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1.
Int J Biol Macromol ; 266(Pt 2): 130996, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38531521

RESUMO

Metal-organic frameworks (MOF)-polymer hybrid hydrogel solves the processable forming of MOF powder and energy consumption of uranium extraction. However, the hybrid hydrogel by conventional synthesis methods inevitably lead to MOF agglomeration, poor filler-polymer interfacial compatibility and slowly adsorption. Herein, we designed that ZIF-67 was implanted into the carboxymethyl cellulose/polyacrylamide (CMC/PAM) by network-repairing strategy. The carboxyl and amino groups on the surface of CMC/PAM drive the uniform growth of ZIF-67 inside the CMC/PAM, which form an array of oriented and penetrating microchannels through coordination bonds. Our strategy eliminate the ZIF-67 agglomeration, increase the interfacial compatibility between MOF and polymer. The method also improve the free and fast diffusion of uranium in CMC/PAM/ZIF-67 hydrogel. According to the experimental, these enhancements synergistically enabled the CMC/PAM/ZIF-67 have a maximum adsorption capacity of 952 mg g-1. The adsorption process of CMC/PAM/ZIF-67 fits well with pseudo-second-order model and Langmuir isotherm. Meanwhile, the CMC/PAM/ZIF-67 maintain a high removal rate (87.3 %) and chemical stability even during ten adsorption-desorption cycles. It is worth noting that the adsorption amount of CMC/PAM/ZIF-67 in real seawater is 9.95 mg g-1 after 20 days, which is an ideal candidate adsorbent for uranium extraction from seawater.


Assuntos
Resinas Acrílicas , Carboximetilcelulose Sódica , Estruturas Metalorgânicas , Água do Mar , Urânio , Urânio/química , Urânio/isolamento & purificação , Adsorção , Resinas Acrílicas/química , Carboximetilcelulose Sódica/química , Estruturas Metalorgânicas/química , Água do Mar/química , Hidrogéis/química , Cinética , Purificação da Água/métodos , Poluentes Radioativos da Água/isolamento & purificação , Poluentes Radioativos da Água/química
2.
Environ Res ; 250: 118486, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38365057

RESUMO

The facile synthesis approach for the adsorbent preparation and recyclability during decontamination of radioactive pollutants is a significant concern in water treatment. The objective of this study is to, synthesis via solid-state reaction of the nanostructured CaTiO3 for the removal and recovery of strontium (Sr2+) from the various water sources. The influence of the adsorption-dependent parameters including, initial concentration, adsorbent dose, pH, contact time and co-existing ions interference were investigated. The prepared adsorbent was characterized by different analytical techniques like FT-IR, SEM with EDAX, TEM, TGA-DTG, Powder XRD and BET surface analysis. The kinetic models were also used, and according to the kinetic models, a pseudo-second-order kinetic model (R2 = 0.999) was better fitted to the adsorption of Sr2+ ions onto CaTiO3 rather than pseudo-first-order kinetics, which could properly represent the observed adsorption of Sr2+. For the isotherm study, the results are best fitted to the Langmuir isotherm model (R2 = 0.98) with a maximum adsorption capacity of 102.04 mg/g. The common ions (Na+, Mg2+, Ca2+, and K+) and Sr2+ having a concentration of 1:2, 1:3, and 1:4, where 82.8, 79.5, and 68.2 % removal was achieved of Sr2+ in each respective matrix. In addition, the adsorption and corresponding recovery and removal for the different Sr2+spiked matrices in deionized water, tap water, well water, lake water, and seawater were investigated with 97, 65.6, 76.5, 73.9 and 17.8 % removal respectively. Also, the CaTiO3 showed excellent recyclability with minimal loss even after 5 consecutive recyclability cycles and >90% removal of strontium achieved. Hence, prepared nanostructured CaTiO3 could be considered a promising adsorbent for the removal and recovery of Sr2+ions from contaminated water bodies.


