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

The kinetics of ethanol adsorption from the aqueous phase onto zeolite NaZSM-5

The kinetics of the isothermal adsorption of ethanol from an aqueous solution onto a hydrophobic zeolite of the NaZSM-5 type in the temperature range 298-333 K was investigated. Specific shape parameters of the adsorption degree curves were determined. The changes in the specific shape parameters of the adsorption degree curves with temperature were determined. The kinetic parameters of ethanol adsorption (E-a, ln A) were determined by the initial rate, the saturation rate and the maximum rate methods as well as from the Johnson, Mehl and Avramy equation. The kinetic model of ethanol adsorption kt=[1-(1-alpha)(1/3)] was determined by the "model fitting" method. Ethanol adsorption from aqueous solution onto NaZSM-5 is a kinetically controlled process limited by the rate of three-dimensional movement of the boundary layer of the adsorption phase. A model for the mechanism of ethanol adsorption onto NaZSM-5 is suggested on the basis of the kinetic model. Ethanol molecules in aqueous solution are associated in clusters. The activation energy of the adsorption process corresponds to the energy required for the detachment of an ethanol molecule from a cluster and its adsorption onto the zeolite

Isothermal kinetics of exchange of water absorbed in calcium alginate hydrogel with ethanol

The isothermal kinetics of the exchange of absorbed water in calcium alginate hydrogels with ethanol was investigated. The isothermal kinetic curves were measured within the temperature range from 297 to 316 K. By the application of differential isoconversional methods, it was found that the process of exchange of water absorbed in calcium alginate hydrogel with ethanol has a unique rate determining step (a single step process). Using the model fitting method, it was determined that the kinetics of the exchange can be mathematically described with the kinetic model of the first-order chemical reaction. The values of the kinetic parameters of water exchange: the rate constants (km), energy of activation (Ea = 18.0 kJ∙mol–1), and the pre-exponential factor (ln[A/min–1] = 4.0) were calculated. By using Eyring's equation, the values of thermodynamics parameters: standard enthalpy of activation (ΔH*), standard entropy of activation (ΔS*), and Gibbs energy of activation (ΔG*) were calculated. It was found that the rate of rearrangements of the bound water around hydrophilic groups of a polymeric network has a dominant effect on the kinetics of the exchange of the absorbed water with ethanol. The mechanism of the exchange of adsorbed water with ethanol was suggested. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172015

Effect of UV/ozone treatment on the nanoscale surface properties of gold implanted polyethylene

The effect of ultraviolet (UV) ozone treatment on the surface properties of gold implanted high density polyethylene (HDPE) was investigated at a nanoscale using Atomic Force Microscopy (AFM). HDPE samples were modified by the implantation of gold ions at a dose of 5 x 10(15) ions/cm(2), using energies of 50, 100, 150, and 200 keV, and subsequently treated with UV/ozone. AFM surface topography images revealed that after UV/ozone treatment, the surface roughness of all Au/HDPE samples increased, while Power Spectral Density function increased only for samples implanted using higher energies, with a maximum for 150 keV. The chemical surface composition was homogenous in all cases, which was evidenced by appearance of single peaks in the histograms obtained from the phase AFM images. For UV/ozone treated samples, the shift of the peaks positions in the histograms to the higher values of the phase lag with respect to untreated ones indicated the decrease of surface hardness. Besides, a significant change of fractal dimension of surface grains is observed after UV/ozone treatment

