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Adsorption

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Articles 121 - 150 of 185

Full-Text Articles in Chemistry

Impact Of Size, Secondary Structure, And Counterions On The Binding Of Small Ribonucleic Acids To Layered Double Hydroxide Nanoparticles, B. V. Rodriguez, J. Pescador, N. Pollok, G. W. Beall, Corina Maeder, L. K. Lewis Jan 2015

Impact Of Size, Secondary Structure, And Counterions On The Binding Of Small Ribonucleic Acids To Layered Double Hydroxide Nanoparticles, B. V. Rodriguez, J. Pescador, N. Pollok, G. W. Beall, Corina Maeder, L. K. Lewis

Chemistry Faculty Research

Use of ribonucleic acid (RNA) interference to regulate protein expression has become an important research topic and gene therapy tool, and therefore, finding suitable vehicles for delivery of small RNAs into cells is of crucial importance. Layered double metal hydroxides such as hydrotalcite (HT) have shown great promise as nonviral vectors for transport of deoxyribose nucleic acid (DNA), proteins, and drugs into cells, but the adsorption of RNAs to these materials has been little explored. In this study, the binding of small RNAs with different lengths and levels of secondary structure to HT nanoparticles has been analyzed and compared to …

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Molecular Approaches To Chromatography Using Single Molecule Spectroscopy, Lydia Kisley Nov 2014

Molecular Approaches To Chromatography Using Single Molecule Spectroscopy, Lydia Kisley

Faculty Scholarship

No abstract provided.

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Thermodynamics, Kinetics, And Activation Energy Studies Of The Sorption Of Chromium(Iii) And Chromium(Vi) To A Mn 3 O 4 Nanomaterial, Yvette Cantu, Abril Remes, Alejandra Reyna, Denise Martinez, Jahaziel Villarreal, Hilda Ramos, Samantha Trevino, C Tamez, A Martinez, Thomas Eubanks, Jason Parsons Oct 2014

Thermodynamics, Kinetics, And Activation Energy Studies Of The Sorption Of Chromium(Iii) And Chromium(Vi) To A Mn 3 O 4 Nanomaterial, Yvette Cantu, Abril Remes, Alejandra Reyna, Denise Martinez, Jahaziel Villarreal, Hilda Ramos, Samantha Trevino, C Tamez, A Martinez, Thomas Eubanks, Jason Parsons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

In this study, a manganese oxide, Mn3O4 was used to remove chromium(III) and chromium(VI) from aqueous solutions. The Mn3O4 nanomaterial was synthesized through a precipitation method, and was characterized using XRD, which confirmed the material had a crystal structure similar to hausmannite. In addition, using Scherrer's equation it was determined that the nanomaterial had an average grain size of 19.5 ± 1.10 nm. A study of the effects of pH on the binding of chromium(III) and chromium(VI) showed that the optimum binding pH was 4 and 3 respectively. Batch isotherm studies were performed to determine the binding capacity of chromium(III), …

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Supramolecular Biopolymeric Composite Materials: Green Synthesis, Characterization And Applications, Tamutsiwa Moven Mututuvari Oct 2014

Supramolecular Biopolymeric Composite Materials: Green Synthesis, Characterization And Applications, Tamutsiwa Moven Mututuvari

Dissertations (1934 -)

Macrocycles, such as crown ethers (CRs) and resorcinarenes (RESs), exhibit selective complexation of heavy metal ions and organic pollutants respectively. Consequently, they have been investigated for their suitability in adsorbing these aqueous pollutants. However, they are difficult to handle and recycle for reuse because, by themselves, they can only be fabricated in powder form. To alleviate this challenge, we developed a method to encapsulate these macrocycles into film-forming polysaccharides--cellulose (CEL) and chitosan (CS). This was achieved by using a green and recyclable solvent, an ionic liquid, to dissolve both macrocycles and polysaccharides and regenerate corresponding composites in water. Resultant composites …

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The Critical Role Of Water At The Gold-Titania Interface In Catalytic Co Oxidation, Johnny Saavedra, H. Doan, Christopher J. Pursell, L. C. Grabow, Bert D. Chandler Sep 2014

The Critical Role Of Water At The Gold-Titania Interface In Catalytic Co Oxidation, Johnny Saavedra, H. Doan, Christopher J. Pursell, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

