Eric Aston - Academia.edu (original) (raw)

Papers by Eric Aston

Journal of Near Infrared Spectroscopy, May 23, 2020

Three methods of measuring coffee roast degree were compared using titratable acidity as an indic... more Three methods of measuring coffee roast degree were compared using titratable acidity as an indicator of roast-dependent flavor change. The first roast degree method was based on prediction of the cracks with online near infrared spectroscopy and partial least squares regression, the second was based on changes in online near infrared absorbance, and the third was the common L* value from the CIELAB color space in the visible spectrum. Roasting trials utilized arabica coffee from eight origins in an air roaster, and results demonstrated the superiority of an online near infrared sensor for real-time roast degree measurement. A second dataset with constant temperature roasts showed how acidity can be controlled by changing both the roasting temperature and roast degree, finding the linear effects of roast time and roast degree on acidity.

International journal of pavement research and technology, Jul 3, 2023

Journal of transportation engineering, Jun 1, 2022

Journal of Food Process Engineering, Nov 7, 2019

The prediction of start and end times of the first and second crack events in roasting coffee is ... more The prediction of start and end times of the first and second crack events in roasting coffee is feasible with in situ near-infrared (NIR) spectroscopy. Roasting samples analyzed herein consist of eight varieties of arabica coffee with different origins and processing methods, roasted with four temperature-time profiles. Real-time analysis of recorded audio from coffee bean popping sounds provides a basis for determining the start and end times of each major event. A custom in situ diffuse reflectance probe improved NIR output, and partial least squares (PLS) regression generated a separate model for each crack event. The resulting PLS models show strong potential for process control implementation. A newly developed roast degree scale based on the progression through crack events is arguably more meaningful than common color cues to connect and correlate the complex chemistries and consumer qualities in roasted coffee. Practical Applications The first and second cracks are two sets of popping sounds that occur during coffee roasting. These events are commonly used as indicators of roast degree for determining the endpoint of the roast, but this judgment can be subjective. This work explores the use of NIR spectroscopy to predict the start and end of the two cracking events to provide a more robust method for controlling the roast based on the cracks. The predictions are used to generate a numerical roast degree scale, which provides a consistent method of comparing the roast degree of coffees from different origins or roasters. 1 | INTRODUCTION Coffee roasting is a complex process involving three modes of heat transfer, elevated pressure, transient evaporation, and changes in material density and phase occurring at the same time as chemical reactions that produce hundreds of different chemical species (Fadai,

Journal of Materials Science, May 27, 2020

Aging of graphite-based materials results in slower heterogeneous electron transfer (HET) kinetic... more Aging of graphite-based materials results in slower heterogeneous electron transfer (HET) kinetics and limits their conducting and catalytic performance. A thermal treatment protocol reportedly maintained a high HET kinetics of graphite by at least nine weeks. The present report investigates the consequences of such HET increases on graphite stabilities. Raman 2D peak evolution, potential windows, EIS, optical AFM, chronoamperometry and potentiodynamic polarization studies were employed to investigate electrochemical, structural and corrosion stabilities and mechanisms of the pristine and thermally treated graphite as they relate to its HET kinetics. Structure-induced electronic changes are suggested to trigger improved tunneling paths through the interfaces from the bulk layer. This tunneling improves and sustains HET kinetics by orders of magnitude in the treated graphite. Except for the graphite fibers, thermal treatment increased HET kinetics without compromises to electrochemical, structural and corrosion stabilities. In most instances, these properties improved over the pristine graphite.

SN applied sciences, Jun 17, 2019

The search has been on for years to find at least, a stable, high surface area scaffold for Pruss... more The search has been on for years to find at least, a stable, high surface area scaffold for Prussian blue (PB) and its analogs. If successful, PB's vast potential applications could be practicable. This, is besides other innate issues with PB such as poor cycle stability, low electronic conductivity to mention a few. For the first time, a stable Prussian blue@thermally activated graphite felt scaffold, with cycling stability of 2100 cycles, from − 0.5 to 1.3 V, and in 1 M KCl, for at least 36 h is reported. At the end of 2100 CV cycles, sample capacitance more than tripled (381 mF cm −2 compared to 120 mF cm −2 at start of experiment). These properties suggest a practical ion-sieve for specific cation removal from contaminated water. Two new synthesis protocols were employed to achieve this: (a) a first time, single solution PB synthesis without externally applied potential, current or even elevated temperature and (b) a two-step solution-dipping process not involving acidic conditions. PB from both protocols exhibited similar electrochemical characteristics even though the electron relay paths along their charge transfer complexes are different. When probed for its HOMO characteristics, the PB@thermally-treated graphite showed no significant electronic difference from the thermally-treated felt scaffold, suggesting non-compromise of the treated graphite by the PB. Besides cation removal, the electrochemical and electronic properties of these PB@treated graphites suggest multiple electrochemical, non-electrochemical and electronic applications with intact structural and functional integrity.

