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Choong Jeon - One of the best experts on this subject based on the ideXlab platform.

  • removal of Cesium Ions from aqueous solutIons using immobilized nickel hexacyanoferrate sericite beads in the batch and continuous processes
    Journal of Industrial and Engineering Chemistry, 2016
    Co-Authors: Choong Jeon
    Abstract:

    Abstract Powdered sericite impregnated into nickel hexacyanoferrate (NiHCF-sericite) was immobilized as a bead form by entrapment method using sodium alginate. The immobilized NiHCF-sericite beads have excellent mechanical strength and the increase of pressure drop caused channeling of flow was not observed through column processes even though long time operation. The existence of Cesium Ions onto the surface of the immobilized NiHCF-sericite beads was verified by the scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The maximum adsorption capacity for Cesium Ions of immobilized NiHCF-sericite beads was determined as the 13.877 mg/g at the initial pH 5.0 of aqueous solution and the equilibrium data followed well the linearized Langmuir isotherm equation which has the higher correlation coefficient (0.993). The breakthrough point was emerged around 50 (1.0 mL/min) and 80 bed volumes (0.5 mL/min) and the bed volumes can be still maintained as the 75 even though secondary reused immobilized NiHCF-sericite beads were used.

  • removal of Cesium Ions from waste solution using sericite incorporated into nickel hexacyanoferrate
    Korean Journal of Chemical Engineering, 2015
    Co-Authors: Choong Jeon
    Abstract:

    To increase adsorption capacity and selectivity for Cesium Ions from waste solution, sericite was chemically modified by means of nickel hexacyanoferrate (NiHCF) with a high selectivity trap agent for Cesium. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were used for the characteristic analysis of surface onto the NiHCF-sericite. The adsorption capacity of Cesium Ions for the NiHCF-sericite increased about 2.5 times, as compared with natural sericite at initial pH 5.0 of waste solution. Adsorption equilibrium was investigated by Langmuir and Freundlich isotherm model, respectively. Maximum adsorption capacity was estimated as 16.583mg/g, and the Langmuir isotherm fits the adsorption data better than Freundlich model. The adsorption process was determined as an exothermic reaction and all adsorption was completed in 30 min. In addition, the adsorption capacity of Cesium Ions was not greatly affected by ionic strength (~0.1M NaCl concentration) and other metals in mixed waste solution.

  • Removal of Cesium ion in aqueous solution using immobilized sericite beads
    Korean Journal of Chemical Engineering, 2014
    Co-Authors: Choong Jeon
    Abstract:

    To apply sericite effectively in the adsorption process, it was immobilized by entrapment method using sodium alginate. Since the immobilized sericite beads have excellent mechanical strength and swelling characteristics, channeling of flow and the increase of pressure drop were not observed through column operatIons. In addition, it was also stable under pH 10 and 45 °C of Cesium solution. The maximum adsorption capacity and Langmuir adsorption constant was 1.430mg/g and 2.329 L/mg, respectively, at initial pH 5 of Cesium solution in batch type and the Langmuir model with higher correlation coefficient of 0.997 fits experimental data better than Freundlich model. The breakthrough point emerged around 15 (1.0 mL/min) and 20 bed volumes (0.5 mL/min), and the Cesium Ions bound to the immobilized sericite beads were readily released and quantitatively recovered by a few bed volumes of 1.0M of HNO3 solution. Furthermore, bed volumes of Cesium Ions for firstly reused sericite beads can be still maintained as 18, which shows good regeneration ability.

  • adsorption characteristics of sericite for Cesium Ions from an aqueous solution
    Chemical Engineering Research & Design, 2014
    Co-Authors: Choong Jeon
    Abstract:

    Abstract To efficiently remove Cesium Ions from aqueous solution, sericite was used as a novel adsorbent. The silanol (SiO 2 ) and aluminol (Al 2 O 3 ) groups in sericite are likely to play an important role in adsorption process. The maximum adsorption capacity ( q m ) and adsorption constant ( K L ) for Cesium Ions obtained from the Langmuir isotherm model were 6.68 mg/g and 0.227 L/mg, respectively and regression curve fit well with the experimental data as the 0.965 of correlation coefficients ( r 2 ). However, when the Freundlich isotherm model was used correlation coefficient ( r 2 ) was 0.973. Therefore, it was concluded that Freundlich model fits equilibrium data better than Langmuir model. When the 6.0 g/L of sericie concentration was added to aqueous solution, Cesium Ions were removed by about 80% and the increase was not happened above 6.0 g/L of sericite concentration any more. The process was determined as exothermic reaction because the removal efficiency of Cesium Ions decreased as temperature increased. Furthermore, all adsorption was completed in 120 min and comparing the pseudo first and second-order kinetic models indicates that the adsorption of Cesium Ions using sericite follows well the pseudo-second-order kinetics.