We provide direct evidence of a water-mediated reaction mechanism for room-temperature CO oxidation over Au/TiO2 catalysts. A hydrogen/deuterium kinetic isotope effect of nearly 2 implicates O-H(D) bond breaking in the rate-determining step. Kinetics and in situ infrared spectroscopy experiments showed that the coverage of weakly adsorbed water on TiO2 largely determines catalyst activity by changing the number of active sites. Density functional theory calculations indicated that proton transfer at the metal-support interface facilitates O2 binding and activation; the resulting Au-OOH species readily reacts with adsorbed Au-CO, yielding Au-COOH. Au-COOH decomposition involves proton transfer to water and was suggested to be …

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Ab-Initio Study Of H2 Adsorption Upon The 001, 110, And 100 Surface Of Magnesium, Thomas F. Armstrong May 2014

Ab-Initio Study Of H2 Adsorption Upon The 001, 110, And 100 Surface Of Magnesium, Thomas F. Armstrong

Theses and Dissertations

Until recently, the only pathway for H2 adsorption onto conventional magnesium thin films was the [001] surface. With the discovery of Mg nanoblade/nanotree fabrication, there are now multiple surfaces for adsorption. A keen understanding of each surface's hydrogen adsorption kinetics is a key part of deciding if these surfaces present a more attractive hydrogen storage material than conventional thin films. This study focused on the use of ab-initio methods to compare the adsorption of H2 molecules onto the [001], [100], and [110] surfaces as well as an analysis of hybrid functionals and their advantages over traditional functionals for minimum energy …

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Synergistic Adsorption Of Heavy Metal Ions And Organic Pollutants By Supramolecular Polysaccharide Composite Materials From Cellulose, Chitosan And Crown Ether, Tamutsiwa M. Mututuvari, Chieu D. Tran Jan 2014

Synergistic Adsorption Of Heavy Metal Ions And Organic Pollutants By Supramolecular Polysaccharide Composite Materials From Cellulose, Chitosan And Crown Ether, Tamutsiwa M. Mututuvari, Chieu D. Tran

Chemistry Faculty Research and Publications

We have developed a simple one-step method to synthesize novel supramolecular polysaccharide composites from cellulose (CEL), chitosan (CS) and benzo-15-crown 5 (B15C5). Butylmethylimidazolium chloride [BMIm+Cl−], an ionic liquid (IL), was used as a sole solvent for dissolution and preparation of the composites. Since majority of [BMIm+Cl−] used was recovered for reuse, the method is recyclable. The [CEL/CS + B15C5] composites obtained retain properties of their components, namely superior mechanical strength (from CEL), excellent adsorption capability for heavy metal ions and organic pollutants (from B15C5 and CS). More importantly, the [CEL/CS + B15C5] …

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Immobilized Metal Ion Affinity Nanospheres For \Alpha-Amylase Immobilization, Tülden Kalburcu, Müni̇re Nalan Tüzmen, Si̇nan Akgöl, Adi̇l Deni̇zli̇ Jan 2014

Immobilized Metal Ion Affinity Nanospheres For \Alpha-Amylase Immobilization, Tülden Kalburcu, Müni̇re Nalan Tüzmen, Si̇nan Akgöl, Adi̇l Deni̇zli̇

Turkish Journal of Chemistry

Immobilized metal chelate affinity chromatography (IMAC) support was practiced for \alpha-amylase immobilization. Poly(hydroxyethylmethacrylate-methacryloylamidotryptophan)-Ni^{2+} [p(HEMA-MAT)-Ni^{2+}] nanospheres, average diameter 100 nm, were produced by surfactant free emulsion polymerization. Characterizations of p(HEMA-MAT)-Ni^{2+} nanospheres were carried out by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM). In addition, average particle size, size distribution, and surface charge were specified. The amount of N-methacryloylamidotryptophan (MAT) incorporated to polymer was determined as 1.95 mmol/g polymers by using nitrogen stoichiometry. The specific surface areas of poly(hydroxyethylmethacrylate) [p(HEMA)] and p(HEMA-MAT) nanospheres were calculated as 1856 m^2/g and 1914 m^2/g, respectively. Protein adsorption increased with increasing initial protein …

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Adsorption Of The Urea Molecule On The B_{12}N_{12} Nanocage, Mohammad Taghi Baei Jan 2014

