bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of biological markers for the identification of oil-type pollutants in recent sediments: Alluvial formation of the Danube river, Oil refinery Pancevo
Authors: Rasovic Aleksandar , Jovancicevic Branimir , Sladic Dusan , Kljajic Zoran , Scheeder Georg , Wehner Hermann
Published: July 2008

The purpose of this paper was to examine to which extent the abundance and distribution of certain biological markers may be used for the identification of oil-type pollutants in recent sediments and ground waters. The samples were taken from the area of the Oil Refinery Pancevo (alluvial formation of the Danube River). The organic matter of the investigated samples was isolated using an extraction method with chloroform. The group composition and usual biological markers were analyzed in the obtained extracts. n-Alkanes and acyclic isoprenoids, pristane and phytane were analyzed using gas chromatographie (GC) analysis of saturated hydrocarbons. Polycyclic alkanes of the sterane and terpane type were analyzed using gas chromatography-mass spectrometry (GC-MS), i.e. by analyzing the carbamide non-adduct of the total alkane fraction (Single Ion Monitoring SIM-technique). The obtained results indicate that n-alkanes can be used for the identification of oil-type pollutants (for example, if the oil-pollutant is biodegraded or present in very low concentrations), and steranes and triterpanes can be used as very reliable indicators of oil-type pollution in recent sediments and ground waters.
Investigation of pretertiary and tertiary surface sediments from Serbia: Organic geochemical interpretation
Authors: Jovancicevic Branimir , Sainovic Aleksandar , Cvetkovic Olga , Filipovic Ivan , Asanin Petar , Vitorovic Dragomir
Published: July 2008

Samples of surface sediments originating from different localities in Serbia which contained more than 0.5 % organic matter were investigated in this paper. According to age, these samples were classified into two groups sediments of pretertiary age and sediments of tertiary age. Bulk and specific organic geochemical parameters were determined for their methylene chloride-methanol extracts, aimed at controling the relationship between the age of the sediment and the maturity of its organic substance. In this sense a general direct proportionality was observed. However, a better linear dependence of the bulk parameters was observed in the case of younger, tertiary sediments. That is to say, with samples of pretertiary age the organic matter maturity was approaching a definite limiting value contributing to an inferior linear dependence of their bulk maturation parameters. Nevertheless, the dependence was found to be preserved with specific maturation parameters (e.g., CPI; Fit/n-C18), the changes of which are generally more intensive at higher maturity degrees.
Sepiolite: A domestic mineral raw material for small and medium enterprises and environmental protection
Authors: Dojcinovic Miroslava , Simic Dana , Martic Miljenko
Published: July 2008

The paper presents the phases in the research of sepiolite - hydrated in fibrous magnesium silicate, and in the development of different products based on sepiolite, at the Institute of General and Physical Chemistry (IGPC). Also, a review on sepiolite world deposits, general properties and practical uses is given in the paper. An the IGPC sepiolite from the mine Golesh was investigated, concerning its uses in paints, as a pigment and rheological aditive; in the rubber industry, as an active filler; in sepiolite, papers, for purifying, waste gases in industry and homes and as a powder combined with sepiolite paper, to purify old transformer oils. It was concluded that a number of technologies based on sepiolite could be developed in small or medium industrial enterprises, which are of the strategic interest for Serbia, especially since domestic sepiolite deposites can be further developed and that some of these technologies are important in environment all protection.
Confirmation of the reaction pathway for obtaining 1-(stearamidoethyl)-2-hepta-decyl-2-i midazoline
Authors: Ruzic Nenad , Petrovic Slobodan
Published: July 2008

2-lmidazolines are components of many products, used in industry and households. 1-(Stearamidoethyl)-2-heptadecyl-2-imidazoline is a surface active compound, which after quaternization with dimethyl sulfate, is used in lubricants, detergents, shampoos, softeners and cosmetics products. Due to its importance, it was essential to establish the exact reaction pathway for obtaining this compound. Diethylene triamine and stearic acid were used as the starting components. Using titrimetric analysis, and IR and 1H NMR spectros-copic analysis, as well as UV-Vis spectrophotometry it was established that the main intermediate was the 1,3-diamide bis(stearamidoethyl)amine. Earlier investigations conducted by some authors, using exclusively titrimetric analysis, showed that the main intermediate was the 1,2-diamide. In this paper it was proved that the assumption of these authors that salicylaldehiyde would react only with the primary and not the secondary amine groups was wrong. 1,2-Diamide is the main product of the hydrolysis of 1-(stearamido-ethyl)-2-heptadecyl-2-imidazoline. It was shown, in this paper that the reaction of diethylene triamine with stearic acid in xylene at the reflux temperature, yields the salt of 1-(stearamidoethyl)-2-heptadecyl-2-imidazoline and stearic acid.
Disinfection of drinking and bathing water with oxyl
Authors: Simonic Marjana
Published: July 2008

