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Recent studies of TiO2/TiS2 nanostructures with various morphologies have been reported, usually showing improved properties with applications from electronics and catalysis to solar cells and medicine. However, there is a limited number of studies on the crystal structures of TiO2/TiS2 compounds with corresponding properties. In this research, relevant crystal structures of TiO1–x S x (x = 0, 0.25, 0.5, 0.75 and 1) solid solutions were investigated using an ab initio method. For each composition, crystal structures adopting anatase, rutile and CdI2 structure type were calculated on LDA-PZ and GGA-PBE levels of theory. Novel phase transitions and predicted structures are presented, and apart from several interesting metastable structures, a very interesting pressure-induced phase transition is found in the TiOS compound. Furthermore, electronic properties were studied through the dependence of semiconducting properties on dopant concentration. The first description of the electronic properties of the mixed TiO1–x S x compounds in crystal form has been presented, followed by a detailed study of the structure–property relationship, which will possibly have numerous industrial and technological applications.

New binary catalytic systems based on sulphated zirconia-alumina were synthesized by controlled hydrolysis of alkoxides using relative molar ratios of constituents 1:1, 1:2 and 1:3 in favour of zirconia. The obtained differences in the final catalytic material’s properties may be related to organic precursor memory effect, the applied calcinations temperatures and used alumina contents. The addition of alumina to zirconia affected the structural and surface properties stabilizing bare zirconia by means of slower phase transformation of tetragonal zirconia crystal phase into monoclinic one, further resulting in smaller crystallites sizes and higher surface density of acidic function (sulphates). The best alumina impact on physico-chemical properties was achieved when the highest amount of alumina (e.g. 50%) and lower calcination temperature (500°C) were used, causing relatively high steady-state activity in isomerization of n-hexane at reaction temperature 250 °C. On the other hand, higher calcination temperature (600 °C) played a role in the genesis of greater sulphate density. Catalytic activity and selectivity are expressed as a complex synergistic function of relative density of acid sites together with positive status of other optimized physico-chemical properties of the catalytic material (by activation and calcination temperatures).

Due to the remarkable properties achieved under ambient conditions and with quite limited components, mollusk shells are very appealing natural bio-composites used as inspiration for new advanced materials. Calcium carbonate which is among the most widespread biominerals is used by mollusks as a building material that constitutes 95-99% of their shells. Within the investigation of calcium carbonate polymorphs present in the shells, diverse theoretical and experimental studies were performed, however, further research of these crystalline forms is required. There are very little researches on the energy landscapes of biogenic calcium carbonate which can provide us information about the free energies of already known as well as newly discovered plausible structures. To investigate the structural, mechanical, elastic, or vibrational properties and to predict new possible structures of biogenic calcium carbonate, different calculation methods could be employed. Some of these studies are presented and discussed in this paper.

This paper reports the preparation and electrochemical study of new glassy carbon electrode (GCE) bulk-modified with synthesized hybrid materials: Pt and MoO2 nanoparticles deposited on the multi-walled carbon nanotubes (MWCNTs). The results of electrochemical study of commercial GCE and electrodes modified with Pt–MWCNT and MoO2–MWCNT were obtained by cyclic voltammetry in K4Fe(CN)6 and NaOH solutions. Morphology and structure of the synthesized hybrid materials were analysed using the method of high resolution transmission electron microscopy, indicating the presence of well dispersed nanoparticles of Pt and MoO2 over MWCNT network. The results of the electrochemical study show that the capacitance of electrode modified with MoO2–MWCNT and Pt–MWCNT is 62–65 times higher than the capacitance of the commercial GCE. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 451-03-68/2020-14/200124]

In this contribution, the preparation of hierarchically structured ETS-10-based catalysts exhibiting notably higher activity in the conversion of triolein with methanol compared to microporous titanosilicate is presented. Triolein, together with its unsaturated analog trilinolein, represent the most prevalent triglycerides in oils. The introduction of mesopores by post-synthetic treatment with hydrogen peroxide and a subsequent calcination step results in the generation of an additional active surface with Brønsted basic sites becoming accessible for triolein and enhancing the rate of transesterification. The resulting catalyst exhibits a comparable triolein conversion (≈73%) after 4 h of reaction to CaO (≈76%), which is reportedly known to be highly active in the transesterification of triglycerides. In addition, while CaO showed a maximum conversion of 83% after 24 h, the ETS-10-based catalyst reached 100% after 8 h, revealing its higher stability compared to CaO. The following characteristics of the catalysts were experimentally addressed – crystal structure (X-ray diffraction, transmission electron microscopy), crystal shape and size (scanning electron microscopy, laser diffraction), textural properties (N2 sorption, Hg porosimetry), presence of hydroxyl groups and active sites (temperature-programmed desorption of NH3 and CO2, 29Si magic angle spinning nuclear magnetic resonance (NMR)), mesopore accessibility and diffusion coefficient of adsorbed triolein (pulsed field gradient NMR), pore interconnectivity (variable temperature and exchange spectroscopy experiments using hyperpolarized 129Xe NMR) and oxidation state of Ti atoms (electron paramagnetic resonance). The obtained results enabled the detailed understanding of the impact of the post-synthetic treatment applied to the ETS-10 titanosilicate with respect to the catalytic activity in the heterogeneously catalyzed transesterification of triglycerides.

