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Articles 2611 - 2640 of 14251

Full-Text Articles in Chemical Engineering

Covalent Organic Frameworks Based On Aldehyde And Amine Linkers As Artificial Solid Electrolyte Interphase For Zinc Anode In Aqueous Electrolyte, Vipada Aupama Jan 2023

Covalent Organic Frameworks Based On Aldehyde And Amine Linkers As Artificial Solid Electrolyte Interphase For Zinc Anode In Aqueous Electrolyte, Vipada Aupama

Chulalongkorn University Theses and Dissertations (Chula ETD)

Aqueous Zinc-based batteries (AZBBs) are an alternative battery technology being developed for commercial use due to their advantages such as low cost, safety, and eco-friendliness compared to Lithium-based batteries (LBBs). However, despite these benefits, AZBBs face challenges on the zinc anode, including the formation of zinc dendrites and side reactions, which reduce the battery's stability and lifespan. Recently, many strategies have been investigated to address these issues, such as modifying the electrolyte, separator, and anode structure, and specially modifying the zinc surface. One particularly promising strategy involves using an Artificial Solid Electrolyte Interphase (ASEI) developed from a covalent organic framework …

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The Effect Of Oxygen Vacancies On The Catalytic Performance For The Ketonization Of Methyl Palmitate Into Palmitone, Mohammad Yazdanpanah Jan 2023

The Effect Of Oxygen Vacancies On The Catalytic Performance For The Ketonization Of Methyl Palmitate Into Palmitone, Mohammad Yazdanpanah

Chulalongkorn University Theses and Dissertations (Chula ETD)

The ketonization of bio-derived fatty acid methyl esters (FAMEs) into added-value products is an increasingly attractive process. However, the role of oxygen vacancies (Ov) in thermal catalytic performance and catalyst lattice oxygen loss has received less attention. This study investigated the relationship between Ov level, acid-base density, and catalytic performance in the ketonization reaction using TiOx catalysts with varying Ov levels prepared by a modified sol-gel method. Density functional theory (DFT) simulations showed that Ov creation increased interatomic distances, leading to the formation of frustrated Lewis pairs (FLPs). The density of acidic and basic sites increased proportionally with Ov concentration. …

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การสังเคราะห์ถ่านกัมมันต์จากกากขมิ้นชันโดยใช้ไมโครเวฟ, ศิราภรณ์ ซำศิริ Jan 2023

การสังเคราะห์ถ่านกัมมันต์จากกากขมิ้นชันโดยใช้ไมโครเวฟ, ศิราภรณ์ ซำศิริ

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในงานวิจัยนี้ศึกษาเกี่ยวกับการนำความร้อนจากไมโครเวฟมาใช้สำหรับการสังเคราะห์ถ่านกัมมันต์จากกากขมิ้นชันโดยกระตุ้นด้วยสารละลายโพแทสเซียมคาร์บอเนต(K2CO3) และสารละลายกรดฟอสฟอริก(H3PO4) เพื่อกำจัดสีย้อมรีแอคทีฟ แบล็ค5 (RB5) โดยจะศึกษาผลของปัจจัยต่างๆ ได้แก่ กำลังของไมโครเวฟและเวลาในการให้ความร้อนต่อการสังเคราะห์ถ่านกัมมันต์ ถ่านกัมมันต์ที่สังเคราะห์ได้จะถูกทดสอบคุณลักษณะด้วยวิธีต่างๆ ได้แก่ การดูดซับและการคายซับไนโตรเจน กล้องจุลทรรศน์อิเล็กตรอนแบบส่องกราด ฟลูเรียร์ทรานส์ฟอร์ม อินฟราเรดสเปคโทรไมโครสโคป และ เอกซ์เรย์ดิฟแฟรกชัน ถ่านกัมมันต์ที่ถูกกระตุ้นด้วยH3PO4ที่กำลังไมโครเวฟ 800 W และใช้เวลาให้ความร้อน 30 min หรือ ถ่านกัมมันต์ H80030 จะมีการพัฒนาของโครงสร้างรูพรุนที่ดีกว่าถ่านกัมมันต์ตัวอื่นๆ โดยจะมีพื้นที่ผิวจำเพาะ, ปริมาตรรูพรุนขนาดเล็กและปริมาตรรูพรุนขนาดกลางที่มีค่าสูงที่สุดเท่ากับ 1339.083 m2/g, 0.725 cm3/g และ 0.524 cm3/g ตามลำดับ ส่งผลให้มีประสิทธิภาพในการดูดซับสูงสุดเท่ากับ 9.830 mg/g และมีร้อยละในการกำจัดมากกว่า90% ในช่วงความเข้มข้นของสารละลายรีแอคทีฟ แบล็ค5 เท่ากับ 10-40 ppm ที่ปริมาณคาร์บอน 100 mg เมื่อทำการศึกษาสมดุลของการดูดซับพบว่าถ่านกัมมันต์ H80030 สอดคล้องกับแบบจำลองไอโซเทอมของ Freundlich และแบบจำลองทางจลน์ศาสตร์แบบ Pseudo-second order (PSO) นอกจากนี้การศึกษาทางเทอร์โมไดนามิกส์ของการดูดซับพบว่าเป็นกระบวนการคายความร้อนและมีกลไกการดูดซับแบบกายภาพ