An electrolysed solution of sodium chloride was examined for its disinfection potential in drinking and bathing water. The electrolysis of NaCl ((=1%) in tap water was performed at room temperature using a 10 A electric current in an electrolysis apparatus. Some laboratory tests were made, initially to determine the stability and efficiency of the disinfectant. Chemical and microbiological measurements of the treated water (according to DIN 19643 for bathing water) were then carried out before and after addition of the disinfectant agent.
Extraction of resinoids from St. John's wort (Hypericum perforatum L): I. Efficiency and optimization of extraction
Authors: Milenovic Dragan , Veljkovic Vlada , Todorovic Branimir , Stankovic Miomir
Published: July 2008

The extraction of resinoids from St. John's wort (Hypericum perforatum L) was studied in a series of two papers. In the first part, the effects of the operating conditions on the yield of resinoids (total extract) were analyzed, while the mathematical models of extraction kinetics were compared in the second one. The extraction was carried out using an aqueous solution of ethanol (70 and 95 % v/v) at a hydromodulus (plant material to solvent ratio, w/v) of 1:5 or 1:10. The plant material was disintegrated and divided into three fractions (mean particle size: 0.23, 0.57 and 1.05 mm). The temperature was 25, 50 or about 80?C (boiling temperature). A higher yield of resinoids was obtained when the plant material of greater disintegration degree (0.23 mm) was treated with 70% v/v aqueous ethanol solution at higher hydromoduli (1:10) and temperatures (80?C). The effects of the operating factors on the yield of resinoids were estimated by using both the full factorial experimental plan 24 and artificial neuronic networks (ANN) of 3-4-1 topology. Of the two methods, the ANN one was found to be advantageous because of its capability of estimating the yield of resinoids in the whole range of the applied operating conditions.
Conversion of sulphur compounds into light gas oil: I. Kinetics of the conversion of model compounds
Authors: Jankovic Jasna , Skala Dejan
Published: July 2008

The problem of sulfur compounds conversion, particularly heterocyclic compounds, from the middle fraction of crude oil (light gas oil) was analyzed and will be published in several articles in the Chemical Industry Journal. Published data in the literature, covering the conversion of tiophene, benzothiophene and dibenzothiophene are presented in the first paper of this series with the goal of comparing and critically analyzing their usage for reactor calculation.
Ethanol is a strategic raw material
Authors: Baras Josip , Gacesa Slobodan , Pejin Dusanka
Published: July 2008

The first part of this review article considers general data about ethanol as an industrial product, its qualities and uses. It is emphasized that, if produced from biomass as a renewable raw material, its perspectives as a chemical raw material and energent are brilliant. Starchy grains, such as corn, must be used as the main raw materials for ethanol production. The production of bioethanol by the enzyme-catalyzed conversion of starch followed by (yeast) fermentation, distillation is the process of choice. If used as a motor fuel, anhydrous ethanol can be directly blended with gasoline or converted into an oxygenator such as ETBE. Finally, bioethanol production in Yugoslavia and the possibilities for its further development are discussed.
Antioxidants in food
Authors: Djilas Sonja , Canadanovic-Brunet Jasna , Cetkovic Gordana
Published: July 2008

This paper attempts to lead the reader an understanding of what free radicals are and how they can form during lipid oxidation. Also, it provides some information out natural antioxidants (tocopherols and tocotrienols flavonoids, polyphenols, tannines, melanoidihes, carotenoids, ascorbates) and the echanisms of their protection from radical damage. The sources of natural antioxidants are: oil seeds, teas, vegetables, fruits, spices and herbs.
The significance and possibility of functional food production
Authors: Dimitrijevic-Brankovic Suzana , Baras Josip , Bojovic Jaroslav
Published: July 2008

Abundant knowledge of the significance of food quality for all human living functions as well as growing human population and the occurrence of world "hidden hunger", directed food producers toward new production processes of and new product development that must satisfy the specific needs of different categories of consumers. The differences are reflected in sex age, religious affiliation, activity, health, social status etc. "Organic", "natural, minimal processing, functional (and often called "therapeutical") food nowadays represents the key interest of nutritionists, physicians and food producers. Such food should have a beneficial influence on human health, besides satisfying the nutritive and energetic necessities, by protective, prophylactic and healing performance. This paper discusses facts about the influence of food on human health, problems of malnutrition in developing and developed countries, presents states of food production in the world and in Yugoslavia, legislation and regulations on nourishment and food production, the disadvantages of former concepts of development of this production and possible directions of future trends with a particular review on functional food production.
The influence of high temperatures on milk proteins
Authors: Macej Ognjen , Jovanovic Snezana , Djurdjevic-Denin Jelena
Published: July 2008

High temperatures Induce certain changes in milk constituents, but the degree of these changes depends on both the temperature and time of heat treatment. The most pronounced changes take place in milk proteins. The forewarming of milk causes an increase in acidity, the precipitation of soluble Ca-phosphate, whey protein denaturation and coagulation, as well as the interaction with casein micelles, the Maillard browning reaction, the dephosphorylation of casein, the hydrolysis of casein micelles, changes in whey proteins, an extension of the rennet coagulation time and an exchange of the rheological properties of the acid and rennet casein gels, changes in the zeta-potential and casein micelle hydration, the interaction between the milk proteins and proteins of milk fat globule membrane.
Drying of biological materials in a spout-fluid bed with a draft tube
Authors: Povrenovic Dragan , Dimitrijevic-Brankovic Suzana
Published: July 2008

