Development of a method for nuclide leaching from glass fiber in HEPA filter

For the disposal of the high efficiency particulate air (HEPA) glass filter to environment, the glass fiber should be leached to lower its radioactive concentration. To derive the optimum method for removal of Co and Cs from HEPA glass fiber, four methods were applied in this study. Results of electrochemical leaching of glass fiber by 4.0 M HNO₃–0.1 M Ce(IV) solution showed that the removal efficiency of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs from glass fiber after 5 h was 96.4, 93.6, and 93.8%, respectively. Results by 5 wt% NaOH solution showed that the removal efficiency of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 30 h was 81.7, 82.1, and 10.0%, respectively. Results by repeat 2.0 M HNO₃ solution showed that the removal efficiencies of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 2 h of three repetitions were 96.2, 99.4, and 99.1%, respectively. Finally, results by repeat 4.0 M HNO₃ solution showed that the removal efficiencies of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 4 h of three repetitions were 100, 99.9, and 99.9%, respectively, and their radioactivities were below 0.1 Bq/g. Therefore, the chemical leaching method by 4.0 M HNO₃ solution was considered as an optimum one for removal of cesium and cobalt from HEPA glass fiber for self disposal. Also the removal efficiencies of ⁶⁰Co, ¹³⁴Cs, and ¹³⁷Cs from the waste-solution after its precipitation-filtration treatment for reuse of 4.0 M HNO₃ waste-solution were 88.0, 95.0, and 99.8%.     

Weak acid leaching of uranium ore from a high carbonate uranium deposit

Journal of Radioanalytical and Nuclear Chemistry - Mineralogical study showed that the Yuejin uranium ore is from a low grade, high carbonate and high pyrite sandstone type uranium deposit. Uranium...     

Effects of oxidant and particle size on uranium leaching from coal ash

In this paper, uranium leaching efficiency from the coal ash was 45.82% on the condition of 0.3 M H₂SO₄, 1:20 g/L, 60 °C and 12 h. According to the result of Sequential chemical extraction, leaching trials and X-ray diffraction, oxidants promoted the uranium leaching with the generation of baratovite. There were differences between uranium content of leachable states and leaching trials. Although the uranium content bounding with exchangeable, carbonates and Fe–Mn oxides all peaked at particle size fraction 75–150 μm, the highest uranium content in leaching trials peaked at size fraction 48–75 μm.     

Mechanism analysis on synergistic leaching of uranium from pyrite oxidized by Acidithiobacillus ferrivorans

Journal of Radioanalytical and Nuclear Chemistry - Low-grade uranium ore, which was challenging to be treated economically by conventional methods, can be treated by uranium leaching by bacteria....     

Emission spectrographic determination of trace elements in airborne particulate matter collected on glass fiber filter.

An emission spectrographic method is described to determine the concentrations of beryllium, cadmium, chromium, copper, iron, lead, manganese, nickel, tin, and vanadium, in airborne particulate matter collected on a glass fiber filter. Sample disks punched out from the glass fiber filter are packed in a shallow cratered electrode; an internal standard solution containing indium and cobalt is added and the disks are decomposed with sulfuric acid-hydrofluoric acid. A calcium fluoride-graphite mixture is added as a spectroscopic buffer before d.c. are excitation. The precision of the method is better than ± 18%.     

A novel fiber optical device for ultraviolet disinfection of water

Since there are several problems in traditional UV disinfection techniques, a highly efficient, reliable and economical method, using quartz optical fibers to deliver UV light is proposed. The principle of the experimental setup is that ultraviolet rays are gathered by a reflector and converge on a light point, the diameter of approximately 5mm. In this way UV light can be transferred into water to kill the bacteria in the water. This paper presents preliminary results on water disinfection using this new UV disinfection setup. Its suitability for application could be shown in experiments with E. coli (ATCC8099) as test microorganisms. We have optimized the distribution of the optical fibers in the water in bench-scale study. This result can provide guidance for pilot-scale and field-scale study of this new technique. The results show that the new technique had a good performance under different conditions as follows: (a) turbidity level=10.2 NTU, (b) ferric ion concentration=0.3 mg/L, and (c) humic acid concentration=5 mg/L. The new technique provides a promising approach to disinfection treatment of drinking water.     

Analysis of natural radionuclides from uranium and thorium series in briney groundwaters

Analytical procedures for measuring various radionuclides in the²³⁸U and²³²Th chains in briney waters are described. Using methods such as mass spectrometry, and alpha, beta and gamma spectrometry, the desired measurement sensitivity required for each of the radionuclides is achieved.²³³U,²²⁸Th,²⁰⁸Po,²¹²Pb, and¹³³Ba are used as tracers for chemical yield recoveries. Typical precision of the results range from 5–20%.     