Assuntos
Nanoestruturas , Óxidos , Estrôncio , Titânio , Purificação da Água , Estrôncio/química , Adsorção , Titânio/química , Óxidos/química , Purificação da Água/métodos , Nanoestruturas/química , Compostos de Cálcio/química , Poluentes Químicos da Água/química , Cinética , Poluentes Radioativos da Água/química , Poluentes Radioativos da Água/isolamento & purificação
3.
PLoS One ; 16(5): e0251828, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34029330

RESUMO

We investigated the radiocaesium content of nine epiphytic foliose lichens species and the adjacent barks of Zelkova serrata (Ulmaceae, "Japanese elm") and Cerasus sp. (Rosaceae, "Cherry tree") at the boundary of the Fukushima Dai-ichi Nuclear Power Station six years after the accident in 2011. Caesium-137 activities per unit area (the 137Cs-inventory) were determined to compare radiocaesium retentions of lichens (65 specimens) and barks (44 specimens) under the same growth conditions. The 137Cs-inventory of lichens collected from Zelkova serrata and Cerasus sp. were respectively 7.9- and 3.8-times greater than the adjacent barks. Furthermore, we examined the radiocaesium distribution within these samples using autoradiography and on the surfaces with an electron probe micro analyzer (EPMA). Autoradiographic results showed strong local spotting and heterogeneous distributions of radioactivity in both the lichen and bark samples, although the intensities were lower in the barks. The electron microscopy analysis demonstrated that particulates with similar sizes and compositions were distributed on the surfaces of the samples. We therefore concluded that the lichens and barks could capture fine particles, including radiocaesium particles. In addition, radioactivity was distributed more towards the inwards of the lichen samples than the peripheries. This suggests that lichen can retain 137Cs that is chemically immobilised in particulates intracellularly, unlike bark.


Assuntos
Radioisótopos de Césio/isolamento & purificação , Centrais Nucleares , Monitoramento de Radiação , Radioisótopos de Césio/química , Acidente Nuclear de Fukushima , Humanos , Líquens/química , Líquens/efeitos da radiação , Casca de Planta/química , Casca de Planta/efeitos da radiação , Ulmaceae/química , Ulmaceae/efeitos da radiação , Poluentes Radioativos da Água/efeitos adversos , Poluentes Radioativos da Água/isolamento & purificação
4.
Int J Phytoremediation ; 23(13): 1376-1381, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33756088

RESUMO

NOVELTY STATEMENT: Ecologically suitable methods for the decontamination of liquid radioactive waste or radioactively contaminated areas are becoming more and more important due to the pollution of the planet. We believe that phytoremediation of radionuclides using microalgae is one of the optimal ecological methods to decontamination of radioactive waste. Microalgae as unicellular organisms have a number of advantages over the other organisms used in bioremediation-high level of tolerance to the environment, fast growth rates, high tolerance to various pH levels, etc. In this study, we used 3 different strains of microalgae for phytoremediation of various radionuclides (137Cs, 60Co, 241Am, and 239Pu). This research was focused on ex situ phytoremediation of radionuclides using microalgae at various pH levels of radioactively contaminated solutions. Due to the ability of microalgae to adapt to sometimes even extreme pH values, this research may be interesting for many institutions and researchers dealing with more environmentally friendly methods of decontamination of radioactive waste.


Assuntos
Biodegradação Ambiental , Chlamydomonas reinhardtii , Chlorella vulgaris , Radioisótopos/isolamento & purificação , Scenedesmus , Poluentes Radioativos da Água/isolamento & purificação , Microalgas
5.
Chemosphere ; 258: 127152, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32544809

RESUMO

Graphene oxide (GO) has been proved with favorable affinity to U(VI), while some drawbacks such as poor dispersity and low adsorption performance limit its application. Herein, cetyltrimethylammonium bromide (CTAB) modified graphene oxide (MGO) composites were successfully fabricated, characterized and compared with graphene oxide (GO) in the sequestration of U(VI) in aqueous solutions. The results showed that maximum adsorption rate of MGO (99.21%) was obviously higher than that of GO (66.51%) under the same initial condition. Simultaneous introduction of C-H and NO coupled with the enhanced dispersity of GO after modification were mainly responsible for the updated performance verified with multiple characterization techniques. Based on the results of kinetics and isotherms investigations, the experimental data were best described by Pseudo-first-order kinetic model and Redlich-Peterson isotherm model. The results of ΔH, ΔS and ΔG show that adsorptive behaviors of uranyl ion on MGO are endothermic and spontaneous. The study provides a feasible alternative to the chemical modification of GO and enhancing the performance towards uranyl ion removal from solution.


