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Full-Text Articles in Chemistry

Characterization Of Small Molecules And Ions By Atmospheric Pressure Ionization-Mass Spectrometry, Maleesha De Silva Dec 2021

Characterization Of Small Molecules And Ions By Atmospheric Pressure Ionization-Mass Spectrometry, Maleesha De Silva

Theses and Dissertations

Mass spectrometry (MS) has become a widely used technique for the characterization of a wide range of substances in diverse fields. The selection of appropriate ionization techniques, source parameters, charge carriers based on the analyte’s polarity is essential in MS as only the ions are detected. When using a soft ionization technique, single stage-MS at best provides only chemical composition; thus, tandem MS is needed to determine structural information and dissociation pathways. This dissertation focuses on the characterization of various small molecules and ions using different ionization techniques, charge carriers, and collision-induced dissociation (CID).

In Chapter II, commercially available ionic …


Cdse Quantum Dot Surface Chemistry Thermodynamics Via Isothermal Titration Calorimetry: An Emphasis On The Fundamentals, Megan Y. Gee Oct 2019

Cdse Quantum Dot Surface Chemistry Thermodynamics Via Isothermal Titration Calorimetry: An Emphasis On The Fundamentals, Megan Y. Gee

Theses and Dissertations

For several decades, the study and development of colloidal semiconductor nanocrystals, or quantum dots (QD), has become a rich field heralding improved integration into applications ranging from photovoltaics and photocatalysis to biomedical imaging and drug delivery. CdxSey is the most extensively studied QD system, however numerous compositional details still confound the nanocrystal field. Although CdSe QDs with native ligand coatings can show high fluorescence quantum yield and may be suitable for some applications, often times these original ligand layers are comprised of long aliphatic chains that preclude incorporation into biological matrices or severely impede charge transfer – depending on the …


Removal Of Chromium(Vi) And Chromium(Iii) Ions From Aqueous Solution Using Bio-Char Generated From Agricultural Waste Products, Diego Fernando Gonzalez May 2018

Removal Of Chromium(Vi) And Chromium(Iii) Ions From Aqueous Solution Using Bio-Char Generated From Agricultural Waste Products, Diego Fernando Gonzalez

Theses and Dissertations

Heavy metals are one of the most persistent and prevalent contaminants in the aquatic environment. The removal of chromium from aqueous solution, especially in the hexavalent form is difficult. New technologies, techniques and/or new materials have been designed in order to effectively and efficiently remove chromium from the aqueous environment. The project focuses on the comparison of the effects of pH, time, temperature, binding capacity on bio-char’ generated from agricultural waste produces vs an amino modified derivative of the bio-char. Pineapple skins were dried, ground, sieved, and pyrolyzed to produce a bio-char material. The bio-char was analyzed using FTIR to …


Remediation Of Lead And Copper Ions From Water Solutions Using Transition Metal Sulfides, Jesus M. Cantu Jr. Dec 2017

Remediation Of Lead And Copper Ions From Water Solutions Using Transition Metal Sulfides, Jesus M. Cantu Jr.

Theses and Dissertations

Heavy metal contamination in water solutions has been a major concern since many transition metals don’t play a role in any biological function and are actually detrimental to human health. There have been several techniques that have been implemented for the remediation of heavy metal contaminants. For this project, three metal sulfides—Fe7S8, ZnS, TiS 2—were synthesized and studied for their capabilities to remove Pb(II) and Cu(II) from water solutions. Several parameters were investigated to determine the effects of pH, time, temperature, binding capacities, and interfering ions. The room temperature adsorption capacities ranged 6.23–333.3 mg/g for Pb(II) and 1.31–250 mg/g for …


Remediation Of Trivalent And Hexavalent Chromium Ions From Aqueous Solutions Using Titanium Dioxide Polymorphs, Yvette Cantu Dec 2017

Remediation Of Trivalent And Hexavalent Chromium Ions From Aqueous Solutions Using Titanium Dioxide Polymorphs, Yvette Cantu