M. Seidl - One of the best experts on this subject based on the ideXlab platform.

  • Catalytic oxidation of silicon by Cesium ion bombardment
    Journal of Applied Physics, 1991
    Co-Authors: A. E. Souzis, W. E. Carr, H. Huang, M. Seidl
    Abstract:

    Results for room‐temperature oxidation of silicon using Cesium ion bombardment and low oxygen exposure are presented. Bombardment with Cesium Ions is shown to allow oxidation at O2 pressures orders of magnitude smaller than with noble gas ion bombardment. Oxide layers of up to 30 A in thickness are grown with beam energies ranging from 20–2000 eV, O2 pressures from 10−9 to 10−6 Torr, and total O2 exposures of 100 to 104 L. Results are shown to be consistent with models indicating that initial oxidation of silicon is via dissociative chemisorption of O2, and that the low work function of the Cesium‐ and oxygen‐coated silicon plays the primary role in promoting the oxidation process.

  • Solid state Cesium ion guns for surface studies (abstract)
    Review of Scientific Instruments, 1990
    Co-Authors: A. E. Souzis, W. E. Carr, M. Seidl
    Abstract:

    Three Cesium ion guns covering the energy range of 5–5000 V are described. These guns use a novel source of Cesium Ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium Ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using Cesium vapor and porous tungsten ionizers. It has been used in ultrahigh‐vacuum (UHV) experiments at pressures of

  • Solid state Cesium ion guns for surface studies
    Review of Scientific Instruments, 1990
    Co-Authors: A. E. Souzis, W. E. Carr, M. Seidl
    Abstract:

    Three Cesium ion guns covering the energy range of 5–5000 V are described. These guns use a novel source of Cesium Ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium Ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using Cesium vapor and porous tungsten ionizers. It has been used in ultrahigh‐vacuum (UHV) experiments at pressures of

Parma Nand Bajaj - One of the best experts on this subject based on the ideXlab platform.

  • preparation and characterization of potassium nickel hexacyanoferrate loaded hydrogel beads for the removal of Cesium Ions
    Environmental Science: Water Research & Technology, 2015
    Co-Authors: Charu Dwivedi, S K Pathak, Manmohan Kumar, S C Tripathi, Parma Nand Bajaj
    Abstract:

    A novel synthetic approach has been used to prepare sorbent hydrogel composite beads of potassium nickel hexacyanoferrate (KNiHCF), using PVA and cross-linked alginate as the binding matrix. The characterization study indicates the high hydrophilicity and high surface area of the synthesized beads. The application potential of these beads for removal of Cesium Ions from low level liquid nuclear waste has been studied in batch mode using a 137Cs radiotracer. The equilibrium sorption and kinetic data are obtained at different initial Cesium ion concentratIons. These data are analysed using various sorption isotherm and kinetic models. It is observed that the sorption process can be best described by the Langmuir isotherm model, and the monolayer capacity of the beads is determined to be 7 mg per g of the swollen beads, which corresponds to ~64 mg per g of the dry beads. The sorption of Cesium Ions onto the sorbent beads is found to follow pseudo second-order kinetics over the entire studied concentration range. The ion-exchange mechanism involves the exchange of Cesium Ions with potassium Ions. The mechanism of the sorption process is also investigated using the intraparticle diffusion model and Boyd's plot, and the results indicate that the sorption of Cesium Ions onto the beads is a complex process, involving both intraparticle diffusion and film diffusion.