The possibility of applying a spout-fluid bed with a draft tube and conical bottom was investigated for drying fluid media with a certain content of suspended material was investigated. The major goal who to study the drying of biological materials and products of food the industry. Experimental results concerning the fluidmechanical characteristics of a spout-fluid bed with a centrally situated draft tube and the drying characteristics were obtained on a pilot scale unit, 0.250 m in diameter, with a toed consisting of polyethylene particles 3.6 mm mean diameter and 940 kg/m3 density. Within the regime of the fluid mechanical stability, the system could be used for drying biological suspensions with satisfactory results.
Partial hydrogenation of edible oils: Synthesis and verification of the nickel catalyst
Authors: Jovanovic Dusan , Markovic Branislav , Stankovic Miroslav , Rozic Ljiljana , Novakovic Tatjana , Vukovic Zorica , Anic Mirjana , Petrovic Srdjan
Published: July 2008

Developed in the late 1800s as a butter substitute, margarine is made with vegetable oils. Margarine was created by a scientist from Provence (France) Hippolyte Mege-Mouries, in response to an offer by the Emperor Louis Napoleon III. To formulate his entry, Mege-Mouries used margaric acid, a fatty acid component isolated in 1813 by Michael Chevreul and named because of the lustrous pearly drops that reminded him of the Greek word for pearl - margarites.
A view on chemical and biochemical engineering: Where are they going?
Authors: Veljkovic Vlada
Published: July 2008

A short history of chemical and biochemical engineering is presented, both industrial and educational aspects being considered. The most important trend in the future development of bio/chemical engineering - biological engineering - is pointed out. The current state and near future of biotechnology are described.
Gas holdup in a reciprocating plate bioreactor: Non-Newtonian - liquid phase
Authors: Naseva Olivera , Stamenkovic Ivica , Bankovic-Ilic Ivana , Lazic Miodrag , Veljkovic Vlada , Skala Dejan
Published: July 2008

The gas holdup was studied in non-newtonian liquids in a gas-liquid and gas-liquid-solid reciprocating plate bioreactor. Aqueous solutions of carboxy methyl cellulose (CMC; Lucel, Lucane, Yugoslavia) of different degrees of polymerization (PP 200 and PP 1000) and concentration (0,5 and 1%), polypropylene spheres (diameter 8.3 mm; fraction of spheres: 3.8 and 6.6% by volume) and air were used as the liquid, solid and gas phase. The gas holdup was found to be dependent on the vibration rate, the superficial gas velocity, volume fraction of solid particles and Theological properties of the liquid ohase. Both in the gas-liquid and gas-liquid-solid systems studied, the gas holdup increased with increasing vibration rate and gas flow rate. The gas holdup was higher in three-phase systems than in two-phase ones under otter operating conditions being the same. Generally the gas holdup increased with increasing the volume fraction of solid particles, due to the dispersion action of the solid particles, and decreased with increasing non-Newtonian behaviour (decreasing flow index) i.e. with increasing degree of polymerization and solution concentration of CMC applied, as a result of gas bubble coalescence.
Simultaneous ultrafiltration and diafiltration
Authors: Zavargo Zoltan , Tekic Miodrag , Djuric Mirjana , Krstic Darko
Published: July 2008

A model with simultaneous ultrafiltration and diafiltration, which includes the rejection coefficients, is presented in this study. Adding a diafiltration solution at a constant, lower rate than the filtrate rate results in a constant decrease of the solution volume in the tank. This enables the simultaneous attainment of the desired macrosolute concentration and microsulute dilution. The proposed model, based on incomplete macrosolute rejection and incomplete mi-crosolute permeation through a membrane, as well as constant permeate flux, is compared to the classical constant volume, diafiltration process. The obtained results show that less diafiltration volume is necessary with this process. Simultaneously, the duration of the process, for higher purification requirements, is shorter in this case.
Oxide electrocatalytic coatings obtained by the sol-gel procedure: Preparation and characterization
Authors: Dekanski Aleksandar , Panic Vladimir , Nikolic Branislav
Published: July 2008

The influence of different parameters (forced hydrolysis duration in the preparation of sols, alcohol addition in the sol mixture for application, as well as sol/alcohol mixture ageing time) on the morphology and electrochemical properties of RuO2-TiO2 coatings obtained by the sol-gel procedure is presented. The oxide sols were sharacterized by spectroscopic and microscopic methods (X-ray diffraction, TEM, etc). The morphology of the obtained coatings was examined by scanning tunneling microscopy, while the electrochemical properties were investigated by cyclic voltammetry polarization measurements, electrochemical impedance spectroscopy and the accelerated stability test. The greatest real surface area was obtained for coatings with the smallest RuO2 particles and largest TiO2 particles. Alcohol addition caused enlargement of the oxide grains and, consequently, a decrease in the real surface area. The same effects of oxide grain size were registered on electrochemically active surface area. The electrocatalytic activity of the obtained anodes for the chlorine evolution reaction increased with growth of the TiO2 particles, but depended on the RuO2 particle size to a small degree. The corrosion stability of the anode coatings consisting of the smallest RuO2 particles and largest TiO2 particles whis the greatest in the electrolysis of a sodium-chloride solution.
Catalytic dry reforming of natural gas for the production of chemicals and hydrogen
Authors: Verykios Xenophon
Published: July 2008