Adsorption Of The Urea Molecule On The B_{12}N_{12} Nanocage, Mohammad Taghi Baei

Turkish Journal of Chemistry

The adsorption of the urea molecule on the external surface of the B_{12}N_{12} nanocage was investigated using density functional theory (DFT) calculations. Adsorption of urea on the nanocage releases energies of about --23.70 to --29.50 kcal/mol with a significant NBO charge transfer from the urea to the nanocage. It was also found that the urea molecule can be strongly chemisorbed on the surface of the nanocage with Gibbs free energies of -7.91 to -14.81 kcal/mol. The HOMO--LUMO gap of the nanocage does not change significantly upon urea adsorption, while the Fermi level is dramatically changed from -4.27 eV in the …

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First-Principles Study Of The Electric Field Effect On The Water-Adsorbed Rutile Titanium Dioxide Surface, Abraham L. Hmiel Jan 2014

First-Principles Study Of The Electric Field Effect On The Water-Adsorbed Rutile Titanium Dioxide Surface, Abraham L. Hmiel

Legacy Theses & Dissertations (2009 - 2024)

TiO2 is a semiconducting material that has been used extensively in many industrial applications, and recently has become a candidate for photocatalytic water splitting, fuel cell anode support materials, sensors, and other novel nanodevices. The interface of TiO2 with water, historically well-studied but still poorly understood, presents a ubiquitous environmental challenge towards the ultimate practical usefulness of these technologies. Ground-state density functional theory (DFT) calculations studying the characteristics of molecular adsorption on model surfaces have been studied for decades, showing constant improvement in the description of the energetics and electronic structure at interfaces. These simulations are invaluable in the …

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Zn(Ii) And Cu(Ii) Adsorption And Retention Onto Iron Oxyhydroxide Nanoparticles: Effects Of Particle Aggregation And Salinity, Rebecca B. Chesne, Christopher S. Kim Jan 2014

Zn(Ii) And Cu(Ii) Adsorption And Retention Onto Iron Oxyhydroxide Nanoparticles: Effects Of Particle Aggregation And Salinity, Rebecca B. Chesne, Christopher S. Kim

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background: Iron oxyhydroxides are commonly found in natural aqueous systems as nanoscale particles, where they can act as effective sorbents for dissolved metals due to their natural surface reactivity, small size and high surface area. These properties make nanoscale iron oxyhydroxides a relevant option for the remediation of water supplies contaminated with dissolved metals. However, natural geochemical processes, such as changes in ionic strength, pH, and temperature, can cause these particles to aggregate, thus affecting their sorption capabilities and remediation potential. Other environmental parameters such as increasing salinity may also impact metal retention, e. g. when particles are transported …

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Microwave-Assisted Synthesis Of Carbon Supported Metal/Metal Oxide Nanocomposites And Their Application In Water Purification, Gunawan Gunawan Dec 2013

Microwave-Assisted Synthesis Of Carbon Supported Metal/Metal Oxide Nanocomposites And Their Application In Water Purification, Gunawan Gunawan

Theses and Dissertations

A novel, easy, and cost effective method for synthesizing carbon supported metal/metal oxide nanocomposites has been studied. Carbon supported metal/metal oxide nanocomposites have niche applications in the area of catalysis, fuel cells, electrodes, and more. The method utilizes a commercial microwave and features the addition of a developed graphite-jacket technique with renewable carbon resources, tannin and lignin. The method has been successfully used to synthesize carbon/nickel, carbon/iron oxide, and carbon/nickel phosphide nanocomposites. The method has shown its versatility in the synthesis of carbon nanocomposites. The process is much simpler when compared with the available methods for synthesizing carbon nanocomposites. The …

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Nonlinear Spectroscopic Investigation Of Adsorption To C-18 Model Stationary Phase, Anthony D. Peterson Dec 2013

Nonlinear Spectroscopic Investigation Of Adsorption To C-18 Model Stationary Phase, Anthony D. Peterson

Theses and Dissertations

Reversed-phase liquid chromatography (RPLC) is a commonly used separation technique in chemistry. Nevertheless, the mechanistic interactions at the molecular level among the eluent, analyte, and the stationary phase are not fully understood. Because of this limited understanding, optimization of the separation must be done experimentally. Learning more about molecular interactions should aid in improving separations. We are currently using second-harmonic generation (SHG) spectroscopy to investigate how analytes adsorb to the surface. SHG is a spectroscopic technique that produces signal only at places of non-isotropic symmetry; this typically occurs at surfaces. SHG can be used to produce surface isotherms of test …

