Chemistry Commons^™

Preparation Of Activated Clay From Ratchaburi Bentonite For Pyrolysis Oil Decolorization, Woranan Koedsang

Chulalongkorn University Theses and Dissertations (Chula ETD)

Bentonite is a clay mineral which widely used in considerable applications, such as bleaching agent in the oil refining process, lubricant in drilling for civil works, filler and additive as well as used to absorb odors from the waste. It can be achieved that bentonite is very tremendously advantageous and employ in many industries. The aims of this research were carried out to study the preparation of activated clay from bentonite Ratchaburi for pyrolysis oil decolorization. The bentonite was processed by activation with sulfuric acid (H2SO4), hydrochloric acid (HCl). sodium hydroxide (NaOH) and potassium hydroxide (KOH), various the ratio of …

Development Of A Novel Highly-Sensitive Brucellosis Sensor Based On Surface Plasmon Resonance Spectroscopy, Amal Kasry, Ihab Adly, Asharf Sayour, Hossam Sayour

Nanotechnology Research Centre

Brucellosis is considered a significant health threat, it is an infectious disease caused by the bacteria Brucella, which can spread from animals to humans causing severe diseases. Through this project, we aim to develop a very highly sensitive biosensor to detect Brucella early before spreading. This sensor is based on surface plasmon resonance (SPR) technique, which is used to analyze kinetics of interaction between biomolecules. It can detect down to picomolar concentrations of some proteins.

Semiempirical Molecular Modeling Analyses For Graphene/Nickel Oxide Nanocomposite, Islam Gomaa, Medhat A. Ibrahim, Hanan Elhaes

Nanotechnology Research Centre

Graphene metal oxide composite show applications in many areas according to their excellent electronic properties. Accordingly, graphene was subjected to interaction with NiO as adsorbing and a complex state. Semiempirical quantum mechanical calculations at PM6 was used to study the total energy, the final heat of formation, ionization energy, total dipole moment as well the charge distribution of the surface of graphene metal oxide composite. Calculated data indicated that graphene symmetry is changed into the C1 point group, forming stable composites with NiO that the complex composites were more stable compared with adsorb state composites. The change in the partial …

Effect Of Cocatalyst Combination In Titanium-Based Ziegler-Natta Catalyst On Olefin Polymerization, Thanyaporn Pongchan

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research focused on effect of cocatalyst types (TEA, TnOA, and TEA+TnOA) on titanium-based Ziegler-Natta catalyst in olefin polymerization both in slurry and gas-phase systems. This study has been divided into four sections. The commercial titanium-based catalyst was selected to investigate effect of reaction temperature and oxidation state of titanium from ESR measurement on slurry ethylene and propylene polymerization in the first and the second parts, respectively. The commercial catalyst with TEA exhibited the highest activity in ethylene polymerization. However, divalent, and trivalent of titanium (Ti2+ and Ti3+) was active in ethylene polymerization to produce more polymer. Stability of Ti3+ …

Development Of Graphite-Based Conductive Patterns By Copper Electroless Plating And Electroplating Techniques, Vipada Aupama

Chulalongkorn University Theses and Dissertations (Chula ETD)

The screen-printing technique has been widely applied in electronic manufacturing field. In this work, graphite is used for fabricating conductive patterns by screen-printing technique. Moreover, enhance the performance of electrical conductivity by electroless plating and electroplating techniques. The study was separated into two parts. Firstly, optimize the mass ratio between graphite and polyvinylidene fluoride (PVDF). In prepared ink from varied mass ratio; 2.0:0.1, 2:0.2, and 2:0.3 respectively. Volume resistivity analysis of conductive patterns, it was found that the mass ratio between graphite and PVDF of 2: 0.2 provided the lowest volume resistivity of 0.0122 Ω-m. In other cases, the mass …

Study Of Interactions Between Magnesium Silicate Particle And Diamond-Like Carbon Using Atomic Force Microscopy, Vipada Dokmai

Chulalongkorn University Theses and Dissertations (Chula ETD)

Interaction between particles and different surfaces under ambient condition is studied using AFM-based force spectroscopy. This work focuses on the adhesion mechanism and factors affecting particle-surface adhesion. The particles of interest consist of magnesium silicate (talcum powder) and zinc oxide (ZnO) particles, which have very attractive properties and are widely used in several applications. The adhesion force measurements were first carried out using silicon/silicon coated with DLC probes pressed on talc particles modified with hydrochloric acid or different organosilanes. These modifications change hydrophobicity and hydrophilicity of the particles. The results show that the adhesion forces are distributed in a bimodal …

