Impregnated fly ash sorbent for cesium-137 removal from water samples

Journal of Radioanalytical and Nuclear Chemistry - Cesium-137 is an important indicator of radioactive pollution in the aquatic environment. The aim of this study was to increase the sorption...     

Separation and measurement of cesium-137 in precipitation

In rainwater samples containing fallout debris of recent origin, the ¹³⁷Cs absorption peak in a γ-ray scintillation spectrum contained, and was often completely obscured by, contributions from other γ-ray emitting radionuclides, so that the ¹³⁷Cs activity could not be determined directly. Precipitation samples were collected with rain funnels and passed through Dowex 50W-X12 cation-exchange columns. The ¹³⁷Cs was selectively eluted with 0.5 M ammonium nitrate. The absolute recovery of ¹³⁷Cs was complicated by the presence of airborne sediments that were invariably collected with the sample and could irreversibly fix ¹³⁷Cs from the rainwater.     

Detecting137Cs breakthrough in an ion exchange process

High-level radioactive wastes can be transformed to low-level wastes by removing¹³⁷Cs through selective ion exchange processes. Since the short-lived daughter,¹³⁷ⁱⁿBa produces the 662-keV gamma-ray normally attributed to¹³⁷Cs, equilibrium may be broken, and observation of the 662-keV gamma-ray cannot be used to detect cesium breakthrough. Two detectors viewing the output line, but separated sufficiently to measure the^137mBa decay between them, are used to detect¹³⁷Cs breakthrough based on deviation from the normal^137mBa decay. Detection evaluated for the process separation time, counting time, fractional breakthrough detectable, and accuracy and confidence of the measurements are discussed.     

Dispersion model of cesium-137 in surface oceanic waters

The¹³⁷Cs radionuclide dispersion in the marine environment through the compartmental model is reported. The model simulates the surface water contamination caused by routine or accidental radionuclide releases. For the simulation the OCEAN program was applied in the North Sea, near to Sellafield and adjacent areas, based on published transfer coefficient data. The results are in good agreement with the literature and the model developed can be applied to the brazilian coastal regions.     

Determination of boron in titanium alloys by means of ion exchange

There is need for a rapid method for the determination of moderate amounts of boron in titanium alloys. In this paper a method is proposed which uses ion exchange. The method is applicable to titanium alloys containing 0.025 to 1 per cent. boron. One or two grams of the sample are dissolved in hydrochloric acid, and the titanium and boron are oxidized with nitric acid. The bulk of the titanium is removed by a cation exchanger. A calcium carbonate separation is made to remove the residual titanium and adjust the acidity. The boron is then titrated with sodium hydroxide, after the addition of mannitol. None of the elements found in commercial titanium alloys interferes with the method.     

Determination of cadmium in uranium by ion exchange and square-wave polarography

Traces of cadmium in uranium and its compounds can be determined by ion-exchange separation and square-wave polarography. With a small column of anion-exchange resin, cadmium can be separated from uranium and recovered quantitatively from hydrochloric acid solution, Separations of cadmium from uranium are not perfect but are sufficient for the determination of traces of cadmium by square-wave polarography. The lower limit of the method is 0.01 p.p.m. of cadmium.     

Determination of manganese in uranium by ion exchange and square-wave polarography

Traces of manganese in uranium and its compounds can be determined by ion-exchange separation and square-wave polarography. When a 9 M hydrochloric acid solution of the sample is introduced into a column of strongly basic anion-exchange resin, manganese can be quantitatively separated from uranium by cluting with 9 M hydrochloric acid. The determination of the separated manganese by square-wave polarography is performed in 1 M potassium hydroxide-0.4 M triethanolamine solution with an excellent sensitivity. The lower limit of the method is 0.5 p.p.m. of manganese.     

Determination of anions in high-purity water by ion chromatography

Summary The determination of the concentration of some different anions in high-purity water (g/l-level) using ion chromatography after concentration on pre-columns is described. The detection ist made by a conductivity cell after passing an anion fiber-suppressor (AFS). Two different separator columns (AS-5 and AS-4) and some different separator systems were tested. In all cases linearity is given for the determined anions.The concentration of the anions was determined not directly but by addition of a standard solution and subsequent graphic extrapolation of the calibration diagram. The determination levels are below 1 g/l. The AS-5 column gives better results than the AS-4 column.

