Selective Adsorption Properties and Stable Solidification of Cs by Insoluble Ferrocyanide Loaded Zeolites

2013 ◽  
Author(s):  
Yuki Ikarashi ◽  
Rana Syed Masud ◽  
Tomonori Nakai ◽  
Hitoshi Mimura ◽  
Eiji Ishizaki ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Cooling System ◽  
Selective Adsorption ◽  
Distribution Coefficients ◽  
Activity Level ◽  
Natural Zeolites ◽  
Zeolite X ◽  
Calcination Temperatures ◽  
X Zeolites ◽  
Cs Ions

In Fukushima NPP-1, large amounts of high-activity-level water (HALW) accumulated in the reactor, turbine building and the trench in the facility is treated by circulating injection cooling system. The development of highly functional adsorbents and stable solidification method contributes to the advancement of the decontamination system and environmental remediation. The present study deals with (1) preparation of insoluble ferrocyanide loaded zeolites, (2) selective uptake of Cs+ in seawater, (3) estimation of Cs immobilization ratio and stable solidification. Various kinds of Cs-selective composites loaded with insoluble ferrocyanides (CoFC, NiFC) into the zeolites (zeolite A (A51, A-51J), zeolite X (LSX), chabazite (modified chabazite) and natural mordenite (SA-5)) matrices have been prepared using successive impregnation/precipitation methods by Tohoku University. As for Cs+ adsorption, these composites had relatively large uptake (%) above 95%, distribution coefficients (Kd) above 103 cm3/g and excellent adsorption kinetics even in seawater. The immobilization ratio (%) of Cs for the CoFC saturated with Cs+ was estimated at different calcination temperatures up to 1,200°C in advance. The immobilization ratio was less than 0.1% above 1,000°C, indicating that the adsorbed Cs+ ions are completely volatilized and insoluble ferrocyanides had no immobilization ability for Cs. In contrast, the insoluble ferrocyanide-loaded zeolites had excellent Cs immobilization ability; in the case of insoluble ferrocyanide-loaded natural zeolites (NiFC-SA-5, CoFC-modified chabazite), the immobilization ratio was above 99% and 96% even after calcination at 1,000°C and 1,100°C, respectively, indicating that nearly all Cs ions are immobilized in the sintered solid form. On the other hand, the immobilization ratio for the insoluble ferrocyanide-loaded A and X zeolites (NiFC-A (A51, A51J), NiFC-X) tended to decrease with calcining temperature; for example, the immobilization ratio for NiFC-X at 1,000°C and 1,100°C was estimated to be 74.9% and 55.4%, respectively, and many spots concentrating Cs were observed on the surface. The difference in immobilization behavior between natural zeolites and synthetic ones is probably due to the phase transformation and surface morphology at higher temperature above 1,000°C. The stable solidification of insoluble ferrocyanides was thus accomplished by using the excellent Cs immobilization abilities of zeolite matrices (Cs trapping and self-sintering abilities).

scholarly journals The study on preparing absorbent of potassium nickel hexacyanoferrate (II) loaded zeolite for removal of cesium from radioactive waste solutions and stable solidification method for those spent absorbents

2021 ◽  
Vol 7 (1) ◽  
pp. 28-36
Author(s):  
Quynh Luong Pham ◽  
Hoang Lan Nguyen ◽  
Van Chinh Nguyen ◽  
Huu Anh Vuong ◽  
Cao Nguyen Luu ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Sea Water ◽  
Selective Adsorption ◽  
Pure Water ◽  
Decontamination Factor ◽  
Precipitation Method ◽  
Radioactive Cesium ◽  
Exchange Equilibrium ◽  
Zeolite X ◽  
Cs Ions

The development of cesium selective adsorbent is urgent subject for the decontamination of intermediate and high level water from nuclear facilities especially in nuclear accidents. For the selective adsorption and stable immobilization of radioactive cesium, K-Ni- hexacyanoferrate (II) loaded zeolite (FCzeolite) (synthesized zeolite of Hanoi University of Science and Technology) were prepared by impregnation/precipitation method. The ion exchange equilibrium of Cs+ for composites FC-zeolite was attained within 5 h and estimated to be above 97% in Cs+ 100mg/l solution at pH: 4-10. Ion exchange capacity of Cs+ ions (Qmax) for FC-zeoliteX was reached 158.7 and 98.0 mg/g in pure water and sea water respectively.Those values for FC-zeolite A was 103.1 and 63.7 mg/g. Decontamination factor (DF) of FC-zeolite X for 134Cs was 149.7 và 107.5 in pure water and sea water respectively. Initial radioactivity of 134Cs ion solution infect to decontamination factor. KNiFC-zeolite X after uptaked Cs (CsFC- zeolite X) was solidificated in optimal experimental conditions: Mixing CsFC-zeolite X with additive of Na2B4O7 (5%), temperature calcined 900oC for 2h in air. Solid forms was determined some of parameters: Cs immobilization, mechanical stability, volume reduction after calcination (%) and leaching rate of Cs+ ions in solution.