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Development Of Ni/Cao-Al2o3 Pellet Catalyst For Hydrogen Production From Treated Biogas Via Sorption-Enhanced Steam Reforming Reaction, Paveenuch Nantapong Jan 2023

Development Of Ni/Cao-Al2o3 Pellet Catalyst For Hydrogen Production From Treated Biogas Via Sorption-Enhanced Steam Reforming Reaction, Paveenuch Nantapong

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this research, multifunctional Ni/CaO-Al2O3-based catalyst was developed for hydrogen production via sorption-enhanced steam reforming (SE-SR) of treated biogas. Parametric effects including reforming temperature (400-900oC), CO2 concentration in the treated biogas (0% - 80% v/v), steam to carbon molar ratio (S/C = 1-4), and type of promoter (Ce and Mg) were studied. The influence of parametric effects was firstly determined using Aspen plus V11 software to find suitable operating condition for experiments. The results showed that at atmospheric pressure, reforming temperature of 650 °C, steam to carbon ratio 3-4, is optimum for the production of H2 via the SE-SR from …

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Structural Evolution Of The Phu Kradung Formation By Calcite Veins Characterization, South Of Lam Sonthi District, Lopburi Province., Ausa Nonthason Jan 2023

Structural Evolution Of The Phu Kradung Formation By Calcite Veins Characterization, South Of Lam Sonthi District, Lopburi Province., Ausa Nonthason

Chulalongkorn University Theses and Dissertations (Chula ETD)

Calcite veins in Mesozoic sedimentary rock localities are found in the southern part of Lam Sonthi district, Lopburi province, in central Thailand, near the Loei-Petchabun fold belt regions. The vein’s host rocks are siliciclastic rocks, primarily mudstone and sandstone. The main aim of this study is to learn more about calcite vein geometry and development, as well as the structural evolution of calcite veins in the Phu Kradung formation in the Lam Sonthi area of Lopburi province. A petrographic and structural analysis of the veins was performed to examine the kinematics and geological structures of the calcite vein in the …

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Geophysical Characteristics Of Kuan Kreng Peat Swamp Forest At Thale Noi Area, Theethach Phiranram Jan 2023

Geophysical Characteristics Of Kuan Kreng Peat Swamp Forest At Thale Noi Area, Theethach Phiranram

Chulalongkorn University Theses and Dissertations (Chula ETD)

Peatlands, as an important carbon sink, store a large amount of atmospheric carbon. However, peatlands are vulnerable to environmental alteration due to anthropogenic and natural processes. While peatlands are degraded, carbon dioxide emissions arise. The Kuan Kreng peat swamp forest is the second largest peatland in Thailand and is in coastal wetland serving for carbon stock in the subsurface. To assess carbon stock in peatland, the thickness and distribution of the peat layer are necessary. This study determines physical and chemical characteristics of the peatlands in the coastal wetland, southern Thailand by conventional core study and geophysical surveys, including ground …

