Synthesis of α-aminophosphonate functionalized chitosan sorbents: Effect of methyl vs phenyl group on uranium sorption

This review describes advances in the XRF group of techniques published approximately between April 2015 and March 2016. Fundamental contributions in the instrumentation sections include the development of synchrotron radiation sources, semiconductor design technology and evaluating the quality of in situ hand-held XRF results. A bench top TXRF spectrometer for the measurement of the elements from carbon to uranium is described that offers achievable detection limits that range from ng g−1 to μg g−1. The applications sections aim to give a representative overview of the range of applications that use XRF techniques with an emphasis on papers that describe technical or application innovation. Sample size investigated ranged from the planet Mercury down to nano-gram quantities of cement secreted by settlement stage barnacle larvae. The archaeological and cultural heritage section this year includes an authentic report on the use of cannabis as a filler in ancient lime plaster and heartening news that the construction of an underground parking garage in the centre of Zurich (Switzerland) unearthed the remains of seven Neolithic settlements from the 4th and 3rd millennium BC. The X-ray excitation of iron present in ancient iron-gall inks was presented as a step toward the non-invasive reading of fragile and/or unopenable documents. Feedback from readers of this review is most welcome and the review coordinator may be contacted using the email address provided.

https://pubs.rsc.org/en/content/articlepdf/2021/ja/d1ja90033a

2016 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and its applications

The adsorption of U(VI) onto dried and pyrolyzed tea and coffee wastes was investigated. The adsorption properties of the materials were characterized by measuring uranium uptake as a function of solution pH, kinetics and adsorption isotherms. pH profile of uranium adsorption where UO2
 2+ is expected to be the predominant species was measured between pH 0 and 4. Both Langmuir and Freundlich adsorption models were used to describe adsorption equilibria, and corresponding constants evaluated. Using the Langmuir model, the maximum adsorption capacity of uranium by dried tea and coffee wastes was 59.5 and 34.8 mg/g, respectively at 291 K. Adsorption thermodynamic constants, ΔH° ΔS° and ΔG° were also calculated from adsorption data obtained at three different temperatures. Adsorption thermodynamics of uranyl ions on dried tea and coffee systems indicated spontaneous and endothermic processes. Additionally, a Lagergren pseudo-second-order kinetic model was used to fit the kinetic experimental data for both adsorbents and the constants evaluated. Dried tea and coffee wastes proved to be effective adsorbents with high capacities and significant advantage of a very low cost.

Uranium extraction from aqueous solution using dried and pyrolyzed tea and coffee wastes

Immobilizing amino-functionalized mesoporous silica into sodium alginate for efficiently removing low concentrations of uranium

A new magnetic functionalized derivative of chitosan is synthesized and characterized for the sorption of metal ions (environmental applications and metal valorization) The chemical modification of the glycine derivative of chitosan consists of: activation of the magnetic support with epichlorohydrin, followed by reaction with either glycine to produce the reference material (ie, Gly sorbent) or glycine ester hydrochloride, followed by hydrazinolysis to synthesize the hydrazide functionalized sorbent (ie, HGly sorbent) The materials are characterized by titration, elemental analysis, FTIR analysis (Fourrier-transform infrared spectrometry), TGA analysis (thermogravimetric analysis) and with SEM-EDX (scanning electron microscopy coupled to energy dispersive X-ray analysis) The sorption performances for U(VI), Cu(II), and Zn(II) are tested in batch systems The sorption performances are compared for Gly and HGly taking into account the effect of pH, the uptake kinetics (fitted by the pseudo-second order rate equation), and the sorption isotherms (described by the Langmuir and the Sips equations) The sorption capacities of the modified sorbent reach up to 114 mmol U g−1, 169 mmol Cu g−1, and 085 mmol Zn g−1 In multi-metal solutions of equimolar concentration, the chemical modification changes the preferences for given metal ions Metal ions are desorbed using 02 M HCl solutions and the sorbents are re-used for five cycles of sorption/desorption without significant loss in performances

Functionalization of Magnetic Chitosan Particles for the Sorption of U(VI), Cu(II) and Zn(II)-Hydrazide Derivative of Glycine-Grafted Chitosan.

Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl) phosphate in n-paraffin at room temperature (27 ± 1 °C). The effect of diluents, nitric acid concentration as well as extractant concentration on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO2(NO3)2·2TBEP and Th(NO3)4·3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency from 1,282 to 1,217 cm−1 indicating the strong complexation of P=O group with UO2
 2+ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction has also been investigated.

Extraction of U(VI) and Th(IV) from nitric acid medium using tri(butoxyethyl) phosphate (TBEP) in n-paraffin

The recovery of uranium from carbonate ore leach solution was studied using novel precipitation method. The uranium from leach liquor was recovered as magnesium diuranate with NaOH in presence of trace amount of Mg2+. Effects of various parameters such as addition of H2SO4, MgO, MgSO4 as well as NaOH were investigated for maximum uranium recovery. Overall uranium recovery of the process was 97 % with improved particle size (~57 µm). Based on the experimental findings, a process flow-sheet was developed for uranium recovery from carbonate ore leach solution with a uranium concentration of <1 g/L.

Novel precipitation technique for uranium recovery from carbonate leach solutions

The act of enrichment or improving the quality of product concentration, i.e. 'pre-concentration', has been studied with respect to uranium plant effluent, which contains uranium in 10?30 ppm level intermingled with a huge number of interfering ions, such as magnesium, in percent level. The effects of different operating conditions, such as concentration of uranium in the effluent, pH, the time required for uptake of uranium and the effect of the presence of other elements in the effluent, in batch experiments have been investigated. Using this in-house novel resin for preferential uranium uptake, the sorbed matrix has been eluted with different eluant concentration for further enrichment of radionuclides in the elute. High uptake values for uranium ions prove its selectivity, and fractional elution ensures further reuse of sorbent and significant improvement in uranium enrichment.

Recovery and pre-concentration of uranium from secondary effluent using novel resin

Evaluation of tris-2-ethyl hexyl phosphate (TEHP) for counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) from nitric acid medium was carried out under wide experimental conditions. Batch extraction studies were carried out to investigate the effect of nitric acid concentration in feed solution, U(VI)/Th(IV) ratio and extractant concentration and the results were compared with established solvent such as tri-n-butyl phosphate (TBP) for separation of U(VI) from nitric acid medium. McCabe–Thiele diagrams for extraction as well as stripping of U(VI) were constructed under simulated conditions. Based on batch experiments, six stage counter-current extraction studies were conducted under various TEHP concentration and it was observed that 0.1 M TEHP/n-paraffin was most suitable for selective recovery of U(VI) from a mixture of U(VI)–Th(IV). An optimized condition, 0.1 M TEHP/n-paraffin, 2 M HNO3 in feed and six number of stages was evaluated for selective extraction and stripping of U(VI) from a solution containing mixture of U(VI)–Th(IV)–Y(III) in nitric acid medium. The U(VI) in strip solution was precipitated using 30 % H2O2 at pH ~3. Average particle size of the final precipitate was found to be ~33 μm.

Counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) using tris-2-ethyl hexyl phosphate (TEHP)

A novel hydrophilic, three dimensionally cross-linked, aliphatic backbones with pendant hydroxamic acid (HA) group as functional moiety has been synthesized and utilized targeting removal of gadolinium [Gd(III)] from laboratory waste aqueous effluent To understand the nature of sorption, gadolinium solution of various concentrations viz, 20, 10, 50, 10, 05 and 01 ppm has been contacted with a dose rate of 1 g/100 mL for 2 h In this study, ICP-AES has been used for determination of concentration (ppm) of gadolinium in feed, filtrate and elute EDXRF study also ensures the presence of gadolinium in the respective medium Loaded gadolinium matrix was eluted with 1 N HCl for determining the elution factor (098)

K. N. Hareendran

Papers

Extraction of U(VI) and Th(IV) from nitric acid medium using tri(butoxyethyl) phosphate (TBEP) in n-paraffin

Novel precipitation technique for uranium recovery from carbonate leach solutions

Recovery and pre-concentration of uranium from secondary effluent using novel resin

Counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) using tris-2-ethyl hexyl phosphate (TEHP)

Poly-hydroxamic acid (PHA) matrix for gadolinium pre-concentration and removal