Conversion Of N-Pentane To Light Olefins Over Modified Zr/Hzsm-5-Based Catalysts, Bharanabha Makkaroon

Chulalongkorn University Theses and Dissertations (Chula ETD)

Ethylene and propylene are important raw materials for producing several types of chemicals and polymers. According to the increase of propylene demand in recent year, the P/E ratio was increased to 0.85. In order to meet the propylene demand, the development of hybrid HZSM-5 catalyst for catalytic cracking becomes more interesting owing to the cracking activity from HZSM-5 zeolite acid site and loaded metal on HZSM-5 that expected to promote the dehydrogenation activity to the catalyst which could possibly enhanced the P/E ratio. The alternative feedstock for this process is n-pentane which is the low-value product from distillation process. The …

Influence Of Mixed Anionic-Nonionic Surfactants On Methane Hydrate Formation : Suppression Of Foam Formation, Chakorn Viriyakul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Solidified natural gas (SNG) via clathrate hydrate is a new technology for natural gas storage with high energy content per unit volume, extremely safe, and ease to recover. Although SNG has several advantages, its limitation is low rate of hydrate formation. Sodium dodecyl sulfate (SDS) is well known as a kinetic promoter used to increase the hydrate formation rate. However, using SDS resulted in a large amount of foam during gas recovery. In order to alleviate this problem, mixtures of SDS with nonionic surfactants were investigated. Polyoxyethylene (n) lauryl ether (EO₃ and EO₅) and alkyl poly glycol (APG) were mixed …

Layer-By-Layer Surface Modification Of Polymer Filament For Catalytic 3d Printed Parts, Pornnutcha Thadasri

Chulalongkorn University Theses and Dissertations (Chula ETD)

Catalyst was constructed in form of microreactor by fused deposition modeling (FDM) or 3D printing method that allow micro scale customization in order to achieve high detail construction. Poly (lactic acid) (PLA) and Poly (acrylonitrile-butadiene-styrene) (ABS) filaments were used as a built-up material. The surface modification was introduced to improve filaments surface adhesion by using alkaline treatment and Polyethyleneimine with variation of time and concentration and then deposited with polyelectrolyte multilayers by layer-bylayer technique before catalyst loading. Catalyst were synthesized by reduction reaction of Silver nitrate (AgNO₃) and sodium borohydride (NaBH4) with using poly (4-styrenesulfonic acid-co-maleic acid) as a capping …

Pyrrolidine As A Promoter For Methane Hydrate Formation: Comparative Study On The Thermodynamics, Kinetics, And Morphology With Tetrahydrofuran, Siravich Junthong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Solidified natural gas (SNG) via clathrate hydrates has been proposed as an alternative approach for natural gas storage and transportation due to its numerous advantages. However, a slow hydrate formation rate and a requirement of operating conditions are the major limitations, which need to be improved to make SNG competitive in a large scale deployment. In this work, the roles of 5.56 mol% pyrrolidine were investigated for the methane hydrate formation in terms of thermodynamics and kinetics along with morphology. The results showed that pyrrolidine generally improved the thermodynamic stability of mixed methane hydrates, enhancing the formation at milder conditions …

Solid-Liquid-Polymer Mixed Matrix Membranes For Gas Separation: Silicone Rubber Membranes Filled With Nax And Ky Zeolites Adsorbed Peg, Sitthikiat Boonchoo

Chulalongkorn University Theses and Dissertations (Chula ETD)

Carbon dioxide (CO₂) is one of the major constituents of natural gas and biogas. The presence of high CO₂ content causes some serious problems including reduction of heating value and corrosion of equipment's surface. Additionally, CO₂ emission is the main issue of the greenhouse effect. In consequence of these problems, membrane technologies have drawn much attention as potential techniques for gas separation. mixed matrix membranes (MMMs) have been studied and developed to provide the synergistic effect of inorganic and organic materials on membranes. In this study, PEG/NaX:KY/SR mixed matrix membranes (PZS MMMs) were prepared by the solution casting method using …

Identification Of Crude Palm Oils By The Analyses Of Fatty Acids, Volatile Organic Compounds, And Carotenoids, Somluk Sanorkham

Chulalongkorn University Theses and Dissertations (Chula ETD)