ACS applied nano materials, Dec 6, 2018

On thermal treatment, eight different graphite materials became resistant to air aging for at lea... more On thermal treatment, eight different graphite materials became resistant to air aging for at least nine weeks compared to the usual time of hours to a few days when assayed in mM ferriferrocyanide solution. In addition, resistance to aging lasted at least seven days when immersed in 1 mM ferri-ferrocyanide solution compared to the frequently reported few minutes to hours. Experimental results confirm that with heat treatment, HOPG-ZYH, graphite rods, pyrolytic graphites, graphite felts, and natural and artificial graphites undergo structural reorganization that leads to restructuring of their electronic nature. This electronic restructuring enhances and sustains their electrochemical properties. The extent of reorganization is dependent on the initial disordered state, which in turn is important to the final structural and electronic conditions. These results strongly suggest that the primary factor enhancing the electronic response of heat-treated materials is from an overall higher density of states (DOS) localized on delocalizing π bonds compared to their controls. This structural reorganization of the graphites also supports a degree of crystallinity along the lattice sites that enables carrier hopping irrespective of adventitious oxygen-containing and hydrocarbon moieties that are associated with aging-induced sluggish electron transfer kinetics. The attributes of this electronic structure demonstrate a strongly correlated system that exhibits a non-perturbative behavior. A one-dimensional Hubbard model describes this behavior to explain the surface-to-electronic chemistry of treated graphites by addressing both their enhanced electrochemical performance and their delayed or reduced aging effects.

Capture and immobilization of volatile radionuclides present in the off-gas from used nuclear fue... more Capture and immobilization of volatile radionuclides present in the off-gas from used nuclear fuel (UNF) recycling operations is an essential component of an integrated nuclear waste management system. Radionuclides of particular concern are the long-lived 129 I, that tends to bioaccumulate and affect the metabolism in humans, and 85 Kr, a chemically inert radioisotope that continues to accumulate in the environment. Control of emissions of these contaminants is necessary to comply with the stringent regulatory limits placed on their releases to protect human health and environment. Off-gas treatment processes based on cryogenic distillation, absorption in solvents and membrane separations suffer from several drawbacks including cost, presence of corrosive materials and the radiation stability of materials. The goal of the proposed research is to evaluate nanostructured sorbent materials for their effectiveness in removing and immobilizing the contaminants of interest for the off-gas treatment from the UNF recycling operations. The specific objectives defined for the research are: 1. To synthesize and characterize various nanosorbents for the removal of radioactive contaminants from the off-gas, 2. To determine the adsorption isotherms for contaminants of interest (I, Kr) on selected sorbents, 3. To investigate the immobilization of the contaminants in a durable form, and 4. To develop a process model that can be used for the design of the capture and immobilization system for the radionuclides in the off-gas. Nanosorbents based on activated carbon and zeolites will be synthesized and characterized with respect to their surface area and other properties. Continuous column experiments will be conducted at various operating conditions to obtain the adsorption equilibria of individual components and those in multicomponent mixtures. Mathematical models will be developed to describe the performance of the sorbents, and the model validated from the experimental data. A comprehensive system will be developed for the treatment of the off-gas on the basis of the model and the experimental data. Development of advanced fuel cycles is essential for the sustainability and growth of the nuclear power. Achieving near-zero emissions of radionuclides by capturing them from the off-gas of recycling operations is one of the integral challenges in the development of the innovative technologies necessary for this purpose. The proposed research addresses a key need in development of off-gas treatment, targeting the emission of radionuclides using nano-structured materials. The studies conducted to accomplish the objectives outlined above will yield data on the adsorption isotherms of individual contaminants and mixtures on different. Theoretical modeling of the processes will offer fundamental insight into the mechanisms, and allow us to design and predict the performance of the system. The predictive capability of the proposed research will help further the progress of the next generation of fuel cycle.