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Microencapsulation Of Holy Basil Oil Using Modified Starch By Spray Drying Method, Artima Lairattanakul Jan 2023

Microencapsulation Of Holy Basil Oil Using Modified Starch By Spray Drying Method, Artima Lairattanakul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Holy basil is a local herb that can planted all over Thailand. It is the significant ingredient in Thai famous dish named “Pad ga prao” because of its unique scent which is released when cooked. Apart from the cuisine, its essential oil has been used in various industries including cosmetics, perfumery, and pharmaceuticals. However, their degradation under light, moisture, and high temperature during storage is the main problem of their utility. In this research, the encapsulation process is selected to prevent the problem. The modified starch was used as wall materials. Holy basil oil (HBO) has three main components: Eugenol, …

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Effect Of Rice Straw Loading On Morphological, Thermal, Gas Barrier, And Mechanical Properties Of Poly(Lactic Acid)/Poly(3-Hydroxybutyrate-Co-4-Hydroxybutyrate) Blend Films, Danaipat Tuangwattanasin Jan 2023

Effect Of Rice Straw Loading On Morphological, Thermal, Gas Barrier, And Mechanical Properties Of Poly(Lactic Acid)/Poly(3-Hydroxybutyrate-Co-4-Hydroxybutyrate) Blend Films, Danaipat Tuangwattanasin

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research focuses on enhancing the properties of polylactic acid (PLA), a biodegradable polymer known for its potential in mitigating waste accumulation issues. The inherent brittleness of PLA poses a significant challenge. To overcome this limitation, the study explores the incorporation of the biodegradable polymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) into PLA. The PLA/P3HB4HB blend films were prepared by varying compositions from 100/0 to 60/40 wt/wt and using compression molding. The investigations indicated that the PLA/P3HB4HB 90/10 blend film exhibits superior properties, such as synergistic toughness and increased %strain. Rice straw (RS) fiber is introduced as a reinforcing fiber in the blends, expanding …

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Tarnish Resistance Of Silver Reinforced With Carbon Material To Artificial Sweat And Hydrogen Sulfide, Kunthida Chanthaban Jan 2023

Tarnish Resistance Of Silver Reinforced With Carbon Material To Artificial Sweat And Hydrogen Sulfide, Kunthida Chanthaban

Chulalongkorn University Theses and Dissertations (Chula ETD)

Due to its immense popularity, silver jewelry has undergone continual development, it an intriguing product. The most significant issue with silver jewelry is the tarnish of the silver metal's surface. Therefore, using a coin making technique, the study team evaluated the properties of silver metal reinforced by carbon materials. To evaluate the silver's to sweat and hydrogen sulfide tarnishing. Effects of adding carbon to samples after performing an artificial sweat test. It was discovered that the use of highly scattered carbon improved the ability to remove tarnish from fake sweat because it reduced the surface area of the silver (Ag) …

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Effect Of Dispersion Of Carbon Nanotubes On Electrical Conductivity And Compressive Strength Of Cnt/Cement Composite, Rittikiat Wandaw Jan 2023

Effect Of Dispersion Of Carbon Nanotubes On Electrical Conductivity And Compressive Strength Of Cnt/Cement Composite, Rittikiat Wandaw

Chulalongkorn University Theses and Dissertations (Chula ETD)

Carbon nanotubes (CNTs) are promising nanomaterials due to their exceptional properties, including high electrical, mechanical, and stability characteristics. These advantageous features position CNTs as suitable candidates for diverse applications, particularly in additive formulations designed to enhance overall performance. One notable application is their use in cement composites to improve mechanical and electrical properties. However, the hydrophobic property of CNTs presents challenges for dispersion within the hydrophilic cement matrix. Consequently, methods have been developed to aid CNT dispersion in both water and cement matrices. In this thesis, Triton X-100 employed as a surfactant, was used to disperse CNTs in water using …