Assuntos
Grafite/química , Urânio/química , Poluentes Químicos da Água/química , Adsorção , Cetrimônio/química , Concentração de Íons de Hidrogênio , Íons , Cinética , Microscopia Eletrônica de Varredura , Modelos Químicos , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Urânio/isolamento & purificação , Água , Poluentes Químicos da Água/isolamento & purificação , Poluentes Radioativos da Água/química , Poluentes Radioativos da Água/isolamento & purificação , Difração de Raios X
6.
Environ Sci Pollut Res Int ; 27(4): 4325-4336, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31832953

RESUMO

Ra-226 is a naturally occurring radionuclide that is derived from uranium-238 series, and it is present at low concentrations in rocks, soil, and groundwater. Many efforts have been exerted for the decontamination of radium from aqueous media in order to meet the increasing water demand of the population. To this aim, a new polymer based on cross-linked phenoxycalix[4]pyrrole was designed and employed in solid/liquid extractions in order to remove radium from aqueous solutions. Preliminary experiments have highlighted the capability of this polymer to extract 22% of Ra-226 from aqueous acidic solution. The optimization of the extraction experimental factors in the direction to attend the maximum removal of Ra-226 from water was carried out employing Ba2+ due to its similar chemical behavior as radium, in order to minimize the consumption of Ra-226 solutions and the risk of radioactive contamination. Doehlert experimental plan was then applied to determine the optimal conditions (pH, time, temperature) for the removal of Ba2+ from aqueous solutions.


Assuntos
Polímeros , Pirróis , Rádio (Elemento)/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação , Projetos de Pesquisa
7.
Sci Rep ; 9(1): 10149, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300718

RESUMO

We evaluated the potential sequestration of cesium (Cs+) by microalgae under heterotrophic growth conditions in an attempt to ultimately develop a system for treatment of radioactive wastewater. Thus, we examined the effects of initial Cs+ concentration (100-500 µM), pH (5-9), K+ and Na+ concentrations (0-20 mg/L), and different organic carbon sources (acetate, glycerol, glucose) on Cs+ removal. Our initial comparison of nine microalgae indicated that Desmodesmus armatus SCK had removed the most Cs+ under various environmental conditions. Addition of organic substrates significantly enhanced Cs+ uptake by D. armatus, even in the presence of a competitive cation (K+). We also applied magnetic nanoparticles coated with a cationic polymer (polyethylenimine) to separate 137Cs-containing microalgal biomass under a magnetic field. Our technique of combining bioaccumulation and magnetic separation successfully removed more than 90% of the radioactive 137Cs from an aqueous medium. These results clearly demonstrate that the method described here is a promising bioremediation technique for treatment of radioactive liquid waste.


Assuntos
Radioisótopos de Césio/isolamento & purificação , Microalgas/metabolismo , Poluentes Radioativos da Água/isolamento & purificação , Bioacumulação , Carbono/metabolismo , Césio/isolamento & purificação , Césio/farmacocinética , Radioisótopos de Césio/farmacocinética , Clorófitas/efeitos dos fármacos , Clorófitas/metabolismo , Concentração de Íons de Hidrogênio , Fenômenos Magnéticos , Nanopartículas de Magnetita/química , Microalgas/efeitos dos fármacos , Polietilenoimina/química , Potássio/farmacologia , Sódio/farmacologia , Especificidade da Espécie , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/farmacocinética , Poluentes Radioativos da Água/farmacocinética
8.
Health Phys ; 116(6): 771-775, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30844900

