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2021

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Articles 661 - 670 of 670

Full-Text Articles in Chemical Engineering

High Water Vapor Permeability Ethylene-Vinyl Acetate Copolymer Composite For Fresh Holy Basil (Ocimum Sanctum L.) Packaging, Nuttinan Boonnao Jan 2021

High Water Vapor Permeability Ethylene-Vinyl Acetate Copolymer Composite For Fresh Holy Basil (Ocimum Sanctum L.) Packaging, Nuttinan Boonnao

Chulalongkorn University Theses and Dissertations (Chula ETD)

Fresh fruits and vegetables still respire, which causes large amount of water vapor inside the package. This results in the growth of fungal and bacterial pathogens and defection in the external appearance. To solve this problem, the packaging film with an appropriate value of gas permeability that matches the respiration rate of fresh fruits and vegetable products will be used. In this study, we produced EVA copolymer composite packaging films by melt blending EVA copolymer with diatomite and sorbitan monostearate additives and adjusted gas permeability which includes water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) to be in …

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The Prediction Of Pm2.5 Dispersion In Bangkok (Pathumwan District)Using Cfd Modeling, Punyisa Chaisri Jan 2021

The Prediction Of Pm2.5 Dispersion In Bangkok (Pathumwan District)Using Cfd Modeling, Punyisa Chaisri

Chulalongkorn University Theses and Dissertations (Chula ETD)

City configuration, meteorological conditions and emission source are the important factors affecting the concentration and dispersion of pollutants within urban street canyon. The dispersion of PM2.5 in Pathumwan district, Bangkok which has a characteristics of street canyon was predicted using a Computational Fluid Dynamics (CFD) model. Flow and dispersion of PM2.5 were analyzed using standard k-ε turbulence model. The concentrations of PM2.5 were investigated under different conditions to demonstrate the effect of city configuration in study area, meteorological characteristics, and lockdown due to COVID-19 on PM2.5 concentration. The numerical model was validated with the measured data from the air quality …

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Development Of Nonaqueous Zinc-Ion Battery Based On Manganese Dioxide Cathode, Wathanyu Kao-Ian Jan 2021

Development Of Nonaqueous Zinc-Ion Battery Based On Manganese Dioxide Cathode, Wathanyu Kao-Ian

Chulalongkorn University Theses and Dissertations (Chula ETD)

Zinc-ion batteries (ZIBs) are considered promising candidates for large-scale applications replacing lithium-ion batteries (LIBs). ZIBs having aqueous electrolytes have many advantages being low-cost, safe, and eco-friendly. However, a number of shortcomings hinder their application e.g. self-corrosion, hydrogen evolution, and Zn dendrite-formation. To mitigate these issues, nonaqueous electrolytes i.e. organic-based and room temperature ionic liquid electrolytes have been proposed. Nevertheless, nonaqueous electrolytes are yet to be elucidated. Herein, this work identifies nonaqueous electrolytes' state of the art and develops a new nonaqueous electrolyte system for ZIBs based on a manganese dioxide (MnO2) cathode. For this purpose, Zn chemistry in nonaqueous electrolytes …

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Depolymerization Of Kraft Lignin To Phenolic Compounds By Electrochemical Advanced Oxidation In Microreactor, Chawakorn Rittirong Jan 2021

Depolymerization Of Kraft Lignin To Phenolic Compounds By Electrochemical Advanced Oxidation In Microreactor, Chawakorn Rittirong

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research focuses on the depolymerization of kraft lignin to phenolic compounds that are valuable and useful in various industries. Depolymerization is performed using an electrochemical advanced oxidation process with the hydroxyl radicals. In this process, microreactors are used. It consists of a graphite anode and a stainless steel cathode. The results of the variables studied were current density (3.7 and 5.55 A/m2), residence time (100-400 s), base pH (9), the base difference (sodium hydroxide and potassium hydroxide). The experiment found that the major product is octadecamide and the minor product propyl guaiacol is increased when the current increases. On …

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Convective-Diffusive Transport In Krogh Cylinders: A Model For Pharmacokinetics, Xianjie Qiu Jan 2021

Convective-Diffusive Transport In Krogh Cylinders: A Model For Pharmacokinetics, Xianjie Qiu

Doctoral Dissertations

"Drug delivery to inside of the tumor is the important problem. The dynamics of drug delivery is presented here. Previously and particularly for directed delivery, a stirred tank model has been used, which appears to have worked well when compared to experiments. However, the stirred tank models do not include all the mass transfer resistances and towards that end we have used a distributed system called Krogh cylinder. This study focuses on the Krogh cylinder model simulation, both on the fluid flow and the mass transfer. The capillary network is broken down into cylindrical cells, each containing a capillary and …

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Investigation Of Packed Bed And Moving Bed Reactors With Benchmarking Using Advanced Measurement And Computational Techniques, Binbin Qi Jan 2021