Ultratrace analysis of uranium and thorium in glass

Three methods of determination for uranium and thorium traces and ultratraces in glass were developed: a simple and powerful ICP-MS method exhibiting limits of determination in the one ng/g-range; a complex method with end-determination by classical photometry and a limit of determination for U and Th of 20 ng/g; and a method with chelate-complex formation for U and Th and subsequent GC-detection with a ⁶³Ni-ECD with limits of determination in the g/g-range. These methods are critically compared and tested for real type samples of special glasses.Abbreviations used AAS Atomic absorption spectrophotometry - ECD Electron capture detector - FOD 1,1,1,2,2,3,3-Heptafluoro-7,7-dimethyl-4,6-octanedion - GC Gas chromatography - HFA 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione - ICP-AES, -MS Inductively coupled plasma-atomic emission spectrometry, metry, -mass spectrometry - LAS Liquid absorption spectrophotometry = classical photometry - NAA Neutron activation analysis - NIST National Institute of Standardization and Technology (Gaithersburg, U.S.A.) - TBP Tri-(n-butyl)-phosphate - TFA 1,1,1-Trifluoro-2,4-pentanedione - TTFA 1-(2-Thenoyl)-3,3,3-trifluoroacetone - XRS X-ray (fluorescence) spectrometry     

Ultratrace analysis of uranium and thorium in glass

It is today a most common phenomenon that ultratrace analyses for quality control have to be carried out in industrial laboratories far from optimum conditions and in spite of the lack of best suited equipment. It was against this setting that the development of a method for the photometric determination of uranium- and thorium-traces in glasses with arsenazo III was envisaged. The method basically consists of a digestion with HF/HClO₄/H₃BO₃, an extractive preseparation of interfering Ti- and Zr-traces with TTFA/hexanol/CCl₄, an extractive separation of U- and Th-traces with TTFA/TBP/toluene and a final determination of thorium alone (in the presence of photometrically inactive U(VI)) and the sum of Th+U(IV) with arsenazo III.The concentration of uranium is calculated from the difference of the sum of both traces minus the thorium content. Uranium can be determined with nearly the same sensitivity as thorium after reduction to uranium(IV). The most suitable reducing agent for uranium(VI) to uranium(IV) is a mixture of Na₂S₂O₄/CH₂O. An optimization of the arsenazo III concentration for the determination of thorium and uranium yielded an optimal concentration of 80 mg/L arsenazo III: For the reduction of uranium concentrations of 2 g/L of Na₂S₂O₄ and 3.2 g/L CH₂O proved to be optimal. Interferences of this photometric end determination by titanium, zirconium and scandium were investigated quantitatively. The permissible excess for these elements was found to be so low that a trace-trace separation method proved to be necessary. Separation methods were checked for the separation of the matrix components of the investigated glasses from thorium and uranium. One of these methods was suitable after optimization: thorium and uranium are extracted with TTFA/TBP/toluene from a solution containing hydrochloric acid. Back-extraction is carried out with HCl/KMnO₄. For the separation of titanium- and zirconium-cotraces an extra separation method had to be developed: they are extracted with TTFA/hexanol/CCl₄ before the separation of uranium- and thorium-traces from the matrix. The glasses were digested with HF/HX. Fluoride from the hydrofluoric acid is incompletely removed by evaporation and interferes with the extraction of uranium and thorium due to complex formation. Depending on the digestion variant used 162 to 0.23 mg F^– remain in the residue of the digestion of a 5 g sample. This interference was eliminated by a digestion with HF/HClO₄/H₃BO₃ and masking of residual fluoride with AlCl₃.Abbreviations used Arsenazo III 1,8-Dihydroxynaphthalene-3,6-disulphonic acid-2,7-bis [(azo-2)-phenylarsonic acid] - Arsenazo I 1,8-Dihydroxynaphthalene-3,6-disulphonic acid-2-[(azo-2)-phenylarsonic acid] - BPAP 2- (5-Bromo-2-pyridy] azo)-5-diethylaminophenol - EDTA Ethylenediaminetetraacetic acid - HX Designation for a high boiling mineral acid - FAAS Flame atomic absorption spectrometry - FOD 1,1,1,2,3,3,-Heptafluor-7, dimethyl-4,6-octanedione - GFAAS Graphite furnace atomic absorption spectrometry - ICP-MS Inductively coupled plasma — mass spectrometry - ICP-OES Inductively coupled plasma — optical emission spectrometry - LAS Liquid absorption spectrophotometry (classical photometry) - m(Th) Mass of thorium - NAA Neutron activation analysis - pK_Diss Negative logarithm to the base 10 of the dissociation constant of a complex - TBP Tri-(n-butyl)-phosphate - TOPO Tri(n-octyl)-phosphinoxide - TTFA 1-(2-Thenoyl)-3,3,3-trifluoroacetone     

A single-view field filter device for rare tumor cell filtration and enumeration

In this work, we demonstrate a single-view field filter (SVFF) device for the efficient filtration and enumeration of rare tumor cells in the blood. In our device, the track-etched membrane is integrated within a low-cost polymer-film microfluidic chip, and multiplex microfiltration chambers are designed. Our device permits the performing of multiple sample tests on a single membrane and the dynamical observation of the entire filtration process in a single field of view. To characterize the device performance, our device is first tested using tumor cells, and three different cell behaviors are observed during the filtration process. Finally, we successfully apply our device for the separation of rare tumor cells from the lysed blood samples at various flow rates. The recovery rates of 93.3, 87.6, and 84.1% can be respectively achieved at the throughputs of 50, 100, and 150 μL/min. Our single-view field filter (SVFF) device offers the advantages of label-free filtration, efficient enumeration, easy integration, and low cost, and holds the potential to be used as an efficient tool for the filtration and enumeration of rare cells.     

