Chemical Engineering Commons^™

Effects Of Crosslinking Conditions On Biofouling Of Polymer Substrates With A Hydrogel Layer, Laura Davila

Williams Honors College, Honors Research Projects

The introduction of a hydrogel coating to a surface has been looked at for different benefits. Certain hydrogels offer antifouling properties that are beneficial to different applications like medical components. Previous attempts (2) (3)have been done to introduce a hydrogel surface to plastic substrates. One of them is to use grafting brushes which works properly but it is not sufficient since the layer is too thin and therefore can be damaged. The second method have a bulkier coating without crosslinking. Opposite to grafting brushes this method has too thick of a layer. Additionally, there is no crosslink therefore the coating …

Modeling Of Rotary Packed Beds For Reactive And Non-Reactive Systems, Chinyere Evangeline Ezeobinwune

Graduate Theses, Dissertations, and Problem Reports (ETD)

Rotary packed beds (RPBs) are used in a wide range of reactive and non-reactive applications. In this research, a 2-d, first-principles, dynamic model of a non-reactive RPB that is used for heat exchange between the outgoing flue gas from a power plant and the incoming air to the boiler/pulverizer of the power plant is developed. A 2-d, first-principles model of a reactive RPB is developed where a functionalized metal-organic framework (MOF) is used for CO₂ capture.

For the non-reactive system, a Ljungstrom-type air preheater (APH) is considered. Existing models for these rotating heat exchangers are typically 1-d. There are …

Cu-Based Electrocatalysts For Carbon Dioxide Conversion To Value-Added Chemicals, Qingyang Li

Graduate Theses, Dissertations, and Problem Reports (ETD)

Massive usage of fossil fuel has being causing considerable emission of CO₂, which increases the temperature of the planet and greatly threaten human living environment, such as soil degradation, lower agricultural productivity, desertification, less biodiversity, fresh-water reduction, ocean acidification, ozone sphere destruction, etc. A number of technologies are being developed to reduce the CO₂ amount, however, all existing technologies except utilizing CO₂ as a feedstock, are hardly to essentially close the anthropogenic carbon loop. Currently, considering the economy and operability, electroreduction of CO₂ seems to be the most promising strategy to convert CO₂ to …

Application Of Flowing Material Balance In Unconventional Reservoirs, Salem Alharbi

Graduate Theses, Dissertations, and Problem Reports (ETD)

The application of the horizontal drilling and hydraulic fracturing to unconventional reservoirs, such as Marcellus Shale, has resulted in a significant increase in gas production in the United States. The estimation of the original hydrocarbons in place is an essential element for evaluating the economic success of any reservoir. There are a number of techniques available for estimating the original hydrocarbon in place such as decline curve analysis, volumetric method, and the material balance equation. Flowing Material Balance (FMB) is a more advanced techniques which has become popular in recent years because it does not require static (shut-in) pressure data …

Formulation And Validation Of Nanoparticle Controlled Delivery For Chemotherapeutic Drug Products, Shani L. Levit

Theses and Dissertations

Taxol, a formulation of paclitaxel (PTX), is one of the most widely used anticancer drugs, particularly for treating recurring ovarian carcinomas following surgery. Clinically, PTX is used in combination with other drugs such as lapatinib (LAP) to increase treatment efficacy. Delivering drug combinations with nanoparticles has the potential to improve chemotherapy outcomes. In this study, we use Flash NanoPrecipitation, a rapid, scalable process to encapsulate weakly hydrophobic drugs (logP in vitro. Encapsulating either PTX or LAP into nanoparticles increases drug potency. When PTX and LAP are co-loaded in the same nanoparticle, they have a synergistic effect that is greater than …

Dendrimer-Based Therapeutic Delivery Vehicle For The Treatment Of Ocular Diseases, Remy C. Cooper