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The Catalytic Behaviour Of Nanoag@Montmorillonite Composite Materials, Martina Karlíková, Libor Kvítek, Robert Prucek, Aleš Panáček, Jan Filip, Jirí Pechoušek, Nathaniel F. Adegboyega Nov 2013

The Catalytic Behaviour Of Nanoag@Montmorillonite Composite Materials, Martina Karlíková, Libor Kvítek, Robert Prucek, Aleš Panáček, Jan Filip, Jirí Pechoušek, Nathaniel F. Adegboyega

Chemistry and Chemical Engineering Faculty Publications

The preparation of nanoAg@montmorillonite composite materials and their catalytic activity is reported in this article. The nanoAg@montmorillonite composite materials were prepared by the adsorption of silver NPs, with an average size about 30 nm, from their aqueous dispersion onto two types of montmorillonite with different chemical composition. Silver NPs were prepared via modified Tollens process, which involves the reduction of [Ag(NH 3)2]+complex cation by maltose. The amount of silver NPs anchored onto the MMT surfaces was determined by UV-VIS spectroscopy; the decrease in absorbance of the dispersion after the adsorption was monitored. Prepared nanocomposite materials were subsequently characterized by means …

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Remediation Of Polychlorinated Biphenyl (Pcb) Contaminated Building Materials Using Non-Metal And Activated Metal Treatment Systems, Tamra Legron-Rodriguez Jan 2013

Remediation Of Polychlorinated Biphenyl (Pcb) Contaminated Building Materials Using Non-Metal And Activated Metal Treatment Systems, Tamra Legron-Rodriguez

Electronic Theses and Dissertations

PCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system (AMTS) for the remediation and degradation of PCBs from concrete, brick, and granite affixed with PCB-laden caulking. The adsorption of PCBs onto the components …

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Application Of Glycyrrhiza Glabra Root As A Novel Adsorbent In The Removal Of Toluene Vapors: Equilibrium, Kinetic, And Thermodynamic Study, Fazel Mohammadi-Moghadam, Mohammad Mehdi Amin,, Mehdi Khiadani, Fariborz Momenbeik, Heshmatollah Nourmoradi, Mohammad Sadegh Hatamipour Jan 2013

Application Of Glycyrrhiza Glabra Root As A Novel Adsorbent In The Removal Of Toluene Vapors: Equilibrium, Kinetic, And Thermodynamic Study, Fazel Mohammadi-Moghadam, Mohammad Mehdi Amin,, Mehdi Khiadani, Fariborz Momenbeik, Heshmatollah Nourmoradi, Mohammad Sadegh Hatamipour

Research outputs 2013

The aim of this paper is to investigate the removal of toluene from gaseous solution through Glycyrrhiza glabra root (GGR) as a waste material. The batch adsorption experiments were conducted at various conditions including contact time, adsorbate concentration, humidity, and temperature. The adsorption capacity was increased by raising the sorbent humidity up to 50 percent. The adsorption of toluene was also increased over contact time by 12 h when the sorbent was saturated. The pseudo-second-order kinetic model and Freundlich model fitted the adsorption data better than other kinetic and isotherm models, respectively. The Dubinin-Radushkevich (D-R) isotherm also showed that the …

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Sorption Kinetic Study Of Selenite And Selenate Onto A High And Low Pressure Aged Iron Oxide Nanomaterial, Christina M. Gonzalez, Jeffrey Hernandez, Jose R. Peralta-Videa, Cristian E. Botez, Jason Parsons, Jorge L. Gardea-Torresdey Apr 2012

Sorption Kinetic Study Of Selenite And Selenate Onto A High And Low Pressure Aged Iron Oxide Nanomaterial, Christina M. Gonzalez, Jeffrey Hernandez, Jose R. Peralta-Videa, Cristian E. Botez, Jason Parsons, Jorge L. Gardea-Torresdey

