New technologies in the production of motor fuels from renewable materials

This work presents resources of the Autonomous Province of Vojvodina available for bioethanol and motor fuels (gasoline and diesel fuel) from sustainable resources: corn-stalks, straw, sweet sorghum, pork fat. The physicochemical basis for novel processes for motor fuel production is coupling microwave pyrolysis of oil shale and catalytic cracking of purified pyrolysis oil, hydrothermal liquefaction of algae and swine manure. The effects of the degree of purification of crude pyrolysis oil and oil shale on the degree of their conversion to gasoline and diesel fuel, as well as the product distribution are investigated. The effects of the duration and temperature of hydrothermal liquefaction of microalga, Botryoccocus braunii, and swine manure on their degrees of conversion into bio-oil and its thermal properties are investigated. The development of novel strategy of biofuel in the Autonomous Province of Vojvodina is presented

Research on treatment of liquid radioactive waste containing cobalt by adsorption on poly(acrilic acid) hydrogel

The poly(acrylic acid) hydrogel (PAA) has been suggested as adsorbent material to treat cobalt-60 in radioactive liquid waste. The kinetics of isothermal adsorption of cobalt ions from an aqueous solution onto PAA hydrogel was investigated in the temperature range from 298K to 315 K. The kinetic model of Co2+ adsorption [1-(1-α)1/3]2=kt, was established by using the model-fitting method. The kinetic parameters of Co2+ adsorption (Ea = 41 kJ mol-1, ln [A/min-1]=12) were determined. It was found that cobalt adsorption was kinetically controlled process which is determined by the rate of three-dimensional diffusion Co2+ ions (D3)

Poređenje kinetike bubrenja hidrogela delimično neutralisane poli(akrilne) kiseline u destilovanoj vodi i fiziološkom rastvoru

The isothermal kinetics Curves of the swelling of a poly(acrylic acid) hydrogel in distilled water and physiological Solution at temperatures ranging from 20 to 40 degrees C were determined. The possibility of applying both the Fick's kinetics model anti kinetics model of the first order chemical reaction to the swelling kinetics of the PAA hydrogel in distilled water and physiological Solution were examined. It was found that the possibilities of applying these models were limited. The new model of the kinetics of swelling in distilled water and physiological solution was established. The kinetic parameters (E-a, ln A) for the swelling in distilled water and physiological solution were determined. The decrease of the equilibrium degree of swelling and the saturation swelling rate of the swelling of the PAA hydrogel in physiological solution compared to swelling in distilled water could be explained by the decreased differences in the ionic osmotic pressures between the hydrogel and the swelling medium. The increase of the initial swelling rate in the physiological solution might be caused by an increased density of charges at the network and by an increased affinity of the network towards the water molecules. The increase of the activation energy of the swelling of the PAA hydrogel in the physiological solution is a consequence of its additional "ionic crosslinking".U radu su ispitivane izotermalne kinetičke krive bubrenja hidrogela delimično neutralisane poli(akrilne) kiseline u destilovanoj vodi i fiziološkom rastvoru u temperaturnom opsegu od 20 do 40 °C. Ispitivana je mogućnost primene Fikovog kinetičkog modela kao i kinetike i reda hemijskih reakcija na kinetiku bubrenja poliakrilnog hidrogela.Utvrđeno je da su mogućnosti za njihovu primenu vrlo ograničene. Iz tih razloga primenjen je novi model kinetike bubrenja. Određeni su kinetički parametri (Ea, lnA) za procese bubrenja u destilovanoj vodi i fiziološkom rastvoru. Smanjenje ravnotežnog stepena bubrenja i saturacione brzine bubrenja hidrogela delimično neutralisane poli(akrilne) kiseline u fiziološkom rastvoru u odnosu na destilovanu vodu može se objasniti smanjenjem razlike u jonskom osmotskom pritisku između hidrogela i medijuma za bubrenje. Povećanje inicijalne brzine bubrenja u fiziološkom rastvoru u odnosu na destilovanu vodu prouzrokovano je povećanjem gustine naelektrisanja na polimernoj mreži i povećanim afinitetom prema molekulima vode. Povećanje energije aktivacije hidrogela delimično neutralisane poli(akrilne) kiseline pri bubrenju u fiziološkom rastvoru se objašnjava dodatnim "jonskim umreženjem" hidrogela u fiziološkom rastvoru