Theses and Dissertations

The treatment of ocular diseases poses a significant challenge to drug delivery design, due to the eye’s complex anatomy, with a semi-permeable blood-ocular barrier and associated immune privilege. To address some of the delivery challenges, polycationic dendrimers are explored as vehicle for the treatment of posterior chamber disease. Dendrimers are a class of polymeric nanoparticles that are highly branched, multivalent and monodisperse, whose three-dimensional globular architecture has given them the nickname of “synthetic proteins”. Dendrimers are synthesized by reacting monomers in a step-wise fashion to produce generationally and radially increasing structures, with core, interior and surface chains that are highly …

Modeling Of Zinc-Air Batteries Using Theoretical And Empirical Approach, Woranunt Lao-Atiman

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nowadays, an energy storage system (ESS) is attracting widespread research interest. Zinc-air battery (ZAB) is a promising candidate for ESS owing to its high energy density at low cost. Although ZAB has been researched in various aspects, the modeling aspect is still insufficient. Therefore, this work aims to study the modeling of ZAB using both theoretical and empirical approaches. At first, the ZAB system was analyzed using a theoretical approach. The studied system was an integrated system of zinc-air flow battery (ZAFB) and zinc electrolyzer. The zero-dimensional mathematical model was developed in MATLAB and validated against experimental data. The model …

Synthesis, Characteristic And Application Of Mesocellular Foam Carbon (Mcf-C) As Catalyst For Dehydrogenation Of Ethanol, Yoottapong Klinthongchai

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aims to investigate the synthesis of MCF-C as catalyst for dehydrogenation of ethanol. The study was classified into 3 parts. In the first part, the mesocellular foam silica (MCF-Si) was converted to mesocellular foam carbon using a surfactant residue as a carbon source, and followed by testing the dehydrogenation of ethanol to acetaldehyde. Surfactant residue in the inside of MCF-Si could be used as the carbon source for MCF-C synthesis. The obtained material could maintain the meso-structure, and exhibited higher activity for ethanol dehydrogenation in comparison to MCF-Si. For the second part, MCF-C was examined for 12 h …

การเตรียมเเละวิเคราะห์คุณลักษณะของอนุภาคลิโพโซมสำหรับกักเก็บสารอาร์บูตินด้วยเครื่องโฮโมจิไนเซอร์เเรงดันสูง, รัชพล ชูทับ

Chulalongkorn University Theses and Dissertations (Chula ETD)