Carbon dioxide reforming of methane to synthesis gas was studied over Ni-based catalysts. It is shown that, in contrast to other Ni-based catalysts which exhibit continuous deactivation with time-on-stream, the rate over the Ni/La2O3 catalyst increases during the initial 2-3 h of reaction and then tends to be essentially invariable, displaying very good stability. X-ray diffraction, hydrogen and CO uptake studies, as well as high resolution TEM indicate that, under reaction conditions, the Ni particles are partially covered by La2O2CO3 species which are formed by interaction of La2O2 with CO2. Catalytic activity occurs at the Ni- La2O2CO3 interface, while the oxycarbonate species participate directly by reacting with deposited carbon, thus restoring the activity of the Ni sites at the interface. XPS and FTIR studies provide evidence in support of this mechanistic scheme. It was also found that methane cracking on Ni sites and surface reaction between deposited carbon and oxycarbonate species are the rate determining steps in the reaction sequence. A kinetic model is developed based on this mechanistic scheme, which is found to predict satisfactorily the kinetic measurements.
Electrocatalysis of fuel cells reaction on Pt and Pt-bimetallic anode catalysts: A selective review
Authors: Stamenkovic Vojislav , Blizanac Berislav , Grgur Branimir , Markovic Nenad
Published: July 2008

In this review we selectively summarize recent progress, primarily from our laboratory, in the development of interrelationships between the kinetics of the fuel cells reactions and the structure/composition of anode catalysts. The focus is placed on two types of metallic surfaces: platinum single crystals and bimetallic surfaces based on Pt. In the first part it was illustrated that the hydcogen reaction is structure sensitive process, with Pt(110) being an order of magnitude more active than either of the atomically "flatter" (100) and (111) surfaces. The hydrogen reaction on Pt(hkl) modified by pseudomorphic Pd (sub)monolayers shows the "volcano-like" behavior, having the maximum rate on Pt(111) modified by 1 ML of Pd. The Pt(111)-Pd system is used to demonstrate how the energetics of intermediates formed in the hydrogen reaction is affected by interfacial bonding and energetic constraints produced between pseudomorphic Pd films and the Pt(111) substrate. In the second part it was shown that the oxidation of Ha in the presence of CO occurs concurrently with CO oxidation on Pt and Pt bimetallic surfaces. The Pt-Ru system is used to demonstrate that both the bifunctional effect and the ligand effect contribute to the influence of Ru on the CO oxidation rate and for Hz oxidation process in the presence of CO. The knowledge is then used to create the real-life catalyst with the catalytic activities which are, to the greatest extend possible similar to the tailor-made surface.
Test experiences with the DaimlerChrysler: Fuel cell electric vehicle NECAR
Authors: Friedlmeier Gerardo , Friedrich J. , Panik F.
Published: July 2008

The DalmlerChrysler fuel cell electric vehicle NECAR 4, a hydrogen-fueled zero-emission compact car based on the A-Class of Mercedes-Benz, is described. Test results obtained on the road and on the dynamometer are presented. These and other results show the high technological maturity reliability and durability already achieved with fuel cell technology.
Oxidation of pyrite: Consequences and significance
Authors: Dimitrijevic Mile , Antonijevic Milan , Dimitrijevic Valentina
Published: July 2008

This paper presents the most important studies on the oxidation of pyrite particularly in aqueous solutions. The consequences of pyrite oxidation was examined, as well as its importance, from both the technical-technological and environmental points of view. The oxidation of pyrite was considered in two parts. The spontaneous oxidation of pyrite in nature was described in the first part, with this part comprising pyrite oxidation in deposits depots and mines. It is explained how way natural electrochemical processes lead to the decomposition of pyrite and other minerals associated with pyrite. The oxidation of pyrite occurring during technological processes such as grinding, flotation and leaching, was shown in the second part. Particular emphasis was placed on the oxidation of pyrite during leaching. This part includes the leaching of sulphide and oxide ores, the leaching of pyrite coal and the leaching of refractory gold-bearing ores (pressure oxidation, bacterial oxidation, oxidation by means of strong oxidants and the electrolysis of pyrite suspensions). Various mechanisms of pyrite oxidation and of the galvanic interaction of pyrite with other sulphide minerals are shown.
The desorption of ammonia and carbon dioxide from multicomponent solutions: I. Model description and development
Authors: Jotanovic Milovan
Published: July 2008