RESUMO

Radiostrontium isotopes (Sr, Sr, and Sr) are major fission by-products in nuclear reactors, in radiological events, and in environmental radioactive contamination. A method to analyze Sr and Sr in water has been developed using gradient elution with dilute hydrochloric acid and cation exchange resin, followed by carbonate precipitation. Counting was done on a gas proportional counter. The sample was recounted a second time after 2 to 3 wk to permit Y, a progeny of Sr, to achieve secular equilibrium and to allow Sr and Sr to be determined. This method was found to be simple, exhibiting high recovery, reduced use of hazardous chemicals, and lower cost compared to other current methods. An extensive comparison of the performance of the cation exchange method vs. a method using strong nitric acid (US Environmental Protection Agency Method 905.0) and a method using a specific strontium resin was conducted on performance test samples containing Sr (in a number of matrices) from the US Department of Energy's Mixed Analyte Performance Evaluation Program and mixed Sr- and Sr-containing water samples from the Environmental Resource Associates quality assurance program. The method described here is shown to yield comparable results to others.


Assuntos
Cromatografia por Troca Iônica/métodos , Monitoramento de Radiação/métodos , Radioisótopos de Estrôncio/análise , Poluentes Radioativos da Água/análise , Humanos , Radioisótopos de Estrôncio/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação
9.
J Hazard Mater ; 371: 586-591, 2019 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-30878909

RESUMO

Occurrence of radium in drinking water may pose a radiological hazard. It is one of the most radiotoxic radionuclides and a major contributor to the Indicative Dose (ID), regulated parameter in UE. Its removal at Drinking Water Treatment Plants (DWTPs) can be considered a preventive action, as it cannot reach the final consumer nor be accumulated in distribution pipes. A filtration system based on greensand designed for radium removal was tested in an actual DWTP. Removal effectiveness depended on the spatial velocity water passed through the filter, range 65-100%. The lower the spatial velocity, the greater contact time, and the longer high removal percentages were achieved. The radium removed from the water was mainly associated to easily reducible fraction in greensand. So radium accumulation in the filter may pose a radiological hazard for the workers in the DWTP. Dose rate was assessed in the worst case scenario for this case study, being about 0.22 mSv/y, significantly lower than reference value 1 mSv/y. Radium accumulated in the greensand filter can be extracted in order to ease waste management, and subsequently, the filtration system can be regenerated showing similar capacity to extract radium as a new one.


Assuntos
Água Potável/química , Rádio (Elemento)/isolamento & purificação , Gerenciamento de Resíduos/métodos , Poluentes Radioativos da Água/isolamento & purificação , Purificação da Água/métodos
10.
Chemosphere ; 222: 106-113, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30699369

RESUMO

Recent characterization of radioactive particles indicate that a large percentage of the radioactivity observed during the Fukushima Daiichi nuclear meltdown was insoluble 137Cs bound within silica microparticles. Therefore, much of the decontamination research performed prior to the Fukushima incident that used either soluble radionuclides deposited onto wet surfaces or large (∼100 µm) particles characteristic of nuclear weapons fallout do not accurately represent the characteristics of potential contamination. Thus, the common practice of extrapolating radioactive decontamination methods generically to all radioactive release events is, at best, suspect. In response, a method to produce chemically-inert, radiolabeled silica particles was developed. Binding 152Eu within a sodium silicate coating required proper temperature control and ethanol was beneficial as a volatile dispersant to limit residues. In the end, a step-wise method, which first deposited 152Eu or 241Am as a nitrate salt, decomposed the salt to a sesquioxide, and finally coated the surface with sodium silicate led to dispersed particles of the desired 2 or 0.5 µm diameters. Dynamic light scattering and scanning election microscopy confirmed the particle size was unchanged. Leaching studies into several common decontaminants were performed to ensure particle inertness. Our approach allows for substitution of other radionuclides making it a robust, simple, and novel method to produce inert particle surrogates for a release event that allows direct comparison of decontamination techniques and contaminant fate studies, greatly aiding the development of response and recovery plans.