  • resorcinol formaldehyde coated xad resin beads for removal of Cesium Ions from radioactive waste synthesis sorption and kinetic studies
    RSC Advances, 2012
    Co-Authors: Charu Dwivedi, Manmohan Kumar, Amar Kumar, Juby K Ajish, Krishan Kant Singh, P K Wattal, Parma Nand Bajaj
    Abstract:

    A novel synthetic method was developed to synthesize resorcinol-formaldehyde (RF) resin in spherical form, of required mesh size, using XAD-4 as template beads. The synthesized RF-coated XAD (RF-XAD) beads were characterized, using different techniques. Suitable size and mechanical stability, along with their spherical shape, make these beads most appropriate for column operation. The efficiency of these beads was evaluated for removal of Cesium from alkaline medium, in batch conditIons, using a radioanalytical technique. The effect of sodium ion concentration, the initial Cesium ion concentration and the contact time were also investigated. It was observed that the Kd value for Cs+ Ions decreases with increase in Na+ ion concentration. The equilibrium data were fitted into different isotherm models, and were found to be represented well by the Langmuir isotherm equation, with a monolayer sorption capacity of 287 mg g−1. Kinetic modeling analysis, using pseudo first-order, pseudo second-order and intraparticle diffusion equatIons, shows that the pseudo second-order equation is the most appropriate model for the description of the sorption of Cesium Ions onto the RF-XAD beads. The rate constants were determined at different initial concentratIons. The process mechanism was found to be complex, consisting of both surface sorption and pore diffusion.

Tsuyoshi Yaita - One of the best experts on this subject based on the ideXlab platform.

  • collective structural changes in vermiculite clay suspensIons induced by Cesium Ions
    Scientific Reports, 2015
    Co-Authors: Ryuhei Motokawa, Hitoshi Endo, Shingo Yokoyama, Shotaro Nishitsuji, Tohru Kobayashi, Shinichi Suzuki, Tsuyoshi Yaita
    Abstract:

    Following the Fukushima Daiichi nuclear disaster in 2011, Cs radioisotopes have been dispersed over a wide area. Most of the Cs has remained on the surface of the soil because Cs+ is strongly adsorbed in the interlayer spaces of soil clays, particularly vermiculite. We have investigated the microscopic structure of an aqueous suspension of vermiculite clay over a wide length scale (1–1000 A) by small-angle X-ray scattering. We determined the effect of the adsorption behavior of Cs+ on the structural changes in the clay. It was found that the abruption of the clay sheets was induced by the localization of Cs+ at the interlayer. This work provides important information for predicting the environmental fate of radioactive Cs in polluted areas, and for developing methods to extract Cs from the soil and reduce radioactivity.

A. E. Souzis - One of the best experts on this subject based on the ideXlab platform.

  • Catalytic oxidation of silicon by Cesium ion bombardment
    Journal of Applied Physics, 1991
    Co-Authors: A. E. Souzis, W. E. Carr, H. Huang, M. Seidl
    Abstract:

    Results for room‐temperature oxidation of silicon using Cesium ion bombardment and low oxygen exposure are presented. Bombardment with Cesium Ions is shown to allow oxidation at O2 pressures orders of magnitude smaller than with noble gas ion bombardment. Oxide layers of up to 30 A in thickness are grown with beam energies ranging from 20–2000 eV, O2 pressures from 10−9 to 10−6 Torr, and total O2 exposures of 100 to 104 L. Results are shown to be consistent with models indicating that initial oxidation of silicon is via dissociative chemisorption of O2, and that the low work function of the Cesium‐ and oxygen‐coated silicon plays the primary role in promoting the oxidation process.

  • Solid state Cesium ion guns for surface studies (abstract)
    Review of Scientific Instruments, 1990
    Co-Authors: A. E. Souzis, W. E. Carr, M. Seidl
    Abstract:

    Three Cesium ion guns covering the energy range of 5–5000 V are described. These guns use a novel source of Cesium Ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium Ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using Cesium vapor and porous tungsten ionizers. It has been used in ultrahigh‐vacuum (UHV) experiments at pressures of

  • Solid state Cesium ion guns for surface studies
    Review of Scientific Instruments, 1990
    Co-Authors: A. E. Souzis, W. E. Carr, M. Seidl
    Abstract:

    Three Cesium ion guns covering the energy range of 5–5000 V are described. These guns use a novel source of Cesium Ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium Ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using Cesium vapor and porous tungsten ionizers. It has been used in ultrahigh‐vacuum (UHV) experiments at pressures of