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Study of intercalation properties of electrode materials based on expanded graphite
Vencelides, Lukáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
The diploma thesis deals with the issue of electrochemical cells and deals in detail with lithium-ion batteries. The thesis describes the history of development of lithium-ion batteries, basic information about lithium and basic types of electrochemical cells. The work is devoted in detail to the description of characteristics and operating principle of lithium-ion batteries with emphasis on the negative electrode and negative electrode materials. Of the negative electrode materials, both the most widely used material graphite and modern materials with a great potential for the future are described. In the measurement methods the work describes methods CV, GCPL and EIS. Great emphasis is placed on the explanation of the principle of the function of electrochemical impedance spectroscopy and its application in measurement of electrochemical properties of materials used in lithium-ion batteries. There is also described the procedure of calculation of diffusion coefficients using the results of electrochemical impedance spectroscopy. In the practical part, two methods are used to calculate the diffusion coefficients of lithium ions into the negative electrode made of expanded flake graphite using the results of a series of electrochemical measurements.
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Mobility of pharmaceuticals in soil systems
Slaninová, Kristína ; Širůček, David (referee) ; Klučáková, Martina (advisor)
As a result of improper disposal, pharmaceuticals from households, industry or hospitals are discharged into the environment. Another source through which pharmaceuticals enter the environment is the fertilization of the soil with organic fertilizers or other natural fertilizers containing animal excreta. Medications penetrate into the environment through sewage, entering wastewater, groundwater, surface water, drinking water, and soil, posing an environmental threat. Chelating properties of the organic component of soil could potentially be a solution to the problem of medication presence in soil by preventing migration of the medication. Sulfathiazole is among the group of medications frequently detected in the environment. Sulfathiazole is a sulfonamide antibiotic primarily used in veterinary medicine. The aim of this bachelor's thesis is to determine the concentration profile of sulfathiazole in the soil column and to identify its diffusion coefficients. The thesis also includes a study of the sorption and desorption of sulfathiazole in soil.
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Modeling controlled release
Čelková, Ivana ; Smilek, Jiří (referee) ; Pekař, Miloslav (advisor)
This bachelor's thesis is focused on the controlled release of drugs from hydrogels and the subsequent simulation of this process using the COMSOL Multiphysics computing platform. The aim of the work is to propose a simple model describing the release from the hydrogel structure, to study the effect of diffusion coefficient and to perform simulations on this model and evaluate the results related to controlled release. As part of the thesis, two models were created to investigate the release of particles from the hydrogel. Simulations of this process were carried out for three selected diffusion coefficients (110-9, 110-10, 110-11 m2s-1) and were subsequently discussed in terms of the influence on the speed of particle transport. Two procedures were chosen to determine the total concentration of the released substance in vicinity of the hydrogel, i.e. using the integration of the area of the aqueous environment (in a two-dimensional model) and monitoring the flow of particles through the phase interface of the hydrogel and the aqueous environment.
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Diffusion of dyes in biopolymeric hydrogels
Vyroubal, David ; Mravec, Filip (referee) ; Klučáková, Martina (advisor)
This thesis is focused on diffusion of dyes in biopolymer-based hydrogels. These hydrogels are based on interaction between biopolymer-like electrolytes with oppositely charged surfactants. When polyelectrolytes interact with oppositely charged surfactants, micelle-like nano-containers can be formed. These nano-containers are able of binding hydrophobic compounds. In this study, combination of modified dextran (diethylaminoethyl dextran) with positive charge and oppositely charged sodium dodecylsulphate as surfactant was used for preparation of hydrogels. Next type of hydrogel was based on hyaluronan and positive charged surfactant Septonex (carbethoxypendecinium bromide). As a diffusion probes in hydrogels dyes Nile red and ATTO 488 were used. The diffusion of these dyes from aqeous solutions of NaCl or surfactants into hydrogels was monitored in time. Transport of dyes into structure of hydrogels was characterized by diffusion coefficients and structural parameters of hydrogels.
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Study of intercalation properties of negative electrode materials
Minda, Jozef ; Kazda, Tomáš (referee) ; Libich, Jiří (advisor)
The bachelor thesis deals with the research of intercalating properties of negative electrode materials for lithium-ion and sodium-ion accumulators. The main focus of this work is on the kinetic aspects associated with the diffusion processes of lithium in graphitic negative electrode material and sodium in titanates materials in relation to the electrochemical parameters. By comparing the materials in terms of kinetic properties expressed by the diffusion coefficient with using of electrochemical impedance spectroscopy in the state of the base material and after creating the passive layer on the electrode, it is possible to determine the application possibilities of the materials and the dependence on the electrochemical parameters. In the thesis is designed a procedure for electrodes preparation, measurement and evaluation of monitored parameters. Within the experimental part, the structural and electrochemical parameters and diffusion coefficients of the studied materials are determined by the proposed method.
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Study of intercalation properties of electrode materials based on naturla graphite
Bílek, Lukáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This diploma thesis deals with the issue of lithium-ion accumulators. The thesis focuses on the negative electrode of lithium-ion accumulators made of natural graphite. The first part of this thesis points to the issue of electrochemical cells. In the theoretical part the thesis deals with the SEI layer, advantages, disadvantages, characteristics, operating principle and the use of lithium-ion accumulators. The practical part focuses on the electrochemical properties of negative electrode, especially the determination of the diffusion coefficient. Thesis also deals with electrochemical impedance spectroscopy (EIS) and its use in determining the equivalent replacement circuit and calculating the diffusion coefficient.
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Study of intercalation properties of electrode materials based on expanded graphite
Vencelides, Lukáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
The diploma thesis deals with the issue of electrochemical cells and deals in detail with lithium-ion batteries. The thesis describes the history of development of lithium-ion batteries, basic information about lithium and basic types of electrochemical cells. The work is devoted in detail to the description of characteristics and operating principle of lithium-ion batteries with emphasis on the negative electrode and negative electrode materials. Of the negative electrode materials, both the most widely used material graphite and modern materials with a great potential for the future are described. In the measurement methods the work describes methods CV, GCPL and EIS. Great emphasis is placed on the explanation of the principle of the function of electrochemical impedance spectroscopy and its application in measurement of electrochemical properties of materials used in lithium-ion batteries. There is also described the procedure of calculation of diffusion coefficients using the results of electrochemical impedance spectroscopy. In the practical part, two methods are used to calculate the diffusion coefficients of lithium ions into the negative electrode made of expanded flake graphite using the results of a series of electrochemical measurements.
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Design and Measurement of Parameters of Acoustic Diffusors
Burda, Jan ; Vrba, Kamil (referee) ; Schimmel, Jiří (advisor)
This work focuses on the issue of acoustic diffusers. The introductory chapter describes the necessary theory of the sound distribution through enclosed space. Acoustic fields are also described. A description of the different diffusion element types and theirs design methods follows. It focuses mainly on design, which uses pseudo-random mathematical sequences. The aim of the work is to produce several types of acoustic diffusors and to verify their diffusion properties by means of measurements. The work uses the AFMG Reflex to simulate the diffusion properties of the proposed elements. Further, the thesis contains a description of the diffusion properties measurement process by the boundary plane method and the process of evaluating the measured data using the Matlab program.
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