Investigation Of Packed Bed And Moving Bed Reactors With Benchmarking Using Advanced Measurement And Computational Techniques, Binbin Qi

Doctoral Dissertations

"Trickle bed reactors (TBR), as typical packed bed reactors (PBR), are widely used in various fields. Very limited information regarding the flow behaviors, hydrodynamic, and mathematical models in extrudate catalyst shapes, such as cylinders, trilobes, and quadrilobes, can be found in literatures because the major focus was on spherical shape. Therefore, a hybrid pressure drops and liquid holdup phenomenological model for extrudate catalyst shapes was developed based on two-phase volume averaged equations, which showed high accuracy against experimental data. The maldistribution and dynamic liquid holdup were investigated in quadrilobe catalyst using gamma-ray computed tomography. A pseudo-3D empirical model was developed …

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Natural Rubber Films Reinforced With Cellulose And Chitosan Prepared By Latex Aqueous Microdispersion, Naipaporn Sutipanwihan Jan 2021

Natural Rubber Films Reinforced With Cellulose And Chitosan Prepared By Latex Aqueous Microdispersion, Naipaporn Sutipanwihan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Plastics are one of the derived products from petroleum material, which have been used in many applications worldwide, because of their various properties. However, plastic wastes create toxic environmental pollutions and problems because of their toxic constituents and non-biodegradability. Accordingly, nature materials have been proposed as a substitute for petroleum materials for bioplastic production. Natural rubber (NR) is a product from natural, which is well-known for its high elasticity. However, there are some drawbacks such as low tensile strength and low abrasion resistance. Moreover, its applications are also limited because of its poor resistance to oil and solvents. Therefore, the …

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Techno-Economic Analysis Of Monoglyceride And Diglyceride Production From Waste Cooking Oil, Napat Olarachin Jan 2021

Techno-Economic Analysis Of Monoglyceride And Diglyceride Production From Waste Cooking Oil, Napat Olarachin

Chulalongkorn University Theses and Dissertations (Chula ETD)

Monoglycerides (MGs) and their derivatives are widely used and considered the most important group of emulsifiers. These emulsifiers can be produced from waste cooking oils (WCOs) via two-step transesterification-glycerolysis or hydrolysis-glycerolysis processes. The transesterification-glycerolysis process has the advantages in terms of a high reaction rate and a high process yield. For hydrolysis, triglycerides are converted to free fatty acids (FFA) at higher reaction temperature, but water is used as a reactant. Therefore, the separation process is not complicated. This study simulated the techno-economic comparison of four different scenarios of MG and DG production using ASPEN Plus V11 simulation software. In …

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Effect Of Hydrogen Co-Feeding On Ethylene Polymerization With Ziegler-Natta Catalysts With Different Amounts Of Titanium, Santhakamol Kittibanpacha Jan 2021

Effect Of Hydrogen Co-Feeding On Ethylene Polymerization With Ziegler-Natta Catalysts With Different Amounts Of Titanium, Santhakamol Kittibanpacha

Chulalongkorn University Theses and Dissertations (Chula ETD)

Effect of hydrogen on the prepared TiCl4-MgCl2 catalysts having loading amounts of titanium was investigated via ethylene homopolymerization and ethylene/1-hexene copolymerization in slurry polymerization process. First, the catalysts were prepared to obtain different Ti loadings from 4.4 to 6.5 wt%. Then, all catalysts were characterized and tested in ethylene homopolymerization and ethylene/1-hexene copolymerization in the presence and absence of hydrogen during polymerization. It was found that hydrogen enhanced the catalyst activities on the catalyst with high Ti content (6.5 wt%) for 2.6 times and 1.9 times for ethylene homopolymerization and ethylene/1-hexene copolymerization, whereas it decreased the activity of the catalyst …

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Strengthening Prestressed Concrete Bridge Girders And Building Beams With Carbon Fiber Reinforced Polymer Sheets, Herish A. Hussein, Zia Razzaq Jan 2021

Strengthening Prestressed Concrete Bridge Girders And Building Beams With Carbon Fiber Reinforced Polymer Sheets, Herish A. Hussein, Zia Razzaq

Civil & Environmental Engineering Faculty Publications

The effect of Carbon Fiber Reinforced Polymer (CFRP) retrofitting and concrete type on the flexural strength of prestressed concrete I-section girders used in bridges and beams in buildings is investigated. Non-linear moment-curvature relationships are predicted using an iterative algorithm for both non-retrofitted and CFRP-retrofitted prestressed concrete girder and beam cross-sections with various concrete types. Two different CFRP-retrofitting schemes are analyzed for comparing their effectiveness. It is found that although non-retrofitted beam section exhibits greater ductility, the use of CFRP retrofitting in both tension and compression regions simultaneously results in a significant increase in flexural strength. It is also found that …

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