Assuntos
Descontaminação/métodos , Monitoramento de Radiação/métodos , Cinza Radioativa/prevenção & controle , Silicatos/farmacologia , Poluentes Radioativos da Água/isolamento & purificação , Amerício , Radioisótopos de Césio , Einstêinio , Acidente Nuclear de Fukushima , Japão , Tamanho da Partícula , Monitoramento de Radiação/normas
11.
Environ Sci Process Impacts ; 21(2): 339-351, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30516236

RESUMO

High concentrations of barium (Ba), strontium (Sr) and radium (Ra) are present in both the liquid and suspended solid portions of wastewater produced from hydraulic fracturing. These high concentrations often require special treatment in which the solid and liquid portions are separated and then independently treated prior to disposal. The solids are typically disposed in landfills while the liquids are further treated, recycled for future hydraulic fracturing, or disposed via injection wells. Finding optimal treatment methods of both the solid and the liquid fractions requires a thorough understanding of potential Ra mobility from both the raw suspended solids and mineral precipitates formed during treatment. Using a sequential extraction procedure, we found that, without treatment, more than 50% of Ra-226 in the suspended solids was associated with soluble salts and readily exchangeable fractions. When the liquid portion of the wastewater was treated by mixing with acid mine drainage (AMD), which contained high sulfate concentrations, approximately 80-97% of the total Ra-226 in the mixture solution is found in the insoluble sulfate fraction of the precipitate. The activity of Ra-226 sequestered in the precipitated solid sulfate fractions is positively correlated with the Sr/Ba ratio of the wastewater-AMD solution. We discuss implications of these findings for effective long-term management of elevated radium in both solid and liquid wastes.


Assuntos
Fraturamento Hidráulico , Rádio (Elemento)/análise , Sulfatos/química , Águas Residuárias/química , Poluentes Radioativos da Água/análise , Mineração , Poluentes Radioativos da Água/isolamento & purificação
12.
Environ Sci Pollut Res Int ; 26(4): 3697-3705, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30535621

RESUMO

A low-cost industrial microorganism, Saccharomyces cerevisiae, was employed as a precursor to synthesize carbon/MnO2 composites (MMCs) via an oxidation-reduction reaction and one-step carbonization method for U(VI) adsorption. Scanning electron microscopy and nitrogen adsorption measurement indicated that the microorganism's carbonization could form surface porous structure and increase the specific surface area. Batch experiments showed that the maximum U(VI) adsorption capacity of MMCs reached 207 mg g-1 at [U(VI)]initial = 25 mg L-1 and pHinitial = 4.5. The obtained thermodynamic and kinetic parameters suggested that the process is endothermic, spontaneous, and chemisorption. FTIR and X-ray photoelectron spectroscopy demonstrated that the surface hydroxyl groups of composites might be the reactive adsorption sites for U(VI). Additionally, 0.5 mol L-1 HNO3 solution could desorb ~ 95% uranium from U(VI)-loaded MMCs, and materials exhibited good regenerated availability. This study suggests that MMCs can be a potential adsorbent for U(VI) preconcentration and removal from radioactive wastewater.


Assuntos
Carbono/química , Compostos de Manganês/química , Óxidos/química , Saccharomyces cerevisiae/química , Urânio/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação , Adsorção , Cinética , Microscopia Eletrônica de Varredura , Nitrogênio/isolamento & purificação , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Urânio/química , Águas Residuárias/química
13.
J Environ Manage ; 223: 108-114, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29908396

RESUMO

Temporary base treatment is a potential remediation technique for heavy metals through adsorption, precipitation, and co-precipitation with minerals. Manipulation of pH with ammonia gas injection may be especially useful for vadose zone environments as it does not require addition of liquids that would increase the flux towards groundwater. In this research, we conducted laboratory batch experiments to evaluate the changes in uranium mobility and mineral dissolution with base treatments including sodium hydroxide, ammonium hydroxide, and ammonia gas. Our data show that partitioning of uranium to the solid phase increases by several orders of magnitude following base treatment in the presence of different minerals and natural sediments from the Hanford site. The presence of dissolved calcium and carbonate play an important role in precipitation and co-precipitation of uranium at elevated pH. In addition, significant incongruent dissolution of bulk mineral phases occurs and likely leads to precipitation of secondary mineral phases. These secondary phases may remove uranium via adsorption, precipitation, and co-precipitation processes and may coat uranium phases with low solubility minerals as the pH returns to natural conditions.