Theses and Dissertations

Three titanium dioxide (TiO2) polymorphs were synthesized and used for the removal of chromium (III) and chromium (VI) from aqueous solutions. Various solution parameters were studied to determine the effects of pH, temperature, time, possible interfering ions, and capacities on the binding of Cr(III) and Cr(VI) to all three polymorphs. pH assays determined the optimum pH for the binding of both Cr(III) and Cr(VI) to each polymorph. Adsorption isotherms determined that the adsorption of Cr(III) was non-spontaneous for the three polymorphs with ΔG values ranging from 6.03 to 12.89 kJ/mol. Furthermore, the binding of Cr(VI) to anatase was also non-spontaneous …


Development And Application Of New Solid-State Models For Low-Energy Vibrations, Lattice Defects, Entropies Of Mixing, And Magnetic Properties, Jacob M. Schliesser Mar 2016

Development And Application Of New Solid-State Models For Low-Energy Vibrations, Lattice Defects, Entropies Of Mixing, And Magnetic Properties, Jacob M. Schliesser

Theses and Dissertations

Low-temperature heat capacity data contain information on the physical properties of materials, and new models continue to be developed to aid in the analysis and interpretation of heat capacity data into physically meaningful properties. This work presents the development of two such models and their application to real material systems. Equations describing low-energy vibrational modes with a gap in the density of states (DOS) have been derived and tested on several material systems with known gaps in the DOS, and the origins of such gaps in the DOS are presented. Lattice vacancies have been shown to produce a two-level system …


Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang Oct 2005

Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang

Theses and Dissertations

A small-scale adiabatic calorimeter has been constructed as part of a larger project to study nano-particles and to facilitate specific heat measurements on samples where it is difficult to obtain enough material to run on the current large-scale adiabatic apparatus. This calorimeter is designed to measure sample sizes of less than 0.8 cc over a temperature range from 13 K to 350 K. Specific heat results on copper, sapphire, and benzoic acid show the accuracy of the measurements to be better than ±0.4% for temperatures higher than 50 K. The reproducibility of these measurements is generally better than ±0.25%. Experimental …


A Potentiometric Method, A Convenient And Rapid Technique For Determination Of The Thermodynamics Of Ionization Reactions For Water, Weak Acids, And Some Slightly Soluble Salts In Aqueous Organic Mixed Solvents, Charanai Panichajakul Aug 1976

A Potentiometric Method, A Convenient And Rapid Technique For Determination Of The Thermodynamics Of Ionization Reactions For Water, Weak Acids, And Some Slightly Soluble Salts In Aqueous Organic Mixed Solvents, Charanai Panichajakul

Theses and Dissertations

A potentiometric method which is devised to be rapid and convenient for determining ionization constants for water, weak acids (or bases), and certain solids in mixed solvents is described. The method has been applied to the determination of ionization for water, acetic acid, benzoic acid, and phenol and the solubility product constant for silver chloride in mixtures of water with methanol, ethanol, acetone, tetrahydrofuran, and p-dioxane containing from 0 to 70 mass percent organic co-solvent at several temperatures between 10 and 40°C. Results are used to study the thermodynamics of ionization in each mixture which is discussed relative to various …


The Thermodynamics Of Transition Metal Chelation In Dilute Aqueous Solution.|Ni.|Pthe Thermodynamics Of Interaction Of Serinate Ion With Divalent Co, Ni, Cu, Zn, And Cd Ions In Aqueous Solution.|Nii.|Pthe Calorimetric Standardization Of Dilute Ferrous Ion Solutions For Use In Determining 2,2'-Bipyridine, Joseph Willard Richards May 1969

The Thermodynamics Of Transition Metal Chelation In Dilute Aqueous Solution.|Ni.|Pthe Thermodynamics Of Interaction Of Serinate Ion With Divalent Co, Ni, Cu, Zn, And Cd Ions In Aqueous Solution.|Nii.|Pthe Calorimetric Standardization Of Dilute Ferrous Ion Solutions For Use In Determining 2,2'-Bipyridine, Joseph Willard Richards