scholarly journals Worldwide Research Analysis on Natural Zeolites as Environmental Remediation Materials

2021 ◽  
Vol 13 (11) ◽  
pp. 6378
Author(s):  
Fernando Morante-Carballo ◽  
Néstor Montalván-Burbano ◽  
Paúl Carrión-Mero ◽  
Kelly Jácome-Francis
Keyword(s):  
Environmental Remediation ◽  
Waste Treatment ◽  
Adsorption Properties ◽  
Natural Zeolites ◽  
Removal Of Heavy Metals ◽  
Long Time ◽  
Notable Increase ◽  
Accelerated Growth ◽  
Treatment Alternatives ◽  
Research Analysis

Society faces a significant problem in regards to the spread of harmful products in the environment, primarily caused by accelerated growth and resource consumption. Consequently, there is a need for materials to be processed in less harmful ways and to remedy the contaminated sources they generate. Microporous materials have been studied for a long time and are used in waste treatment alternatives. Natural zeolites, on which this study is based, are attractive to the scientific and technological communities, due to their numerous applications as decontaminants and adsorption properties. This study analyzes the intellectual structures of publications related to natural zeolites in environmental remediation, using bibliometric methods to determine their volumes and trends. The methodology comprises of an analysis based on 1582 articles, using VOSviewer software, with data from 1974 to 2020, via the Scopus database. Results reflect a notable increase in publications from the end of the 1990s; the greatest contribution in the area comes from Eurasian countries. The study considers that development in this line of research will continue to increase and serve as a great contribution to preserve the environment in coming years, with themes that focus on water treatment (e.g., drinking water, wastewater, greywater), removal of heavy metals, ammonium, ammonia, and construction.

scholarly journals Assessment of the Radioactive Contamination of the RBMK-1500 Reactor’s Steam Pipelines and High Pressure Rings

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
G. Poškas ◽  
P. Poškas ◽  
A. Šimonis
Keyword(s):  
High Pressure ◽  
Radioactive Contamination ◽  
Cooling System ◽  
Computer Code ◽  
Activity Level ◽  
Nuclear Facilities ◽  
Circulation Circuit ◽  
Hydraulic Conditions ◽  
Main Circulation ◽  
Activated Corrosion Products

Data analyses of radioactive contamination of the RBMK-1500 reactor’s steam pipelines (SP) and components of high pressure rings (HPR) are presented in this paper. Also, modelled results of the SP-HPR system are compared to the results of other RBMK-1500 systems at Ignalina NPP Unit 1. Characteristics of SP-HPR components, thermal-hydraulic conditions of the coolant, and system operational regimes were evaluated employing the computer code LLWAA-DECOM (Tractebel Energy Engineering, Belgium). The presented results complement radiological characterization activities and facilitate the decommissioning process of nuclear facilities with RBMK type reactors. Analysis of the modelled results showed that the spread of radioactive contamination is very uneven between different components of the SP-HPR. The overall activity level of deposits of the SP-HPR is mostly determined by activated corrosion products and is lower than the activity level in the main circulation circuit (MCC) and nonpurified water subsystem activity of the purification and cooling system (PCS).

Wearable Engine-Driven Vapor-Compression Cooling System for Elevated Ambients

2009 ◽  
Vol 1 (2) ◽  
Author(s):  
Timothy C. Ernst ◽  
Srinivas Garimella
Keyword(s):  
Cooling System ◽  
Average Rate ◽  
Heat Removal ◽  
Activity Level ◽  
Working Environment ◽  
Gear Train ◽  
Reduction Gear ◽  
Small Scale ◽  
Vapor Compression ◽  
Wide Range

The development of a wearable cooling system for use in elevated-temperature environments by military, fire-fighting, chemical-response, and other hazardous duty personnel is underway. Such a system is expected to reduce heat-related stresses, increasing productivity and allowable mission duration, to reduce fatigue, and to lead to a safer working environment. The cooling system consists of an engine-driven vapor-compression system assembled in a backpack configuration, to be coupled with a cooling garment containing refrigerant lines worn in close proximity to the skin. A 2.0 l fuel tank powers a small-scale engine that runs a compressor modified from the original air compression application to the refrigerant compression application here. A centrifugal clutch and reduction gear train system was designed and fabricated to couple the engine output to the refrigerant compressor and heat rejection fan. The system measured 0.318×0.273×0.152 m3 and weighed 4.46 kg. Testing was conducted in a controlled environment to determine performance over a wide range of expected ambient temperatures (37.7–47.5°C), evaporator refrigerant temperatures (22.2–26.1°C), and engine speeds (10,500–13,300 rpm). Heat removal rates of up to 300 W, which is the cooling rate for maintaining comfort at an activity level comparable to moderate exercise, were demonstrated at a nominal ambient temperature of 43.3°C. The system consumes fuel at an average rate of 0.316 kg/h to provide nominal cooling of 178 W for 5.7 h between refueling.