NaY zeolite: A useful catalyst for nitrile hydrolysis

The NaY zeolite catalysed hydrolysis of nitriles to primary amides is reported. It is found that aryl nitriles with strong electron-withdrawing substituents and cyanopyridines are readily hydrolysed in the water suspension, while aliphatic nitriles do not react

Rezultati post mortem analize koncentracije alkohola u krvi u Srbiji tokom 2011 godine

The prevalence of alcohol in blood samples from medicolegal autopsies performed in the Institute of Forensic Medicine in Belgrade, in 2011, was studied. In total, 293 blood samples were analyzed for alcohol by headspace gas chromatography. The blood alcohol concentrations were evaluated according to sex, age, and cause of death. The blood alcohol concentrations were . 0.5 g/L in 23.9% of the cases; in suicides 22.4%, accidents 34.4% and homicides 25.0%. The largest proportion of high BACs were found in the sample from subjects killed in traffic accidents. These findings confirm that alcohol use is an important factor in many fatal accidents, suicides and cases of violent death.U ovom radu su razmatrani rezultati post mortem koncentracije alkohola (BAC) u 293 uzorka krvi dobijena na osnovu sudsko-medicinskih autopsija sprovedenih na Institutu za sudsku medicinu u Beogradu tokom 2011. godine. Gasna hromatografija sa headspace tehnikom (HS GH) se koristi kao rutinska i referentna metoda za određivanje alkohola. Podaci su analizirani prema godištu i polu žrtve u trenutku smrti i prema uzroku smrti. Od ukupnog broja žrtava, svaka treća žrtva je bila pod uticajem alkohola u momentu smrti. BAC je bila - 0.5 g/L u 23.9% slučajeva, i to 22.4% kod samoubistava, 34.4% kod nesrećnih slučajeva i 25.0% u slučajevima ubistava. Najveći procenat visokih vrednosti BAC utvrđen je u uzorcima subjekata nastradalih u saobraćajnim nesrećama. Kod žrtava saobraćajnih nesreća, od 42 slučaja pozitivnih na alkohol, 26 žrtava ima koncentracija alkohola u krvi veću od 2 g/L. 90% žrtava pozitivno testiranih na alkohola su muškarci.Analiza pokazuje da je alkohol visok faktor rizika kod mnogih fatalnih nesreća, samoubistava i slučajeva nasilne smrti. Podaci izneti u ovom radu svakako bi trebalo da pomognu u razumevanju uloge alkohola u momentu smrti ali i da skrenu pažnju celom društvu u borbi protiv alkoholizma

About the influence of different external fields on the swelling kinetics of PMAA hydrogels

Hydrogels are 3D cross-linked structures that, due to their unique physical and chemical properties and possible applications, are the subject of intensive research in recent decades. In this work, the effects of external physical fields (ultrasonic (US) and microwave (MW)) on the isothermal swelling kinetics of poly(methacrylic acid) hydrogel were examined. A sample of poly(methacrylic acid) (PMAA) xerogel (PMMAX) was synthesized by the process of cross-linking free radical polymerization, which is described in detail in the paper [1]. The basic primary structural properties of PMMA-X including the equilibrium swelling degree in distilled water (SDeq), the density of xerogel (ρxg), the average molar mass between the crosslinks of a network (Mc), the degree of crosslinking (ρc) and the distance between the macromolecular chains (ξ), were determined and calculated. The isothermal kinetic swelling curves were determined by the tee-bag method at a temperature range of T= 293-323K in the presence of thermal, ultrasonic, and microwave fields. The isothermal kinetic curves of swelling were fitted with the Peppas’ kinetic model [2]. The values of the isothermal kinetic parameters of the Peppas model (k, n) were calculated. Based on the temperature dependence of the parameter using the Arrhenius equation, all values of the activation energy (Ea) and the pre-exponential factor (lnA) of the swelling process in the presence of different physical fields were calculated. The obtained results indicate that the presence of US and MW fields leads to an increase in the values of k, n, Ea, and compared to the corresponding values during conventional heating. The US field relatively slightly increases the value of SDeq, while the MW field significantly reduces the value of SDeq. The values of Ea and lnA at different physical fields are interrelated by a correlation relationship (compensation effect) which is given by the relation: lnAf=0.326+0.406Ea, f The existence of a compensation effect [3] is an indication of the unique mechanism of activation of the polymer network at different physical fields for swelling and of the quantum nature of Ea. The influence of US and MW fields on the diffusion of water molecules through the polymer network, activation of the polymer network for swelling, and relaxation of the polymer network was analyzed