A mathematical model of the desorption process based on the synthesised technological topology of the regeneration process gas components NH3 and CO2, was developed. The logical principle methodology of the mathematical modelling of desorption processes was worked out in detail. The mathematical model of the process, including the following: - The synthesized technological scheme of the desorption of components NH3 and CO2, with all the necessary requirements and limitations of the mathematical model; - The relevant multicomponent systems which exist in the process were defined in which the interphase transformation occurs; - The considered units (aparatus) are defined which make up the basic technological topology of the process; - Desorption processes in towers with different types of trays were defined and mathematically described; - The cooling process and condensation of gas phase in a complex multicomponent system was of the gas phase in a complex multicomponent system was defined and mathematically described. Many variants of the process were analyzed by using developed model with the aim of determining the relevant functional dependences between some basic parameters of the process. They will be published in the second part of this study.
Complexometric determination: Part I - EDTA and complex formation with the Cu2+ ion
Authors: Rajkovic Milos
Published: July 2008

Compounds forming very stable complexes - chelates, have a wide field of application in analytical chemistry. The most famous group of these compounds are complexons. Complexons represent organic polyaminocarbonic acids as for example ethylenediaminetetraacetic acid (EDTA) and its salts. The EDTA molecule has six coordinative sites. It is a hexadentate ligands i.e. it has two binding nitrogen atoms and four oxygen atoms from carboxyl groups and it forms complexes with almost all metal ions. EDTA as a tetraprotonic acid, H4Y disociates through four steps, yielding the ions HsY-, H2Y2-, HY3- and Y4-. Which of the EDTA forms will be encountered in a solution, depends on the pH. Due to the poor solubility of EDTA in pure water, as well as in most organic solvents, the disodium salt of EDTA Na2H2Y-2H2O, under the commercial name complexon III, is utilized for analytical determinations. In water, EDTA forms soluble, stabile chelate complexes with all cations, at the molar ratio 1:1, regardless of the charge of the metal ion. In contrast to other equilibria, which are mainly defined by Le Chatellier's principle, equilibria related to metal-EDTA complex formation are also dependent on the influence of the secondary equilibria of EDTA complex formation. Complexing reactions, which are equilibrium reactions, are simultaneously influenced by the following factors: solution pH and the presence of complexing agents which may also form a stabile complex with metal ions. The secondary reaction influence may be viewed and monitored through conditional stability constants. In the first part of the paper, the reaction of the formation of the Cu2+-ion complex with EDTA is analyzed beginning from the main reaction through various influences of secondary reactions on the complex Cu2+-EDTA: pH effect, complexation effect and hydrolysis effect. The equations are given for conditional stability constants, which include equilibrium reactions under actual conditions.
Mechanical and failure bahaviour in carbon/epoxy composites
Authors: Stevanovic Momcilo , Sekulic-Pesikan Danijela
Published: July 2008

A review of the mechanical properties and failure initiation and propagation in carbon/epoxy composites is presented. The results of the study of the macromechanical static characteristics, non-linear elastic behavior flexural modulus and shear properties of unidirectional composites (UDC), as well as, of tensile, compression and flexural moduli, strength analysis edge and hybrid effects in multidirectional composites (MDC) were discussed A discussion of the non-linear elastic behavior of carbon/epoxy UDC, the flexural moduli of both UDC and MDC, strength analysis and edge effects of laminates is emphasized.
Synthesis of thin films by the pyrosol process
Authors: Tucic Aleksandar , Brankovic Goran , Marinkovic Zorica , Mancic Lidija , Milosevic Olivera
Published: July 2008

Among many aerosol routes, the Pyrosol process, due to its simplicity, low cost and quality of obtained films, represents a promising technique for the synthesis of thin films. The pyrosol process is based on the transport and pyrolysls of an aerosol of processor solution, generated in an ultrasonic atomizer, on a heated substrate. The theoretical principles of the pyrosol process are presented in this paper, as well as the influence of some synthesis parameters on the deposition of SnO2 thin films.
Fractionation of the mixture obtained by the enzymatic hydrolysis of penicillin G
Authors: Cascaval Dan , Oniscu Corneliu , Galaction Anca-Irina
Published: July 2008

Using the experimental data on the individual physical and reactive extraction of 6APA with 1,2-dichlororethane, D2EHPA and Amberlite LA-2 together with data on the influence of the pH value of the aqueous phase and the Amberlite LA-2 concentration on the selective separation of 6APA, PG and PAA from a mixture, a process flow sheet for the fractionation of the solution obtained by the enzymatic hydrolysis of PG has been elaborated and applied. Thus, at pH=10, 6APA was selectively separated by four extraction stages, the overall extraction degree being 98.8%. PG was selectively extracted from the raffinate at pH=6 by three extraction stages, adjusting the molar concentration of Amberlite LA-2 to the value of the PG molar concentration for each extraction stage. The antibiotic extraction degree was 99.6%.
Acetylsalicylic acid: Incoming 150 years of the first synthesis
Authors: Mijin Dusan , Stankovic Milena , Petrovic Slobodan , Blagojevic Milorad
Published: July 2008