The TiO2 /carbonized materials in composites provide a synergistic effect of adsorption and photocatalysis. The activated carbon or carbonized material can be prepared using various raw materials that present agricultural waste. The most commonly used process for the preparation of the activated carbon (AC)/carbonized material is chemical activation. Chemical activation produces the activated carbon with a good surface area and pore system, which contributes to better adsorption of organic pollutants. The TiO2 /AC composite materials can be prepared by sol-gel, hydrothermal and metal organic chemical vapor deposition (MOCVD) techniques. The most commonly used techniques for characterization of the TiO2 /AC materials are XRD, BET, TG Analysis and UV-Vis DRS, and will therefore be discussed in this paper. The TiO2 /AC composite materials have shown significant efficiency in removal of organic pollutants from aqueous solutions. The adsorption process of organic pollutants can be affected by various process parameters that will be observed in this paper.

The electrocatalytic reduction of hydrogen peroxide in an alkaline solution has been studied on a hybrid material based on hydrothermally obtained palladium particles supported on graphene (Pd@G). The morphology, structure, and chemical composition of the prepared hybrid material, including spatial distribution of palladium nanoparticles, were examined by SEM, XRD, EDX, elemental mapping, XPS, FTIR, and BET. The hydrogen peroxide reduction reaction (HPRR) was studied by cyclic and square wave voltammetry in an oxygen-free and air-saturated alkaline medium. The Pd@G exhibited pronounced electrocatalytic activity for HPRR, which proceeds via complex electrode mechanisms coupled with adsorption phenomena and hydrogen peroxide disproportionation reaction as a heterogeneous chemical process on the surface of palladium nanoparticles.

The synthesis route by solution combustion, a glycine nitrate procedure (GNP) of CoMoO 4 nanopowders by a glycine as a fuel and as a complexant was examined concerning the photocatalytic aspects and powder characteristics. The synthesized samples were investigated by differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Ultraviolet-Visible (UV/Vis) spectroscopy and nitrogen adsorption method. In this work, we presented a simple and effective method for controlling the composition and morphology of CoMoO 4 . A single-phase α and β crystalline form of CoMoO 4 compound was confirmed by X-ray diffraction (XRD). The photocatalytic activity of CoMoO 4 nanopowders was estimated by the photocatalytic degradation of crystal violet in aqueous solution. In addition, the obtained specific CoMoO 4 nanopowder demonstrated acceptable specific surface area, which can be of particular importance for the photocatalytic processes.

Spider silk fibers, collected from Pholcus Phalangioides spider were used as a template for obtaining magnesium oxide (MgO, periclase) as well as magnesium hydroxide (Mg(OH)2, brucite) fibers. Magnesium oxide fibers were obtained in a simple manner by heat induced decomposition of magnesium salt (MgCl2) in the presence of the spider silk fibers, while magnesium hydroxide fibers were synthesized by hydration of MgO fibers at 50, 70 and 90 C, for 48 and 96 h. According to Scanning electron microscopy (SEM), dimensions of spider silk fibers determined the dimension of synthesized MgO fibers, while for Mg(OH)2 fibers, the average diameter was increased with prolonging the hydration period. The surface of Mg(OH)2 fibers was noticed to be covered with brucite in a form of plates. X-Ray diffraction (XRD) analysis showed that MgO fibers were single-phased (the pure magnesium oxide fibers were obtained), while Mg(OH)2 fibers were two- or single-phased brucite depending on incubation period, and/or incubation temperature. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45012]

Magnesium silicate hydrate (M-S-H) was prepared via one-pot hydrothermal synthesis and electrophoretically deposited (EPD) onto stainless steel substrate (Type 304), varying different process parameters. The optimal conditions for the EPD process were found to be as follows. A stable suspension of material was achieved using isopropanol containing 1% water as dispersing medium and Mg-nitrate as charging additive. The best coating was obtained after three successively repeated EPD processes at a voltage of 30 V, accompanied by drying at room temperature between each EPD cycle. The coating showed a thickness of 31 µm and very smooth surface. After calcination at 900 °C coating retains its adherence to the substrate but undergoes a structural transformation from poorly crystallized M-S-H to well-crystallized clinoenstatite phase which is known for its biocompatibility. As a result, it densifies and shrinks giving grainy and slightly rough surface. Structural properties and parameters of the magnesium silicate hydrate (M-S-H) and clinoenstatite were acquired by XRD technique, while morphology was examined by the analysis of SEM micrographs. This study demonstrates that: i) M-S-H can be synthesized through simple hydrothermal route starting from simple, low-cost precursors, ii) EPD process is an effective technique for deposition of M-S-H materials onto stainless steel and iii) inosilicate mineral (clinoenstatite) can be successfully obtained from M-S-H by calcination at 900 °C. HIGHLIGHTS Magnesium silicate hydrate (M-S-H) was prepared via a one-pot hydrothermal synthesis. The optimal conditions for the electrolytic deposition process were determined. Kinetics of the process were investigated using the Hamaker`s equation. Clinoenstatite can be successfully obtained from M-S-H by calcination.

AX 2-type compounds can be ionic, covalent or molecular types of structure, which depends on the size of atoms and the polarization properties. The materials of such type of the structure have different properties that can find the application in various areas of science and industry. Titanium dioxide, as a material of AX 2-type of the structure is a wide band gap semiconductor that has been widely investigated due to its photocatalytic properties and applicability for various purposes, such as the production of solar cells, decontamination of pollutants, elimination of microorganisms, suppression of cancer cells, etc. Experimental and theoretical studies of this metal oxide can give different data on the stability of individual crystalline modifications and their transitions. This study has presented an overview of theoretically examined TiO 2 modifications and current problems that can be encountered (such as various band gap values obtained by different methods and functionals; the difference between the stability of modifications examined on ab initio level and experimentally; the character of chemical bonds and transitions at the specific temperature and pressure conditions…) and overrun by optimal corrections added in calculations.