Chemical Engineering Journal, 2017

A novel Engelhard titanosilicate-10 (ETS-10) supported 10 wt% hollow carbon nanopolyhedron (10 wt... more A novel Engelhard titanosilicate-10 (ETS-10) supported 10 wt% hollow carbon nanopolyhedron (10 wt% C@ETS-10) sorbent developed in our laboratory was investigated for adsorption of the radioactive iodine and krypton from off-gas stream using a continuous flow adsorption column. Adsorption experiments were performed to determine the capacity of 10 wt% C@ETS-10 sorbent for iodine and krypton in multicomponent mixture system by varying operating parameters, such as inlet concentration of iodine (I 2) and krypton (Kr), and adsorption column temperature. Pristine and used sorbents were characterized by scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy to identify the morphology, elemental and vibration analysis of the sorbent before and after the experiments. EDS and XPS spectra of the used samples clearly indicate the presence of iodine on the sorbent. Multicomponent sorption capacities of I 2 and Kr of 10 wt% C@ETS-10 sorbent calculated from the breakthrough curves at 20°C at 25 ppm I 2 and 70 ppm Kr balanced with nitrogen were found to be 41.5 and 0.0323 mg g-1 , respectively.

Chemical Engineering Journal, 2016

Nuclear energy production is growing rapidly worldwide to satisfy increasing energy demands. Repr... more Nuclear energy production is growing rapidly worldwide to satisfy increasing energy demands. Reprocessing of used nuclear fuel (UNF) is expected to play an important role for sustainable development of nuclear energy by increasing the energy extracted from the fuel and reducing the generation of the high level waste (HLW). However, during the reprocessing of Used Nuclear Fuel (UNF) gaseous radioactive nuclides including iodine, krypton, xenon, carbon, and tritium are released into the atmosphere through off-gas streams. The volatile iodine (129 I), and krypton (85 Kr) gases have long lived-isotopes; which have adverse effects on the environment as well as human health. Consequently, the capture of these two target radionuclides (species) is essential for the enhanced growth of nuclear energy. In this review we discuss several techniques for capture of volatile contaminants iodine, krypton, and xenon, focusing upon adsorption using solid sorbents, which has shown promising results for more than 70 years. Commonly used and recently developed sorbents are summarized in this article along with a short review of the results. Metal-organicframeworks (MOFs), gaining favor in recent years as sorbents for the capture of off-gas contaminants are also discussed. Finally, some considerations of future trends and prospects for investigations of the capture of volatile radionuclides are presented.

Adsorption, 2016

Porous microspheres of magnesium oxide were synthesized by calcination of precursor obtained via ... more Porous microspheres of magnesium oxide were synthesized by calcination of precursor obtained via hydrothermal method. A sample of microsphere was characterized by transmission electron microscopy, scanning electron microscopy–energy dispersion spectroscopy, X-ray diffraction, thermogravimetric analysis, N2 adsorption–desorption isotherms, and BET surface area. The average pore size and surface area of the microsphere were found to be 9.0 nm and 83.1 m2 g−1, respectively. The performance of sorbent was investigated in a continuous adsorption system. Iodine adsorption on sorbent was studied by varying temperature of adsorption column, sorbent calcination temperature and initial concentration of iodine. The capacity of sorbent increased by ~25 % when calcination temperature was raised from 350 to 500 °C. The maximum iodine adsorption capacity of sorbent was found to be 196 mg g−1 using Langmuir isotherm. These results indicate the microspherical form of MgO to be effective sorbent to capture iodine vapor from off-gas stream.

Chemical Engineering Journal, 2016

ETS-10 supported hollow carbon nanostructured polyhedron adsorbent, C@ETS-10, was synthesized by ... more ETS-10 supported hollow carbon nanostructured polyhedron adsorbent, C@ETS-10, was synthesized by wet impregnation method to evaluate removal of iodine from off-gas stream from a used nuclear fuel reprocessing operation. The characteristics of the adsorbent were investigated by various techniques such as transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), powder X-ray diffraction (P-XRD) and thermogravimetric analysis (TGA), revealing uniform hollow carbon nanostructured polyhedrons with particle size 10-30 nm supported onto ETS-10. The total BET surface area of 10 wt % C@ETS-10 adsorbent was 149 m 2 g-1. The performance of C@ETS-10 nanostructured adsorbent for capture of volatile iodine from gas stream was determined as a function of parameters such as the carbon loading, operating temperatures and empty bed contact time (EBCT). Observed sorption capacity of adsorbent was 28.9 mg g-1 of volatile iodine at 20 ºC without any chemical reaction with sorbent. The maximum dynamic capacity of a column of 10 wt % C@ETS-10 was calculated to be 40 mg g-1. The nanostructured adsorbent has potential to capture environmental impact of radionuclide off-gas emission from nuclear industry.