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Activity And Stability Of Tio2-Encapsulated Cspbbr3/Cs4pbbr6 For Photocatalytic Degradation Of Rhodamine B, Nutzeya Plainoen Jan 2023

Activity And Stability Of Tio2-Encapsulated Cspbbr3/Cs4pbbr6 For Photocatalytic Degradation Of Rhodamine B, Nutzeya Plainoen

Chulalongkorn University Theses and Dissertations (Chula ETD)

Due to the excellent optoelectronic performance of cesium lead bromide(CsPbBr3), it has shown promising potential as a photocatalyst for the degradation of organic compounds under sunlight. During the synthesis of CsPbBr3, Cs4PbBr6, another formation of CsPbBr3, is also produced, which exhibits desirable properties such as strong and narrow photoluminescence (PL) and enhanced thermal stability. In this study, we successfully synthesized a mixture of CsPbBr3/Cs4PbBr6 nanoparticles using a simple precipitation method. However, the stability of CsPbBr3/Cs4PbBr6 was found to be sensitive to high temperatures, moisture, and oxygen, which could affect its photocatalytic degradation performance. To enhance both stability and activity, we …

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Effect Of Type And Concentration Of Acid On Characteristics Of Functionalized Biochar And Its Performance In Converting Fructose To 5-Hmf, Pimlapas Bunwichian Jan 2023

Effect Of Type And Concentration Of Acid On Characteristics Of Functionalized Biochar And Its Performance In Converting Fructose To 5-Hmf, Pimlapas Bunwichian

Chulalongkorn University Theses and Dissertations (Chula ETD)

Biomass, with its high cellulosic content, represented renewable source capable of being converted into essential platform chemicals like 5-hydroxymethylfurfural, levulinic acid, formic acid, and furfural. Currently, conversion of fructose to 5-HMF was achievable through various acid homogeneous catalysts. Although these catalysts yield higher outputs, they might pose challenges in recycling and corrosion issues. This thesis's novel approach involved preparing heterogeneous catalysts through pyrolysis and hydrothermal treatment of watermelon rind to create watermelon rind biochar (WB). Subsequently, WB underwent functionalization using HCl, H2SO4, and H3PO4 at concentrations of 1.6, 3.2, and 4.8N, respectively, at temperatures of 150 °C. These treated WB …

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A Comparative Study Of Sustainable Aviation Fuel Production From Hydroprocessing Process Between Hydrogen Recovery Unit From Steam Reforming And Hydrogen Generation Unit From Biomass Gasification, Praeva Pongsripipat Jan 2023

A Comparative Study Of Sustainable Aviation Fuel Production From Hydroprocessing Process Between Hydrogen Recovery Unit From Steam Reforming And Hydrogen Generation Unit From Biomass Gasification, Praeva Pongsripipat

Chulalongkorn University Theses and Dissertations (Chula ETD)

Sustainable aviation fuel (SAF) can be generated using various processes. Among the well-established approaches, one that stands out is the hydrotreating of esters and fatty acids (HEFA). However, the HEFA process requires a source of hydrogen for the hydroprocessing reactions. Hydrogen is often considered as an expensive component, and its cost can have a significant impact on the overall economic viability of renewable aviation fuel production. In this work, the SAF process is developed using Aspen Plus simulation. There are 2 scenarios to be considered. Scenario 1 involves a plant in which the hydrotreating of palm oil is performed to …

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Carboxymethyl Cellulose As Artificial Solid/Electrolyte Interphases And Separator For Zn-Based Battery, Phonnapha Tangthuam Jan 2023

Carboxymethyl Cellulose As Artificial Solid/Electrolyte Interphases And Separator For Zn-Based Battery, Phonnapha Tangthuam

Chulalongkorn University Theses and Dissertations (Chula ETD)