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Ionen-chromatographische Bestimmung von Anionen in Reinstwasser

Zusammenfassung Die Bestimmung der Konzentration verschiedener Anionen in Reinstwasser (g/l-Bereich) mittels der Ionen-Chromatographie nach Anreicherung auf Konzentriersäulen wird beschrieben. Die Detektion erfolgt über eine Leitfähigkeitsmeßzelle mit vorgeschaltetem Anionen-Hohlfasermembransuppressor (AFS). Es wurden zwei verschiedene Trennsäulen (AS-4 und AS-5) und mehrere Trennsysteme getestet und optimiert. In allen Fällen ergab sich Linearität für die untersuchten Anionen. Die Bestimmung der Anionenkonzentrationen in Reinstwasser erfolgte nicht direkt, sondern durch Aufstocken mit Standardlösung und anschlie\ender graphischer Extrapolation der erstellten Eichgraden. Die Nachweisgrenzen liegen unter 1 g/l. Die AS-5-Säule erwies sich für die beschriebene Methode als geeigneter.

     

Kinetics of water vapor adsorption by ion exchange polyacrylonitrile fibres

Kinetics of water vapor adsorption by ion exchange PAN fibres has been studied. Adsorption can be described by an exponential kinetic equation. Experimental results permit the assumption that the surface of the materials studied behaves as uniformly nonhomogeneous with more strongly expressed entropy nonhomogeneity, connected with cross-linking of the modified fibres. The dependence between the kinetic characteristics and the solubility of the materials in DMF shows that the main factor affecting unfavorably the adsorption kinetics is cross-linking. Increase of N-containing anion exchange groups reduces the effect of adsorption delay due to cross-linking.

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分光光度法测定水中氟离子的优化

氟离子在弱酸性缓冲介质中与显色剂反应生成蓝色三元络合物,络合物在620 nm波长处的吸光度与氟离子浓度成正比,据此建立检测水中氟化物含量的分光光度法.研究了缓冲液和显色剂加入量、络合物稳定剂、稳定时间对测定结果的影响,并确定了最佳分析条件:向适量水样中加入1 mL缓冲液、1 mL显色剂、1 mL乙醇,静置20 min,...     

Natural radionuclides and cesium-137 content in Arabian Gulf bottom sediments

The activity concentration of natural radionuclides and¹³⁷Cs in the bottom sediment samples from the coastal area of Kuwait on the Arabian Gulf have been determined by -ray spectrometry with REGe detector. The data for the samples are very similar to those obtained for surface soil samples in Kuwait.¹ Two parent-progeny ratios for:^23$Th–²²⁶Ra and²²⁸Ac–²⁰⁸Tl to evaluate the geochemical behavior of the radionuclides have been estimated. The existence of a serious disequilibrium between²³⁴Th and²²⁶Ra for samples taken from the vicinity of Kuwait islands and the Ras Al-Zoor area was found. The strait between the coast of Kuwait and Bubiyan island is proposed for the future sedimentation rate determinations on the basis of²¹⁰Pb measurements. No serious contamination by technogenic radionuclides for this region of Arabian Gulf was observed.     

Determination of the apparent ion exchange capacity

A numerical-graphical method is described for determining the apparent capacity of an ion exchanger for univalent and multivalent ions, assuming that other interactions with the electrolyte, such as adsorption, precipitation, etc., are vanishingly small in comparison with the ion exchange process.     

Determination of inorganic ions in drinking water by ion chromatography

Ion chromatography (IC) is now a well established methodology for the analysis of ionic species. The technique is applicable to the determination of a wide range of solutes in many sample types, although the determination of inorganic ions in drinking water continues to be the most widely used application of ion chromatography. Many regulatory and standard organizations, such as ASTM, AOAC, ISO, and US EPA, have approved methods of analysis based upon IC, most of which have been published within the last 10 years. Recent developments in the field of IC, such as the use of higher capacity columns, larger loop injections, more complex sample preparation and detection schemes, have been incorporated into new approved methods to allow the determination of inorganic contaminants, such as bromate, perchlorate, and chromate, at low μg/l levels in drinking waters. IC appears certain to remain an important technique for drinking water analysis and new methods based on IC will continue to be developed as more inorganic contaminants become regulated at lower limits in the future.     

顶空气相色谱法测定离子交换树脂中8种有机溶剂残留

建立了功能食品加工用离子交换树脂中甲基异丙基甲酮、丁酸甲酯、3-戊酮、1,3-二乙基苯、1,4-二乙基苯、1,2-二氯乙烷、间二氯苯、甲基丙烯酸甲酯8种有机残留物的顶空气相色谱检测方法,研究了不同类型树脂中的有机残留物种类及含量,为食品和药品中安全使用离子交换树脂提供依据.优化了样品的提取溶剂和顶空气相色谱条件,样品经...     