Adsorption, 2015

Hollow carbon nano-polyhedrons (HCNPHs) supported on Engelhard Titanosilicate-10 (ETS-10) were sy... more Hollow carbon nano-polyhedrons (HCNPHs) supported on Engelhard Titanosilicate-10 (ETS-10) were synthesized by wet impregnation technique using tetrahydrofuran as a solvent. Synthesized HCNPHs/ETS-10 nanosorbent was characterized by X-ray diffraction, Raman spectra, N2-adsorption–desorption isotherm, BET surface area, and scanning electron microscopy to confirm the morphology and uniformity of carbon particles ranging from 50 to 70 nm in diameter. Sorption characteristics of this nanosorbent for krypton at various carbon loadings were determined using a bench-scale column apparatus. The dynamic sorption capacity of HCNPHs/ETS-10 nanosorbent calculated from the breakthrough curve, 0.75 mmol/kg, which was ~15 % higher than for that of activated carbon. The effect of temperature on the adsorption capacity was studied between 263–293 K. Operational capacity of the nanosorbent was found to be 0.45 mmol/kg at 263 K. The experimental results indicate that 10 wt% HCNPHs/ETS-10 nanosorbent showed promising results for krypton adsorption, indicating its potential as an economical and active sorbent for krypton removal from the off-gas streams resulting from operations for recycle of used nuclear fuel.

The Journal of Physical Chemistry C, 2010

Silica nanosprings with large surface-to-volume ratios were coated with noble metal nanoparticles... more Silica nanosprings with large surface-to-volume ratios were coated with noble metal nanoparticles (NPs) using chemical vapor deposition or chemisorption of presynthesized or in situ synthesized nanoparticles. Chemisorption of presynthesized silver NPs onto amine-...

ACS Applied Materials & Interfaces, 2009

Networks of nano/microfibers (fiber mats) have been electrospun from solutions of dispersed poly(... more Networks of nano/microfibers (fiber mats) have been electrospun from solutions of dispersed poly(vinylpyrrolidone) (PVP) and a titania precursor onto glass and indium-tin oxide (ITO) plates to study their wettability. Collection time and electrode separation are the two key fabrication parameters investigated, along with the flow rate, polymer molecular weight, and drying conditions, to determine the effects on network morphology and the relationship to contact angles. Measurements indicate that the fiber mats on both glass and ITO increase in thickness and contact angle for longer spinning time and shorter distance, resulting in an extreme case of apparent ultrahydrophobicity on ITO of up to 169.9 degrees with water. The fiber mats are shown by optical microscopy to exhibit differences in morphology for insulating glass (straight) and conductive ITO (loopy) substrates responsible for the wide-ranging and well-controlled wettability to within 1-2 degrees. Fiber mats baked at 200 degrees C for 24 h show excellent mechanical stability with wetting even against frequent heavy rinsing, conducive for reusable aqueous applications such as biosensors or cellular scaffolding.

Transactions of the American Nuclear Society, 2017

Applied and Environmental Microbiology, 2011

Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy were used to study the cel... more Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy were used to study the cell injury and inactivation of Campylobacter jejuni from exposure to antioxidants from garlic. C. jejuni was treated with various concentrations of garlic concentrate and garlic-derived organosulfur compounds in growth media and saline at 4, 22, and 35°C. The antimicrobial activities of the diallyl sulfides increased with the number of sulfur atoms (diallyl sulfide < diallyl disulfide < diallyl trisulfide). FT-IR spectroscopy confirmed that organosulfur compounds are responsible for the substantial antimicrobial activity of garlic, much greater than those of garlic phenolic compounds, as indicated by changes in the spectral features of proteins, lipids, and polysaccharides in the bacterial cell membranes. Confocal Raman microscopy (532-nm-gold-particle substrate) and Raman mapping of a single bacterium confirmed the intracellular uptake of sulfur and phenolic components. Scanning ele...

In this study, a process for developing nanospring-based electrical biosensors is presented. Impe... more In this study, a process for developing nanospring-based electrical biosensors is presented. Impedance spectroscopy is used to characterize silica (SiO2) nanospring-based biosensors. The sensor is a capacitor consisting of two conducting surfaces with silica nanosprings as the dielectric spacer layer. The nanosprings are grown on glass substrates coated with indium tin oxide (ITO) to form one of the electrodes of the capacitor. The top electrode is an ITO coated glass substrate. Placing one slide on top of the other slide produces a capacitor with nanosprings as the dielectric spacer layer. The initial phase of biosensor development is to characterize the response of the device with an aqueous solution consisting of sodium chloride in a phosphate buffer. The experimental impedance data is analyzed using a model equivalent resistor-inductor-capacitor (RLC) circuit. Analysis of the impedance spectra of the nanospring-based biosensor requires a much more complex equivalent circuit relative to the blank biosensor where nanosprings are not present.

