol-1 for benzene and xylene as diluents. Release of the element from the loaded solid particles into 0.01M HNO 3 is ≅85% and ≅53% from 8-HQ/benzene/silica gel and 8-HQ/xylene/silica gel.
The uptake of lanthanide elements by naturally abundant materials, is a matter of great economic and environmental interest. This study is an exploration of the potential utilization of malt spent rootlets (MSR), which are by-products of malting process, for a cost effective preconcentration of Eu(III). The effect of solution pH, contact time and initial concentration under constant ionic strength and temperature were studied. Kinetic data were applied to pseudo-first, second order and Elovich equations, as well as intra-particle diffusion model. Pseudo-second order and Elovich equation seem to fit our data equally well, whereas diffusion contributes to the whole process. Equilibrium data were evaluated using Langmuir, Freundlich and Dubinin-Radushkevich equations. According to Langmuir model, which fits the data better, europium maximum capacities for MSR and active carbon were found 156 and 86 mg/g respectively, indicating that MSR is a promising biosorbent.