Acetylsalicylic acid is one of the most fascinating and versatile drugs known to medicine, as well as one of the oldest. Acetylsalicylic acid is a drug which is safe, with analgetic, antirheumatic, anti-inflammatory antiplatelet and antithrombotic action. It may be applied not only in clinical practice, but also as prevention. The first known use of an acetylsalicylic acid-like preparation can be traced to ancient Greece. In 1853 Charles Gerhardt published the first synthesis of acetylsalicylic acid. Felix Hoffmann, a chemist for Friedrich Bayer, a German dye company obtained a patent on acetylsalicylic acid some 40 years later. Bayer coined the name Aspirin for the new product. The 20 in century was the century in which many researchers in many companies tried to improve the synthesis of acetylsalicylic acid not only in terms of yield but also purity. This paper describes the history, use, mechanism of action, synthesis and production as well as the purification and stability of acetylsalicylic acid.
Ammonia and carbon dioxide regeneration from multicomponent solutions: II - Simulation and analysis of results
Authors: Jotanovic Milovan
Published: July 2008

This study describes the simulation of the technological process of NH3 and CO2 regeneration from the multicomponent solution NH3-CO2-NaCl-NH4Cl, based on a developed mathematical model of the process. All the parameters of the technological process were obtained from the simulation, and they represent the mass flow rates as well as the physical and chemical properties (pressure, temperature,..) of all the flows shown on the process flowsheet. The calculation of numerous variations of the process also enabled the analysis and establishment for a relation between the crucial process variables and the steam and liquid phase supply. These relations are important for the absorption-desorption process of synthesis, operating process analysis and process control.
Polymers based on renewable raw materials
Authors: Jovanovic Slobodan , Stojanovic Zeljko , Jeremic Katarina
Published: July 2008

The basic raw materials for the chemical industry, which also means for polymer production, are mineral oil and natural gas. Mineral oil and natural gas resources are limited so that sooner or later they will be consumed. For this reason alternative, renewable raw materials for the chemical industry have become the object of intensive investigation all over the world. Some of the results of these investigations concerning renewable raw materials for the production of polymer materials are presented in this paper.
Thermal stability of aliphatic hyperbranched polyesters
Authors: Vukovic Jasna , Bozic Branislav , Lechner Manfred , Jovanovic Slobodan
Published: July 2008

The influence of the molar mass (generation), number and type of end groups on the thermal stability of aliphatic hyperbranched polyesters are presented in this study. Different end groups were obtained by modification of the samples with chlorides of propionic acid and stearic acid. The thermal stability of the hyperbranched polyesters was determined by thermogravimetry using a NET-ZSCH TG 209 instrument in nitrogen atmosphere at a heating rate of 10?C/min. A comparison of the temperatures obtained for mass losses of 5 20 and 40 wt% for unmodified samples showed that the thermal stability increased up to the fourth generation and then remained practically constant. An increase in the thermal stability of modified samples of the second, third and fourth generation was observed.
The thermal degradation of Poly(methyl methacrylate)/silicon carbide nanocomposites
Authors: Popovic Ivanka , Katsikas Lynne , Curovic Slobodanka , Cosic Branka , Cerovic Ljiljana
Published: July 2008

The thermal stability of poly(methyl methacrylate) (PMMA) and silicon carbide (SiC) composites was studied by thermogravimetry. The influence of particle size, SiC structural modification and particle specific surface was analyzed. It was established that particle size had the greatest influence on PMMA/SiC thermal stability and that the most stable composites were those with the smallest particle diameter, i.e the largest particle specific surface. The values of the thermal degradation activation energy indicated that in some cases particle deagglomeration probably did occur which enabled polymer-filler nanoscale interaction and indicated that the system PMMA/SiC could form nanocomposites.
Polymers contamination by heavy metal compounds
Authors: Jovanic Sasa , Stoiljkovic Dragoslav , Popovic Ivanka
Published: July 2008

The contamination of important synthetic (surface unmodified) polymers by various heavy metal compounds (such as copper, manganese and lead) in aqueous medium was investigated in this study. The influence of the pH of the aqueous medium, temperature and metal type on contamination was investigated during a 10 day period. It was found that increasing pH contributed to higher polymer contamination (at higher pH 100 times for copper and up to 400 times for lead), as well as contact with easily penetrable substances. Increasing temperature decreased contamination by the metal compound for PELD and PET which was not the case for PEHD and PR.
Experimental validation of computational fluid dynamic codes (CFD) for liquid-solid risers in clean alkylation processes
Authors: Dudukovic Milorad , Al-Dahhan Muthanna , Roy Shantanu , Kemoun Abdenour
Published: July 2008

This manuscript, based on the presentation given by one of the authors (M.P. Dudukovic) at the Technological and Engineering Forum in Pancevo, May 21 2002, summarizes the use of the computer automated radioactive particle tracking (CARPT) and gamma computed tomography (CT) in obtaining the data needed to validate the Euler-Euler based CFD simulations for solids distribution, flow pattern and mixing in a liquid-solid riser. The riser is one of the reactors considered for acid solid catalyst promoted alkylation. It is shown that CFD calculations, validated by CARPT-CT data, show promise for scale-up and design of this novel reactor type.
Modeling of mixing for stirred bioreactors: 3. Mixing time for aerated simulated broths
Authors: Cascaval Dan , Oniscu Corneliu , Galaction Anca-Irina , Ungureanu Fiorina
Published: July 2008