การกักเก็บสารสำคัญในรูปแบบของอนุภาคลิโพโซม เป็นวิธีการที่ได้รับความนิยมเป็นอย่างมาก เนื่องจากอนุภาคลิโพโซมมีส่วนประกอบที่สามารถเข้ากับร่างกายได้ ไม่มีความเป็นพิษ และสามารถย่อยสลายได้เอง รวมไปถึงช่วยเพิ่มเสถียรภาพของสารที่นำมากักเก็บให้ดีขึ้น วิธีการเตรียมอนุภาคลิโพโซมเพื่อกักเก็บสารเป็นหนึ่งปัจจัยที่จะต้องคำนึงถึง เพราะจะส่งผลต่อการกระจายตัวและขนาดของอนุภาค รวมไปถึงอัตราการปลดปล่อยของสารและเสถียรภาพความคงตัวของอนุภาคลิโพโซมด้วย งานวิจัยนี้มีความสนใจที่จะศึกษาการเตรียมอนุภาคลิโพโซมสำหรับกักเก็บสารอาร์บูตินด้วยเครื่องโฮโมจิไนเซอร์แรงดันสูง เนื่องจากอาร์บูตินเป็นสารที่มีเสถียรภาพต่ำการกักเก็บสารในรูปแบบของอนุภาคลิโพโซมมีความเป็นไปได้ที่จะช่วยเพิ่มเสถียรภาพให้กับสารอาร์บูติน การเตรียมอนุภาคด้วยเครื่องโฮโมจิไนเซอร์แรงดันสูงเป็นวิธีที่สะดวกและรวดเร็ว สามารถเตรียมอนุภาคลิโพโซมได้ในปริมาณที่มาก อีกทั้งยังมีความต่อเนื่องของกระบวนการโดยไม่ต้องผ่านหลายขั้น โดยวัตถุประสงค์ของงานวิจัยต้องการศึกษาปัจจัยต่างๆ ได้แก่ อัตราส่วนระหว่างฟอสโฟลิพิด คลอเรสเตอรอล และสารอาร์บูติน อัตราการปลดปล่อยของสารอาร์บูตินและเสถียรภาพความคงตัวของอนุภาคลิโพโซม รวมไปถึง สภาวะของเครื่องโฮโมจิไนเซอร์แรงดันสูง ได้แก่ ความดันและจำนวนรอบ ที่ใช้ในการเตรียมอนุภาคลิโพโซมเพื่อกักเก็บสารอาร์บูติน จากการศึกษาพบว่า การเตรียมอนุภาคลิโพโซมที่กักเก็บสารอาร์บูตินด้วยเครื่องโฮโมจิไนเซอร์แรงดันสูง ทำให้ได้ลิโพโซมขนาดเล็กที่มีผนังสองชั้นเพียงชั้นเดียว ซึ่งจะมีขนาดของอนุภาคลดลงอย่างมีนัยสำคัญเมื่อเพิ่มความดันและจำนวนรอบของเครื่องโฮโมจิไนเซอร์แรงดันสูง โดยมีขนาดเฉลี่ยอยู่ระหว่าง 150 ถึง 200 นาโนเมตร ผลการทดลองความเข้มข้นของลิพิดต่อความสามารถในการกักเก็บสารอาร์บูติน พบว่า เมื่อเพิ่มความเข้มข้นโดยรวมของลิพิด ประสิทธิภาพการกักเก็บสารมีค่าเพิ่มขึ้น ซึ่งมีค่าประสิทธิภาพการกักเก็บสารเฉลี่ยสูงสุดอยู่ที่ 74.29 เปอร์เซ็นต์ นอกจากนั้น ผลการทดลองยังแสดงให้เห็นว่าการกักเก็บสารสำคัญไว้ในรูปแบบของอนุภาคลิโพโซมและมีการเติมสารคลอเรสเตอรอลลงไปจะสามารถช่วยควบคุมอัตราการปลดปล่อยของสารสำคัญได้ รวมไปถึงช่วยเพิ่มเสถียรภาพความคงตัวให้กับอนุภาคลิโพโซมได้อีกด้วย ดังนั้น สภาวะของเครื่องโฮโมจิไนเซอร์แรงดันสูงและสัดส่วนระหว่างฟอสโฟลิพิดกับคลอเรสเตอรอลที่เหมาะสมในการเตรียมอนุภาคลิโพโซมสำหรับกักเก็บสารอาร์บูติน คือ ความดัน 1000 บาร์ จำนวน 3 รอบ ที่ความเข้มข้นโดยรวมของลิพิดร้อยละ 2 โดยน้ำหนัก อัตราส่วนระหว่างฟอสโฟลิพิดกับคลอเรสเตอรอล 10:2 โดยน้ำหนัก และสภาวะอุณหภูมิในการเก็บรักษาที่ 4 องศาเซลเซียส

Enhanced Methane Hydrate Formation Using Promoters For Natural Gas Storage And Transportation Application, Katipot Inkong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Solidified natural gas (SNG) is an alternative technology for natural gas storage and transportation in the clathrate hydrate formed. It has higher volumetric energy storage with the ease to handle not to mention its safety. Effects of different hydrate promoters, including methyl ester sulfonate (MES), tetrahydrofuran (THF), hollow silica (HS), and sodium dodecyl sulfate (SDS), on the methane hydrate formation was investigated. All experiments were performed in an unstirred tank reactor at desired experimental conditions. The results indicated that all promoters significant enhanced the hydrate formation both kinetics and methane uptake compared with pure water. The increase in the MES …

Synthesis Of Mwcnts By Chemical Vapor Deposition From Methane Using Femo/Mgo Catalyst : Role Of Hydrogen And Kinetic Study, Chawalkul Chotmunkhongsin