Razlaganje N2O na katalizatoru Cu-ZSM-5 - analiza modela reakcije

The model of mechanism of the nitrous oxide (N2O) decomposition over the catalyst Cu-ZSM-5 proposed in 1999 in the article of Ochs and Turek, is adapted for mentioned process in open reactor and analyzed by the stoichiometric network analysis. Under these conditions five reaction pathways that all contribute to same overall process with defined but different contributions are found. Analyzing stoichiometric reactions of all obtained reaction pathways, in only one of them the nitric oxide (NO) as a product of reaction is found. Controlling the contribution of this reaction pathway to overall process, the control of production of NO as pollutant is makes possible.Model mehanizma reakcije razlaganja azotsuboksida (N2O) na zeolitnom katalizatoru CuZSM-5 predložen 1999. godine u radu Ochsa i Tureka, podešen je za pomenuti proces u otvorenom reaktoru i analiziran stehiometrijskom mrežnom analizom. Pokazano je da pod tim uslovima model predviđa pet reakcionih puteva. Svi oni doprinose ukupnom procesu sa definisanim, ali različitim udelima. Analizom stehiometrijskih jednačina reakcionih puteva nađeno je da se samo u jednom od njih pojavljuje azotmonoksid (NO) kao proizvod. Kontrolom doprinosa ovog reakcionog puta celokupnom procesu otvara se mogućnost kontrole proizvodnje zagađivača azotmonoksida (NO)

Razlaganje N2O na katalizatoru Cu-ZSM-5 - analiza modela reakcije

The model of mechanism of the nitrous oxide (N2O) decomposition over the catalyst Cu-ZSM-5 proposed in 1999 in the article of Ochs and Turek, is adapted for mentioned process in open reactor and analyzed by the stoichiometric network analysis. Under these conditions five reaction pathways that all contribute to same overall process with defined but different contributions are found. Analyzing stoichiometric reactions of all obtained reaction pathways, in only one of them the nitric oxide (NO) as a product of reaction is found. Controlling the contribution of this reaction pathway to overall process, the control of production of NO as pollutant is makes possible.Model mehanizma reakcije razlaganja azotsuboksida (N2O) na zeolitnom katalizatoru CuZSM-5 predložen 1999. godine u radu Ochsa i Tureka, podešen je za pomenuti proces u otvorenom reaktoru i analiziran stehiometrijskom mrežnom analizom. Pokazano je da pod tim uslovima model predviđa pet reakcionih puteva. Svi oni doprinose ukupnom procesu sa definisanim, ali različitim udelima. Analizom stehiometrijskih jednačina reakcionih puteva nađeno je da se samo u jednom od njih pojavljuje azotmonoksid (NO) kao proizvod. Kontrolom doprinosa ovog reakcionog puta celokupnom procesu otvara se mogućnost kontrole proizvodnje zagađivača azotmonoksida (NO)

The Effects of Different Physical Fields on Swelling Kinetics of PMAA-LTA Zeolite Composite Hydrogel Under Controlled Isothermal Conditions

Composite hydrogels are the subject of intensive research due to there specific 3D cross-linked structure with extraordinary physical and chemical properties which enables variety of applications In spite of increasing interest for using different external fields in physical-chemical processes, three are no available literature data about the effects of external fields on swelling and swelling kinetics of hydrogels. Therefore, the effects of (conventional) thermal (TH), ultrasonic (US) and microwave (MW) fields, on the swelling degree and swelling kinetics. A sample of poly(methacrylic acid) (PMAA) xerogel with 10%wt of LTA-zeolite (PMMA-LTA) was synthesized and thoroughly characterized. The isothermal kinetic swelling curves were determined within a temperature range T= 293-323K in the TH, US and MW fields. The results were well fitted with the Peppas’ kinetic model. At all applied fields, with an increase in temperature, there is an increase in the equilibrium swelling degree (SDeq) and the swelling rate constant (k), while the parameter of Pepass's model (n) decreases. The maximum value of SDeq and parameter n is achieved at TH, while the US assisted process leads to the maximum value of k. The minimum value of the activation energy (Ea) and at the same time the maximum value of the pre-exponential factor (lnA) lnA were achieved by applying the MW field. 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 analysed

Insight and Comparison of Property Improvement in LTA and MFI Zeolite Reinforced Poly(methacrylic acid) Highly Concentrated Composite Hydrogels