A visible-light-responsive hybrid material was prepared by surface-modification of γ-Al2O3, an insulator with a bandgap of about 8.7 eV, with 5-aminosalicylic acid (5-ASA), leading to the formation of an interfacial charge transfer (ICT) complex. The microstructural characterization of pristine γ-Al2O3 includes X-ray diffraction analysis, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The pristine γ-Al2O3 powder consists of agglomerated rod-like nanoparticles ((2-3) × (15-20) nm, diameter × length) with the large specific surface area (~420 m2/g). An enormous absorption red-shift is observed upon the formation of the ICT complex. The absorption onset of the inorganic-organic hybrid was found to be at 730 nm by diffuse reflection spectroscopy. The photocatalytic performance of prepared samples was thoroughly tested using the decolorization of the organic dye crystal violet (CV) under illumination in different spectral regions and different light intensities. Excitation with UV light leads to complete decolorization of CV, while the degradation kinetics are impeded when a visible light source is used. Also, the increase of UV light intensity induced significantly faster degradation kinetics of CV, while the degradation rates of CV are quite insensitive to the increase of visible light intensity.

Biomaterials are characterized as any material of natural or synthetic origin that comes into contact with the tissue, blood or biological fluids of a patient and which are, due to their exceptional structural characteristics but also potential applications in many branches of industry and medicine (prosthetic, diagnostic, therapeutic, or storage applications, etc.) used to improve the patient's life. Biomaterials which can be found everywhere in nature, both on land and in water, are of particular importance. These are materials based on spider silk, silkworms, corals, shells, fish bones as well as eggshells. The structure of these materials is extremely interesting because of the features such as remarkable physicochemical and mechanical properties that further allow the application in various branches of medicine such as orthopedics, neurology, dentistry, tissue engineering. The application is based on the use of these materials in the form of various implants, biomolecule carriers, wound healing agents, antimicrobial agents, dental fillings because they have an extremely long duration time and there is a minimal need for replacement or repair.

A glassy carbon electrode was functionalized by MoO2 nanoparticle–decorated multiwalled carbon nanotubes (MWCNTs) and examined as a working electrode in oxyfluorfen (OXY) detection by differential pulse stripping voltammetry (DPSV). Measurement parameters were as follows: initial potential − 0.1 V, end potential + 0.5 V, accumulation potential − 0.15 V, accumulation time 80 s, and scan rate 50 mV s−1. A stripping potential of + 0.315 V vs. Ag/AgCl was employed. The pPesticide oxyfluorfen was determined in model samples by DPSV with good reproducibility (RSD

A glassy carbon electrode was functionalized by MoO

This study examined the hepatoprotective and anti-inflammatory effects of anthocyanins from Vaccinim myrtillus (bilberry) fruit extract on the acute liver failure caused by carbon tetrachloride-CCl4 (3 mL/kg, i.p.). The preventive treatment of the bilberry extract (200 mg anthocyanins/kg, orally, 7 days) prior to the exposure to the CCl4 resulted in an evident decrease in markers of liver damage (glutamate dehydrogenase, sorbitol dehydrogenase, malate dehydrogenase), and reduced pro-oxidative (conjugated dienes, lipid hydroperoxide, thiobarbituric acid reactive substances, advanced oxidation protein products, NADPH oxidase, hydrogen peroxide, oxidized glutathione), and pro-inflammatory markers (tumor necrosis factor-alpha, interleukin-6, nitrite, myeloperoxidase, inducible nitric oxide synthase, cyclooxygenase-2, CD68, lipocalin-2), and also caused a significant decrease in the dissipation of the liver antioxidative defence capacities (reduced glutathione, glutathione S-transferase, and quinone reductase) in comparison to the results detected in the animals treated with CCl4 exclusively. The administration of the anthocyanins prevented the arginine metabolism&rsquo, s diversion towards the citrulline, decreased the catabolism of polyamines (the activity of putrescine oxidase and spermine oxidase), and significantly reduced the excessive activation and hyperplasia of the Kupffer cells. There was also an absence of necrosis, in regard to the toxic effect of CCl4 alone. The hepatoprotective mechanisms of bilberry extract are based on the inhibition of pro-oxidative mediators, strong anti-inflammatory properties, inducing of hepatic phase II antioxidant enzymes (glutathione S-transferase, quinone reductase) and reduced glutathione, hypoplasia of Kupffer cells, and a decrease in the catabolism of polyamines.