Journal of Near Infrared Spectroscopy, May 23, 2020

Three methods of measuring coffee roast degree were compared using titratable acidity as an indic... more Three methods of measuring coffee roast degree were compared using titratable acidity as an indicator of roast-dependent flavor change. The first roast degree method was based on prediction of the cracks with online near infrared spectroscopy and partial least squares regression, the second was based on changes in online near infrared absorbance, and the third was the common L* value from the CIELAB color space in the visible spectrum. Roasting trials utilized arabica coffee from eight origins in an air roaster, and results demonstrated the superiority of an online near infrared sensor for real-time roast degree measurement. A second dataset with constant temperature roasts showed how acidity can be controlled by changing both the roasting temperature and roast degree, finding the linear effects of roast time and roast degree on acidity.

International journal of pavement research and technology, Jul 3, 2023

Journal of transportation engineering, Jun 1, 2022

Journal of Food Process Engineering, Nov 7, 2019

The prediction of start and end times of the first and second crack events in roasting coffee is ... more The prediction of start and end times of the first and second crack events in roasting coffee is feasible with in situ near-infrared (NIR) spectroscopy. Roasting samples analyzed herein consist of eight varieties of arabica coffee with different origins and processing methods, roasted with four temperature-time profiles. Real-time analysis of recorded audio from coffee bean popping sounds provides a basis for determining the start and end times of each major event. A custom in situ diffuse reflectance probe improved NIR output, and partial least squares (PLS) regression generated a separate model for each crack event. The resulting PLS models show strong potential for process control implementation. A newly developed roast degree scale based on the progression through crack events is arguably more meaningful than common color cues to connect and correlate the complex chemistries and consumer qualities in roasted coffee. Practical Applications The first and second cracks are two sets of popping sounds that occur during coffee roasting. These events are commonly used as indicators of roast degree for determining the endpoint of the roast, but this judgment can be subjective. This work explores the use of NIR spectroscopy to predict the start and end of the two cracking events to provide a more robust method for controlling the roast based on the cracks. The predictions are used to generate a numerical roast degree scale, which provides a consistent method of comparing the roast degree of coffees from different origins or roasters. 1 | INTRODUCTION Coffee roasting is a complex process involving three modes of heat transfer, elevated pressure, transient evaporation, and changes in material density and phase occurring at the same time as chemical reactions that produce hundreds of different chemical species (Fadai,

Journal of Materials Science, May 27, 2020

Aging of graphite-based materials results in slower heterogeneous electron transfer (HET) kinetic... more Aging of graphite-based materials results in slower heterogeneous electron transfer (HET) kinetics and limits their conducting and catalytic performance. A thermal treatment protocol reportedly maintained a high HET kinetics of graphite by at least nine weeks. The present report investigates the consequences of such HET increases on graphite stabilities. Raman 2D peak evolution, potential windows, EIS, optical AFM, chronoamperometry and potentiodynamic polarization studies were employed to investigate electrochemical, structural and corrosion stabilities and mechanisms of the pristine and thermally treated graphite as they relate to its HET kinetics. Structure-induced electronic changes are suggested to trigger improved tunneling paths through the interfaces from the bulk layer. This tunneling improves and sustains HET kinetics by orders of magnitude in the treated graphite. Except for the graphite fibers, thermal treatment increased HET kinetics without compromises to electrochemical, structural and corrosion stabilities. In most instances, these properties improved over the pristine graphite.

SN applied sciences, Jun 17, 2019

The search has been on for years to find at least, a stable, high surface area scaffold for Pruss... more The search has been on for years to find at least, a stable, high surface area scaffold for Prussian blue (PB) and its analogs. If successful, PB's vast potential applications could be practicable. This, is besides other innate issues with PB such as poor cycle stability, low electronic conductivity to mention a few. For the first time, a stable Prussian blue@thermally activated graphite felt scaffold, with cycling stability of 2100 cycles, from − 0.5 to 1.3 V, and in 1 M KCl, for at least 36 h is reported. At the end of 2100 CV cycles, sample capacitance more than tripled (381 mF cm −2 compared to 120 mF cm −2 at start of experiment). These properties suggest a practical ion-sieve for specific cation removal from contaminated water. Two new synthesis protocols were employed to achieve this: (a) a first time, single solution PB synthesis without externally applied potential, current or even elevated temperature and (b) a two-step solution-dipping process not involving acidic conditions. PB from both protocols exhibited similar electrochemical characteristics even though the electron relay paths along their charge transfer complexes are different. When probed for its HOMO characteristics, the PB@thermally-treated graphite showed no significant electronic difference from the thermally-treated felt scaffold, suggesting non-compromise of the treated graphite by the PB. Besides cation removal, the electrochemical and electronic properties of these PB@treated graphites suggest multiple electrochemical, non-electrochemical and electronic applications with intact structural and functional integrity.