As the quest for robust large-scale energy storage systems (EESs) intensifies, aqueous rechargeable zinc-based batteries are gaining traction for grid-scale applications due to their high theoretical capacity and safety. Despite this, their practical application is compromised by several zinc anode issues, including hydrogen evolution, corrosion, dendritic growth, and passivation. An artificial solid electrolyte interphase (ASEI) using polyelectrolytes, such as carboxymethyl cellulose (CMC), is emerging as a solution, offering economic and environmental advantages. CMC's structure, enriched with carboxyl groups, allows for the refined management of zinc ion distribution at the electrode surface, promising enhanced surface stability. This study delves into CMC's …

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Synthesis Of N-Doped Tio2 Nanoparticles With Enhanced Photocatalytic Activity For 2,4-Dichlorophenol Degradation And H2 Production, Javed Ali Khan, Murtaza Sayed, Noor S. Shah, Sanaullah Khan, Ashfaq Ahmad Khan, Muhammad Sultan, Ammar M. Tighezza, Jibran Iqbal, Grzegorz Boczkaj Jan 2023

Synthesis Of N-Doped Tio2 Nanoparticles With Enhanced Photocatalytic Activity For 2,4-Dichlorophenol Degradation And H2 Production, Javed Ali Khan, Murtaza Sayed, Noor S. Shah, Sanaullah Khan, Ashfaq Ahmad Khan, Muhammad Sultan, Ammar M. Tighezza, Jibran Iqbal, Grzegorz Boczkaj

All Works

Nitrogen-doped titanium dioxide (N-TiO2) nanoparticles were prepared using a modified sol-gel method. The as-prepared nanoparticles were characterized by state-of-the-art techniques for their optical, structural and morphological properties. The crystallite size, surface area and bandgap energy of reference TiO2 and N-TiO2 nanoparticles were found to be 16.1 and 10.9nm, 83.6 and 131.8 m2 g−1 and 3.23 and 2.89eV, respectively. The photocatalytic activities, in terms of 2,4-dichlorophenol (2,4-DCP) degradation, of reference TiO2 and N-TiO2 were found to be 46.9 and 65.4% at 120min of treatments under UV light irradiation and 21.5 and 77.6% at 240min of treatment under visible light irradiation, employing …

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Techno-Economic Analysis And Intensification Of Biosurfactant Production From Palm Fatty Acid For Oil Recovery Enhancement, Chanapol Charoentanaworakun Jan 2023

Techno-Economic Analysis And Intensification Of Biosurfactant Production From Palm Fatty Acid For Oil Recovery Enhancement, Chanapol Charoentanaworakun

Chulalongkorn University Theses and Dissertations (Chula ETD)

Currently, Biosurfactants are receiving the interest as a substitute for surfactants synthesized from petroleum products due to their biodegradability. Palm oil derivatives are one of the interesting candidates of biosurfactant production because of the superior properties of hydrocarbon structure in the range of C16-C18. Thus, this research studied the economic and environmental impact analysis of production processes, and adsorption and oil recovery performance for different anionic biosurfactants synthesized from palm oil derivatives, i.e. palm fatty acid distillate (PFAD). Moreover, the optimal design and essential operating condition of batch reactive distillation column were also studied to intensify the equilibrium limitation of …

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Green Synthesis For Silver Nanoparticle /Natural Rubber/ Nanocellulose Bio-Polymeric Composites, Puttakhun Meemai Jan 2023

Green Synthesis For Silver Nanoparticle /Natural Rubber/ Nanocellulose Bio-Polymeric Composites, Puttakhun Meemai

Chulalongkorn University Theses and Dissertations (Chula ETD)

A green synthesis method was developed to produce biobased semiconducting composites of silver nanoparticles (AgNPs), skim natural rubber (SNR), and bacteria cellulose. A solution of silver nitrate (AgNO3) ranging from 40 to 160 mM was added to skim natural rubber latex (SNRL) to facilitate the reduction of silver ions to AgNPs at temperatures between 50 and 80 °C. Subsequently, BC pellicle was immersed in the prepared AgNPs-SNRL suspension for 48 hours, followed by washing and drying. The resulting AgNPs/SNR/BC films were then analyzed for their chemical, mechanical, antibacterial, and electrical properties. The strain at break of the films was significantly …