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

The sorption of selenite (SeO32−) and selenate (SeO42−) onto Fe3O4 nanomaterials produced by non microwave-assisted or microwave-assisted synthetic techniques was investigated through use of the batch technique. The phase of both synthetic nanomaterials was determined to be magnetite by X-ray diffraction. The average grain sizes of non microwave-assisted and microwave-assisted synthetic Fe3O4 were determined to be 27 and 25 nm, respectively through use of the Scherrer's equation. Sorption of selenite was pH independent in the pH range of 2-6, while sorption of selenate decreased at pH 5 and 6. The addition of Cl− had no significant effect on selenite or …

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Theory Of Adsorption Equilibria Analysis Based On General Equilibrium Constant Expression, Abdul Sattar Ali Khan Jan 2012

Theory Of Adsorption Equilibria Analysis Based On General Equilibrium Constant Expression, Abdul Sattar Ali Khan

Turkish Journal of Chemistry

Adsorption equilibria were analyzed on the basis of general equilibrium constant expression for the development of fundamental adsorption equations (Freundlich, Langmuir, and BET) in connection with the establishment of a general approach towards physical interpretations of adsorption parameters. Theoretically it was proved that Freundlich plot analysis cannot be used to find useful parameters such as the monolayer adsorption capacity of an adsorbent. The present theory also indicated that the adsorption process with known value of monolayer adsorption capacity can be studied for finding various equilibrium constants on the basis of the Fronaeus equation, which is commonly used in the complexation …

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Density Functional Theory Calculations On Hydrated Dimethylarsinic Acid And Iron Oxide Clusters, Adrian Adamescu Jan 2012

Density Functional Theory Calculations On Hydrated Dimethylarsinic Acid And Iron Oxide Clusters, Adrian Adamescu

Theses and Dissertations (Comprehensive)

Dimethylarsinic Acid (DMA) or (CH3)2AsO2H is an important organoarsenical compound detected in arsenic speciation studies of environmental samples and synthesized during pyrolysis of oil shale. DMA was used historically as a herbicide on large agricultural fields and can be detected in the leachates of landfills rich in waste containing arsenic such as glass, alloys, and semiconductors, as well as biologically pre-treated municipal solid waste. Under certain soil conditions DMA can become bio-available and has the potential to be recycled to more toxic inorganic forms of arsenic. Bioavailability of DMA is largely controlled by the …

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Effects Of Activated Carbon Surface Chemistry Modification On The Adsorption Of Mercury From Aqueous Solution, Emily K. Faulconer Jan 2012

Effects Of Activated Carbon Surface Chemistry Modification On The Adsorption Of Mercury From Aqueous Solution, Emily K. Faulconer

Publications

Mercury (Hg), a naturally occurring element, is toxic and can lead to negative health impacts for humans and ecosystems. Activated carbon adsorption is effective in treating Hg-laden aqueous effluent for safe discharge. Two modifications of commercially available activated carbon were investigated: iron impregnation to allow for magnetic sorbent recapture and wet chemical oxidation to enhance aqueous Hg capture. The modified carbons were characterized by nitrogen adsorption-desorption, XRD, pHpzc, vibrating sample magnetometry, elemental analysis, and total acidity titration. The 3:1 C:Fe magnetic powdered activated carbon (MPAC) retained a high surface area of 790 m2 /g and was 95% magnetically recoverable, with …

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Removal Of 2,4-Dichlorophenoxyacetic Acid By Calcined Zn–Al–Zr Layered Double Hydroxide, Allen Chaparadza, Jeanne Hossenlopp Nov 2011

Removal Of 2,4-Dichlorophenoxyacetic Acid By Calcined Zn–Al–Zr Layered Double Hydroxide, Allen Chaparadza, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

The adsorption equilibrium, kinetics, and thermodynamics of removal of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solutions by a calcined Zn–Al layered double hydroxide incorporated with Zr4+ were studied with respect to time, temperature, pH, and initial 2,4-D concentration. Zr4+ incorporation into the LDH was used to enhance 2,4-D uptake by creating higher positive charges and surface/layer modification of the adsorbent. The LDH was capable of removing up to 98% of 2,4-D from 5 to 400 ppm aqueous at adsorbent dosages of 500 and 5000 mg L−1. The adsorption was described by a Langmuir-type isotherm. The percentage 2,4-D …

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Influence Of Electric Field On The Adsorption And Bioactivity Of Hemoglobin On A Macroporous Gold Electrode, Cui-Hong Wang, Yi-Bing Kong, Xing-Hua Xia Feb 2011

