RESUMO
Efficient decontamination of radioactive Ba2+ is of great significance to human health and environmental safety. Herein, an adsorbent based on the sulfonic acid functionalized Zr-MOF has been successfully developed, which could efficiently decontaminate radioactive Ba2+ with excellent selectivity, recyclability, a high adsorption capacity up to 60.8 mg g-1 as well as a short adsorption kinetic time of less than 5 min. This outstanding adsorption performance is attributed to the strong affinity between Ba2+ and high density -SO3H active sites in MOFs which were introduced by an in situ ligand modification strategy during the assembly of MOFs.
Assuntos
Radioisótopos de Bário/isolamento & purificação , Estruturas Metalorgânicas/química , Ácidos Sulfônicos/química , Zircônio/química , Radioisótopos de Bário/química , Estruturas Metalorgânicas/síntese químicaRESUMO
In this paper, both maghemite (γ-Fe2O3) and titanium oxide (TiO2) nanoparticles were synthesized and mixed in various ratios and embedded in PVA and alginate beads. Batch sorption experiments were applied for removal of barium ions from aqueous solution under sunlight using the beads. The process has been investigated as a function of pH, contact time, temperature, initial barium ion concentration and TiO2:γ-Fe2O3 ratios (1:10, 1:60 and 1). The recycling attributes of these beads were also considered. Furthermore, the results revealed that 99% of the Ba(II) was eliminated in 150min at pH 8 under sunlight. Also, the maghemite and titania PVA-alginate beads can be readily isolated from the aqueous solution after the process and reused for at least 7 times without significant losses of their initial properties. The reduction of Ba(II) with maghemite and titania PVA-alginate beads fitted the pseudo first order and second order Langmuir-Hinshelwood (L-H) kinetic model.
Assuntos
Bário/isolamento & purificação , Nanopartículas Metálicas , Resíduos Radioativos/análise , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Alginatos , Radioisótopos de Bário/isolamento & purificação , Compostos Férricos , Ácido Glucurônico , Ácidos Hexurônicos , Humanos , Concentração de Íons de Hidrogênio , Cinética , Nanopartículas de Magnetita/ultraestrutura , Nanopartículas Metálicas/ultraestrutura , Microscopia Eletrônica de Varredura , Modelos Químicos , Processos Fotoquímicos , Álcool de Polivinil , Titânio , Poluentes Radioativos da Água/isolamento & purificaçãoRESUMO
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Assuntos
Idoso de 80 Anos ou mais , Humanos , Masculino , Lantânio/administração & dosagem , Radiografia Abdominal , Radioisótopos de Bário/isolamento & purificaçãoRESUMO
Sodium aluminosilicate has been synthesized by solution route for use as a sorbent for various radionuclides. It was characterized by XRD, zeta potential, BET surface area, FTIR spectroscopy and site density measurement. Sorption studies of (137)Cs, (133)Ba and (154)Eu on synthesized sodium aluminosilicate have been carried out at varying pH (3-10). Sorption of all the metal ions was found to increase with pH of suspension with the saturation value increasing with the oxidation state of metal ion. Effect of Aldrich humic acid (2mg/l) on sorption was also investigated. In case of (137)Cs, the sorption was not affected by the presence of humic acid, while in case of (133)Ba and (154)Eu, sorption was enhanced at lower pH and decreased at higher pH in presence of HA. A series of experiments were carried out for (154)Eu sorption on sodium aluminosilicate at various conditions. Sorption of europium was analyzed by different sorption isotherms, viz., Freundlich and D-R isotherm. Thermodynamic data reveal sorption phenomena as endothermic and spontaneous. Studies were further extended to find out effect of diverse ions (Ca(2+) and CO(3)(2-)) on sorption of europium.
Assuntos
Silicatos de Alumínio/química , Radioisótopos de Bário/isolamento & purificação , Radioisótopos de Césio/isolamento & purificação , Európio/isolamento & purificação , Adsorção , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Cinética , Radioisótopos/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Difração de Raios XRESUMO
We have characterized "MnO2 Resin," a new resin developed by the PG Research Foundation, for radium adsorption over wide ranges of pH, reaction times and salt concentrations. We show that the sorption of 133Ba (used as a proxy for Ra) is highly dependent on pH with the most useful range from pH 4 to 8. The surface layers of the Mn oxides apparently become more positively charged under acidic conditions (below pH 4), which prevents diffusion of positively charged alkaline earth species (e.g. Ba2+, Ra2+) into the sorption sites. Adsorption at higher pH is thought to be inhibited because of carbonate complexation. We found that the sorption characteristics for radium onto MnO2 Resin are especially favorable for low-salinity waters but the sorption is still very satisfactory for highly salted solutions (KD=2.8x10(4) in both cases) but with slower kinetics. For analytical purposes, both column and pump experiments showed high recoveries with no measurable discrimination between Ra and Ba regardless of flow rates in fresh water. Seawater tests showed that recoveries of Ra and Ba are lower than fresh water at elevated flow rates with Ra adsorption higher than Ba at flow rates above 10 ml/min.