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this study, carbon nanotubes (CNTs) were synthesized by chemical vapor deposition (CCVD) of methane over FeMo/MgO catalyst in a fixed-bed reactor. The role of hydrogen on CNTs synthesis and kinetics of CNTs formation were experimentally investigated. The study revealed that hydrogen in the catalyst reduction process plays an important role in the structural changes of FeMo/MgO catalyst. The catalyst structure fully transformed into metallic FeMo, resulting in the increased yield of 5 folds higher than the non-reduced catalyst. However, the slightly larger diameter and lower crystallinity ratio of CNTs was obtained. The hydrogen co-feeding during the synthesis can slightly …

Deposition Of Tio2-Coated Cspbbr3 Perovskite Heterostructure Thin Film, Chutikan Sairot

Chulalongkorn University Theses and Dissertations (Chula ETD)

All-inorganic lead halide perovskite quantum dots have been emerged in recent years for optoelectronic and photovoltaic devices due to their excellent optical properties. In this work, surface coating was carried out by titanium dioxide (TiO2) to coat on the surface of CsPbBr3 PQDs to improve the stability and charge separation property. The FTIR spectra confirmed the formation of TiO2 with an amorphous phase (am-TiO2). The crystallite size of CsPbBr3/am-TiO2 QDs composite was increased to be 13.30 nm from 12.65 nm of CsPbBr3. A slightly decrease of energy bandgap was found compare to CsPbBr3 QDs owing to quantum confinement effect. The …

Preparation And Characterization Of Sequential Curing With Off-Stoichiometric Amine-Diglycidyl Ether Of Bisphenol A /Novolac Epoxy Blended Systems, Pakawat Suttitham

Chulalongkorn University Theses and Dissertations (Chula ETD)

B-stage epoxy adhesives are used in many applications such as electronic devices and prepreg composites. The most common available form is in the film form, rolls, sheets, or custom preforms. In this work, B-staged epoxy adhesives were prepared by using sequential curing with off-stoichiometric amine technique. Diethylenetriamine (DETA) was used as the curing agent for the first curing step. While dicyandiamide (DICY) was used as the latent curing agent for the second curing step and 3-(3,4-dichlorophenyl)-1,1dimethylurea (DIURON) as accelerator for reducing the curing temperature of DICY. Novolac epoxy was blended in diglycidyl ether of bisphenol A (DGEBA) with various ratio …

Reaction Profiling Of Extracellular Protein Phosphorylation Through A Microfluidic Reactor Coupled With Raman Spectroscopy, Abigail Casey

Theses and Dissertations

Diseases and disorders in the human body are considered abnormalities of proper cellular function. Understanding the signal transduction mechanisms that cause these abnormalities is crucial to developing earlier detection methods, better treatment options and effective cures. While current diagnostic procedures are powerful tools in diagnosing diseases, they are ineffective in informing physicians on the real-time behavior of the signal transduction mechanisms associated with diseases and disorders. Currently, disease progression is monitored over time through routine patient visits and testing by one or more of the above techniques. By developing an approach that can monitor structural and conformational changes of proteins …

Structure, Morphology And Composition-Property Elucidation Of Ni–Mo And Ni−Mo−P Nanocrystals For Water Splitting Reactions And Group Iv Alloy And Silicate Nanocrystals For Visible To Near Ir Optoelectronics, Ebtesam Hassan Abuelenein Eladgham

Theses and Dissertations

Abstract

Structure, Morphology and Composition-Property Elucidation of Ni–Mo and Ni−Mo−P Nanocrystals for Water Splitting Reactions and Group IV Alloy and Silicate Nanocrystals for Visible to Near IR Optoelectronics

by

Ebtesam Hassan Abuelenein Eladgham

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Advisor: Indika U Arachchige

Associate Professor, Department of Chemistry

Nanomaterials have gained a great attention because of their unique physical properties with size intermediate between molecular materials and extended solids. They have a large surface to volume ratio and display size tunable physical properties that was not …