An in-depth analysis of crude palm oil is important to differentiate crude palm oil (CPO) from different geographic provenance for administrative control purposes to prevent and solve the problem of smuggling CPO from abroad to Thailand. In this study, eleven CPO samples from five provinces in Thailand were studied for their composition. The compositions of fatty acids, volatile organic compounds (VOCs), and carotenoids were characterized by GC-FID, GC-MS, and HPLC-DAD techniques, respectively. The chromatograms of fatty acids distribution were similar for all samples. The main components of fatty acids are palmitic acid, oleic acid, linoleic acid, and stearic acid. In …

Silver Surface Enrichment On Zsm-5 Zeolites For The Catalytic Cracking Of N-Pentane To Produce Light Olefins, Warisara Angguravanich

Chulalongkorn University Theses and Dissertations (Chula ETD)

The effects of Ag-incorporation on the catalytic performance of ZSM-5 zeolites have been investigated. Since Ag-incorporation can promote the formation of light olefins and significantly enhance catalytic performance in n-pentane catalytic cracking. However, the Ag-incorporated ZSM-5 zeolite was rapidly deactivated in npentane catalytic cracking. Thus, CLD and sulfation methods were introduced to improve catalytic activity and stability of Ag-incorporated ZSM-5 zeolites. The Agincorporated ZSM-5 zeolites have been prepared by the incipient wetness impregnation and CLD methods. Moreover, the sulfated catalyst was prepared by the sequential CLD and sulfation of commercial HZSM-5 zeolite. The catalytic activity and stability of Ag-incorporated ZSM-5 …

A Biophysical Investigation Of Stability, Ligand Binding, And Iron State Of Cyp102a1, Catherine A. Denning-Jannace

Theses and Dissertations--Chemistry

Cytochrome P450s (CYPs) are cysteine ligated Fe-heme monooxygenases that are found in all domains of life. In mammals, they have a role in xenobiotic metabolism and steroid synthesis, making them a fundamental requirement for survival. In addition, their ability to perform a variety of chemical reactions on an array of substrates makes CYPs highly sought for biotechnical applications such as wastewater remediation, production of potential drug candidates, and creation of drug metabolites. By mutating specific amino acids, these enzymes can be engineered to change their substrate binding profiles and achieve stereo- and regio-specific chemistry. While these mutations are essential to …

Derivatization Of Stable, Soluble Redox-Active Organic Materials For Non-Aqueous Redox Flow Batteries, Thilini Malsha Suduwella

Theses and Dissertations--Chemistry

In screening active materials for redox flow batteries (RFBs) – in which solubility is important to raise the volumetric energy density – scientists are slave to trial and error, modifying organic molecules in an attempt to optimize (increase) solubility without compromising other important properties such as stability and redox potential. A trained chemist can often predict the trends of solubility with the structural modifications in the neutral state of the materials, but when it’s come to the charged state of the materials, it doesn’t follow the same trend as the neutral species and relative values are hard to predict. The …

Laser Ablation In Liquid For The Controlled Production Of Photoluminescent Graphene Quantum Dots And Upconverting Nanoparticles, Rosemary Lynn Calabro

Theses and Dissertations--Chemistry

Photoluminescent­ (PL) nanomaterials play an important role in areas including displays, sensing, solar, photocatalysis, and bio applications. Traditional methods to prepare PL materials suffer many drawbacks such as harsh chemical precursors, complicated synthetic steps, and production of many byproducts. Laser ablation in liquid (LAL) has emerged as a promising alternative to prepare materials that is single-step, fast, uses fewer precursors, produces fewer side products, and has simple purification steps. During LAL, a solid target is irradiated with a pulsed laser source. The laser pulses cause plasma plumes of the target material to form which are cooled, condensed, and can react …

Uncovering Structure-Property Relationships Of Inorganic Nanomaterials Via Transmission Electron Microscopy, Melonie Thomas

Theses and Dissertations--Chemistry

The rapid increase of research in nanoscale devices and nanotechnology in the past few decades has revealed that nanomaterials may possess exceptional properties that are significantly different from the bulk counterpart, due to local rearrangements of the atoms at surfaces and defects. Transmission electron microscopy (TEM) is an indispensable tool when it comes to the characterization of nanomaterials, primarily due to its ability to resolve the local-structure of materials at the atomic-scale. To study dynamic processes, however, regular TEM experiments are inadequate, as they provide only before and after information rather than the real-time data essential to understanding a reaction …

Structure, Surface, And Interfacial Modifications Of Carbon And Supported-Metal Electrodes For Electrochemical Carbon Dioxide Conversion, Namal Wanninayake