Theses and Dissertations

Calorimetrically determined ΔH° values are given for the stepwise formation of chelate species between serinate ion and the divalent metal ions of Co, Ni, Cu, Zn, and Cd. These values of ΔH° are compared with those reported in the literature and were combined with values of ΔG° (log K) found in the literature to calculate values of ΔS°. These values of ΔG° and ΔS° are listed also. A new method of standardizing dilute ferrous ion solutions is reported. This procedure makes use of the thermometric titration technique to detect the equivalence point for the reaction of K_2Cr_2O_7 with ferrous ion. …


The Thermodynamics (Log K, [Delta]H°, [Delta]S°, [Delta]Cp°) Of Metal Ligand Interaction In Aqueous Solution.|Ni.|P Design And Construction Of An Isothermal Titration Calorimeter.|Nii.|Pthe Interaction Of Cyanide Ion With Bivalent Nickel, Zinc, Cadmium And Mercury.|Niii.|Pthe Interaction Of Glycinate Ion With Bivalent Manganese, Iron, Cobalt, Nickel, Copper, Zinc And Cadmium, Harlin Dee Johnston Aug 1968

The Thermodynamics (Log K, [Delta]H°, [Delta]S°, [Delta]Cp°) Of Metal Ligand Interaction In Aqueous Solution.|Ni.|P Design And Construction Of An Isothermal Titration Calorimeter.|Nii.|Pthe Interaction Of Cyanide Ion With Bivalent Nickel, Zinc, Cadmium And Mercury.|Niii.|Pthe Interaction Of Glycinate Ion With Bivalent Manganese, Iron, Cobalt, Nickel, Copper, Zinc And Cadmium, Harlin Dee Johnston

Theses and Dissertations

A new isothermal titration calorimeter has been designed to facilitate the study of heats of reaction and heats of solution at constant temperature. With this calorimeter, endothermic or exothermic processes can be studied at temperatures constant to ±0.0002°C. Heat effects are compensated by balancing the heat effect of the process taking place in the calorimeter against a variable heat and a constant cooling Peltier device. The calorimeter was tested by measuring the heat of ionization of water and the heat of dilution of aqueous HClO_4 solutions. For these systems heats were measured to an accuracy of ±0.02 calorie. Log K, …


Thermodynamics Of Metal-Ligand Interactions In Solution I. The Thermodynamics Of Metal-Cyanide Interaction ; Ii. Application Of The Entropy Titration Technique To Metal-Ligand Systems ; Iii. Log K, [Delta]H And [Delta]S Values For The Interaction Of Sulfate Ion With Metal Ions ; Iv. Interaction Of Mercuric Cyanide With Thiourea In Water-Ethanol Solvent Mixtures, Delbert J. Eatough Aug 1967

Thermodynamics Of Metal-Ligand Interactions In Solution I. The Thermodynamics Of Metal-Cyanide Interaction ; Ii. Application Of The Entropy Titration Technique To Metal-Ligand Systems ; Iii. Log K, [Delta]H And [Delta]S Values For The Interaction Of Sulfate Ion With Metal Ions ; Iv. Interaction Of Mercuric Cyanide With Thiourea In Water-Ethanol Solvent Mixtures, Delbert J. Eatough

Theses and Dissertations

Log K values, valid at zero ionic strength are reported for the interaction in aqueous solution of CN- with Ni2+ and Hg2+ at 10°, 25° and 40°C, and with Pd2+ at 25°C. ∆H° and ∆S° values valid at zero ionic strength and 25°C are also reported for the interaction of CN- with Hg2+ and for the reaction Pd(CN)42- + CN- = Pd(CN)53-. In connection with the study of Pd2+ - CN- interaction, log K values for the hydrolysis of Pd2+ to give PqOH+ and Pd(OH)2 and an E° value for the reaction Pd(s) = Pd2+ + 2e- are reported. A …