This paper presents the experiments on mixing efficiency for aerated media for a laboratory stirred bioreactor with a double turbine impeller. The effects of stirrer rotation speed, air volumetric flow rate and stirrer position on the shaft on mixing time for aerated water and simulated broths (CMCNa solutions) were analyzed. Compared to non-aerated broths, the results indicated that the variation of mixing time with the considered parameters is very different, due to the complex flow mechanism of the gas-liquid dispersion, a mechanism which is changed by changing the broth properties or fermentation conditions. Using the Statistics Toolbox of MATLAB some correlations between the mixing time and rotation speed, air volumetric flow rate and stirrer position on the shaft were established. The proposed equations agree well with the experiments, the average deviation being ?9.02%.
Aerogels: II. Applications in catalysis
Authors: Orlovic Aleksandar , Janackovic Djordje , Kostic-Gvozdenovic Ljiljana , Skala Dejan
Published: July 2008

Sol-gel synthesis, and the resulting materials (xerogels and aerogels) are finding increasing application in the synthesis of catalysts, due to their unique characteristics. The most important features of the sol-gel process are: the ability to achieve homogeneity at the molecular level, the introduction of several species in only one step and the ability to stabilize metastable phases. The supercritical drying process produces aerogels with structural features quite different to conventional materials. Some of these characteristics of aerogels can make them very effective catalysts.
Kinetics of glycoalkaloid hydrolysis and solanidine extraction in liquid-liquid systems
Authors: Stankovic Mihajlo , Nikolic Nada
Published: July 2008

The kinetics of glycoalkaloid hydrolysis and solanidine extraction in Analyzed in this study. obtained from dried and milled potato haulm to to which hydrochlotic acid was added is the first liquid phase, while chloroform trichloroethylene or carbon tetrachlondeisthe second organic, liquid phase. The purpose of this paper was to combine the processes of glycoalkaloid hydrolysis to solanidine and solanidine extraction into one step, and to find the optimal liquid-liquid system for such a process.
Synthetic lubricants based on copolymers of n-butyl methacrylate and α-olefins
Authors: Djakov Tatjana , Filipovic Jovanka , Petrovic-Djakov Dusanka
Published: July 2008

Synthetic fluids obtained by the copolymerization of ? -olefins with alkyl esters of unsaturated carboxylic acids have a unique combination of properties of non-polar poly-a-olefins (PAOs) and polar esters in a single molecule. These compounds are characterized by superior thermal, oxidative and hydrolytic stability, miscibility with mineral and synthetic base oils solubility of additives and neutral elastomer behavior. Depending on the molar masses and comonomer ratios in the copolymer molecule, synthetic fluids with a wide range of properties are obtained. These compounds are valuable components in lubricating oil formulations for different applications.
Hydrodesulfurization of light gas oil: Kinetic determination in a batch reactor
Authors: Skala Dejan , Orlovic Aleksandar , Markovic Branislav , Tarlecki-Baricevic Ana , Jovanovic Dusan
Published: July 2008

The performed investigations were directed toward the analysis of the performance and activity of the fresh and regenerated Cyanamid HDS 20C catalyst in a laboratory batch reactor (2 dm3) for the HDS of the diesel fraction (light gas oil, LGO). Testing of the regenerated catalyst was performed with light gas oil (LGO) of different characteristics. The determined values of the reaction rate constant were compared to some published data in the literature for the HDS of specific sulfur compounds as well as the values of the activation energy. The rates of deactivation of the fresh and regenerated catalyst actually existed compared to some other results recently published in the literature. However, such an observed differences were not sufficient to derive a relation which could be used for the determination of the rate of catalyst deactivation.
Inorganic substances in drinking water and their influence on the human body
Authors: Rajkovic Milos
Published: July 2008