A new, simple, rapid, sensitive and selective kinetic spectrophotometric method for Pd(II) traces determination was elaborated in this paper. It is based on the catalytic effect of palladium ions upon the oxidation of methylene blue B (MBB) by (NH4)2S2O8 (APS) in citric buffer (BUF) solution. At the working temperature of 25 C and the wavelength of 662.4 nm, the optimal conditions for palladium determination were found. RSD value was found to be 2.6 to 4.9% for the investigated concentration range of Pd(II). Limit of detection (LD) was found to be 2.0 ng cm–3 Pd(II), and limit of quantification (LQ) is 6.9 ng cm–3 Pd(II). Only the presence of Pb2+, Hg2+ and Sn2+ in the reaction mixture interferes the determination of palladium by this method, while Au3+ and Ag+ have the catalytic effect upon the reaction rate. By this method, it is possible to determine the Pd(II) traces in the concentration range of 3.3x10–8 to 1.0x10–6 g cm–3. The method was confirmed by determination of Pd(II) traces in alloy PtRhG as well as in the powder of Pt. The obtained results were compared to those obtained by ICP-OES method and good agreement of results was found. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172051]

In this review article, we summarize the current knowledge about the applicability of advanced oxidation processes (AOPs) such as UV/H2O2, Fenton and photo-Fenton for removal of textile dyes from wastewater and the effect of operational parameters (initial dye concentration, initial H2O2 concentration, initial Fe2+ concentration and initial pH) on these processes. Numerous studies have reported the use of AOPs for degradation of textile dyes, and the results show that they are very effective. By comparing the results of the previous studies, it seems that the photo- Fenton process is more efficient than the Fenton and UV/H2O2 process.

Titania based catalyst and TiO2 doped with zirconia were prepared by modified sol–gel method. The synthesized catalysts samples were characterized by BET, XRD, SEM and FTIR techniques. Photocatalytic activity was tested in the reaction of crystal violet (CV) dye decolorization/decomposition under UV light irradiation. The effect of several operational parameters, such as catalyst dosage, initial dye concentrations, duration of UV irradiation treatment and number of reaction cycles were also considered. The obtained results indicated faster dye decolorization with the increase of the catalyst amount and a decrease of initial CV concentrations. An influence of doping with zirconia on the physico-chemical properties of bare titania was studied. The doping procedure had affected photocatalytic properties of the final catalytic material, and had improved photocatalytic performances of doped catalyst on crystal violet decolorization/degradation in comparison to bare titania. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 1612008, Grant no. 45012 and Grant no. 172061]

This study examined the nephroprotective effects of 15 different anthocyanins from the bilberry extract on the acute kidney injury caused by CCl4. The acute nephrotoxicity in rats was induced 24 h after the treatment with a single dose of CCl4 (3 mL/kg, i.p.).The nephroprotective effects of the anthocyanins were examined in the animals that had been given the bilberry extract in a single dose of 200 mg of anthocyanins/kg daily, 7 days orally, while on the seventh day, 3 h after the last dose of anthocyanins, the animals received a single dose of CCl4 (3 mL/kg, i.p.) and were sacrificed 24 h later. When the nephrotoxicant alone was administered, it resulted in a substantial increase of the pro-oxidative (TBARS, CD, H2O2, XO, and GSSG) and pro-inflammatory markers (TNF-α, NO, and MPO), as well as a noticeable reduction of the antioxidant enzymes (CAT, SOD, POD, GPx, GST, GR) and GSH when compared to the results of the control group. Moreover, the application of CCl4 significantly influenced a reduction of the renal function, as well as an increase in the sensitive and specific injury indicators of the kidney epithelial cells (β2-microglobulin, NGAL, KIM1/TIM1) in the serum and urine of rats. The pretreatment of the animals poisoned with CCl4 with the anthocyanins from the bilberry extract led to a noticeable reduction in the pro-oxidative and pro-inflammatory markers with reduced consumption of the antioxidant defence kidney capacity, compared to the animals exposed to CCl4 alone. Anthocyanins have been protective for the kidney parenchyma, with an apparent absence of the tubular and periglomerular necrosis, severe degenerative changes, inflammatory mononuclear infiltrates and dilatation of proximal and distal tubules, in contrast to the CCl4-intoxicated animals. The nephroprotective effects of anthocyanins can be explained by strong antioxidant and anti-inflammatory effects achieved through the stabilization and neutralization of highly reactive and unstable toxic CCl4 metabolites.

Simple route was used for synthesis of nanostructured titania samples doped with 3 and 6 mol% of Cr3+ Titanium(IV)-isopropoxide and water were used as starting materials and as an agents for controlling hydrolysis and condensation reactions. The phase evolution of titania (TiO2) was followed by calcination at 400, 600 and 800 degrees C. The synthesized powders were examined by field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). Single-phase anatase was obtained at low temperature (400 degrees C) in all cases. The photocatalytic activity of TiO2 doped nanopowders was evaluated by the photocatalytic degradation of crystal violet in aqueous solution. The present study indicates that this simple synthesis method can be an effective route to produce efficient photoactive doped anatase nanopowders. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Heterogeneous catalysis is in recent focus of research for biodiesel production from vegetable oils because of advantages such as easy separation and reuse of catalysts, although homogeneous catalysis is most commonly used method. The aim of this study was preparation of γ-Al2O3 support by modified sol-gel procedure, synthesis of the KI/Al2O3 catalyst and testing its activity in the transesterification of sunflower oil with methanol. Influences of different process parameters on conversion of sunflower oil to methyl esters were examined. The gained results implicate that the potassium iodide incorporation into/onto the structure of γ-Al2O3 significantly influences textural and structural properties of the catalyst. Additionally, the catalyst basic strength is increased and all together those properties are positively affecting the activity of the catalyst in the reaction of transesterification of sunflower oil with methanol. The impregnation of alumina with potassium iodide resulted in the additional formation of basic catalytically active sites. The surface properties of the catalyst have an essential impact on its catalytic performance. Under relatively mild process conditions and relatively short reaction time, the usage of the KI/Al2O3 catalyst resulted in very high conversion to fatty acids methyl esters (i.e. 99.99 %). [Projekat Ministarstva nauke Republike Srbije, br. 172061 i br. TR 34008]

