RESUMEN
MXene is an innovative multilayered material that has been prepared by an acid-salt (HCl + NH4F) etching route and tested for the removal of 133Ba and 137Cs in radioactive conditions for the first time. MXene has exhibited high uptake capacity of about 154.9 and 121.5 mg g-1 for 133Ba and 137Cs, respectively, in 0.01 mol L-1 solution and using 5 g L-1 of adsorbent at natural pH.
RESUMEN
The use of knowledge from technetium radiochemistry (even from nuclear medicine applications) allows us to select an sorbent for 99mTc radionuclide sorption, which is hydroxyapatite. Using radioisotope indication, the 99mTcO4- sorption process on synthetic hydroxyapatite was studied by the batch method in the presence of SnCl2 and FeSO4 reducing agents. The complexing organic ligands' effect on the 99mTcO4- sorption under reducing conditions was investigated. In the presence of Sn2+ ions without the addition of organic ligand, the sorption percentage reached above 90% independently of the environment. In the presence of Fe2+ ions without the addition of organic ligand, the sorption of 99mTcO4- was significantly lower and was at approximately 6%, depending on the concentration of Fe2+ ions in solution. The effect of complexing organic ligands on the 99mTcO4- sorption on hydroxyapatite from the aqueous solution, acetate buffer and phosphate buffer decreases in the following order for Sn2+: oxalic acid > ethylenediaminetetraacetic acid > ascorbic acid. In the presence of Fe2+ ions without organic ligands, the sorption reached up to 15% depending on the composition of the solution. The addition of oxalic acid and ascorbic acid increased the sorption up to 80%. The ethylenediaminetetraacetic acid had no significant effect on the sorption of technetium on hydroxyapatite.
Asunto(s)
Pertecnetato de Sodio Tc 99m , Tecnecio , Indicadores y Reactivos , Tecnecio/análisis , Durapatita/química , Ligandos , Ácido Edético , Agua , Ácido Oxálico , AdsorciónRESUMEN
The efficiency of 133Ba and 137Cs removal from aqueous solution is vital to mitigate ecological concerns over spreading these radionuclides in the environment. The present work focused on the use of Turkish perlite for the sorptive removal of 133Ba and 137Cs from aqueous solution by the radioindicator method. Perlite was characterized by XRF, XRD, FTIR, SEM−EDX, and BET analyses. The maximum percentage removals of 88.2% and 78.7% were obtained for 133Ba and 137Cs at pH 6 and pH 9, respectively. For both ions, the sorption equilibrium was attained relatively rapidly. Experimental kinetic data were well described with pseudo-second-order and intraparticle diffusion models. The uptake of both ions increased with the increase in metal concentration (1 × 10−5 to 5 × 10−2 mol/L) in solution. The maximum uptake capacities of 133Ba and 137Cs were found to be 1.96 and 2.11 mmol/g, respectively. The effect of competing ions decreased in the order of Ca2+>K+>Ni2+>Na+ for 133Ba sorption, whereas for 137Cs sorption, the order was determined as Ca2+>Ni2+>K+>Na+. Selectivity studies pointed out that sorption of 133Ba onto perlite is preferable to 137Cs. Therefore, Turkish perlite is a promising, cost-effective, and efficient natural material for the removal of 133Ba and 137Cs from relatively diluted aqueous solution.
RESUMEN
Growing concern over the hazardous effect of radionuclides on the environment is driving research on mitigation and deposition strategies for radioactive waste management. Currently, there are many techniques used for radionuclides separation from the environment such as ion exchange, solvent extraction, chemical precipitation and adsorption. Adsorbents are the leading area of research and many useful materials are being discovered in this category of radionuclide ion separation. The adsorption technologies lack the ability of selective removal of metal ions from solution. This drawback is eliminated by the use of ion-imprinted polymers, these materials having targeted binding sites for specific ions in the media. In this review article, we present recently published literature about the use of ion-imprinted polymers for the adsorption of 10 important hazardous radionuclides-U, Th, Cs, Sr, Ce, Tc, La, Cr, Ni, Co-found in the nuclear fuel cycle.
RESUMEN
The work deals with the evaluation of biochar samples prepared from Phyllostachys Viridiglaucescens bamboo. This evaluation consists of the characterization of prepared materials' structural properties, batch and dynamic sorption experiments, and potentiometric titrations. The batch technique was focused on obtaining basic sorption data of 88áµTcO4â» on biochar samples including influence of pH, contact time, and Freundlich isotherm. ReO4 -, which has very similar chemical properties to 88áµTcO4â», was used as a carrier in the experiments. Theoretical modeling of titration curves of biochar samples was based on the application of surface complexation models, namely, so called Chemical Equilibrium Model (CEM) and Ion Exchange Model (IExM). In this case it is assumed that there are two types of surface groups, namely, the so-called layer and edge sites. The dynamic experimental data of sorption curves were fitted by a model based on complementary error function erfc(x).
RESUMEN
The study summarizes the results of monitoring the properties of two types of sorbents, BC1 (biochar sample 1) and BC2a (biochar sample 2), prepared by pyrolysis of bamboo biomass (BC1) and as its composite with montmorillonite K10 (BC2a). The main goal was to study their applicability to the Tc (VII) separation from liquid wastes, using NH4ReO4 as a carrier. The research was focused on determining the sorbents surface properties (by XRF (X-ray fluorescence) method and potentiometric titration in order to determine the properties of surface groups-Chemical Equilibrium Model (CEM) and Ion Exchange Model (IExM) models were applied here). As well as monitoring Tc (VII) (+Re(VII)) sorption, especially to determine equilibrium isotherm, the influence of pH and kinetics. The subject of research was also the dynamics of sorption, including its mathematical-physical modeling. Both sorbents have good properties against Tc (VII), however BC2a, due to the presence of montmorillonite, is more advantageous in this respect. It has a higher sorption capacity and faster kinetic investigation. An important finding is that the optimal pH is 2-3, which is related not only to the protonation of surface groups (they have a positive charge), but also to the negative form of the existence of Tc (VII) and Re (VII): TcO4- and ReO4-.
RESUMEN
Biochar is a promising immobilization tool for various contaminants in liquid wastes, aqueous solutions and soils. To further improve the sorption characteristics, a biochar/montmorillonite composite was produced and synthesized in an experimental pyrolysis reactor, using bamboo as biomass feedstock. The composite was characterized by physico-chemical and structural methods (FTIR, SEM, SEM/EDX, SSA, Low temperature nitrogen adsorption method). Based on these methods, the successful preparation of a bamboo based biochar/montmorillonite composite preparation has been demonstrated. The particles of montmorillonite were distributed across the biochar surface. The adsorption studies for removal nitrates from aqueous solutions were investigated by a batch method at laboratory temperatures. The experimental data were fitted by three adsorption models (Langmuir, Freundlich and DR; R2â¯>â¯0.93). The maximum adsorption capacity achieved by biochar at pH 4, was about 5â¯mgâ¯g-1 and by biochar/montmorillonite composite 9â¯mgâ¯g-1. The results suggest that the bamboo-based biochar/montmorillonite composite can be used effectively in the treatment of industrial effluents or waste water containing anionic pollutants such as nitrates.