Influence Of Electric Field On The Adsorption And Bioactivity Of Hemoglobin On A Macroporous Gold Electrode, Cui-Hong Wang, Yi-Bing Kong, Xing-Hua Xia

Journal of Electrochemistry

The adsorption and bioactivity of proteins at interfaces have been widely studied due to their important role in the construction of biosensors,bioelectronics and biofuel cells.Interfacial electric field is one of the important factors which could affect the adsorption and bioactivity of proteins at materials surfaces.It could dramatically change the adsorption density,molecular conformation and orientation at material surfaces.In this paper,the influence of interfacial electric field on the adsorption kinetics and bioactivity of hemoglobin(Hb) on a three-dimensional(3D) macroporous gold electrode surface has been studied using electrochemical methods and infrared spectroscopy.It was found that the interfacial electric field created excess surface charge which …

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Detection Of Quercetin Using Polymer Coated Quartz Crystal Microbalance And The Modification Of Á-Zirconium Phosphate To Develop A Sorbent For Organic Pollutant Removal, Darlington Mlambo Oct 2010

Detection Of Quercetin Using Polymer Coated Quartz Crystal Microbalance And The Modification Of Á-Zirconium Phosphate To Develop A Sorbent For Organic Pollutant Removal, Darlington Mlambo

Dissertations (1934 -)

Sorption processes involve physical and chemical interactions of sorbents with analytes. These may involve the physical and/or chemical processes in which a substance is accumulated at an interface between two phases, or the intermixing of a substance with the matrix of a second phase. The two processes are referred to as adsorption and absorption respectively. The sorption capacities of different classes of sorbents have many potential and demonstrated applications such as sensor development, water treatment, environmental remediation and chromatographic separations. The goal of this work is to explore the sorption capacity of polymers as well as nanodimensional layered materials for …

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Electrochemical Surface-Enhanced Raman Spectroscopy—Current Status And Perspective, Bin Ren, Jian-Feng Li, Yi-Fan Huang, Zhi-Cong Zeng, Zhong-Qun Tian Aug 2010

Electrochemical Surface-Enhanced Raman Spectroscopy—Current Status And Perspective, Bin Ren, Jian-Feng Li, Yi-Fan Huang, Zhi-Cong Zeng, Zhong-Qun Tian

Journal of Electrochemistry

Electrochemical interface is a very important interface closely related to various energy and life processes. Surface-enhanced Raman scattering was widely used in electrochemistry soon after its discovery to understand the surface bonding,configuration,and orientation of the surface species. In recent 10 years,the fast development of nanoscience and nanotechnology has offered SERS with abundant substrates and characterization methods,which has allowed impressive development of electrochemical SERS. This articles will follow the time line to make systematically overview of SERS on Au and Ag,thin-layer transition-metal SERS,pure transition metal SERS,core-shell SERS and those methods for studying single crystal surfaces,including gap-mode SERS, TERS and SHINERS. Emphasis …

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Density Functional Theory Studies Of Surface-Enhanced Raman Spectroscopy In Electrochemical Interfaces, Liu-Bin Zhao, De-Yin Wu, Bin Ren, Zhong-Qun Tian Aug 2010

Density Functional Theory Studies Of Surface-Enhanced Raman Spectroscopy In Electrochemical Interfaces, Liu-Bin Zhao, De-Yin Wu, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

Quantum chemical density functional theory and Raman scattering theory were used to study the bonding mechanism and surface-enhanced Raman spectroscopy of pyridine adsorbed on transition metals (Ⅷ group) and coinage metals (IB group) . SERS studies of pyridine-metal systems have been reviewed. Chemical bonding mechanism as well as photo-driven charge transfer mechanism was considered to investigate the vibrational frequency shift and the enhancement of SERS intensity in electrochemical interfaces. Our theoretical results can be used to interpret the SERS phenomena dependent on metals,excitation wavelengths,and applied potentials.