Selective Decontamination and Stable Solidification of Cs-Insoluble Ferrocyanide by Zeolites

2014 ◽  
Vol 94 ◽  
pp. 75-84 ◽  
Author(s):  
Hitoshi Mimura ◽  
Yuki Ikarashi ◽  
Eiji Ishizaki ◽  
Minoru Matsukura
Keyword(s):  
Large Volume ◽  
Cooling System ◽  
Selective Decontamination ◽  
Activity Level ◽  
Solid Wastes ◽  
High Activity Level ◽  
Gas Trapping ◽  
The Press ◽  
Higher Temperature ◽  
Sintering Method

Large amounts of high-activity-level water (HALW) were generated from the nuclear accident in Fukushima NPP-1 caused by the Great East Japan Earthquake. At present, the cold shutdown is completed by cooling system, while large amounts of HALW (> 300,000m3) and secondary solid wastes such as insoluble ferrocyanide sludge adsorbing137Cs are still stored. For the stable solidification of Cs-insoluble ferrocyanides, the press/sintering method was developed by mixing zeolites. In this method, the excellent abilities of zeolites such as Cs adsorbability, gas trapping and self-sintering abilities were used for the stable solidification; zeolites are effective for the stable solidification of Cs-insoluble ferrocyanides as a solidification matrix. Cs adsorbed insoluble ferrocyanides tend to release all Cs at higher temperature above 1,000°C, while the immobilization ratio of Cs about 100% was maintained by sintering the mixtures of Cs-insoluble ferrocyanide and zeolite. The advantages of sintered products are large volume reduction of 30-50%, no effect of NaCl on Cs immobilization and low leachability of Cs, indicating the excellent solidification properties of sintered products of insoluble ferrocyanide and zeolite. This method can be applied to the stable solidification of the secondary solid wastes such as insoluble ferrocyanide sludge in Fukushima NPP-1.

Radiolabelling Measurements of Free Radicals Derived from Aromatic Volatile Organic Compounds Adsorbed in Zeolite Nanomaterials to and above Saturation Loadings

2011 ◽  
Vol 36 (4) ◽  
pp. 287-322 ◽  
Author(s):  
Christopher J. Rhodes ◽  
Timothy C. Dintinger
Keyword(s):  
Activation Energy ◽  
External Surface ◽  
Muon Spin ◽  
Film Coating ◽  
Activation Energies ◽  
Channel Structure ◽  
Essential Difference ◽  
Zeolite X ◽  
Saturation Loadings ◽  
X Zeolites

Benzene, para-xylene and mesitylene were adsorbed into silicalite, Na - morde- nite, Na - ZSM5 and Li - X zeolites, and studied using the longitudinal field muon spin relaxation (LF-μSRx) technique. The zeolites ZSM5/silicalite and mordenite contain microporous channels while zeolite X has only supercages. For cyclohex- adienyl radicals/benzene adsorbed in Na-ZSM5, silicalite and Na - mordenite, a fraction was detected with a common reorientational activation energy in the region of ca 5kJ mol−1; however, in all cases there appeared a second fraction with an activation energy of ca 12kJmol’. [In Li-X only a single fraction was observed with Ea = 8.1kJ mol−1, from molecules adsorbed in supercages]. Given that high loadings of benzene, beyond the saturation capacities of the zeolites were employed, we believe the two distinct motional distributions represent the channel intersection and channel/external-surface niche locations in ZSM5/silicalite, the latter having the higher activation energy. An extraneous fraction may also be present (possibly as a thin film coating the zeolite grains), which probably also contributes to the detected ca 5 kJ mol−1 component in which, as at the channel-intersections, the motion tends toward bulk behaviour. Mordenite has only a single accessible channel structure and is hence devoid of the relatively unrestricting channel intersecting pores that are present in ZSM5/silicalite. However, the channels are wider (ca 7 A diameter) and we may ascribe therefore, the ca 5 kJ mol−1 fraction to the formation of benzene clusters within these channels that exhibit bulk-type behaviour, while we assign, in analogy with the results for ZSM5/silicalite, the ca 12kJ mol−1 fraction to molecules adsorbed in niches on the external surface. It is thought that the essential difference between the two activation energies is that the ca 5 kJ mol -1 processes involve molecular motion within clusters of benzene molecules with properties similar to the bulk phase (6.6 kJ mol -1 was measured in pure benzene), while those characterised at ca 12kJ mol−1 reflect single benzene molecules or small, ordered molecular clusters interacting with a zeolite surface. The results for dimethylcyclohexadienyl radicals (derived from p-xylene) are rather similar, but indicate slightly reduced activation energies. The larger mesitylene molecules can penetrate zeolite X and (more slowly) mordenite, but are excluded from the internal pores of ZSM5/silicalite.