Assuntos
Urânio/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação , Adsorção , Animais , Sedimentos Geológicos , Água Subterrânea , Minerais , Suínos , Urânio/química , Poluentes Radioativos da Água/química
14.
Water Res ; 142: 167-175, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-29870950

RESUMO

This study demonstrated the removal and recovery of uranium(VI) in a fed-batch stirred tank reactor (STR) using waste digested activated sludge (WDAS). The batch adsorption experiments showed that WDAS can adsorb 200 (±9.0) mg of uranium(VI) per g of WDAS. The maximum adsorption of uranium(VI) was achieved even at an acidic initial pH of 2.7 which increased to a pH of 4.0 in the equilibrium state. Desorption of uranium(VI) from WDAS was successfully demonstrated from the release of more than 95% of uranium(VI) using both acidic (0.5 M HCl) and alkaline (1.0 M Na2CO3) eluents. Due to the fast kinetics of uranium(VI) adsorption onto WDAS, the fed-batch STR was successfully operated at a mixing time of 15 min. Twelve consecutive uranium(VI) adsorption steps with an average adsorption efficiency of 91.5% required only two desorption steps to elute more than 95% of uranium(VI) from WDAS. Uranium(VI) was shown to interact predominantly with the phosphoryl and carboxyl groups of the WDAS, as revealed by in situ infrared spectroscopy and time-resolved laser-induced fluorescence spectroscopy studies. This study provides a proof-of-concept of the use of fed-batch STR process based on WDAS for the removal and recovery of uranium(VI).


Assuntos
Urânio/isolamento & purificação , Gerenciamento de Resíduos/métodos , Poluentes Radioativos da Água/isolamento & purificação , Adsorção , Técnicas de Cultura Celular por Lotes/instrumentação , Reatores Biológicos , Concentração de Íons de Hidrogênio , Cinética , Esgotos , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Gerenciamento de Resíduos/instrumentação
15.
Environ Sci Pollut Res Int ; 25(22): 22120-22135, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29802617

RESUMO

A comparative study between two nanosorbents, nanopolyaniline (NPANI) and nanopolyaniline coated with nanosilver oxide (NPANI-NAg2O) is explored to dispose the divalent species of Zn/Co from water and radioactive isotopes 65Zn/60Co from radioactive wastewater using batch and column techniques. NPANI-NAg2O nanocomposite was synthesized via solid-solid reaction. Characterization was achieved using FT-IR, TGA, XRD, SEM, HR-TEM, and surface area analysis. The images of SEM and HR-TEM confirmed the success of the modification process and the particle size was found in the range 28.78-68.28 nm (NPANI) and 25.74-85.71 nm (NPANI-NAg2O), respectively. Solution pH, contact time, solid dosage, and ionic concentration of the metals were studied as fundamental factors. The obtained results indicated that the optimum conditions to dispose Zn/Co divalent species using NPANI were pH 7 and 30-33 min, while NPANI-NAg2O exhibited the optimum conditions at pH 7 and 20-30 min. The maximum removal capacities were 100.1 and 139.75 mg/g for Zn(II) and 57.93 and 112.1 mg/g for Co(II) using NPANI and NPANI-NAg2O, respectively. Graphical abstract ᅟ.


Assuntos
Compostos de Anilina/síntese química , Radioisótopos de Cobalto/química , Nanocompostos/química , Óxidos/química , Compostos de Prata/química , Poluentes Radioativos da Água/isolamento & purificação , Radioisótopos de Zinco/química , Adsorção , Química Verde , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias/química , Purificação da Água/métodos , Zinco
16.
Appl Radiat Isot ; 136: 10-17, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29448060