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Sustainable Toughening Of Polylactic Acid With Ultra-Fine Fully Vulcanized Powdered Natural Rubber, Reza Gholami Jan 2023

Sustainable Toughening Of Polylactic Acid With Ultra-Fine Fully Vulcanized Powdered Natural Rubber, Reza Gholami

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study investigated the sustainable toughening of polylactic acid (PLA) by incorporating ultra-fine fully vulcanized powdered natural rubber graft-copolymerized with poly-styrene-co-acrylonitrile (UFPNR-SAN). We investigated the effect of the styrene-to-acrylonitrile ratio (ST:AN) used during the grafting process on the final UFPNR-SAN compatibility with PLA. The ST:AN ratio was systematically varied during the grafting reaction to prepare UFPNR-SAN with a range of different surface energies. The ST:AN ratio of 4:1 resulted in higher compatibility of UFPNR-SAN with the PLA matrix among other ratios. This could be explained by the desirable interfacial interactions and better dispersion shown by the contact angle measurements and …

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Shape Memory Polymer Based On Copolybenzoxazines: Effects Of Chain Length Of Aliphatic Monoamines On Shape Memory Performance, Attachai Sriwattana Jan 2023

Shape Memory Polymer Based On Copolybenzoxazines: Effects Of Chain Length Of Aliphatic Monoamines On Shape Memory Performance, Attachai Sriwattana

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research was successful in completely synthesizing benzoxazine copolymers for shape memory polymers (SMPs) by mixing bisphenol A-aniline (BA-a) and bisphenol A-aliphatic monoamines of various chain lengths (BA-aMAs). Our studies have shown that shorter chain lengths will provide higher crosslinking densities, which play an important role in promoting the stiffness of the polymer, resulting in a higher shape-fixity ratio (Rf). While longer chains result in a lower crosslinking density and a larger free volume, thus promoting a higher shape-recovery ratio (Rr), Therefore, selecting the appropriate aliphatic monoamine chain length is crucial. From the study of this work, it was found …

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Methyl Isobutyrate Production Via Hydrogenation Of Methyl Methacrylate Derived From Pyrolysis Of Acrylic Plastic Waste, Ramzi Nasser Ahmed Saif Jan 2023

Methyl Isobutyrate Production Via Hydrogenation Of Methyl Methacrylate Derived From Pyrolysis Of Acrylic Plastic Waste, Ramzi Nasser Ahmed Saif

Chulalongkorn University Theses and Dissertations (Chula ETD)

According to zero waste and upcycling policy, this work aims to utilize waste polymethyl methacrylate (PMMA) to methyl isobutyrate (MIB) via hydrogenation over nickel (Ni) based catalysts supported on commercial zeolites: HY, H-Beta-27 (SiO2/Al2O3 = 27 by mole), H-Beta-40 (SiO2/Al2O3 = 40 by mole) and H-ZSM-5. The appropriate catalyst support was first screen by using MMA monomer as the substrate for hydrogenation. Under 30 bar initial H2 pressure (PH2) at 250 °C for 3 h, Ni/H-Beta-27 catalyst effectively promoted hydrogenation to achieve 85% MMA conversion with 56.2 wt% MIB yield because of its larger external surface area and pore size. …

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Investigation Of Mechanical Regulation On Stat3 Activity And Mmp Production, Jaxson R. Libby Jan 2023

Investigation Of Mechanical Regulation On Stat3 Activity And Mmp Production, Jaxson R. Libby

Honors Theses and Capstones

Transcription factor, STAT3, is inappropriately expressed in cancer cells, and has contrasting activation in 2D versus 3D microenvironments. 2D plates are often used for drug screening and do not always recapitulate in vivo responses. To combat inaccurate 2D drug studies, a 3D hydrogel was created to support the growth of cancer cells into a tumor-like environment. The hydrogel consists of a biocompatible dextran homopolysaccharide, cell adhesion RGD sequences, and crosslinker MMP labile peptides. A pH dependent reaction couples the RGD sequences to dextran then the polymers are crosslinked into a gel. Crosslinking is accomplished using terminal cysteine peptide sequences, allowing …