A new biosorbent, abbreviated as LVB-ZrO₂, was synthesized by chemically modifying Lagenaria vulgaris shell with ZrO₂. The removal of textile dye RB19 from aqueous solution by LVB-ZrO₂was studied. Characterization by SEM, FTIR and XRD confirmed the chemical modification of the biomaterial, which showed significant improvement of removal efficiency compared with unmodified Lagenaria vulgaris shell. LVB-ZrO₂point of zero charge is 5.49. The biosorption process is highly pH dependent and the optimal pH is 2.0, at which complete dye removal was attained. The results are the best by a pseudo-second order kinetic model. The optimal adsorbent dosage is 4 mg/dm³.The RB19 biosorption follows the Langmuir isotherm model (R² = 0.9978), with the maximum sorption capacity of 75.12 mg/g. LVB-ZrO₂is a mechanically stable, easy to synthesize, cost-effective, biocompatible and environmentally-friendly biosorbent with the high potential for the removal of RB19 from aqueous solution.

Three types of functional ceramic composites were designed, synthesized and probed for effective sulfide removal from aqueous solutions. The main goal was to examine complex influence of graphite, surpluses of Fe (similar to 4%) and micro-additions of Cu (similar to 0.2%) on the functional features of the composites. The structural, textural, morphological and surface characteristics of the composites were examined in detail by XRD, nitrogen sorption, SEM and FTIR. It has been shown that all composites are solid heterogeneous systems containing amorphous and crystalline phases (graphite, hematite, montmorillonite, quartz, etc.) with pronounced redox activity in contact with sulfide aqueous solutions. Great enhancment of sulfide consumption was detected for composites which contained graphite and it was established that reaction kinetics is fitted to irreversible second-order batch reaction with two reactants. After the treatment of 1 mM S2- solution, using composite dossage of 1 g/dm(3), concentration dropped down to 0.02 mM. In addition, cyclic voltammetry at 50 mV/s revealed the key role of dopants in electrochemical aspect of the process. Obvious boost of S2- uptake is ascribed to numerous electrochemical, chemical and sorption processes on the composite's developed surface.

Titanium dioxide, as environmental (decontamination) photocatalyst, is increasingly gaining importance in the removal of organic pollutants from water and air, as well. Different methods can be used for obtaining TiO2 catalyst, but sol-gel and hydrother­mal methods are most commonly used for the synthesis and modification of TiO2. The properties of nanostructured materials such as crystal phase, surface features and electronic structures can be changed with doping. In this paper, the influence of Fe and Zn as dopants on the physico-chemical properties of TiO2 catalyst will be presented based on the reported literature data. Usually applied instrumental tech­niques for the materials characterizations are X-ray diffraction (XRD), SEM, TEM, FTIR and UV-vis spectroscopy. The removal efficiency of various organic pollutants (organic dyes, antibiotics, pesticides, xenobiotics) is determined by the characteristics and dosage of the catalyst, nature and initial concentration of pollutants.

An application of coatings composed of mixed (hydr)oxides over bentonite particles in aqueous suspension, in narrow range of pH, has been proven as a useful method for obtaining bentonite based composite with a developed, specific surface area and pronounced adsorption features toward cationic pollutants. This paper deals with detailed characterization of structure as well as textural and adsorption properties of bentonite based composite. The structure of the composite was examined by using XRD technique providing results that confirm changes in orientation of layered quasi-crystalline particles of montmorillonite, which is the most common component of bentonite clay. Surface area and pore volumes were determined by N-2 adsorption at -196 degrees C using BET, t-plot, alpha(s)-plot, Dubinin Radushkevich and Dolli-more Heal method. The results have revealed that the specific surface area for composite is about two times higher than for starting bentonite. Moreover, modification of bentonite leads to significant changes in the meso- and microporosity. Adsorption properties of the composite were studied by analyzing the adsorption of dye methylene blue which was used in this study as a model of cationic pollutant in water. The most prominent role in the mechanism of dye molecules retention on the surface, interlayers and in the pores of the adsorbent is ascribed to establishing of electrostatic, van der Waals and hydrogen bonds. The shape of adsorption isotherm indicates that methylene blue can be adsorbed onto composite in more than one layer. (C) 2014 Elsevier Inc. All rights reserved.

The influence of the physicochemical properties of a series of CaO catalysts activated at different temperatures on the biodiesel production was investigated. These catalysts show dissimilar yields in the transesterification of triglycerides with methanol. We have found significant relationships between structural properties (the type of the pore system, the typical CaO crystal phase and the sizes of crystallites (up to 25 nm), the minimal weight percentage of CaO phase, the total surface basicity and potential existence of two types of basic active sites) of CaO prepared and activated by means of thermal treatment at highest temperature and catalytic efficiency. Benefits of this catalyst are short contact time, standard operating temperature and atmospheric conditions, relatively low molar ratios and small catalyst loading. These all together resulted in a very high biodiesel yield of high purity. The properties of different biodiesel (obtained with the use of the prepared CaO catalyst) blends with different diesel and biodiesel ratios indicate that the higher the fraction of biodiesel fuel the better the achieved fuel properties according to the EU standards. A significant reduction of CO2 and CO emissions and only a negligible NOx increase occurred when blends with an increased biodiesel portion was used. The use of biodiesel derived blends, and the eventual complete replacement of fossil fuels with biodiesel as a renewable, alternative fuel for diesel engines, would greatly contribute to the reduction of greenhouse gases emissions. [Projekat Ministarstva nauke Republike Srbije, br. ON 172061 i TR 34008]