RESUMO

A new sequential separation method for the determination of polonium and actinides (Pu, Am and U) in drinking water samples has been developed that can be used for emergency response or routine water analyses. For the first time, the application of TEVA chromatography column in the sequential separation of polonium and plutonium has been studied. This method utilizes a rapid Fe+3 co-precipitation step to remove matrix interferences, followed by plutonium oxidation state adjustment to Pu4+ and an incubation period of ~ 1 h at 50-60 °C to allow Po2+ to oxidize to Po4+. The polonium and plutonium were then separated on a TEVA column, while separation of americium from uranium was performed on a TRU column. After separation, polonium was micro-precipitated with copper sulfide (CuS), while actinides were micro co-precipitated using neodymium fluoride (NdF3) for counting by the alpha spectrometry. The method is simple, robust and can be performed quickly with excellent removal of interferences, high chemical recovery and very good alpha peak resolution. The efficiency and reliability of the procedures were tested by using spiked samples. The effect of several transition metals (Cu2+, Pb2+, Fe3+, Fe2+, and Ni2+) on the performance of this method were also assessed to evaluate the potential matrix effects. Studies indicate that presence of up to 25 mg of these cations in the samples had no adverse effect on the recovery or the resolution of polonium alpha peaks.


Assuntos
Amerício/isolamento & purificação , Cromatografia Líquida/métodos , Água Potável/química , Plutônio/isolamento & purificação , Polônio/isolamento & purificação , Urânio/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação , Reprodutibilidade dos Testes , Análise Espectral/métodos , Elementos de Transição/química
17.
J Environ Manage ; 212: 210-218, 2018 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-29433000

RESUMO

The present study explores a novel application of Huma-K, a commercially available, unrefined humic substance, as a promising low-cost source of organic matter for in situ remediation of contaminated acidic groundwater plumes. This can be achieved by creating a humic-rich coating on the surface of minerals which can enhance the sorption of contaminants from groundwater. Huma-K was characterized by means of scanning electron microscopy equipped with energy dispersive spectroscopy, Fourier-transform infrared analysis, and potentiometric titrations. Batch experiments were performed to investigate the sorption-desorption behavior of Huma-K and to evaluate what conditions (pH, contact time, and initial Huma-K concentration) affect these processes upon injection into aquifer sediments. As evidenced by potentiometric titrations, Huma-K possesses functional groups that have an acidic nature, with pK values in the range of 4-6 (carboxylic) and 9-10 (phenolic). Sorption, homogeneous precipitation, and surface-induced precipitation seem to be favored in the presence of sediment at pH 4, where there is less deprotonation of acidic functional groups. As the pH is increased, functional groups become negatively charged, leading to electrostatic repulsion and dissolution of Huma-K from sediment. Kinetic experiments indicate that Huma-K sorption is a slow-rate process, most likely governed by film diffusion. The enhanced sorption of Huma-K in acidic conditions suggests that it may be used to create a subsurface treatment zone in acidic aquifers for the sequestration of contaminants such as uranium. The treatment zone will persist as long as the pH does not increase sufficiently to cause soil-bound Huma-K to be released, remobilizing aqueous contaminants.


Assuntos
Água Subterrânea , Substâncias Húmicas , Poluentes Radioativos da Água/isolamento & purificação , Adsorção , Urânio
18.
Sci Rep ; 7(1): 12578, 2017 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-28974754

RESUMO

Spatial variations in tritium concentrations in groundwater were identified in the southern part of the coastal region in Fukushima Prefecture, Japan. Higher tritium concentrations were measured at wells near the Fukushima Daiichi Nuclear Power Station (F1NPS). Mean tritium concentrations in precipitation in the 5 weeks after the F1NPS accident were estimated to be 433 and 139 TU at a distance of 25 and 50 km, respectively, from the F1NPS. The elevations of tritium concentrations in groundwater were calculated using a simple mixing model of the precipitation and groundwater. By assuming that these precipitation was mixed into groundwater with a background tritium concentration in a hypothetical well, concentrations of 13 and 7 TU at distances of 25 and 50 km from the F1NPS, respectively, were obtained. The calculated concentrations are consistent with those measured at the studied wells. Therefore, the spatial variation in tritium concentrations in groundwater was probably caused by precipitation with high tritium concentrations as a result of the F1NPS accident. However, the highest estimated tritium concentrations in precipitation for the study site were much lower than the WHO limits for drinking water, and the concentrations decreased to almost background level at the wells by mixing with groundwater.


