Journal of Engineering & Processing Management (EPM)
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PHOTOCHEMICAL ACTIVATION OF AIR POLLUTANTS, RELATED TO THE PRESERVATION OF CULTURAL HERITAGE
Get PDFIt is well known that the exposition to air and weather markedly enhances derogation of all artifacts. In this report, the contribution of light (particularly sunlight) to marked speed-up of the oxidation and other changes by exposition to atmosphere will be analyzed. Five major mechanisms of the effect of insolation can be identified: 1. First is a trivial one – the heating effect which enhances all chemical processes. 2. Photoexcitation of material from which the item is made, turning it more reactive toward air oxygen (and to other present substances). 3. Sensitization of oxygen by excitation to singlet state in which it is extremely reactive, and can react even with inert materials. 4. Photochemical transformation of volatile organic compounds (VOC), primarily aldehydes and ketones, that can with oxygen yield organic acids and hydroperoxides which definitely harm majority of materials. 5. In contact of oxygen and another material, upon the absorption of light quanta, a charge transfer process can occur, giving yield to pairs of ion-radicals, which further can be transformed in various reactive products
CHROMATOGRAPHIC BEHAVIOR AND LIPOPHILICITY OF N-(4-PHENYLSUBSTITUTED)-2,3-DIPHENYLPROPANAMIDES
Get PDFRetention behavior of some N-(4-phenylsubstituted)-2,3-diphenylpropanamides was investigated on reversed phase thin layer chromatography (RP-C18). Retention constants of investigated compounds were determined in the following solvent systems: water-ethanol, watern-propanol and water-i-propanol. Linear relationships were obtained between retention, RM and volume fraction of organic solvent, ϕ. As a measure of lipophilicity of tested propanamides, Hansch`s lipophilicity parameter, π, were calculated. Chromatography retention constants RM0 were correlated with Hansch`s lipophilicity parameter, and good linear relationships were obtained. These results confirm, that retention constants, (RM0 ), determined in reversed phase thin-layer chromatography (RP-TCL) can be used, as criteria of lipophilicity
SYSTEMS USING ENERGY SOLAR RADIATION
No full textEnergy is now one of the most important components of development and functioning of the economy and society in general. The development of civilization use different energy sources – fossil fuels and other energy sources like wind and water that are used to drive windmills, water mills and boats. Many countries begin the rationalization of energy consumption in the field, while applying more and more alternative energy sources (solar radiation, wind, etc.) would reduce its energy dependence. In line with this, this paper provides an overview of the system energy use sunlight as an aspect of rationalization of energy consumption
EXAMPLES OF LCA METHODOLOGY IMPLEMENTATION IN STEEL INDUSTRY
Get PDFSteel industry kept pace with actual trends for environmental protection in many ways – through different technological improvements considering environment protection, important share of recycling in the steel production, design of so called “eco-steels”, materials designed according to recent environmental directives and legislatives, etc. In the frame of steel production monitoring, LCA methodology is very important for obtaining an accurate environmental picture of a process, due to the fact that the process should be evaluated over its entire life cycle. A number of tools and methodologies have been developed in recent years to assess the potential environmental impacts associated with a product, process or activity during its entire life cycle. The examples of Life Cycle Assessment (LCA) are used by large steel industrial companies as potentially helpful tool for improving the production processes, efficiency of resource utilization and significantly reduction of waste generation and emissions are presented in this paper
PET PACKAGING CHARACTERIZATION BY MEANS OF DIELECTRIC THERMAL ANALYSIS AND IMPEDANCE SPECTROSCOPY
No full textChemical inertness and physical properties like adequate gas barrier, transparency, light weight and good recyclability, have made poly(ethylene therephtalate) (PET) particularly suitable in food packaging applications, especially in beverages and drinking water. However, several studies have shown the presence of compounds not expected a priori in packed food or bottled water and other beverages. One of the possible sources of these substances is a migration of constituents like monomers, catalysts, additives, degradation products, impurities in starting substances etc, from PET packaging. Therefore, migration of possible contaminants from PET, in normal and extreme conditions, is extensively studied and huge amount of data are reported elsewhere. As the migration process from plastics is closely related to the structure and physical properties of the packaging material, the aim of this work was to study structural changes of PET packaging in different media and under different conditions, and to correlate the data with the possibilities for migration of possible contaminants into the food in contact. It was shown that both techniques, especially DETA, could indicate structural changes into the polymer material, under certain conditions related with packaging applications, which could promote migration process