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Faceted Nanomaterial Synthesis, Characterizations And Applications In Reactive Electrochemical Membrane Filtration, Qingquan Ma Dec 2022

Faceted Nanomaterial Synthesis, Characterizations And Applications In Reactive Electrochemical Membrane Filtration, Qingquan Ma

Dissertations

Facet engineering of nanomaterials, especially metals and metal oxides has become an important strategy for tuning catalytic properties and functions from heterogeneous catalysis to electrochemical catalysis, photocatalysis, biomedicine, fuel cells, and gas sensors. The catalytic properties are highly related to the surface electronic structures, surface electron transport characteristics, and active center structures of catalysts, which can be tailored by surface facet control. The aim of this doctoral dissertation research is to study the facet-dependent properties of metal or metal oxide nanoparticles using multiple advanced characterization techniques. Specifically, the novel atomic force microscope-scanning electrochemical microscope (AFM-SECM) and density functional theory (DFT) …

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Hydrodynamic Investigation Of The Discharge Of Complex Fluids From Dispensing Bottles Using Experimental And Computational Approaches, Baran Teoman Dec 2022

Hydrodynamic Investigation Of The Discharge Of Complex Fluids From Dispensing Bottles Using Experimental And Computational Approaches, Baran Teoman

Dissertations

The discharge of non-Newtonian, complex fluids through orifices of industrial tanks, pipes, dispensers, or packaging containers is a ubiquitous but often problematic process because of the complex rheology of such fluids and the geometry of the containers. This, in turn, reduces the discharge rate and results in residual fluid left in the container, often referred to as heel. Heel formation is undesired in general, since it causes loss of valuable material, container fouling, and cross-contamination between batches. Heel may be of significant concern not only in industrial vessels but also in consumer packaging. Despite its relevance, the research in this …

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Microhydrodynamic, Kinetic And Thermal Modeling Of Wet Media Milling For Process Optimization And Intensification, Gulenay Guner Dec 2022

Microhydrodynamic, Kinetic And Thermal Modeling Of Wet Media Milling For Process Optimization And Intensification, Gulenay Guner

Dissertations

Nanoparticle production by wet stirred media milling (WSMM) is a common method for the formulation of poorly water-soluble drugs. While most of the studies in the WSMM literature focus on the formulation aspects to overcome the stability challenges, a thorough mechanistic understanding of the process is lacking, and the process is slow, costly, and energy-intensive. This dissertation presents experimental and modeling work with the ultimate goals of (i) gaining a deeper and more mechanistic understanding of the WSMM process and breakage kinetics of the particles using a microhydrodynamic model with various improvements and advancements, (ii) examining the heat dissipation during …

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Lead Acid Battery Recycling In The Current Tanzania Industrialization Drive: Challenges And Opportunities, Divina D. Kaombe Dec 2022

Lead Acid Battery Recycling In The Current Tanzania Industrialization Drive: Challenges And Opportunities, Divina D. Kaombe

Tanzania Journal of Engineering and Technology (TJET)

ABSTRACT Advancements in automotive technologies, Information and Communications Technology and renewable energy technologies have increased the use of lead acid batteries as a source of portable and rechargeable energy. This has considerably increased the number of spent batteries with adverse effects on the environment and human health; which calls for recycling of spent batteries. This work was conducted to investigate challenges facing the formal business of recycling spent batteries and potential manufacturers of new lead-acid batteries in Tanzania. The work involved collection of information from key stakeholders such as collectors, dealers, Tanzania Revenue Authority and recyclers. It was found out …

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A Novel Biomaterial Platform For Cardiac Tissue Engineering, Andrew House Dec 2022

A Novel Biomaterial Platform For Cardiac Tissue Engineering, Andrew House

Dissertations

Heart disease is one of the leading causes of death in the world. With a growing demand for in vitro cardiac models that can recapitulate the complex physiology of the cardiac tissue, there is a desire to create novel therapies and treatments. However, due to a lack of fundamental understanding of the heart's inflammatory response to myocardial infarction, the development of new therapies is both time consuming and costly. In this work, a novel approach to fabricating a dynamic hydrogel cardiac platform is reported. This platform better mimics the dynamic changes occurring in the native cardiac tissue microenvironment during cardiac …