Thermodynamics Of Charge Transfer Complexes, Reed J. Jensen May 1965

Thermodynamics Of Charge Transfer Complexes, Reed J. Jensen

Theses and Dissertations

Charge transfer complexes were studied spectrophotometrically in the liquid state by a modified Benesi-Hildabrand method. TiCl_4 - Benzene and TiCl_4 - diphenyl ether solutions were found to form contact charge transfer complexes, that is complexes with very weak and non-directional interactions. The systems TiCl_4 - anisole and TiCl_4 - diethyl ether form complexes of the types AD and AD_2 where A stands for TiCl_4 and D stand s for the organic donor. The formation constants for the complexes were, for the TiCl_4 - anisole, K_1 = 0.077, K_2 = 0.01; and TiCl_4 - diethyl ether, K_1= 3.0, K_2 = 1.0. …


A Thermodynamic Study Of Complex Formation In Aqueous Solution.|Ni.|Pthe Hg(Ii)-, Zn(Ii)-, Cd(Ii)-, Ag(I)-Serine Systems.|Nii.|Pthe Hg(Ii)-, Zn(Ii)-, Cd(Ii)-, In(Iii)- Thioglycollic Acid System :|Ba Study Of The Effect Of D[Pi]-D[Pi] Bonding On These Complexes, Marriner Lee Morrell Aug 1961

A Thermodynamic Study Of Complex Formation In Aqueous Solution.|Ni.|Pthe Hg(Ii)-, Zn(Ii)-, Cd(Ii)-, Ag(I)-Serine Systems.|Nii.|Pthe Hg(Ii)-, Zn(Ii)-, Cd(Ii)-, In(Iii)- Thioglycollic Acid System :|Ba Study Of The Effect Of D[Pi]-D[Pi] Bonding On These Complexes, Marriner Lee Morrell

Theses and Dissertations

Thermodynamic equilibrium constants were obtained potentiometrically using a Beckman pH meter for metal-serine and metal-thioglycolloc acid complexes to study the thermodynamic properties of the complexes and the effect of dπ - dπ bonding on the equilibrium constants. The following calculations were made: 1. The stepwise dissociation of protons from serine at 10, 20, 30, and 40°C and the stepwise dissociation of protons from thioglycollic acid at 20, 30, and 40°C. 2. The thermodynamic formation constants for Zn(II), Cd(II), Hg(II), and Ag(I) with serine at 10, 20, 30, and 40°C and at two ionic strengths. 3. The thermodynamic formation constants for …


Thermodynamic Properties Of Water Absorbed On Silica, Conrad V. Hatch Aug 1952

Thermodynamic Properties Of Water Absorbed On Silica, Conrad V. Hatch

Theses and Dissertations

The object of the work presented in this thesis was to obtain quantitative values of the thermodynamic changes in water upon adsorption by silica. Two methods were used. The first was a determination of the differential entropy and heat of adsorption independent of any theory of adsorption. The second method included a new interpretation of the "c" constant of the Brunauer, Emmett, and Teller Theory in which c was expressed in terms of the standard free energy of adsorption. The experimental data gave satisfactory results in determining the differential heat and entropy of adsorption. The results obtained in determining the …


An Electrochemical Determination Of The Thermodynamic Properties Of Silver And Mercury Sulfides, Arthur G. Cole Sep 1949

An Electrochemical Determination Of The Thermodynamic Properties Of Silver And Mercury Sulfides, Arthur G. Cole

Theses and Dissertations

The problem consists of measuring accurately the free energy of formation, heat of formation, entropy, and solubility product constant of silver and mercury sulfides, and is a part of a larger study extending to many other metal sulfides. The confusion now existing in the chemical literature amply justifies a study of this nature. The thermodynamic properties of several important metal sulfides have never been measured, and the only values available for them are estimates. Determinations of the properties of many other metal sulfides have been carried out, but the results given by different authors often differ widely.