ACTIVATED CARBONS OBTAINED BY PYROLYZING OF RESORCINOL FORMALDEHYDE GELS
Get PDFActivated carbon is used in different industrial domains due to highly developed specific surface area and its specific chemistry. Properties of activated carbons obtained by pyrolyzing formaldehyde gels are presented in this paper. The gels were synthesized on several temperatures in order to follow the kinetics of gelling process. The relationship between gel synthesis conditions and properties of activated carbons was examined especially in terms of its influence on value of specific surface area and porosity. Carbon was activated with water vapor and cited activation was examined in terms of influence of water vapor on the value of specific surface area and porosity. The capability of modifying activated carbon surface by HN03 oxidation was examined. Characterization of activated carbons was carried out using methods of BET and SEM, IR spectroscopy and by determination of surface electric density
PLANIRANJE LJUDSKIH RESURSA NA PRIMJERU METALOPRERAĐIVAČKOG PREDUZEĆA
Get PDFStrategijsko upravljanje ljudskim resursima postaje presudno za pronalaženje originalnih rješenja u proizvodnom sektoru. U ovome radu rasprava je usmjerena na planiranje ljudskih resursa u jednom metaloprerađivačkom preduzeću radi udovoljavanja sve većim tržišnim zahtjevima i poboljšanja konkuretskog položaja. Uključivanjem svih procesa planiranja i razvoja ljudskih resursa u dugoročnu razvojnu politiku, moguće je povećati inovativnost i ostvariti visoke razvojne ciljeve preduzeća. Primjenom Normativne metode, u posmatranom preduzeću je planiran ukupan broj ljudskih resursa, a primjenom metode kadrovske strukture, planirana je i struktura ljudskih resursa s obzirom na kvalifikacionu strukturu i stepen stručnosti. Planiranje ljudskih resursa, primjenom navedenih metoda, ukazuje da u preduzeću, za naredni period, postoji višak od 169 zaposlenih ili 28,7% u odnosu na trenutno stanje. Rješenje višaka zaposlenih treba tražiti u uvođenju odgovarajuće strategije, za čiji je izbor neophodno postaviti kriterij najmanje cijene i najveće dobiti za preduzeće i zaposlene
WHAT DETERMINES THE WATER QUALITY
Get PDFIn natural waters as a highly complex environment, a different matter, regardless of whether they are natural water ingredients or substances which mature in water by man activity, are subject to one or several different processes. Physical, chemical or biochemical processes are determining finding shapes, behavior and fate of substances in the aquatic environment. Particularly important are: dissolution, adsorption, evaporation, photolysis, hydrolysis, oxidation-reduction, metabolic processes, and bioaccumulation. Depending on which processes are dominant in a given locality, what is the chemical composition of soil, biological activity, and human influence will determine quality of water, whether it is surface, underground or atmospheric. This paper presents the underlying processes that affect water quality. All processes are illustrated by examples
DETERMINATION THE QUALITY OF DRINKING WATER BY INDIRECT METHOD ON SCALE TEST
Get PDFInvestigation of the composition of elements in drinking water, from water network of Belgrade city, with indirect method. This method is based on the scale that is made with precipitation from the water during heating, indicated presence of alkali and alkaline earth elements to a greater extent and heavy metals which is quite expected. Somewhat unexpectedly the presence of some elements, whose presence leads to a greater amount isn’t desirable, because they have the cumulative effect (Hg, Pb, Ni, As ), which indicates that these are areas of developed industrial production. The water from which was formed scale found a greater presence of Fe, Cu, and Mn. Scale testing determined the presence of radioactive elements U and Sr in drinking water. Based on X-ray diffraction analysis of the composition of the sample is composed of a mixture Mg calcite and aragonite. Multidisciplinary approach to the analysis of the scale is defining the new original indirect method of determining the quality of drinking water, so far not recorded in the literature
THE INFLUENCE OF CRITICAL PARAMETERS OF BIODIESEL QUALITY ON USE OF BIODIESEL
Get PDFBiodiesel is a mixture of methyl esters of long chain fatty acids, produced typically by alkalicatalyzed transesterification from vegetable oils. Biodiesel products in the EU must meet EN 14214 quality standard specification. In this specification, values of physical properties and impurities for commercial products are set out, including viscosity, water and sediment, cetane number, CFPP, acid number, glycerol, phosphorus, etc. One of the important parameters, oxidation stability, European standard EN 14214 require a higher level of oxygen stability. Other factors affecting biodiesel quality are environmental conditions, which are mainly the cold flow properties. Biodiesel has a relatively higher CFPP, which limits its application as B100 in low temperature conditions. In addition, biodiesel has a strong tendency to absorb moisture due to its chemical properties.The Objective of this work was to identifications critical parameters of biodiesel quality and their influence on use of biodiesel