In drinking water, which is consumed daily, either directly, or with food there is a number of compounds, organic or inorganic, depending on the water type, origin and processing. The presence of these substances, due to their daily consumption, may exert a negative influence on human health and even lead to tragic outcomes.A list of inorganic substances and elements that may be found in water is presented in this paper, together with their permitted concentrations (MAC values) and the consequences they may cause, if present in concentrations higher than those permitted by regulations. Special emphasis is placed on heavy metals, because in most instances, they influence the human body unfavourably.
Granulated zeolite plant "Alusil", Zvornik
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC's Engineering Department designed basic technological and machine projects for a granulated zeolite production plant, on the basis of which a pilot plant with an initial capacity of 5,000 t/y was constructed in 1984, within Birac - Zvornik production complex. The technology in these projects was developed in the laboratories of the IGPC.Several goals were realized by designing a granulated zeolite production plant. This technology is one of the newest state of the art high tech technologies. The product meets all quality demands, as well as environmental regulations, by which granulated zeolite production for various uses was developed. The granulated zeolite production process is fully automatized, and the product has uniform quality. There is no waste material in granulated zeolite production, because all products with unsatisfactory quality are returned to the process. The production process can be controlled manually, which is necessary during start - up, and repairs.
Detergent zeolite complex "Ceosil", Tallinn, Estonia
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department, together with the "Birac", Zvornik Engineering Department designed basic projects for detergent zeolite production, using waste flotation sand and hydrates. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, production plant in Tallinn, Estonia was constructed, with a capacity of 100,000 t/y from 1989. to 1993. This plant became the biggest producer of detergent zeolite in the world.Several goals were realized by designing the "Ceosil" plant. Waste flotation sand was used and detergent zeolite was produced in a market which is not properly supplied with this zeolite. The product meets all quality demands, as well as environmental regulations. The detergent production process is fully automatized and the product has uniform quality. There is no waste material in detergent zeolite production, because all products with unsatisfactory quality are returned to the process. The production process can be controlled manually, which is necessary during start - up, and repairs.
Wet water glass production plant
Authors: Stankovic Mirjana , Kovacevic Branimir , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant of a capacity of 75,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997. and 1998, increasing detergent zeolite production, from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate dissolution plant. The main goal was increasing the detergent zeolite production. The technological cycle of NaOH was closed, and no effluents emitted, and there is no pollution (except for the filter cake). The wet water glass production process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start - up, and repairs. By installing additional process equipment (centrifugal pumps and heat exchangers) technological bottlenecks were overcome, and by adjusting the operation of autoclaves, and water glass filters and also by optimizing the capacities of process equipment.
Copolymer production plant
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed a project for the reconstruction of the copolymer production plant at "Zeolite Mira", Mira, Italy, using technology developed in the laboratories of the IGPC. The capacity of the reconstructed plant was increased from 17,000 to 25,000 t/y, in 1991 and the product quality was also improved.The product meets all quality regulation, as well as environmental regulations. There is no waste materials, and precautions were chosen to provide safe operation. This process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start-up, and repairs.
Powder detergents production plant
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed basic projects for powder detergent production plant, using technology developed in the IGPC laboratories, in 1998. - 2000. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with a capacity of 25,000 t/y was manufactured, at "Delta In", Zrenjanin, in 2000.This technology was an innovation, because new approach in mixing a powder materials was used, as well as introducing a new type of dryer in detergent production. The product meets all quality demands for detergents with high specific weight (1000 g/l), as well as environmental regulations. The detergent production process is fully automatized, and the product has uniform quality. There is no waste material in detergent zeolite production, because all products with unsatisfactory quality are returned to the process. The production process can be controlled manually, which is necessary during start-up, and repairs.
Dry alcohol production plant
Authors: Stankovic Mirjana , Pezo Lato
Published: July 2008

The IGPC Engineering Department designed basic projects for dry alcohol production plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects a production plant with a capacity of 40 m3/y was manufactured, at "Zorka Pharma", Sabac in 1995-1996. The product meets all quality demands, as well as environmental regulations. The dry alcohol production process is fully automatized. There is no waste in the process, neither gaseous, nor liquid. The chosen process provides safe operation according to temperature regime and resistance in the pipes, air purification columns and filters. Working at increased pressure is suitable for evaporation and condensation at increased temperatures. The production process can be controlled manually, which is necessary during start-up, and repairs.
Cadmium immobilization by hydroxyapatite
Authors: Smiciklas Ivana
Published: July 2008

The contamination of air, soil and water by cadmium is a great environmental problem. If cadmium occurs in nature in ionic form, soluble in water, it easily enters into the food chain. Hydroxyapatite (HAP), Ca-\o(POA)e(OH)2 is a sparingly soluble salt and an excellent matrix for the removal of heavy metals from solutions. Considerable research attention has been paid to the bond between Cc/2+ ions and synthetic hydroxyapatite of known composition. The sorption mechanism is complex. The dominant process is ion exchange, but surface adsorption, surface complexation and coprecipitation can also contribute to the overall mechanism. The sorption capacity depends on the characteristics of hydroxyapatite itself and on the experimental conditions. Under optimum conditions a maximum capacity of 0.8 mol Cd2+/mol HAP can be achieved. HAP is a potential sorbent for the remediation of contaminated water and soil, for industrial waste treatment, and it is also referenced as a material that can be used as a barrier around waste depositories.
Rutin estraction from hardhay flowers - Hyperici herba and underbrush fruits - Hippophaes fructus
Authors: Galaction Anca-Irina , Cascaval Dan
Published: July 2008

The study of rutin extraction from autochthonous hardhay flowers (Hyperici herba) and underbrush fruits (Hippophaes fructus) with methanol, ethanol and 1-propanol at different concentrations, temperatures and duration indicated that the most efficient solvent was 1-propanol, the optimum concentration being determined by the amount and type of natural compounds from the two plants.Using statistical analysis and a factorial second order experiment two mathematical correlations between the degree of rutin extraction and the main parameters influencing the process (1-propanol concentration temperature, duration) were established. For both extraction systems, the considered variables control the extraction process to an extent of 99.2 99.5%, the solvent concentration exhibiting the most important influence especially for rutin extraction from underbrush fruits (Hippophaes fructus).