Theses and Dissertations--Chemistry

Currently, the global emission of greenhouse CO₂ is over 36 billion tons per year. Consequently, the atmosphere's CO₂ concentrations have exceeded 400 ppm, which is the highest reported in the last three million years. The accumulation of CO₂ is the most critical origin for today's climate change; thus, closing the carbon cycle is vital to reverse the detrimental impacts of climate change. Under this goal, the electrochemical reduction of CO₂ into commodity fuels and chemicals via renewable energy is one of the most promising strategies to recycle CO₂. Despite significant progress made in electrocatalysis, …

Multi-Component Material For Solar Energy Conversion And Fundamentals Of Lead Acid Batteries, Crystal Ferels

Graduate Research Theses & Dissertations

Synthesis of complex inorganic materials is desirable because their complex composition allows more degrees of freedom and tunability, whose properties differ from their parent components. As an expansion on this concept, we synthesized a quinary compound Ce3FeWS3O6, using a molten flux method and a solvothermal method. The compound crystallizes into a hexagonal crystal system with space group P63/m. Its electric partition shows an anion with the form [(Ce3+)3W6+(S2-)3(O2-)6]3- forcing the transition metal Fe3+ state and leaving no conduction electrons, making the material a semiconductor. This compound is the right candidate as photoelectric material capable of absorbing photons from the solar …

Fundamental Study Of Supported Metal Catalysts Prepared By Metal In Lithium Solution For Energy Science, Haiping Xu

Graduate Research Theses & Dissertations

Electrochemical carbon dioxide reduction reaction (CO2RR) is a promising technique for energy conversion and storage from intermittent electricity sources (ie. wind and solar). By coupling electrochemical CO2 reduction (CO2R) to a renewable energy source atmospheric CO2 could be converted back into a fuel such as ethanol, or a commodity chemical such as ethanol or acetic acid. These products could then be consumed for energy or used to generate more valuable chemical products effectively removing CO2 from the atmosphere. To commercialize this process, it is highly desired to prepare catalysts that selectively reduce CO2 at low overpotential with long durability. Research …

Rational Design Of Memory-Based Sensors: The Case Of Molecular Calorimeters, Obianuju Augusta Nwokolo

Graduate Research Theses & Dissertations

Thermodynamic characterization is crucial for understanding molecular interactions. However, methodologies for measuring heat changes in small open systems are extremely limited. We document a new approach for designing molecular sensors that function as calorimeters: sensors based on memory. To design a memory-based sensor, we take advantage of the unique kinetic properties of nucleic acid scaffolds. Particularly, we elaborate on the differences in folding and unfolding rates in nucleic acid quadruplexes. DNA-based i-motifs unfold fast in response to small heats but do not fold back when the system is equilibrated with surroundings. We translated this behaviour into a molecular memory function …

Effects Of Hole Transporting Layers And Surface Ligands On Interface Energetics And Photovoltaic Performance Of Methylammonium Lead Iodide Perovskites, So Min Park

Theses and Dissertations--Chemical and Materials Engineering

Organic metal halide perovskites are promising materials for various optoelectronic device applications such as light emitting diodes (LED) and photovoltaic (PV) cells. Perovskite solar cells (PSCs) have shown dramatic increases in power conversion efficiency over the previous ten years, far exceeding the rate of improvement of all other PV technologies. PSCs have attracted significant attention due to their strong absorbance throughout the visible region, high charge carrier mobilities, color tunability, and ability to make ultralight weight devices. However, organic metal halide perovskites still face several challenges. For example, their environmental stability issue must be overcome to enable widespread commercialization. Meeting …

Applications Of Drones In Atmospheric Chemistry, Travis J. Schuyler

Theses and Dissertations--Chemistry

The emission of greenhouse gases (GHGs) has changed the composition of the atmosphere during the Anthropocene. A major technical and scientific challenge is quantifying the resulting fugitive trace gas fluxes under variable meteorological conditions. Accurately documenting the sources and magnitude of GHGs emission is an important undertaking for discriminating contributions of different processes to radiative forcing. Therefore, the adverse environmental and health effects of undetected gas leaks motivates new methods of detecting, characterizing, and quantifying plumes of fugitive trace gases. Currently, there is no mobile platform able to quantify trace gases at altitudes(UASs), or drones, can be deployed on-site in …

Multiscale Modeling Of Structure-Function Relationships Of Organic Semiconductors, Shi Li

Theses and Dissertations--Chemistry

While optoelectronic devices built from organic semiconductors (OSC) continue to find their way into the commercial landscape, there remain numerous challenges to overcome to supplant traditional semiconductors in many technologies. Chief among these are low performance metrics relative to devices with conventional semiconductors and device stability. In order to overcome these challenges, a wide range of new OSC and processing technologies have been developed. However, there remains limited fundamental understanding of the relationship between molecular structure, packing in the solid state, and the resulting materials properties. Here, we make use of multiscale molecular models and utilize classical all-atom molecular dynamic …