Determination of praseodymium in lanthanum compounds by neutron activation and ion exchange separation

Summary A procedure was developed to determine small amounts of praseodymium in lanthanum compounds by neutron activation analysis. After irradiation of the sample in a reactor praseodymium is separated from lanthanum by anion exchange and Pr-142 is measured by a gamma-ray spectrometer. From the high decontamination factor of 110⁸ a detection limit of 5ppb praseodymium in lanthanum may be calculated. Because of the strong activation of lanthanum, the handling of samples with activities of about 1 Ci La-140 would be required. For the analyses carried out here with respect of sample weights, neutron flux and irradiation time a detection limit of 2.4ppm was obtained.

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Bestimmung von Praseodym in Lanthanverbindungen durch Neutronenaktivierung und Ionenaustausch

Zusammenfassung Zur Bestimmung von geringen Mengen Praseodym in Lanthanverbindungen wurde ein auf Neutronenaktivierungsanalyse basierendes Verfahren entwickelt. Nach Bestrahlung der Probe im Reaktor wird Praseodym mit einem Anionenaustauscher von Lanthan getrennt und Pr-142 mit einem Gamma-Spektrometer gemessen. Der mit der Trennung erreichte Reinigungsfaktor von 110⁸ würde eine Nachweisgrenze von etwa 5ppb Praseodym in Lanthan erlauben. Wegen der starken Aktivierung des Lanthans würde das aber den Umgang mit Proben von ca. 1 Ci La-140 erfordern. Mit den hier gewählten Probenmengen, Neutronenflüssen und Bestrahlungszeiten wurde eine Nachweisgrenze von 2,4ppm erreicht.

Presented at the Ulmer Symposium Analytische Chemie — Elementanalyse mit chromatographischen Methoden, Sept. 19–21, 1979, D-7900 Ulm     

Determination of haloacetic acids in water by ion chromatography--method development.

The microextraction/ion chromatographic (IC) method developed in this study involves extraction of 9 haloacetic acids (HAAs) from aqueous samples (acidified with sulfuric acid to a pH of < 0.5 and amended with copper sulfate pentahydrate and sodium sulfate) with methyl tert-butyl ether (MTBE), back extraction into reagent water, and analysis by IC with conductivity detection. The separation column consists of an Ion Pac AG-11 (2 mm id x 50 mm length) guard column and an Ion Pac AS-11 (2 mm id x 250 mm length) analytical column, and the concentration column is a 4 mm id x 35 mm length Dionex TAC-LP column. Use of the 2 mm id Dionex AS-11 column improved detection limits especially for trichloracetic acid (TCAA), bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), and tribromoacetic acid (TBAA). The peak interfering with BCAA elutes at the same retention time as nitrate; however, we have not confirmed the presence of nitrate. Stability studies indicate that HAAs are stable in water for at least 8 days when preserved with ammonium chloride at 100 mg/L and stored at 4 degrees C in the dark. At day 30, recoveries were still high (e.g., 92.1-106%) for dichloroacetic acid (DCAA), BCAA, dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), BDCAA, and DBCAA. However, recoveries of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and TBAA were only 54.6, 56.8, and 66.8%, respectively. Stability studies of HAAs in H2SO4-saturated MTBE indicate that all compounds except TBAA are stable for 48 h when stored at 4 degrees C in the dark. TBAA recoveries dropped to 47.1% after 6 h of storage and no TBAA was detected after 48 h of storage. The method described here is only preliminary and was tested in only one laboratory. Additional research is needed to improve method performance.     

Removal of fluoride from water through ion exchange by mesoporous Ti oxohydroxide

In our previous study, we found that Ti(OH)(4) exhibited fluoride ion exchange properties. In order to improve the ion exchange capacity, mesoporous Ti oxohydroxide (TiOx(OH)y) had been prepared by using dodecylamine as template. Zirconia and silica had been introduced into the mesoporous Ti oxohydroxide to enhance the ion exchange capacity. The mesoporous structure and the morphology of the mesoporous materials obtained were confirmed using XRD and SEM, respectively. A fluoride ion exchange study was done on each sample. Results showed that mesoporous Ti oxohydroxide containing zirconia exhibited the highest fluoride ion exchange capacity, as it has the smallest particle size, with high uniformity among the mesoporous materials prepared.