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A Chemical Study Of Archaeometallurgical Ceramics From Southwestern Tanzania, Edwinus Lyaya Dec 2022

A Chemical Study Of Archaeometallurgical Ceramics From Southwestern Tanzania, Edwinus Lyaya

Tanzania Journal of Engineering and Technology (TJET)

Archaeometallurgical ceramics, including furnaces, tuyères, and potteries, were required for successful pre-industrial iron smelting and refining. However, there are limited chemical studies on archaeometallurgical ceramics in Tanzania. This paper examined the nature of clay source in terms of refractoriness, determined whether there were multiple clay sources, and verified the refractoriness of the archaeometallurgical ceramics. An x-ray fluorescence (XRF) analytical technique and experimental re-firing of the archaeometallurgical ceramics were employed. The chemical data clustered in the mullite region on the Al2O3-SiO2-FeO ternary system indicate that iron smelters and refiners chose refractory clay sources for making archaeometallurgical ceramics. Small range and standard …

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Properties Of (Cd, Zn)S Films Deposited By Dc Co-Sputtering, Lwitiko P. Mwakyusa Dec 2022

Properties Of (Cd, Zn)S Films Deposited By Dc Co-Sputtering, Lwitiko P. Mwakyusa

Tanzania Journal of Engineering and Technology (TJET)

CdS thin film is commonly used as a buffer layer in most thin film solar cells. However, the buffer layer with less absorption in the visible region of the solar spectrum as well as that which provides perfect lattice matching with the absorbers is required. The incorporation of Zn in the CdS films can affect the structural and optical properties of the buffer layer. In this work, films of CdS and (Cd,Zn)S films were deposited by DC sputtering utilizing CdS and Zn targets. The concentration of Zn in the CdS was varied by changing the sputtering power of the Zn …

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Design And Implementation Of Cardiopulmonary Resuscitation Simulation Model, Mbazingwa Mkiramweni Dec 2022

Design And Implementation Of Cardiopulmonary Resuscitation Simulation Model, Mbazingwa Mkiramweni

Tanzania Journal of Engineering and Technology (TJET)

Cardiopulmonary resuscitation (CPR) is a life-saving procedure that can multiply a person's chances of survival after a cardiac arrest. The effectiveness of CPR procedures is heavily influenced by the individual skills of the rescuer providing assistance. Chest compressions delivered at an appropriate depth and rate, allowing full chest recoil and with minimal interruptions, are critical for improving cardiac arrest survival. The lack of quality CPR training models in developing countries has a significant impact on the quality of CPR training and skills acquired. Therefore, in this paper, we aim at improving CPR training by designing a high-fidelity CPR training manikin. …

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Synthesis, Characterisation And Catalytic Evaluation Of Castor Oil-Templated Mesoporous Sulfated Solid Acid Catalysts For Esterification Reaction, Steven Nyandoro Pr Dec 2022

Synthesis, Characterisation And Catalytic Evaluation Of Castor Oil-Templated Mesoporous Sulfated Solid Acid Catalysts For Esterification Reaction, Steven Nyandoro Pr

Tanzania Journal of Engineering and Technology (TJET)

In bio-refinery and other catalytic reactions, heterogeneous catalysts confer advantage over homogenous catalysts due to minimized recovery and separation costs. However, templating surfactant and solid support for the synthesis of heterogeneous catalysts ought to consider their cheap sources and environmentally friendliness for their sustainable use. Thus, with the vision to make the process significantly benign, in the present work, solid acids were synthesised from renewable sources (castor oil as surfactant and rice husk as the source of silica). The synthesised castor oil-templated mesoporous sulfonic acid modified catalysts (SO3H-MTS and SO3H-MT-RHS) were characterised and evaluated for catalytic esterification of acetic acid …

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