Emulsion Stability Of Heavy Oil With Surfactants And Nanoparticles, Zainab Abdulmohsein, Baojun Bai, Parthasakha Neogi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The recovered crude oil is often in form of an emulsion and the recovery is cut off when water to oil ratio exceeds a certain amount. The emulsions vary from water-in-oil to oil-in-water and the step that follows is to coalesce droplets to get two continuous liquids. Difficulties arise when the oil contains emulsifiers. There are naturally occurring surfactants, or the oil recovered is by enhanced oil recovery techniques which have additives that stabilize the droplets. We have considered below a heavy oil (viscosity 650-750 mPa.s) containing one of the three surfactants: a nonionic surfactant or a cationic surfactant or …

Electrode Improvement And Neural Network-Based Dynamic Optimization Of Vanadium Redox Flow Battery, Apisada Chutimasakul

Chulalongkorn University Theses and Dissertations (Chula ETD)

The performance improvement of a vanadium redox flow battery (VRFB) was focused on this study. The two objectives of this study were (1) to investigate the effect of the operating temperatures of the Atmospheric Pressure Plasma jets (APPJs) process on the energy efficiency of the VRFB and (2) to determine the optimal electrolyte flow rate of the VRFB by solving a dynamic optimization based on a neural network model of the VRFB. The APPJs graphite felt electrode treatment temperature providing the highest energy efficiency of the VRFB was 550°C, explained by the Energy Dispersive X-ray Spectrometry (EDX) and X-ray photoelectron …

A Comparative Simulation Of Glycerol Steam Reforming With Foam And Conventional Pellet Catalysts In Packed Bed Reactor, Chattharika Phitchayakorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aimed to study the effect of different catalyst structures to the hydrogen production process with glycerol steam reforming in packed bed reactors via the COMSOL Multiphysics program. 2D pseudo-homogeneous steady-state model of a 6-inch diameter adiabatic reactor has been developed to describe a transport phenomenon inside the packed bed reactors with two different catalyst structures of conventional 1-inch pellet catalyst and 10-30PPI foam catalyst. The simulated results show that the novel foam catalyst improved the process performance in terms of pressure drop and hydrogen yield comparing to the conventional 1-inch pellet catalyst. The reactor packed with the conventional …

Property Estimation Of Palmitoylethanolamide And Sucrose Palmitate For Process Design From Methyl Palmitate, Janetiya Wongprathed

Chulalongkorn University Theses and Dissertations (Chula ETD)

Methyl palmitate is the primary component of palm oil-based biodiesel. It is a saturated fatty acid methyl ester which has a high melting point that results in low cold flow properties of biodiesel. Besides, lack of government support may affect the revenue of biodiesel business. For that reason, the producers turn attention to using biodiesel as a raw material for the production of value-added chemicals. Initially, we selected the studied products based on the gross profit margin, production process, market demand and application. This work simulated the production of palmitoylethanolamide, sucrose palmitate and normal alkanes from methyl palmitate using Aspen …

Production Of Γ-Valerolactone (Gvl) From One-Pot Cascade Transformation Of Furfural Over Pt/Zeolite-Based Catalysts, Jukkapan Saengin

Chulalongkorn University Theses and Dissertations (Chula ETD)

γ-valerolactone (GVL) is a green renewable resource, which can be used as fuel additives, organic solvent in food industries, pharmaceutical intermediates. The direct production of GVL from furfural in a one-pot transformation is highly desirable in order to minimize the use of solvents, the number of unit operations, and the production cost. The cascade reaction was carried out in a single reactor, using a secondary alcohol as the hydrogen donor with acid catalysts (so-called Meerwein–Ponndorf–Verley reaction). In this work, the transfer hydrogenation of furfural with 2-propanal as a hydrogen donor was investigated on various zeolites including of HY with Si/Al …

Electrochemical Reduction Of Carbon Dioxide To Formate On Bi And Bisn Electrodes Prepared By Electrodeposition On Copper Foil, Jutamas Wasombut