Assuntos
Radioisótopos de Césio/isolamento & purificação , Monitoramento de Radiação , Trítio/isolamento & purificação , Poluentes Radioativos da Água/isolamento & purificação , Radioisótopos de Césio/química , Radioisótopos de Césio/toxicidade , Água Potável/química , Acidente Nuclear de Fukushima , Água Subterrânea/química , Humanos , Trítio/química , Trítio/toxicidade , Poluentes Radioativos da Água/química , Poluentes Radioativos da Água/toxicidade
19.
Water Res ; 125: 81-90, 2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-28834769

RESUMO

Sodium-copper hexacyanoferrate (NaCuHCF)-functionalized magnetic nanoadsorbents were fabricated for the highly efficient magnetic removal of radioactive caesium from seawater. The magnetic nanoclusters (MNCs), composed of many individual Fe3O4 nanoparticles, were covalently coated with polyethyleneimine (PEI) to functionalize the MNC surfaces with NaCuHCF. After simple immobilization of Cu and Na ferrocyanide on the NC surface, the resulting NaCuHCF-functionalized MNCs showed good magnetic properties and a significant adsorption capacity for Cs+ with a high content of NaCuHCF (36.04%). The adsorption kinetics and isotherms were well fit to a pseudo-second-order model and Langmuir isotherm, respectively. The sorption of 97.35% Cs by the NaCuHCF-PEI-MNCs completed in less than 5 min, and the maximum adsorption capacity of the adsorbent was 166.67 mg/g. The NaCuHCF-PEI-MNCs selectively adsorbed Cs even in the presence of various competing ions, such as Na, K, Mg, and Ca, and the Cs removal mechanism was revealed as ion exchange between Cs in solution and Na in the NaCuHCF-PEI-MNCs. In radioactive tests, our adsorbent displayed excellent removal performance in real seawater with a high removal efficiency exceeding 99.73%, a decontamination factor exceeding 372, and a high stability in water over a wide pH range from 4 to 10 with negligible leaching of Fe.


Assuntos
Radioisótopos de Césio/isolamento & purificação , Nanopartículas/química , Água do Mar/química , Poluentes Radioativos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cobre/química , Ferrocianetos/química , Concentração de Íons de Hidrogênio , Cinética , Magnetismo , Microscopia Eletrônica de Transmissão , Polietilenoimina/química , Sódio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/isolamento & purificação , Difração de Raios X
20.
J Hazard Mater ; 338: 323-333, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28582713

RESUMO

Radioactive isotopes and fission products have attracted considerable attention because of their long lasting serious damage to the health of humans and other organisms. This study examined the toxicity and accumulation behavior of cesium towards P. aeruginosa PAO1 and its capacity to remove cesium from waste water. Interestingly, the programmed bacterial growth inhibition occurred according to the cesium environment. The influence of cesium was analyzed using several optical methods for quantitative evaluation. Cesium plays vital role in the growth of microorganisms and functions as an anti-microbial agent. The toxicity of Cs to P. aeruginosa PAO1 increases as the concentration of cesium is increased in concentration-dependent manner. P. aeruginosa PAO1 shows excellent Cs removal efficiency of 76.1% from the contaminated water. The toxicity of cesium on the cell wall and in the cytoplasm were studied by transmission electron microscopy and electron dispersive X-ray analysis. Finally, the removal of cesium from wastewater using P. aeruginosa PAO1 as a potential biosorbent and the blocking of competitive interactions of other monovalent cation, such as potassium, were assessed. Overall, P. aeruginosa PAO1 can be used as a high efficient biomaterial in the field of radioactive waste disposal and management.


Assuntos
Biodegradação Ambiental , Radioisótopos de Césio/toxicidade , Pseudomonas aeruginosa/efeitos da radiação , Águas Residuárias , Poluentes Radioativos da Água/toxicidade , Biofilmes/crescimento & desenvolvimento , Biofilmes/efeitos da radiação , Parede Celular/efeitos da radiação , Radioisótopos de Césio/química , Radioisótopos de Césio/isolamento & purificação , Citoplasma/efeitos da radiação , Microscopia Eletrônica de Transmissão , Potássio/química , Pseudomonas aeruginosa/crescimento & desenvolvimento , Poluentes Radioativos da Água/química , Poluentes Radioativos da Água/isolamento & purificação
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