ACS applied nano materials, Dec 6, 2018

On thermal treatment, eight different graphite materials became resistant to air aging for at lea... more On thermal treatment, eight different graphite materials became resistant to air aging for at least nine weeks compared to the usual time of hours to a few days when assayed in mM ferriferrocyanide solution. In addition, resistance to aging lasted at least seven days when immersed in 1 mM ferri-ferrocyanide solution compared to the frequently reported few minutes to hours. Experimental results confirm that with heat treatment, HOPG-ZYH, graphite rods, pyrolytic graphites, graphite felts, and natural and artificial graphites undergo structural reorganization that leads to restructuring of their electronic nature. This electronic restructuring enhances and sustains their electrochemical properties. The extent of reorganization is dependent on the initial disordered state, which in turn is important to the final structural and electronic conditions. These results strongly suggest that the primary factor enhancing the electronic response of heat-treated materials is from an overall higher density of states (DOS) localized on delocalizing π bonds compared to their controls. This structural reorganization of the graphites also supports a degree of crystallinity along the lattice sites that enables carrier hopping irrespective of adventitious oxygen-containing and hydrocarbon moieties that are associated with aging-induced sluggish electron transfer kinetics. The attributes of this electronic structure demonstrate a strongly correlated system that exhibits a non-perturbative behavior. A one-dimensional Hubbard model describes this behavior to explain the surface-to-electronic chemistry of treated graphites by addressing both their enhanced electrochemical performance and their delayed or reduced aging effects.

Capture and immobilization of volatile radionuclides present in the off-gas from used nuclear fue... more Capture and immobilization of volatile radionuclides present in the off-gas from used nuclear fuel (UNF) recycling operations is an essential component of an integrated nuclear waste management system. Radionuclides of particular concern are the long-lived 129 I, that tends to bioaccumulate and affect the metabolism in humans, and 85 Kr, a chemically inert radioisotope that continues to accumulate in the environment. Control of emissions of these contaminants is necessary to comply with the stringent regulatory limits placed on their releases to protect human health and environment. Off-gas treatment processes based on cryogenic distillation, absorption in solvents and membrane separations suffer from several drawbacks including cost, presence of corrosive materials and the radiation stability of materials. The goal of the proposed research is to evaluate nanostructured sorbent materials for their effectiveness in removing and immobilizing the contaminants of interest for the off-gas treatment from the UNF recycling operations. The specific objectives defined for the research are: 1. To synthesize and characterize various nanosorbents for the removal of radioactive contaminants from the off-gas, 2. To determine the adsorption isotherms for contaminants of interest (I, Kr) on selected sorbents, 3. To investigate the immobilization of the contaminants in a durable form, and 4. To develop a process model that can be used for the design of the capture and immobilization system for the radionuclides in the off-gas. Nanosorbents based on activated carbon and zeolites will be synthesized and characterized with respect to their surface area and other properties. Continuous column experiments will be conducted at various operating conditions to obtain the adsorption equilibria of individual components and those in multicomponent mixtures. Mathematical models will be developed to describe the performance of the sorbents, and the model validated from the experimental data. A comprehensive system will be developed for the treatment of the off-gas on the basis of the model and the experimental data. Development of advanced fuel cycles is essential for the sustainability and growth of the nuclear power. Achieving near-zero emissions of radionuclides by capturing them from the off-gas of recycling operations is one of the integral challenges in the development of the innovative technologies necessary for this purpose. The proposed research addresses a key need in development of off-gas treatment, targeting the emission of radionuclides using nano-structured materials. The studies conducted to accomplish the objectives outlined above will yield data on the adsorption isotherms of individual contaminants and mixtures on different. Theoretical modeling of the processes will offer fundamental insight into the mechanisms, and allow us to design and predict the performance of the system. The predictive capability of the proposed research will help further the progress of the next generation of fuel cycle.