The preparation of zeolite rich polymeric materials presents a challenge due to the zeolite settlingduring synthesis, poor miscibility, the phase separation and generally insufficient interactionsbetween polymers and zeolites. Combination of LTA, i.e. MFI, zeolite and poly(methacrylic acid) in theform of soft hydrogel network provided the stabilization of the zeolite particles and enabled synthesisof composite hydrogels with very high zeolite concentrations (26-52 mass%).The investigated morphological, mechanical and primary structural properties, water swelling abilityand thermal stability revealed high dependence on zeolite concentration and type. Zeolite particleswere uniformly dispersed in PMAA matrix as confirmed by SEM and there was no agglomeration orzeolite leaching despite very high concentrations. FTIR spectra disclosed the existence of functionalgroups of PMAA network and both zeolite types that interacted mutually and led to increasedcrosslinking density. The established interactions changed the PMAA chain dynamics around theparticles, especially of the LTA type, as showed by XRD. Having much more surface groups capable togenerate interaction with PMAA, LTA zeolite stronger affected all of the investigated properties.Composites’ mechanics was improved both in dry and swollen state compared to the PMAA hydrogel(up to 21.8 times for the sample with the highest LTA concentration). Thermal stability of thecomposites increased with increasing zeolite concentration.The composition-property correlations were determined making this work the base for furtherdevelopment of tailor-made zeolite-PMAA composite hydrogels aimed for specific application.Composites were tested as low-cost, regenerative, environmentally friendly sorbents and showedbetter removal of cationic dye compared to both components (PMAA and zeolite) alone

Insight and Comparison of Property Improvement in LTA and MFI Zeolite Reinforced Poly(methacrylic acid) Highly Concentrated Composite Hydrogels

The preparation of zeolite rich polymeric materials presents a challenge due to the zeolite settling during synthesis, poor miscibility, the phase separation and generally insufficient interactions between polymers and zeolites. Combination of LTA, i.e. MFI, zeolite and poly(methacrylic acid) in the form of soft hydrogel network provided the stabilization of the zeolite particles and enabled synthesis of composite hydrogels with very high zeolite concentrations (26-52 mass%). The investigated morphological, mechanical and primary structural properties, water swelling ability and thermal stability revealed high dependence on zeolite concentration and type. Zeolite particles were uniformly dispersed in PMAA matrix as confirmed by SEM and there was no agglomeration or zeolite leaching despite very high concentrations. FTIR spectra disclosed the existence of functional groups of PMAA network and both zeolite types that interacted mutually and led to increased crosslinking density. The established interactions changed the PMAA chain dynamics around the particles, especially of the LTA type, as showed by XRD. Having much more surface groups capable to generate interaction with PMAA, LTA zeolite stronger affected all of the investigated properties. Composites’ mechanics was improved both in dry and swollen state compared to the PMAA hydrogel (up to 21.8 times for the sample with the highest LTA concentration). Thermal stability of the composites increased with increasing zeolite concentration. The composition-property correlations were determined making this work the base for further development of tailor-made zeolite-PMAA composite hydrogels aimed for specific application. Composites were tested as low-cost, regenerative, environmentally friendly sorbents and showed better removal of cationic dye compared to both components (PMAA and zeolite) alone

Structure–property correlations for composite hydrogels based on poly(methacrylic acid) and high concentrations of LTA zeolite

High concentrations of LTA zeolite (27-52mass%) were embedded in poly(methacrylic acid) (PMAA) matrix to obtain composite hydrogels with porosity and active sites originating from both components. Substandard mechanics of PMAA and aggregation of zeolite particles, were thereby overcome. The composites had remarkably higher density than PMAA xerogel (1700 to1400 kg m−3), higher crosslinking density (54.8 to1.29 mol m−3) and lower swelling degree (41 to 420 kg kg−1). Zeolite particles were uniformly dispersed in PMAA matrix and there was no agglomeration or leaching of zeolite despite very high concentrations. XRD patterns revealed that the inclusion of zeolite particles affected the short-range order in the PMAA matrix. Being an active filler LTA zeolite notably improved thermal stability and mechanics of PMAA hydrogel, multiplying the storage modulus 5.2 times in dry and 21.8 times in swollen state. Structure–property correlations were provided making the base for further development of tailor-made zeolite-PMAA composite hydrogels