scholarly journals IMPROVEMENT OF GAS MONITORING METHODS IN WATER OF THE HYDROGEN-WATER COOLING SYSTEM OF NPP’S TURBINE GENERATOR

2021 ◽  
Vol 29 (1) ◽  
pp. 49-58
Author(s):  
Anatolii Tykhomyrov ◽  
Sergey Zaitsev ◽  
Vadim Chichеnin ◽  
Victor Kуshnevsky
Keyword(s):  
Cooling System ◽  
Degradation Products ◽  
Distribution Coefficients ◽  
Flow Chart ◽  
Gas Mixture ◽  
Water Cooling ◽  
Dissolved Gases ◽  
Dissolved Gas ◽  
Hydrogen Water ◽  
Water Cooling System

The relevance of research is to ensure and improve the reliability of turbine generators (TG) with a hydrogen-water cooling system by monitoring the content of dissolved gases in the water of a hydrogen-water cooling system with monoethanolamine (MEA) – C2H7NO and water vapor in the cooling hydrogen of the turbine. In this work, the influence of ultrasonic vibrations on the decomposition of a mixture of water and turbine oil, organic acids (acetic acid - С2Н4О2, formic acid - СН2О2, oxalic acid - С2Н2О4) or monoethanolamine was determined. The distribution coefficients values were definedd for the following dissolved gases Н2, О2, N2, СО, СН4, С2Н2, С2Н4, С2Н6, С3Н6, С3Н8, which are of degradation products of water mix components when exposed to ultrasonic oscillation in the following system: «dissolved gas – mixture «water + monoethanolamine» – extractant argon (Ar)». The obtained values of the Кі distribution coefficients for dissolved gases in systems «dissolved gas – mixture «water + С2Н7NО» – extractant argon (Ar)» at a temperature of 293 K and a concentration of С2Н7NО at the level of 1 g/dm3 are close to similar values for dissolved gases in deionized water. The principle flow chart of multichannel gas chromatograph for detecting dissolved gases in water and steam of water in hydrogen was developed. Developed flow chart of 4-chennel gas chromatographer for defining dissolved gases in water includes the one gas chromatographer with conductivity detector, methanator, flame ionization detector, argon gas-bearing and supplementary gases of hydrogen and air.

scholarly journals Zeolite-Rich Composite Materials for Environmental Remediation: Arsenic Removal from Water

2020 ◽  
Vol 10 (19) ◽  
pp. 6939
Author(s):  
Bruno de Gennaro ◽  
Paolo Aprea ◽  
Barbara Liguori ◽  
Barbara Galzerano ◽  
Antonio Peluso ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Arsenic Removal ◽  
Fixed Bed ◽  
Exchange Capacity ◽  
Order Kinetic ◽  
Natural Zeolites ◽  
Dynamic Conditions ◽  
Good Ability ◽  
Adsorption Rates ◽  
Surface Modified

Natural zeolites are used as adsorbents in purification processes due to their cation-exchange ability and molecular sieve properties. Surface modified natural zeolites (SMNZs), produced by attaching cationic organic surfactants to the external surface, can simultaneously act as ionic exchangers and organic molecule adsorbents. In this paper, SMNZs were produced and investigated as adsorbents for As(V) removal from wastewater: two natural zeolites, clinoptilolite and phillipsite, were modified using HDTMA-Br and HDTMA-Cl as surfactants. The obtained samples were then characterized under static and dynamic conditions. Results showed that As(V) removal follows a pseudo-second order kinetic, with fast adsorption rates: every sample reached 100 % removal in 2 h, while equilibrium data showed a Langmuir-like behavior, with a greater anion uptake by the HDTMA-Br modified SMNZs due to the formation of a compact and complete micellar structure. Finally, fixed-bed tests were performed to characterize the samples under dynamic conditions assessing the effect of severe operating parameters on the dynamic exchange capacity, selectivity and efficiency of the process. The obtained results demonstrate a good ability of the tested materials to adsorb As(V) from wastewater, confirming the effectiveness of the proposed surface modification technique in expanding the possibility of using natural zeolites in these processes.

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