Flavodoxin, The Hydrogen Atom Of Flavoproteins: A 19f Nmr Study Of Dynamics And Conformational Changes Utilizing Flavodoxin From Rhodopseudomonas Palustris, Taylor Varner

Theses and Dissertations--Chemistry

Flavodoxin is a small, highly stable protein that contain a single FMN cofactor used to transfer single electrons at low potentials. The organism Rhodopseudomonas palustris contains a long-chain flavodoxin. Long-chain flavodoxins are characterized by a 20 amino acid loop that is proposed to allow interactions with partner proteins. We plan to utilize this protein as a model to build our repertoire with protein fluorination and fluorine NMR in flavoproteins. This tool kit will then be applied to the study of a partner protein of interest that is capable of performing electron bifurcation. We have incorporated m-fluoro tyrosine into flavodoxin and …

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle

Theses and Dissertations--Chemistry

This project was motivated by an in situ heating experiment in the transmission electron microscope (TEM) in which gold (Au) nanoparticles were observed to dissolve tin dioxide (SnO2) nanowires (NWs) under vacuum. The explanation for this observation was that the high-temperature and low-pressure environment of the TEM caused the reverse reaction of the well-known vapor-liquid-solid (VLS) method commonly used to grow NWs. In the VLS process, a metal catalyst absorbs reactant vapor until it becomes supersaturated. The precipitation of the NW occurs at the liquid-solid interface, which ceases when there is no longer reactant vapor, and the diameter of the …

Threshold Ionization Spectroscopy And Spin-Orbit Coupling Of Lanthanide Complexes, Yuchen Zhang

Theses and Dissertations--Chemistry

The C-C and C-H bonds have high bond strength and low polarization, which make many small hydrocarbons too inert to react with other molecules under ambient pressure and temperature conditions. Therefore, activation of these bonds is required to convert such small molecules into other value-added chemicals. Among various bond activation methods, metal activation is widely used and reported in the literature, because of its relatively mild reaction conditions and high selectivity.

In this work, Ce atom reactions with several small hydrocarbons are carried out in a pulsed laser vaporization supersonic molecular beam source, and Ce -hydrocarbon species are observed with …

Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm

Theses and Dissertations--Chemistry

Halide perovskites have generated tremendous interest as low-cost semiconductors for optoelectronics, such as photovoltaics, lasers, and light emitting diodes due to their extraordinary optical and transport properties. Perovskite photovoltaics in particular have demonstrated a meteoric rise in power conversion efficiencies and drawn considerable interest as a next-generation solar energy technology. The rapid development has centered around lead-based derivatives, and concerns regarding the toxicity of lead has sparked interest in low toxicity and more environmentally friendly perovskite derivatives. In this regime tin (Sn) is regarded as a prominent alternative owing to the ideal bandgap and reduced toxicity exhibited by Sn-halide perovskites. …

Towards The Rational Design Of Organic Semiconductors Through Computational Approaches, Qianxiang Ai

Theses and Dissertations--Chemistry

Though organic semiconductors have illustrated potential as industry-relevant materials for electronics applications, there are few guidelines that can take one from molecular design to functional materials. This limitation is, in part, due to incomplete understanding as to how the atomic-scale construction of the π-conjugated molecules that comprise the organic semiconductors determines the nature and strength of both the noncovalent intramolecular interactions that govern molecular conformation and noncovalent intermolecular interactions that regulate the energetic preference for solid-state packing. Hence, there remain several fundamental questions that need to be resolved in order to design organic semiconductors from a priori knowledge, including: What …

Designing Metal-Halide Perovskites With Enhanced Optical Properties And Stability Using Surface Ligands, Md Aslam Uddin

Theses and Dissertations--Chemistry

Metal-halide perovskites (MHPs), with formula ABX₃ (A = methylammonium, formamidinium, or Cs⁺; B = Sn²⁺ or Pb²⁺; and X = Cl^-, Br^-, or I^-) are versatile and attractive materials because of their tunable optical and electronic properties. These optical and electronic properties include tunable direct band gaps, high absorption coefficients, low exciton binding energies, relatively high electron and hole mobilities, narrow emission line-widths, and high photoluminescence (PL) quantum yields (Φ_PL). Much of the initial excitement around organic metal-halide perovskites focused on their application in photovoltaics (PVs) …