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Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson May 2010

Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson

Chemistry Faculty Research

New bimetallic Ni-Au supported nanoparticle catalysts were prepared by using dendrimer templated nanoparticles. Amine-terminated generation 5 polyamidoamine (PAMAM) dendrimers were anchored to a commercial silica with a siloxane linked anhydride. The dendrimer was then alkylated and used to template Ni-Au nanoparticles, which were subsequently extracted into organic solution as thiol monolayer protected clusters (MPCs). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) indicated bimetallic nanoparticles of about 2 nm in size. Nanoparticles were deposited onto P-25 TiO2, and the capping thiol ligands were removed under flowing H2. DRIFTS infrared spectra of adsorbed CO showed only Au on the catalyst …

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Distance Dependence Of Electron Transfer Kinetics For Azurin Protein Adsorbed To Monolayer Protected Nanoparticle Film Assemblies, Morgan Lynn Vargo, Chris P. Gulka, John K. Gerig, Christopher M. Manieri, Jonathan D. Dattelbaum, Carolyn B. Marks, Nathaniel T. Lawrence, Matthew L. Trawick, Michael C. Leopold Aug 2009

Distance Dependence Of Electron Transfer Kinetics For Azurin Protein Adsorbed To Monolayer Protected Nanoparticle Film Assemblies, Morgan Lynn Vargo, Chris P. Gulka, John K. Gerig, Christopher M. Manieri, Jonathan D. Dattelbaum, Carolyn B. Marks, Nathaniel T. Lawrence, Matthew L. Trawick, Michael C. Leopold

Chemistry Faculty Publications

The distance dependence and kinetics of the heterogeneous electron transfer (ET) reaction for the redox protein azurin adsorbed to an electrode modified with a gold nanoparticle film are investigated using cyclic voltammetry. The nanoparticle films are comprised of nonaqueous nanoparticles, known as monolayer-protected clusters (MPCs), which are covalently networked with dithiol linkers. The MPC film assembly serves as an alternative adsorption platform to the traditional alkanethiolate self-assembled monolayer (SAM) modified electrodes that are commonly employed to study the ET kinetics of immobilized redox proteins, a strategy known as protein monolayer electrochemistry. Voltammetric analysis of the ET kinetics for azurin adsorbed …

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Fundamental Aspects Of Small Molecules And Macromolecules On Poly(Ethylene Terephthalate) Capillary-Channeled Polymer Fibers, Christine Straut May 2009

Fundamental Aspects Of Small Molecules And Macromolecules On Poly(Ethylene Terephthalate) Capillary-Channeled Polymer Fibers, Christine Straut

All Dissertations

Stationary phases and adsorbents are continually being developed to enhance separations in high performance liquid chromatography (HPLC). Polymeric stationary phases have gained popularity due to their ability to be employed over a large pH range and because they are more chemically robust when compared to silica based phases. Capillary-channeled polymer (C-CP) fibers are an alternative to traditional porous packed bed beads. These fibers have a unique geometry with increased the surface area/volume ratios when compared to cylindrical fibers. Very unique characteristics are realized in the use of the C-CP fibers, including drastically reduced backpressures and selection of solute-surface interaction through …

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Adsorption Of Co On Supported Gold Nanoparticle Catalysts: A Comparative Study, Heather Hartshorn, Christopher J. Pursell, Bert D. Chandler Apr 2009

Adsorption Of Co On Supported Gold Nanoparticle Catalysts: A Comparative Study, Heather Hartshorn, Christopher J. Pursell, Bert D. Chandler

Chemistry Faculty Research

The adsorption of CO on three different gold nanoparticle catalysts supported on high surface area TiO2 was studied using infrared transmission spectroscopy at room temperature and CO pressures typically used in CO oxidation reactions. The three, real-world catalysts were Au catalysts synthesized in our laboratory from thiol monolayer protected clusters (MPCs) and two commercial catalysts from the World Gold Council (WGC and AuTEK). Within experimental reproducibility, the adsorption data for the three catalysts are indistinguishable. While showing approximately Langmuir behavior, the adsorption data also show coverage dependence, as others have observed for many catalyst systems. Two approaches were used …

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The Role Of The Entropy Factor On The Adsorption Of An Optical Brightener On Pulp, Greta Radeva, Eva Valcheva, Stefka Veleva Jan 2009

The Role Of The Entropy Factor On The Adsorption Of An Optical Brightener On Pulp, Greta Radeva, Eva Valcheva, Stefka Veleva

Turkish Journal of Chemistry

The present paper reports results of the thermodynamic study of adsorption of 2 optical brighteners (Tinopal UP and Leucophor AP) on pulp. The entropy non-homogeneity of the pulp surface was confirmed and the coefficients of entropy non-homogeneity were determined. The entropy effect on the variation of Gibbs free energy of the process studied was followed.

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