Sorption characteristics of three Lagenaria vulgaris-based biosorbents: raw biomass (rLVB), acid–base-activated biomass (aLVB) and sulfuric acid-treated biomass (ccLVB), were compared as a function of contact time, initial methylene blue concentration, and initial pH, in order to evaluate the effect of chemical modifications. The adsorption studies of raw and chemically modified L. vulgaris biomass were compared in batch mode. The Fourier transform Infrared spectroscopy (FTIR) results of biosorbents’ characterization showed presence of different functional groups which can be responsible for sorption of MB from aqueous solutions. Moreover, FTIR analysis reveals that acid–base activation of raw biomaterial resulted in hydrolysis of esters providing more reactive sites (–COO−), while sulfuric acid-treatment method introduced new functional groups such as –SO3−. Surface functional groups containing oxygen, such as carboxylic, lactonic, and phenolic, are quantified using the Boehm’s method. The kineti...

Nanosized Mg-doped ceria powders were obtained by self-propagating room temperature reaction without using surfactants or templates. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are solid solutions with fluorite-type structure and spherical morphology. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Mg concentration. This increasing results in a narrowing of the bandgap of CeO2. The photocatalytic performances of the Mg-doped ceria solid solutions were evaluated by decomposing an organic dye, crystal violet under UV irradiation. The Mg-doped ceria solid solutions exhibit significantly better photocatalytic activity than the pure CeO2 and commercial TiO2. The higher first rate constant of the Mg-doped samples demonstrated that they are much more efficient than TiO2 and CeO2 under UV light. Mg2+ dopant ions and oxygen vacancies play a significant role in the enhancement of photocatalytic performances of the Mg-doped ceria.

This paper presents a complete characterization of rapeseed oil, of Banaćanka variety, as well as the potential use of oil generated after filtering, in order to obtain biodiesel. Researches are based on the fact that Banaćanka is the oldest domestic rapeseed variety, the so-called double zero "00" (low in erucic acid, below 5%, and glucosinolates below than 30 mmol g-1), suitable for use in the region, since it is low temperatures tolerant, posseses high genetic potential for seed yield of about 5.2 t/ha, and high oil content of around 45%. Transesterification was carried out in batch reactor Parr 4520, with KOH as a catalyst. Cold pressed oil without prior treatment was used as feedstock for transesterificataion. The paper analyses the effects of temperature, reaction duration, catalyst amount and rate of agitation on the synthesis of biodiesel at constant pressure and molar methanol/oil ratio.[Projekat Ministarstva nauke Republike Srbije, br. TR-31046: Improvement of the quality of tractors and mobile systems with the aim of increasing competitiveness and preserving soil and environment]

Samples of natural peat (NP) were hydrothermally treated at different temperatures in oxidative and acidic aqueous medium to tailor their acid-base, adsorption, morphological and other properties. The obtained materials were thoroughly characterized by SEM, XRD and FTIR techniques, followed by determination of pH(pzc), examination of adsorption characteristics and the extent of organic matter leaching in water. Acid-base characteristics of these materials were examined by potentiometric and conductometric titration of corresponding aqueous suspensions. Experimental potentiometric data were interpreted using ProtoFit software (NEM, non-electrostatic model) which provided pKa values and concentrations of surface sites which are compared with corresponding values obtained by conductometric titration method. There are two main types of surface groups (carboxylic and phenolic) that are dominant in the materials and determine their acid-base behavior in the aqueous medium. Temperature during oxidative hydrothermal treatment has no significant effect on the total number of surface groups, but influences the ratio of carboxylic and phenol-type groups. Hence, acid-base properties of peat can be tailored, which is useful in designing and improving adsorptive characteristics of peat for the preferential removal of certain pollutants from water.

The procedure for obtaining a bentonite based composite involves the application of mixed Fe and Mg hydroxides coatings onto bentonite particles in aqueous suspension and subsequent thermal treatment of the solid phase at 498K. Structural and textural modifications of montmorillonite which occurred during the synthesis of composite were confirmed by XRD technique and N-2 adsorption at 77K. The composite structure was found to be less ordered, while its specific surface area was about two times higher than the specific surface area of the starting/native bentonite. The effectiveness of the composite in Pb(II) removal from aqueous solutions at different initial concentrations, pH and ionic strengths of the solutions was examined. The equilibrium adsorption data were analyzed using three widely applied isotherms: Langmuir, Freundlich and Dubinin-Radushkevich. The composite effectively removes both ionic and colloidal forms of Pb(II) from water and the maximum adsorption capacity obtained from the Langmuir equation was 95.88 mg/g. The main mechanisms of Pb(II) removal at low pH values were ion-exchange and outer-sphere surface complexation. (C) 2011 Elsevier B.V. All rights reserved.

Adsorption of a cationic phenothyazine dye methylene blueonto activated carbon prepared from pine cones was investigated with the variation in parameters of contact time, dye concentration and pH. The kinetic data were found to follow the pseudo-second-order kinetic modelclosely. The equilibrium data were best represented by the Langmuir isotherm with maximum adsorption capacity of 233.1 mg g-1. Adsorption was favored by using a higher solution pH. Textural analysis by nitrogen adsorption was used to determine specific surface area and pore structure of the obtained carbon. Boehm titrations revealed that carboxylic groups are present in the highest degree on the carbon surface. The results indicate that the presented method for activation of pine cones could yield activated carbon with significant porosity, developed surface reactivity and considerable adsorption affinity toward cationic dye methylene blue.

