Porous elements based on granular materials and inorganic binders

Tato diplomová práce zkoumá možnosti tvorby porézních struktur za použití partikulárních materiálů pojených anorganickými pojivy bez dodatečné tepelné úpravy vypalováním. Jako základní pojiva byly použity portlandský a hlinitanový cement a pojiva na bázi alkalicky aktivovaného metakaolinu (geopolymeru). Jako základní kamenivo byl použit karbid křemíku v různých frakcích podle velikosti částic. Byly taktéž použity další zrnité materiály, např. křemenný písek anebo odpadních materiálů (mleté sklo a porcelán) roztříděných do frakcí podle velikosti částic. Byl sledován vliv složení a množství kameniva na vytváření porézní struktury a tím i na mechanické vlastnosti, které byly testovány pomocí mechanických zkoušek. Pevnostní zkoušky byly provedeny na trámečcích 20 × 20 × 100 mm připravených z testovacích směsí. Granulometrické a fázové složení vstupních surovin bylo studováno metodou laserové granulometrie resp. RTG difrakce. Porézní struktura byla studována metodami rtuťové porozimetrie, dále pomocí světelné a rastrovací elektronové mikroskopie a taktéž pyknometrickou metodou. V rámci charakterizace přepážek (terčíky o průměru 90 mm) připravených z jednotlivých materiálů bylo provedeno stanovení efektivní permeability průtokem vzduchu. Dále byly provedeny testy vzlínavosti kapaliny v připravených materiálech. V závěru práce byly provedeny pokusy o filtraci jemných suspenzí přes uvedené přepážky.This master thesis aims at the possibilities of porous structures formation using granular materials cemented with inorganic binders without additional heat treatment by firing. As the basic binders were used Portland and aluminate cement and agglutinates on alkali-activated metakaoline (geopolymer) basis. Silicon carbide classified according to particle sizes was used as main aggregates, the next materials were quartz sand and some secondary material were used as well (milled glass and porcelain), which were also divided into particle size fractions. The influence of composition and aggregates quantity upon the porous structure generation was pursued and mechanical properties were characterized by mechanical strength testing of columns with proportions of 20 × 20 × 100 mm prepared of testing mortars. Grain size measurement and characterization of phase composition of input materials were performed by means of laser granulometry and X-ray diffraction, respectively. Porous structure was investigated using methods of mercury porosimetry, light and scanning electron microscopy and pycnometric measurement. The barriers in the form of disks with 90 mm in diameter prepared of individual materials were tested by air flux to determine effective permeability. Furthermore, the capillarity testing of the materials were carried out. Lastly, experiments to try to clarify suspensions of fine particles were accomplished.

The concentration of particulate matter in the air of selected areas of the city of Brno and its health risks

Tato práce se zabývá znečištěním ovzduší pevnými prachovými částicemi v lokalitách města Brna. V teoretické části je pojednáno o možných zdrojích prachových částic, o chemickém složení a velikostní klasifikaci polétavých částic a dalších fyzikálně-chemických charakteristikách. Další část je věnována zdravotním rizikům prašnosti. V této souvislosti práce pojednává o anatomii dýchacího systému a účincích prachu na něj. Jsou taktéž rozebrány zdravotní efekty prachového znečištění, včetně uvedení možných nemocí respiračního a kardiovaskulárního systému, jejichž může být prach příčinou. V praktické části byl proveden sběr prachu. Byly vybrány celkem čtyři lokality, kde byly prováděny odběry vzorků. Následně byly stanoveny koncentrace polétavých částic PM10 a PM2,5. Dále byly u vybraných lokalit stanoveny koncentrace těžkých kovů a polyaromatických uhlovodíků vázaných na prachových částicích. V závěru bylo provedeno srovnání s legislativou a stanovena zdravotní rizika.This thesis deals with air pollution caused by particulate matter (PM) in the city of Brno areas. The theoretical part focuses on potential sources of PM, its chemical composition and size classification and other physic-chemical properties. The next section is devoted to the health risks of PM. In this context, the work aims at the anatomy of respiratory system and the effects of PM on it. Health effects of dust pollution including the potential respiratory and cardiovascular disorders are also discussed. In experimental part, a collection of dust was carried out. The dust collection was carried out in four selected areas. Concentrations of airborne particles PM10 and PM2.5 were determined, subsequently. Concentration of heavy metals and polycyclic aromatic hydrocarbons bound to dust particles was determined. Finally, the comparison between the regulatory standards and results of analysis was done as well as the health risk assessment.