Liquid membranes for separating uranium from vanadium and uranium from molybdenum

This is the third paper in which we describe the transport of uranium ions through liquid membranes. The subject of this paper is the use of liquid membranes to separate uranium from other metals that are present in hydrometallurgical leach solutions derived from uranium ores. It is demonstrated that liquid membranes can cleanly separate uranium from vanadium. The separation of uranium and molybdenum is also investigated. Although this separation is not as clean as that of uranium and vanadium, the results indicate that further refinement of operating conditions of the liquid membrane could lead to substantial improvement. Based on the potential of the membranes to separate the various metal ions, several process schemes are suggested that could be used to recover uranium from hydrometallurgical leach solutions     

A kinetic model for heap leaching of uranium ore considering variation of model parameters with depth of heap

Many kinetic models for heap leaching of low grade ores have been proposed and the model parameters have been treated as constants. However, some of these model parameters change with the depth of the heap. In the present work an apparatus consisted of six columns with different heights was designed and used to simulate the leaching behavior within a 3-m-high uranium ore heap at a uranium mine in South China. It was found that the model parameters α and ω for heap leaching of the uranium ore varied with the depth of the heap, and that the relationships between α and between ω and the depth of the heap were in the form of the logistic and the quadratic functions, respectively. Furthermore, a kinetic model for heap leaching of the uranium ore considering the variation of the model parameters with the depth of the ore was proposed. The kinetic model gave the fitting precision of more than 95 % and prediction precision of more than 93 %. The present work provided an approach for establishing the kinetic model for heap leaching of low grade uranium ores.     

A conductance sensor for dissolved sulphur dioxide using a series piezoelectric crystal device

A new piezoelectric crystal impedance sensor for the determination of sulphur dioxide in aqueous solution is presented. It is realized using a series piezoelectric crystal device which is constructed by connecting an AT-cut piezoelectric crystal to a probe in series. The probe is filled with an internal electrolyte solution that is separated from sample solutions by a gas-permeable membrane. The present sensor exhibits a favourable frequency response to 1 x 10(-7)-1 x 10(-3) M sulphur dioxide. The detection limit is 1 x 10(-8) M. The effects of the sensor preparation are considered. Dynamic range, reproducibility, response time and selectivity of the sensor are also discussed. The proposed sensor has been used successfully for lamp sulphur determinations in petroleum samples.     

Separation of uranium from molybdenum using a diamine functional group bonded to controlled-pore glass

A method for selective extraction of uranium from carbonate solutions containing molybdate is reported. A liquid chromatography column, packed with N-β-aminoethyl-γ-ammopropyltrimethoxysilane immobilized on a glass substrate, was utilized in a continuous How system. The selective retention of the uranyl carbonate species [UO₂(CO₃)₂? 2H₂O]^2- and UO₂(CO₃)^4- on protonated immobilized diamine is the basis for this separation Recoveries of uranium and molybdenum from synthetic samples ranged from 96.7 to 113.4% for uranium and from 96.7 to 110.5% for molybdate for a range of recommended conditions.     

Fractionation of thorium and uranium isotopes in the acid leaching experiments on monazite

A series of leaching experiments with water and gradually harsher acid solutions have been carried out on a monazite.²²⁸Th/²³²Th,²³⁰Th/²³²Th, and²³⁴U/²³⁸U activity ratios in the acid fractions show a common variation pattern: high — low — close to bulk values, which can be explained in terms of preferential solution effect of recoil atoms. Compared with²²⁸Th, the preferential solution effect of²³⁴U is suppressed due to self-annealing of recoil tracks.     

Lead leaching behaviors during panel-funnel glass waste separation from cathode-ray tube glass using thermosol,acid etching or mechanical cutting methods

Discarded cathode-ray tube (CRT) glass is considered harmful waste because it contains poisonous lead. Hence, a study on the disposal of CRT glass and the potential risk of lead leaching is needed. This work performs the research on the panel-funnel glass separation method, an important step for CRT glass recycling. In the thermosol method, moderate temperatures of 565 ～ 572 °C and 5 ～ 7 min holding time are suitable for a complete panel-funnel glass separation. The acid etching method can achieve panel-funnel glass separation with low energy consumption by using a 10 wt% nitric acid solution as an agent. Panel-funnel glass can be quickly separated by a mechanical cutting method within four minutes and achieve a high glass recovery. A glass size of 2–10 mesh, a rotary shaking speed of 240 rpm, and a retention time of 120 h can accelerate the lead leaching of 133.34 mg/L from CRT glass in the leaching solution at pH 4.93. This work gives a systematic exploration into panel-funnel glass separation and lead leaching from CRT glass, which is potentially beneficial for CRT glass waste recycling, management, and disposal.