Chemical Engineering Journal, 2017

A novel Engelhard titanosilicate-10 (ETS-10) supported 10 wt% hollow carbon nanopolyhedron (10 wt... more A novel Engelhard titanosilicate-10 (ETS-10) supported 10 wt% hollow carbon nanopolyhedron (10 wt% C@ETS-10) sorbent developed in our laboratory was investigated for adsorption of the radioactive iodine and krypton from off-gas stream using a continuous flow adsorption column. Adsorption experiments were performed to determine the capacity of 10 wt% C@ETS-10 sorbent for iodine and krypton in multicomponent mixture system by varying operating parameters, such as inlet concentration of iodine (I 2) and krypton (Kr), and adsorption column temperature. Pristine and used sorbents were characterized by scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy to identify the morphology, elemental and vibration analysis of the sorbent before and after the experiments. EDS and XPS spectra of the used samples clearly indicate the presence of iodine on the sorbent. Multicomponent sorption capacities of I 2 and Kr of 10 wt% C@ETS-10 sorbent calculated from the breakthrough curves at 20°C at 25 ppm I 2 and 70 ppm Kr balanced with nitrogen were found to be 41.5 and 0.0323 mg g-1 , respectively.

Chemical Engineering Journal, 2016

Nuclear energy production is growing rapidly worldwide to satisfy increasing energy demands. Repr... more Nuclear energy production is growing rapidly worldwide to satisfy increasing energy demands. Reprocessing of used nuclear fuel (UNF) is expected to play an important role for sustainable development of nuclear energy by increasing the energy extracted from the fuel and reducing the generation of the high level waste (HLW). However, during the reprocessing of Used Nuclear Fuel (UNF) gaseous radioactive nuclides including iodine, krypton, xenon, carbon, and tritium are released into the atmosphere through off-gas streams. The volatile iodine (129 I), and krypton (85 Kr) gases have long lived-isotopes; which have adverse effects on the environment as well as human health. Consequently, the capture of these two target radionuclides (species) is essential for the enhanced growth of nuclear energy. In this review we discuss several techniques for capture of volatile contaminants iodine, krypton, and xenon, focusing upon adsorption using solid sorbents, which has shown promising results for more than 70 years. Commonly used and recently developed sorbents are summarized in this article along with a short review of the results. Metal-organicframeworks (MOFs), gaining favor in recent years as sorbents for the capture of off-gas contaminants are also discussed. Finally, some considerations of future trends and prospects for investigations of the capture of volatile radionuclides are presented.

Adsorption, 2016

Porous microspheres of magnesium oxide were synthesized by calcination of precursor obtained via ... more Porous microspheres of magnesium oxide were synthesized by calcination of precursor obtained via hydrothermal method. A sample of microsphere was characterized by transmission electron microscopy, scanning electron microscopy–energy dispersion spectroscopy, X-ray diffraction, thermogravimetric analysis, N2 adsorption–desorption isotherms, and BET surface area. The average pore size and surface area of the microsphere were found to be 9.0 nm and 83.1 m2 g−1, respectively. The performance of sorbent was investigated in a continuous adsorption system. Iodine adsorption on sorbent was studied by varying temperature of adsorption column, sorbent calcination temperature and initial concentration of iodine. The capacity of sorbent increased by ~25 % when calcination temperature was raised from 350 to 500 °C. The maximum iodine adsorption capacity of sorbent was found to be 196 mg g−1 using Langmuir isotherm. These results indicate the microspherical form of MgO to be effective sorbent to capture iodine vapor from off-gas stream.

Chemical Engineering Journal, 2016

ETS-10 supported hollow carbon nanostructured polyhedron adsorbent, C@ETS-10, was synthesized by ... more ETS-10 supported hollow carbon nanostructured polyhedron adsorbent, C@ETS-10, was synthesized by wet impregnation method to evaluate removal of iodine from off-gas stream from a used nuclear fuel reprocessing operation. The characteristics of the adsorbent were investigated by various techniques such as transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), powder X-ray diffraction (P-XRD) and thermogravimetric analysis (TGA), revealing uniform hollow carbon nanostructured polyhedrons with particle size 10-30 nm supported onto ETS-10. The total BET surface area of 10 wt % C@ETS-10 adsorbent was 149 m 2 g-1. The performance of C@ETS-10 nanostructured adsorbent for capture of volatile iodine from gas stream was determined as a function of parameters such as the carbon loading, operating temperatures and empty bed contact time (EBCT). Observed sorption capacity of adsorbent was 28.9 mg g-1 of volatile iodine at 20 ºC without any chemical reaction with sorbent. The maximum dynamic capacity of a column of 10 wt % C@ETS-10 was calculated to be 40 mg g-1. The nanostructured adsorbent has potential to capture environmental impact of radionuclide off-gas emission from nuclear industry.