Application of Polymeric Hollow-Fiber Membranes in Air Filtration

Membrány z dutých vláken jsou široce využívány v aplikacích týkajících se úpravy kapalin jako např. při čištění odpadních vod, v membránových kontaktorech a bioreaktorech, membránové destilaci apod. I když jsou často využívány při separacích směsí plynů, je jejich použití pro mechanickou filtraci aerosolů velmi vzácné. Tato práce se zabývá filtrací vzduchu pomocí polypropylenových membrán z dutých vláken včetně jejich filtrační účinnosti, tlakových ztrát a také zanášením při dlouhodobé filtraci. Filtrační účinnost byla proměřena za použití různých aerosolů jako TiO2 a síran amonný. Tlakové ztráty byly měřeny při různých konfiguracích, tj. různé filtrační ploše a průměru vlákna membrány. Zanášení membrán bylo testováno použitím normovaného prachu definovaného normou ANSI/ASHRAE 52.2. Predikční modely pro filtrační účinnost a permeabilitu/tlakovou ztrátu membrány byly aplikovány na parametry membrán z dutých vláken a porovnány. Tyto membrány mají velikost pórů kolem 90 nm a poměrně nízkou porositu a tím vysoký potenciál pro separaci nanočástic ze vzduchu. Dále byla provedena analýza filtračního koláče a vyhodnocení energetických nároků a porovnány s teoretickými modely. V závěru práce je nastíněn odhad ceny životního cyklu při filtraci pomocí těchto membrán.Hollow-fiber membranes (HFMs) have widely been applied to many liquid treatment applications such as wastewater treatment, membrane contactors/bioreactors, membrane distillation etc. Despite the fact that HFMs are widely used for gas separation from gas mixtures, their use for mechanical filtration of aerosols is very scarce. This work studied filtration performance of polypropylene HFMs including filtration efficiency, pressure drop and pressure drop evolution with long-term dust loading. Filtration efficiency was measured using different challenging aerosols including micronized titanium dioxide powder and aerosolized ammonium sulfate. Pressure drop was measured in various configurations, including different HFM area and fiber diameter. Pressure drop evolution with long-term particle loading was carried out using a challenge dust as defined in ANSI/ASHRAE 52.2 standard. Mathematical models developed for prediction of air filtration efficiency and membrane permeability/pressure drop were compared applying them on the structural parameters of the HFMs. These membranes are characteristic of pore diameters of about 90 nm and relatively low porosity, thus high potential for nanoparticle removal from air. Furthermore, analysis on cake pressure drop and evaluation of energy demands for fun operation were done and compared with theoretically predicted values. Finally, an attempt to estimate life-cycle cost of air filtration using HFMs was outlined.

Preparation and characterization of concretes based on blended geopolymeric binder

This bachelor thesis focuses on preparation of concretes based on alkali activated binding systems (geopolymers). Finely ground blast-furnace slag was used as a basic aluminosilicate compound for preparation of an alkali activated binder. A mixture of sodium water glass and 50 % KOH solution, which was replaced by cement kiln dust in some cases, was used as an activator. The prepared testing samples (columns 40x40x160 mm) were mechanically tested for strength and the influence of the substitution of KOH solution by cement kiln dust on strength was observed. Then the work aims at structure analysis of binders prepared – the thermal analysis was carried out and the phase composition was explored with RTG diffraction

Numerical Comparison of Prediction Models for Aerosol Filtration Efficiency Applied on a Hollow-Fiber Membrane Pore Structure

Hollow-fiber membranes (HFMs) have widely been applied to many liquid treatment applications such as wastewater treatment, membrane contactors/bioreactors, membrane distillation etc. Despite the fact that HFMs are widely used for gas separation from gas mixtures, their use for mechanical filtration of aerosols is very scarce. In this work, we compared mathematical models developed for prediction of air filtration efficiency applying them on the structural parameters of polypropylene HFMs. These membranes are characteristic of pore diameters of about 90 nm and high solidity, thus high potential for nanoparticle removal from air. Single fiber/collector and capillary pore approach were chosen to compare between models developed for fibrous filters and capillary-pore membranes (Nuclepore filters) based on three main mechanisms occurring in aerosol filtration (inertial impaction, interception and diffusion). The collection efficiency due to individual mechanisms differs significantly. The differences are caused by the parameters for which the individual models were developed, i.e. given values of governing dimensionless numbers (Reynolds, Stokes and Peclet number) and also given values of filter porosity and filter fiber diameter. Some models can be used to predict the efficiency of HFMs based on assumptions depending on the conditions and exact membrane parameters

An Assessment on Average Pressure Drop and Dust-Holding Capacity of Hollow-Fiber Membranes in Air Filtration

In this work, we tried to analyze dust loading behavior of polypropylene hollow fiber membranes using average pressure drop models. Hollow fiber membranes varying in fiber diameter were loaded with a standardized test dust to simulate particle-polluted air. We measured pressure drop development of the membranes at different flowrates and dust concentrations, and, after each experiment, the dust deposited on the membrane fibers was weighed to obtain dust holding capacity (DHC). The obtained experimental data was analyzed using various average pressure drop models and compared with average pressure drop obtained from pressure drop/dust load dependence using a curve fit. Exponential and polynomial fitting was used and compared. Pressure drop in relation to the dust load followed different trends depending on the experimental conditions and inner fiber diameter. At higher flowrate, the dependence was polynomial no matter what the fiber diameter. However, with higher fiber diameter at lower permeate velocities, the dependence was close to exponential curve and followed similar trends as observed in planar filter media. Dust-holding capacity of the membranes depended on the experimental conditions and was up to 21.4 g. However, higher dust holding capacity was impossible to reach no matter the experiment duration due to self-cleaning ability of the tested membranes

Methodology of Environmental Damage Assessment Caused by Road Accidents

The current status of assessing the amount of environmental damage is mainly focused on the long-term consequences of negative factors, such as traffic and industry emissions. Significant damage may be caused even due to short-term effects, such as an accident during transportation of hazardous substances, where there is a loss caused either by the vehicle failure, or road accident. Damage which is subsequently solved, in most cases reflects only the costs associated with the removal and rehabilitation of the affected area. It is however important to note that since the damage occurrence until the return of the environment to its original state, if at all possible, there are many changes bearing other related costs associated with their replacement. The paper analyses the current status of assessing the amount of environmental damage and suggests appropriate methods for the unification process in the framework of expert activities