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this study, The Bix/Cu electrocatalysts were prepared by electrodeposition of Bi on Cu foil, and the BixSny/Cu electrocatalysts were prepared by electrodeposition of Bi and Sn on Cu foil in deposition solution bath with different Bi3+ ion concentrations of 0.05, 0.1, and 0.2 M (Bi0.05/Cu, Bi0.1/Cu, Bi0.2/Cu), while the Sn2+ ion concentration was constant at 0.025 M (Bi0.05Sn0.025/Cu, Bi0.1Sn0.025/Cu, Bi0.2Sn0.025/Cu). The electrocatalysts were characterized by SEM-EDX, XRD, and XPS and tested in the electrochemical CO2 reduction reaction. The results demonstrate that the Bi concentrations in the deposition bath affect the structure of Bi into different forms, including bulky structure …

Selective Hydrogenation Of Acetophenone To 1-Phenylethanol On Pt/ Tio2 Catalysts Prepared By Pulsed Dc Magnetron Sputtering, Khunarnon Ditsataporncharoen

Chulalongkorn University Theses and Dissertations (Chula ETD)

1-Phenylethanol (PHE) is a high-value chemical with various applications in fragrance and pharmaceutical industries. It is extensively used as strawberry fragrance additives in yogurts and chewing gums and an intermediate of anti-inflammatory drugs such as Ibuprofen. In this study, selective hydrogenation of acetophenone (AP) to PHE was investigated using platinum catalysts supported on different types of titanium dioxide including PC500 (pure anatase) and P25 (anatase mixed rutile). Pt was deposited on the titanium dioxide supports by pulsed direct current magnetron sputtering (PDC-MSD) method with deposition time spent on Pt coating at 3, 6, and 9 minutes. For comparison purposes, Pt/TiO2 …

Electrochemical Reduction Of Co2 To Co On Zn Electrodes Prepared By Electrodeposition Method, Krongkwan Poonbun

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this work, the effect of substrates including Cu and Ti on the catalytic activity of Zn electrocatalysts prepared by electrodeposition method was investigated in the electrochemical reduction of CO2 (CO2ER). As analyzed by SEM-EDX and XRD results, it indicated that the different substrates did not have any influence on the morphologies of catalysts and the conductivity of substrate was the main factor on the CO2ER performance. The effect of Zn precursor concentration in the range of 0.025 M to 0.4 M was further studied on the characteristics and the activity of Zn/Cu catalysts in the CO2ER. . At low …

Comparative Study Of Gross Split And Cost Recovery Production Sharing Contracts In Indonesia, Mohammad Ubaidillah

Chulalongkorn University Theses and Dissertations (Chula ETD)

In upstream oil and gas business, Indonesian has introduced Production Sharing Contract Cost Recovery (PSC CR) in 1966 and still implementing that fiscal system until nowadays. In January 2017, The Indonesian Minister of Energy and Mineral Resources (MEMR or ESDM) introduce new PSC system called Production Sharing Contract Gross Split (PSC GS) following with three amendments until 2019. Ministries believe this new Fiscal regime can attract more investor to invest Oil & Gas business in Indonesia by delivering three main values which are certainty, efficiency, and simplicity policies. This study evaluates and compares the financial aspect of new Indonesian fiscal …

Effect Of Single Metal Loading On Cao/Al2o3 Pellet Catalyst For Biodiesel Production, Nattawadee Munbupphachart

Chulalongkorn University Theses and Dissertations (Chula ETD)

Biodiesel is a sustainable biofuel mainly derived from transesterification of vegetable oil or animal fat. Transesterification is increasingly being catalyzed by heterogeneous catalysts in recent years. As a result of a high-pressure drop, solid base catalysts in a powder form are not suitable for a continuous process. A pellet catalyst is more convenient, but it has lower surface per volume as well as lower in its catalytic activity for transesterification. This research aims at studying the effect of metal oxides loading on CaO/Al2O3 pellet catalyst for improvement of catalytic activity of transesterification. The 20 wt.% single metal loading of metal …