Adsorption, 2015

Hollow carbon nano-polyhedrons (HCNPHs) supported on Engelhard Titanosilicate-10 (ETS-10) were sy... more Hollow carbon nano-polyhedrons (HCNPHs) supported on Engelhard Titanosilicate-10 (ETS-10) were synthesized by wet impregnation technique using tetrahydrofuran as a solvent. Synthesized HCNPHs/ETS-10 nanosorbent was characterized by X-ray diffraction, Raman spectra, N2-adsorption–desorption isotherm, BET surface area, and scanning electron microscopy to confirm the morphology and uniformity of carbon particles ranging from 50 to 70 nm in diameter. Sorption characteristics of this nanosorbent for krypton at various carbon loadings were determined using a bench-scale column apparatus. The dynamic sorption capacity of HCNPHs/ETS-10 nanosorbent calculated from the breakthrough curve, 0.75 mmol/kg, which was ~15 % higher than for that of activated carbon. The effect of temperature on the adsorption capacity was studied between 263–293 K. Operational capacity of the nanosorbent was found to be 0.45 mmol/kg at 263 K. The experimental results indicate that 10 wt% HCNPHs/ETS-10 nanosorbent showed promising results for krypton adsorption, indicating its potential as an economical and active sorbent for krypton removal from the off-gas streams resulting from operations for recycle of used nuclear fuel.

The Journal of Physical Chemistry C, 2010

Silica nanosprings with large surface-to-volume ratios were coated with noble metal nanoparticles... more Silica nanosprings with large surface-to-volume ratios were coated with noble metal nanoparticles (NPs) using chemical vapor deposition or chemisorption of presynthesized or in situ synthesized nanoparticles. Chemisorption of presynthesized silver NPs onto amine-...

ACS Applied Materials & Interfaces, 2009

Networks of nano/microfibers (fiber mats) have been electrospun from solutions of dispersed poly(... more Networks of nano/microfibers (fiber mats) have been electrospun from solutions of dispersed poly(vinylpyrrolidone) (PVP) and a titania precursor onto glass and indium-tin oxide (ITO) plates to study their wettability. Collection time and electrode separation are the two key fabrication parameters investigated, along with the flow rate, polymer molecular weight, and drying conditions, to determine the effects on network morphology and the relationship to contact angles. Measurements indicate that the fiber mats on both glass and ITO increase in thickness and contact angle for longer spinning time and shorter distance, resulting in an extreme case of apparent ultrahydrophobicity on ITO of up to 169.9 degrees with water. The fiber mats are shown by optical microscopy to exhibit differences in morphology for insulating glass (straight) and conductive ITO (loopy) substrates responsible for the wide-ranging and well-controlled wettability to within 1-2 degrees. Fiber mats baked at 200 degrees C for 24 h show excellent mechanical stability with wetting even against frequent heavy rinsing, conducive for reusable aqueous applications such as biosensors or cellular scaffolding.

Transactions of the American Nuclear Society, 2017

Applied and Environmental Microbiology, 2011

Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy were used to study the cel... more Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy were used to study the cell injury and inactivation of Campylobacter jejuni from exposure to antioxidants from garlic. C. jejuni was treated with various concentrations of garlic concentrate and garlic-derived organosulfur compounds in growth media and saline at 4, 22, and 35°C. The antimicrobial activities of the diallyl sulfides increased with the number of sulfur atoms (diallyl sulfide < diallyl disulfide < diallyl trisulfide). FT-IR spectroscopy confirmed that organosulfur compounds are responsible for the substantial antimicrobial activity of garlic, much greater than those of garlic phenolic compounds, as indicated by changes in the spectral features of proteins, lipids, and polysaccharides in the bacterial cell membranes. Confocal Raman microscopy (532-nm-gold-particle substrate) and Raman mapping of a single bacterium confirmed the intracellular uptake of sulfur and phenolic components. Scanning ele...

In this study, a process for developing nanospring-based electrical biosensors is presented. Impe... more In this study, a process for developing nanospring-based electrical biosensors is presented. Impedance spectroscopy is used to characterize silica (SiO2) nanospring-based biosensors. The sensor is a capacitor consisting of two conducting surfaces with silica nanosprings as the dielectric spacer layer. The nanosprings are grown on glass substrates coated with indium tin oxide (ITO) to form one of the electrodes of the capacitor. The top electrode is an ITO coated glass substrate. Placing one slide on top of the other slide produces a capacitor with nanosprings as the dielectric spacer layer. The initial phase of biosensor development is to characterize the response of the device with an aqueous solution consisting of sodium chloride in a phosphate buffer. The experimental impedance data is analyzed using a model equivalent resistor-inductor-capacitor (RLC) circuit. Analysis of the impedance spectra of the nanospring-based biosensor requires a much more complex equivalent circuit relative to the blank biosensor where nanosprings are not present.