This paper presents a procedure for the removal of manganese in ionic (Mn 2+ ) and colloidal (MnO 2 ) forms from synthetic waters, by reduction and adsorption processes on electrochemically active alumosilicate ceramics based composite material. Synthesis procedure of the composite material consists of two phases. Firstly, composite particles were synthesized by applying Al/Sn oxide coating on the bentonite particles in an aqueous suspension. In the second phase, aluminum powder was added to the previously obtained plastic mass and after shaping in the form of spheres 1 cm in diameter and drying, sintering was performed at 900 °C. Elemental tin, resulting from the reduction of Sn 2+ ion, comes into contact with liquid aluminum in the pores of the matrix performing aluminum microalloying and activation. Moreover, due to a low partial pressure of oxygen, nonstoichiometric oxides with metal excess are obtained, and they play an important role in the electrochemical activity of composite material. In accordance with this, a redox potential of water is changed in contact with composite. The detailed characterization of the composite was carried out by SEM, FTIR and XRD techniques and the influence of pH values on the removal of ionic form of manganese from water was investigated as well.

Activated carbon prepared from the cones of the European Black pine was used as adsorbent for the removal of lead(II) ions from aqueous solutions. The effect of pH, initial concentration of lead(II) ions, contact time, and adsorbent dosage on the adsorption was studied in a batch process mode. Equilibrium data were analyzed by the Langmuir, Freundlich and Temkin isotherm model. Langmuir isotherm provided the best fit to the equilibrium data with maximum adsorption capacity of 27.53 mg/g. The kinetic data were found to follow closely the pseudo-second-order model. The microstructures of the activated carbon before and after adsorption of lead(II) ions were observed by scanning electron microscope. Textural analysis was employed in order to determine specific surface area and pore size distribution of the prepared activated carbon. Surface structure was characterized by using Fourier transform infrared spectroscopy and Boehm titration.

The heavy metals (Fe, Cu, Zn and Mn) contents of selected plant species, grown in Southeast region of Serbia, that are traditionally used in alternative medicine were determined. Among the considered metals, iron content was the highest one and varied from 137.53 up to 423.32 mg/kg, while the contents of Cu, Zn and Mn were remarkably lower, and ranged from 8.91 to 62.20 mg/kg. In addition, an analysis of plants extracts showed a significant transfer of heavy metals during extraction procedure; therefore, the corresponding extraction coefficients reached values up to 88.8%. Those were especially high in the ethanol based extracts. Moreover, it is established that such coefficients mostly depend on the solvent nature and also on the treated plant species. The obtained results impose that medicinal plants from Southeast region of Serbia due to rather low content of heavy metals are appropriate for preparation of teas and medicinal extracts.

Cones of the European Black pine and Horse chestnut kernel, regarded as brown municipal waste, was utilized in this work as a precursor for powdered activated carbons. Chemical activation was employed at 500?C in inert atmosphere of nitrogen. Standard physico-chemical analyses were performed to examine obtained products. FTIR method was employed to determine fuctional groups which were found to be typical for activated carbons. Acidic oxygen groups were quantitatively determined using Boehm titrations. It was established that carboxylic groups on pine cone activated carbon, and phenolic groups on chestnut kernel activated carbon were dominant from all acidic oxygen groups. Since both contact pH and pHPZC were determined to be fairly acidic, it could be concluded that obtained activated carbons belong to L-type. Shape and layout of micrometer dimensioned particles were observed by scanning electron microscopy. Particles of different shapes and dimensions along with small cracks and wide crevices and voids were noticed. Textural analysis was used to determine specific surface area and pore distribution of obtained activated carbons. Obtained products possess highly developed surface area and wide pore distribution.

Calcium oxide as a heterogeneous catalyst was investigated for its effect on the biodiesel synthesis from refined sunflower oil. Experiments were carried out using a commercial bench stirred tank reactor of 2 dm 3 volume, at 200 rpm, with a methanol to oil ratio 6 to 1 and 1 mas.% catalyst loading as constant parameters. Ester yields were followed as a function of temperature (60–120 °C), pressure (1–15 bars) and reaction time (1.5–5.5 h). The temperature of 100 °C was found to be optimal for the maximum (91%) conversion to methyl esters, while pressure had a positive impact up to 10 bars at 80 °C. The catalyst activation in air leading to the formation of strong basic sites was found to occur at 900 °C. Catalyst particle coalescence took place during the reaction, giving a gum-like structure, and resulted in a significant catalyst deactivation. The pseudo-first order reaction was established, with a “knee” at 80 °C in the Arrhenius plot separating the kinetic and diffusion regimes. During the reaction progress, an activation energy decrease from 161 to 101 kJ/mol, and from 32 to (−3) kJ/mol, was found for the kinetic and diffusion regimes, respectively.

Fruits and vegetables constitute the cheapest source of essential trace elements for the majority of people living in developing countries. The Cu, Fe and Zn contents in twenty selected wine samples produced in the South-East region of Serbia were determined by flame atomic absorption spectrometry. The Cu concentrations varied from 0.07 to 0.57 ppm in wines, and the Fe concentrations fluctuated from 2.93 to 36.2 ppm, while the Zn levels were in the range from 0.21 to 0.67 ppm. The established contents of Cu and Zn showed that wines from this part of the world could serve as good dietary sources of the essential trace metals, and the determined values were within the allowed metals levels in wines for human consumption.