Isothermal kinetics of (E)-4-(4-metoxyphenyl)-4-oxo-2-butenoic acid release from poly(acrylic acid) hydrogel

The isothermal kinetics of the release of the drug (E)-4-(4-metoxyphenyl)-4-oxo-2-butenoic acid (MEPBA) from poly(acrylic acid) hydrogel were studied. The isothermal kinetic curves of MEPBA release from the poly(acrylic acid) hydrogel in bidistilled water at different temperatures ranging from 22 °C to 42 °C were determined. The reaction rate constants of the investigated process were determined using the initial rate, saturation rate and power law. Also, to quickly determine the kinetic model of drug release, the so-called method of reduced time was applied. The influence of the degree of the MEPBA released (α) at the values of the kinetic parameters as well as the presence of a compensation effect was established. The procedure for determining the distribution function of activation energies was developed. This procedure was based on the experimentally determined relationship between the activation energy and the degree of drug released. The process of MEPBA release from PAA hydrogel, almost in entire range, can be described with the model of the drug desorption from the active centers with different specific energies

Kinetic investigation of the immobilization of chromotropic acid derivatives onto anion exchange resin

The adsorption kinetics of pyrazol- (РАСА) and imidazol-azo-chromo-tropic acid (IACA) onto Dowex 1-X8 resin, as a function of the dye concentration and temperature were investigated at pH 4.5. The pseudo-first- and second-order kinetic models and intraparticle diffusion model were used to describe the obtained kinetic data. The adsorption rate constants were found to be in the order of magnitude 10-2 min-1 for all of the used kinetics models. The adsorption capacity increases with increasing initial dye concentration. The study of adsorption kinetics at different temperatures (in the range from 5 to 25 °C) reveals an increase in the rate of adsorption and adsorption capacity with increasing temperature. The activation energy (in the case of РАСА 16.6 kJ/mol, and for IACA 11.3 kJ/mol) was determined using the Arrhenius dependence. Electrostatic interactions between the dye and resin beads were shown to be the adsorption mechanism

Isothermal green microwave-assisted extraction of caffeine from guarana: a kinetic study

The kinetics of isothermal green microwaveassisted extraction of caffeine from guarana seed powder with water at a temperature range from 40 degrees C to 60 degrees C was investigated. The caffeine concentration in the water extract was determined by UV-Vis spectrophotometry. By applying the isoconversional method, it was established that the kinetics of the caffeine extraction from the guarana seed powder with microwave heating is an elementary kinetic process. The model fitting method was used to determine the kinetic model of the caffeine extraction under microwave heating. It was found that the kinetics of the caffeine extraction can, under microwave heating, be modeled by the Jander's model of three dimensional diffusion. The kinetic parameters, activation energy and pre-exponential factor of the caffeine extraction were determined

Effect of ultrasonic field on isothermal kinetics of fullerene polyhydroxylation

The isothermal kinetics of fullerene polyhydroxylation under ultrasonic field was investigated. The isothermal kinetic curves of fullerene polyhydroxylation at different temperatures ranging from 293 K to 313 K were determined. By application of the isoconversion method it was established that the reaction of fullerene polyhydroxylation with sodium hydroxide and cetyl trimethyl ammonium bromide as phase transfer catalyst was kinetically an elementary reaction. The model-fitting method confirmed that the kinetics model of first-order chemical reaction best described the kinetics of fullerene polyhydroxylation under ultrasonic field and the kinetics parameters of fullerene polyhydroxylation were determined (Ea,= 29 kJ/mol and lnA=9.4 min-1). It was established that the reaction rate of fullerene polyhydroxylation under ultrasonic field is higher from 1.5 times to 2.2 times than the rate of comparative reaction under the conventional heating. The activation energy is 28% lower than the value of activation energy determined under the conventional heating, whereas the value of pre-exponential factor is 40 times higher. The decreased value of activation energy (Ea,) and pre-exponential factor (lnA) in the ultrasonic field is explained with the increase in the value of ground energy level of the resonant vibration mode (ν = 500 cm-1) of C60 molecule (Ag(1) vibrational mode) and toluene molecule (out-of plane bending C-C-C vibration) and with the decreased value of anharmonicity factor. [Projekat Ministarstva nauke Republike Srbije, br. 172015OI