Preparation And Characterization Of Nanopaper From Regenerated Cellulose, Nattorn Paijit

Chulalongkorn University Theses and Dissertations (Chula ETD)

Cellulose nanopapers (RCNP) were prepared from regenerated cellulose (RC) via the solvent casting method. RC was prepared by dissolution of bleached eucalyptus cellulose pulp (BEP) with 85% H3PO4 at -20oC. Water was applied as anti-solvent in the regenerated process. Effects of storage time after dissolution on fiber solubility were investigated at 0, 20, 40, 60 min, 1, and 2 days. ATR FT-IR spectra and crystalline index proved that regenerated cellulose was obtained. The crystalline index of the fiber became stable at 60 min, indicating the fibers were completely dissolved at 60 min. The results from thermogravimetric analysis showed that after …

Sodium Doping Effects On Properties Of Czts Thin Filmsfabricated By Sol-Gel Convective Deposition Technique, Orawan Sukchoy

Chulalongkorn University Theses and Dissertations (Chula ETD)

Cu2ZnSnS4 (CZTS) is an interesting candidate for thin-film solar cell applications due to its availability and attractive properties (energy band gap of 1.5 eV and high absorption coefficient). However, CZTS solar cell performance is limited because of the defect formation from small grain size, pinholes, rough surface, and negative defects in CZTS such as CuZn. One of the most possible ways to reduce these negative defects, and to increase solar cell performance is by doping with sodium. In this work, CZTS films were synthesized by sol-gel convective deposition technique and Na was doped in CZTS film using 2 different methods: …

Methanol Synthesis Via Hydrogenation Of Mixed Co/Co2 Over Mn Modified Cu/Zno/Al2o3 Catalyst, Papawin Tunyasitikun

Chulalongkorn University Theses and Dissertations (Chula ETD)

The purposes of this study are to investigate the methanol synthesis by using mixed CO/CO2 hydrogenation on Mn modified Cu/ZnO/Al2O3 catalyst which is prepared by the co-precipitation method and to investigate the overall energy consumption of methanol synthesis based on experimental results through the simulation process using Aspen Plus V.9. The improvement of catalytic activity is performed by a continuous fixed bed microreactor at 250°C under atmospheric pressure for 5 hours on the stream through hydrogenation of different feed composition of CO2/H2, CO/H2, and CO/CO2/H2, and 24000 ml/gcat∙h of GHSV. The physical and chemical properties of the catalysts are measured …

Stability Enhancement Of Cspbbr3 Quantum Dots By Coating Tio2 As A Surface Encapsulation, Parina Nuket

Chulalongkorn University Theses and Dissertations (Chula ETD)

The cesium lead bromide quantum dots (CsPbBr3 QDs) have exhibited the excellent optical properties which have been widely used in the applications of optoelectronic and photoelectrochemical devices. However, the instability of CsPbBr3 QDs against the environment factors has been a major obstacle hindering the commercialization of corresponding devices. Herein, the new encapsulation process, in-situ method, for CsPbBr3/TiO2 was presented to prevent the agglomeration of the particles and improve the stability of CsPbBr3 QDs without heat treatment at high temperature. The CsPbBr3 QDs were coated with TiO2 by using titanium tetraisopropoxide (TTIP) as a titanium source which was injected during the …

Performance Of Carbon Nanotubes As Supports Of Nickel-Iron Catalysts For Carbon Dioxide Methanation, Phanatchakorn Mala

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nowadays, an increase in CO2 emission is one of the main reasons of global warming. Many studies have tried to solve the problem by developing catalysts to efficiently convert CO2 into CH4. Herein, bimetallic Ni-Fe catalyst was studied to improve the catalyst activity of Ni-based catalyst which has low activity and is easily deactivated. Carbon nanotubes (CNTs) have been identified as one of the most promising nanomaterials with unique electrical, thermal, and mechanical properties. In this thesis, CNTs was synthesized from eucalyptus oil as a renewable carbon source and then employed as catalyst support material in methanation. Variations of synthesis …