Removal of americium from aqueous nitrate solutions by sorption onto PC88A-impregnated macroporous polymeric beads

Sponge-like Ca-alginate/Lix-84 beads for selective separation of Mo(VI) from some rare earth elements

In this investigation, a novel alginate complex was developed for the selective separation of molybdenum (Mo(VI)) ions from some rare earth elements (REEs). In this regard, alginate as a natural polysaccharide was impregnated and modified with 2-hydroxy-5-nonylacetophenone oxime (Lix-84) and characterized using FT-IR, TGA/DTA and SEM-EDX. The relation between medium acidity, adsorption kinetics, sorbent dose, isotherm models, temperature and Mo(VI) recovery was investigated. It was concluded that the impregnation stage promoted the Mo(VI) separation. The kinetics and isotherm data were well-fitted and matched with the pseudo-first-order model and Langmuir isotherm model; respectively. The Langmuir maximum adsorption capacity of Mo(VI) reached 72.2 mg/g. The developed material showed excellent separation performance towards Mo ions over the investigated REEs. The desorption and recovery of the loaded Mo(VI) ions were achieved using 1.0 M HCl. Reutilization of Alg/Lix-84 was confirmed up to three adsorption-desorption cycles with no damage of the beads as proved with SEM analysis. The adsorption mechanism of molybdenum onto Alg/Lix-84 was elucidated through FTIR and XPS measurements and was found to be governed by both electrostatic interaction and ion exchange. Therefore, the developed material has a promising potential for the selective separation of molybdenum from REEs-containing solution.

Solvent impregnated resins for the treatment of aqueous solutions containing different compounds: a review

In this review paper, a complete study and analysis of the research articles dealing with the removal of various organic and inorganic pollutants using solvent impregnated resins (SIR) is carried out. The method of impregnation, characterizations of prepared resin, and regeneration techniques of different SIRs for batch and continuous fixed bed columns are presented. The effects of different operating parameters (e.g., loading of solvent on the resin, dosage of adsorbent, initial solute concentration, pH, temperature, time, ionic strength) on the separation efficiency of SIR in the batch mode are discussed. Thermodynamic parameters (change in Gibbs free energy, enthalpy, and entropy) are tabulated from the data available in the literature, and if not given, then their values are calculated and presented. The influence of parameters (flow rate, bed height, pH, concentration of the solution, etc.) on the fixed bed column performance is analyzed. Design aspects of the column are also discussed, and the dimensions of fixed bed columns for industrial applications are proposed.

Encapsulated polymeric beads impregnating unexplored amide, N,N′-bis(2-ethyl hexyl) α-hydroxy acetamide (BEHGA) – preparation, sorption and kinetic studies for tri-, tetra- and hexavalent radionuclides

Removal of actinides (trivalent, tetravalent and hexavalent) from nitric acid medium was studied using solid-liquid extraction technique employing polymeric encapsulated beads (PEBs) using an indigenously synthesized, unexplored novel monoamide, N,N′-bis(2-ethyl hexyl) α-hydroxy acetamide (BEHGA). The PEBs were synthesized by phase inversion technique. The structure and morphology of the synthesized PEBs were evaluated by employing various characterization techniques like FT-IR, TGA and SEM. The well characterized PEBs were studied for its Am(III), Pu(IV) and U(VI) sorption behavior from nitric acid medium. Kinetics studies showed that the sorption is fast with equilibrium being reached within 60 min of equilibration. The sorption mechanism follows pseudo-second-order mechanism with intraparticle diffusion playing an important role. Langmuir isotherm model was found to best describe the sorption isotherm. The maximum Am(III) sorption capacity of the PEBs was found to be 8.45 mg/g (experimental) and 8.43 mg/g (Langmuir). Back extraction was possible using 0.5 M HNO3. Stability of the PEBs was found to be quite good with no significant structural deformation or leaching out of the extractant in 4.0 M HNO3 solution for at least up to 8 days.

Unveiling the Susceptibility of Functional Groups of Poly(ether sulfone)/Polyvinylpyrrolidone Membranes to NaOCl: A Two-Dimensional Correlation Spectroscopic Study

A clear understanding of membrane aging process is essential for the optimization of chemical cleaning in membrane-based facilities. In this study, two-dimensional (2D) Fourier transformation infrared (FTIR) correlation spectroscopy (CoS) analysis was first used to decipher the sequential order of functional group changes of NaOCl-aged poly(ether sulfone)/polyvinylpyrrolidone (PES/PVP) membranes. The synchronous maps showed 12 major autopeaks in total. Based on the asynchronous maps, a similar aging sequence of membrane groups was clearly identified at three pHs (i.e., 6, 8, and 10): 1463, 1440, and 1410 (cyclic C-H structures) > 1662 (amide groups) > 1700 (succinimide groups) > 1320, 1292 (S═O asymmetric) > 1486, 1580 (aromatic structures) > 1241 (aromatic ether bands) > 1105, 1150 cm^-1 (O═S═O symmetric). Among them, membrane chlorination occurred at 1241, 1410, and 1440 cm^-1. Moreover, the initial degradation of PVP and the subsequent transformation of PES could be highly responsible for the increased water permeability and the enlargement of membrane pores, respectively, both leading to serious fouling with humic acid filtration. In summary, the 2D-FTIR-CoS analysis is a powerful approach to reveal the interaction mechanisms of NaOCl-membrane and could be also useful to probe the process of membrane fouling and chemical cleaning.

Amazing selectivity for Am(iii) uptake by composite graphene oxide-PES polymeric beads prepared by phase inversion

Novel polyethersulphone (PES) based polymeric beads containing graphene oxide (GO), prepared by a phase inversion technique for the first time, were evaluated for actinide ion uptake from acidic feed solutions.