Using sulfuric acid as the sulfating agent, two catalyst series were obtained from hydroxide and nitrate precursor with a sulfate loading identical to commercial sulfated hydroxide, i.e., 4.2 mass%. After calcination at 500, 600 and 700?C, all nine samples had various contents of residual sulfates depending on the origin of the catalyst. Accordingly, their surface properties were different, which, together with various textural properties, govern the formation of the active phase and their catalytic activity in the n-hexane isomerization reaction. The dominant activity and yield of mainly mono-branched isomers were attained in reaction at 200?C with a commercially sulfated zirconia catalyst calcined at 500?C. Among the SZ catalyst series synthesized from hydroxide and nitrate, the second according to its activity profile was similar to that of the commercially sulfated one, while samples originating from hydroxide showed some activity only after calcination at 600?C. This is due to the poorer textural properties of the hydroxide series, necessitating a higher calcination temperature in order to promote the simultaneous decomposition of S-containing species and their re-adsorption into the zirconia matrix following interaction and active phase formation. It seems that the tetragonal zirconia phase was not responsible for the catalytic activity but a synergistic effect of the textural properties of the samples and the sulfate loadings, which determine different acid strengths on the catalyst surface.

Properties of two catalysts tailored in the laboratory conditions by sulfation of commercial Zr-hydroxide and Zr-hydroxide of nitrate origin were compared with those of commercial SO4-Zr-hydroxide. Equally thermally treated samples in the temperature interval 500–700°C, and having the same amount of sulfur, show different properties indicating memory effect of their solid parent materials. The catalyst obtained by sulfation of commercial Zr-hydroxide differs in amount of residual sulfates upon calcination from other two catalysts. The instability of sulfates in the previous case might be connected to the lowest surface area values of catalyst and the highest fraction of monoclinic phase observed at all applied calcination temperatures.

Spider silk poses excellent mechanical properties, tenacity and elasticity and it has been used as a template for calcite mineralization to improve load bearing strength of osteoconductive calcite. The samples were obtained by mimicking biomineralization for five days in order to follow formation and growth of calcite on the surface of spider silk. Crystal phase was detected by XRD and FTIR spectroscopy. Microstructure, crystal size and its morphology were studied by means of FESEM. After two days of processing, pure calcite phase was obtained, and a size of the formed crystals increased with prolongation of biomineralization.

Magnesium-orthotitanate (Mg2TiO4) nano-powder was synthesized using a Pechini-type polymerized complex route. Microstructural characterization involving transmission electron microscopy, X-ray diffraction analysis and nitrogen adsorption-desorption isotherms indicated that well-crystallized Mg2TiO4 nanoparticles are small in size (about 10 nm) with large specific surface area (72 m(2) g(-1)). The surface modification of Mg2TiO4 nano-powders with 5-amino salicylic acid and catechol induced a significant shift of absorption to the visible spectral region due to charge transfer complex formation. It should be emphasized that tunable optical properties of Mg2TiO4 nano-powders have never been reported in the literature. Degradation reactions of an organic dye (crystal violet) were used to test the photocatalytic ability of pristine and surface-modified Mg2TiO4 nano-powders under illumination in different spectral regions. Excitation with UV light indicated, for the first time, photocatalytic ability of Mg2TiO4. Also, improved photocatalytic performance of surface-modified Mg2TiO4 nano-powders was found in comparison to unmodified ones.

Preparation, characterization and application of materials modified with TiO2 nanoparticle have been reviewed. Chitosan, bacterial biomass and dendrimers were the starting material for modification. Sorbents characterization was performed by scanning electron microscopy (SEM). In order to investigate the sorption capabilities of sorbents, we used them for removal of heavy metal ions from aqueous solution. The effect of contact time on heavy metal ions sorption and maximum sorption capacities of biosorbents are shown. As a very important parameter of the sorption process, the effect of initial pH values on heavy metal removal was examined. This paper indicates that sorption using the material modified with TiO2 is becoming a promising alternative to conventional adsorbents in removing heavy metal ions.

Due to its biocompatibility, biodegradability, hydrophility, technological properties and vast availability, polysaccharides are widely used as natural non-toxic polymers in different branches of industry (food, cosmetic, textile, construction industries). Exopolysaccharides (as dextran, pullulan) have recently taken up a significant position in pharmaceutical industry. Alginate has an irreplaceable role in biomedicine, since its hydrogel form is successfully applied for immobilization of a wide range of enzymes, therapeutics, biochemical agents and different kinds of microorganisms and cells (herbal, animal or human). Alginate microspheres and microcapsules are used for controlled release of biologically active molecules, as well as cell carriers in tissue engineering. Special benefits are brought by the simplicity of configuration of alginate hydrogel, including the possibility of the controlled production of micro- and nanoparticles. Taking into account a very important role of alginates in the form of hydrogel in biomedicine, in this paper a specific attention is paid on the preparation and application of alginate matrices, microspheres and microcapsules that may have essential and unexchangeable usage/application. This paper therefore displays various possibilities of use of polysaccharide matrices for biomolecules, polysaccharide as excipients of pharmaceutical products for oral or local application, and provides a review of the examples of innovative applications.