Microwave heating and reactions of selected polyaromatic hydrocarbons

Import 03/08/2012Hlavnú podstatu bakalárskej práce tvorí praktická časť zaoberajúca sa mikrovlnným ohrevom dodaných vzoriek smoly. V ďalšej časti je porovnaný mikrovlnný a konvenčný ohrev vzoriek smôl. Výsledné hodnoty sú znázornené pomocou grafov, tabuliek a obrázkov. Teoretická časť obsahuje charakteristiku čiernouhoľnej smoly, jej výrobu a použitie. Zároveň je v nej definovaný mikrovlnný ohrev a jeho vplyv na chemické reakcie a procesy.The main thesis is the essence of the practical part, dealing with the microwave heating of samples of the pitch. The next section compares the conventional and microwave heating of samples of the pitch. The resulting values are shown by graphs, tables and images. The theoretical part contains the characteristics of coal-tar pitch, its production and use. It is also defined by microwave heating and its effects on chemical reactions and processes.617 - Katedra chemievýborn

Adsorption of volatile organic compounds on solid sorbents

Import 05/08/2014Táto práca sa zaoberá prípravou adsorbentov pomocou chemickej aktivácie a porovnaním adsorpcie organických prchavých látok na vyrobených adsorbentoch. V teoretickej časti sú zhrnuté poznatky z literatúry o adsorpcii, histórii adsorpcie, izotermách a adsorbentoch. V praktickej časti tejto práce je preskúmaná metodika prípravy adsorbentov na báze čiernouhoľnej smoly. Na základe výsledkov z adsorpcie rôznych organických prchavých látok je skúmaný vplyv rôznych druhov, pomerov prímesí a aktivácie vzorky adsorbenta. Výsledky boli vyhodnotené pomocou mapy izoteriem, priradenia typu izotermy, výpočtu plochy adsorbenta pomocou jednobodovej metódy a pomocou lineárnych metód BET a Langmuirovej izotermy. Z rezultátov v praktickej časti bol vypracovaný záver tejto práce.This work deals with the preparation of adsorbents by chemical activation and comparing the adsorption of volatile organic substances on produced adsorbents. Theoretical section summarizes the findings from the literature about adsorption, adsorption isotherms, history of adsorption and adsorbents. In the practical part of this thesis is reviewed methodology for the preparation of adsorbents based on coal-tar pitch. Based on the results of the adsorption of various organic volatiles is studied the impact of various kinds, ratios of impurities and activation of adsorbent samples. Results were analyzed using map of isotherms, assignment type isotherms, calculate the surface area of the adsorbent using the single point method and using the linear methods of BET and Langmuir isotherm. From the results of the practical part were made conclusions of this work.617 - Katedra chemievýborn

Determination of specific surface of activated mesocarbons by sorption of organic vapors

The determination of specific surface of activated mesocarbons prepared from coal tar pitch by sorption of organic vapors and the operating factors affecting their performances were investigated. Proposed paper deals with alternative experimental method based on weight registration during adsorption of pure vapors of volatile organic compounds VOCs on tested samples. Thermogravimeter TGA-HP50 was used for sorption experiments where activated mesocarbon microbeads were the sorbent and vapors of benzene, toluene, acetone and cyclohexane were used as adsorbate. Primary data were actual weight of the tested sorbent and absolute pressure of organic vapor. Experimental data were fitted by Langmuir model of adsorption isotherm. Specific surface was determined from evaluated parameters. Obtained results were compared with results from standard nitrogen S-BET method. Specific surfaces evaluated from both methods are comparable. The influence of important parameters such as chemical activation, extraction and addition of catalytic agents on activated mesocarbons was studied too. Coal tar pitch as raw material was thermally treated together with Lewis acid (FeCl3). Final solid sorbents were prepared by chemical activation of pyridine-insoluble (PI) matters using potassium hydroxide. Weight ratio of activated agent (potassium hydroxide) to PI matters was 1:5, and temperature of activation was 850 °C. It was found that three samples which were activated had greater specific surface area than the one (B) that was not activated, also as they are appropriate for adsorbing the selected adsorptives.Web of Science121143642

Effect of soaking time on the photoluminescence properties of cerium oxide nanoparticles

The structural and photoluminescence properties at room temperature of CeO2 nanoparticles synthesized by a microwave-assisted hydrothermal method (MAH) under different soaking times on KOH mineralizer added to a cerium ammonium nitrate aqueous solution were undertaken. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) and photoluminescence (PL) measurements were employed. XRD revealed that the nanoparticles are free of secondary phases and crystallize in the cubic structure. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. The most intense PL emission was obtained for nanoparticles which represent a lower particle size.Web of Science4019