Serbian Institute of General and Physical Chemistry

Belgrade, Serbia

Serbian Institute of General and Physical Chemistry

Belgrade, Serbia
SEARCH FILTERS
Time filter
Source Type

Gizdavic-Nikolaidis M.R.,University of Auckland | Easteal A.J.,University of Auckland | Zujovic Z.D.,University of Auckland | Zujovic Z.D.,Serbian Institute of General and Physical Chemistry
Journal of Physical Chemistry C | Year: 2010

Facile and fast microwave- (MW) assisted synthesis of copolymers of aniline and 2-aminobenzoic acid (2ABA) or 2-aminosulfonic acid (2SULFO) was performed by chemical polymerization of several mole ratios of aniline to functionalized aniline (FA). The physicochemical properties of the copolymers thus prepared were compared with the poly(aniline-co-2-aminobenzoic acid) (2ABAPANI) and poly(aniline-co-2-sulfonic acid) (2SULFOPANI) copolymers synthesized by conventional synthesis (CS) at the same temperature. FTIR and UV-vis spectra show the 2ABAPANI or 2SULFOPANI structure in all samples synthesized either conventionally or in the microwave reactor, however the yield was 2.5-3 times higher for nanostructured functionalized copolymers (fPANI) synthesized by MW. The effect of microwave irradiation on the antioxidant properties of the nanostructured 2ABAPANI and 2SULFOPANI copolymers was investigated. These samples showed 2.1-2.4 times better radical scavenger efficacy than their conventionally synthesized counterparts. A formation mechanism of polyaniline nanofibers under MW conditions is tentatively proposed based on thermal and nonpurely thermal effects on the nucleation modes. © 2010 American Chemical Society.


Gizdavic-Nikolaidis M.R.,University of Auckland | Jevremovic M.,Public Company Nuclear Facilities of Serbia | Zujovic Z.D.,University of Auckland | Zujovic Z.D.,Serbian Institute of General and Physical Chemistry
Journal of Physical Chemistry C | Year: 2012

A series of energy- and time-efficient enhanced microwave syntheses (EMS) of polyaniline (PANI) have been performed and are discussed herein. The syntheses were performed at different microwave power levels while keeping the reaction system at a constant temperature of 24 ± 1 °C, with the samples extracted after 10 min of reaction. Molecular weights were determined with GPC (gel permeation chromatography) and showed that the molecular weight of the microwave-generated materials depends on applied power: the higher the power level, the greater the molecular weight. The chemical structure was investigated by FTIR and UV-vis spectroscopy, while the morphology was imaged using scanning electron microscopy (SEM). FTIR and UV-vis spectroscopy confirmed the formation of PANI, and SEM indicated the presence of a mixed morphology, with a prevalence of nanofibers with different aspect ratios. The conductivity of the samples (ca. 3-3.5 S cm -1) was found to be relatively independent of microwave power levels. Surface area measurements were carried out using Brunauer-Emmett-Teller (BET) method, with samples synthesized using EMS showing higher surface areas when compared with conventionally synthesized PANI. The fact that molecular weight depends on applied power implies that microwave-enhanced synthesis can be used to fine-tune PANI reaction conditions, directing it toward specific properties. © 2012 American Chemical Society.


Gizdavic-Nikolaidis M.R.,University of Auckland | Easteal A.J.,University of Auckland | Zujovic Z.D.,University of Auckland | Zujovic Z.D.,Serbian Institute of General and Physical Chemistry
Macromolecular Rapid Communications | Year: 2010

We present the first fast and facile microwave assisted synthesis of polyaniline (PANI) nanofibers ("MWA synthesis"). Under conventional synthesis (CS), the polymer was produced with 79.7% yield after 5 h at ambient temperature. However, under microwave irradiation, the nanofibers were produced with yield of 76.2% after only 5 mm, i.e., with 78.8% after 20 min at ambient temperature. The FTIR and Raman spectra show the PANI structure in all samples either synthesized conventionally or in the microwave. SEM and TEM confirm the nanofibrillar morphology. (Figure Presented) © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.


Gavrilov N.,University of Belgrade | Dasic-Tomic M.,Serbian Institute of General and Physical Chemistry | Pasti I.,University of Belgrade | Ciric-Marjanovic G.,University of Belgrade | And 2 more authors.
Materials Letters | Year: 2011

Nitrogen-containing carbonized polyaniline nanotubes/nanosheets were used to synthesize a novel type of supported Pt nanoparticles electrocatalyst PtNPs/Carb-nanoPANI, with the Pt nanoparticles of ∼ 9 nm in diameter. PtNPs/Carb-nanoPANI nanocomposite was characterized by transmission electron microscopy, cyclovoltammetry, thermogravimetric and XRD analyses. Its electrocatalytic activity towards the oxygen reduction reaction in both the alkaline and acidic solutions was studied by a rotating disc technique. In acidic media, this electrocatalyst was compared to both smooth platinum and commercial C-supported Pt-based electrocatalyst. Its higher specific electrocatalytic activity, which amounted to ∼ 1 mA cm- 2 in the region of diffusion control, was proved. High electrocatalytic activity of PtNPs/Carb-nanoPANI towards the ethanol oxidation reaction in acidic medium was also evidenced. © 2010 Elsevier B.V. All rights reserved.


Suznjevic D.Z.,Serbian Institute of General and Physical Chemistry | Pastor F.T.,University of Belgrade | Gorjanovic S.Z.,Serbian Institute of General and Physical Chemistry
Talanta | Year: 2011

Behavior of hydrogen peroxide in alkaline medium has been studied by direct current (DC) polarography with dropping mercury electrode (DME) aiming to apply it in antioxidant (AO) activity determination. Development of a peroxide anodic current having form of a peak, instead of common polarographic wave, has been investigated. As a base for this investigation the interaction of H 2O 2 with anodically dissolved mercury was followed. Formation of mercury complex [Hg(O 2H)(OH)] has been confirmed. The relevant experimental conditions, such as temperature, concentration and pH dependence, as well as time stability of hydrogen peroxide anodic current, have been assessed. Development of an AO assay based on decrease of anodic current of hydrogen peroxide in the presence of antioxidants (AOs) has been described. Under optimized working conditions, a series of benzoic acids along with corresponding cinnamate analogues have been tested for hydrogen peroxide scavenging activity. In addition, the assay versatility has been confirmed on various complex samples. © 2011 Elsevier B.V. All rights reserved.


Bascarevic Z.,University of Belgrade | Komljenovic M.,University of Belgrade | Miladinovic Z.,Serbian Institute of General and Physical Chemistry | Nikolic V.,University of Belgrade | And 3 more authors.
Construction and Building Materials | Year: 2013

The geopolymers based on fly ash were exposed to the concentrated (6 M) NH4NO3 solution for 540 days. The highest compressive strength decrease occurred in the initial 28 days testing period. Study of the effects of the NH4NO3 solution on the geopolymer structure indicated leaching of alkali and alkaline earth cations and breaking of -Si-O-Al- bonds in aluminosilicate gel. The reduction of compressive strength of the geopolymers was associated with the structural defects in the aluminosilicate gel created by breaking of -Si-O-Al- bonds. Subsequent fluctuation in compressive strength was a result of the structural defects reparation by silicon.© 2013 Elsevier Ltd. All rights reserved.


Gorjanovic S.Z.,Serbian Institute of General and Physical Chemistry | Novakovic M.M.,Serbian Institute of Chemistry | Potkonjak N.I.,Serbian Institute of General and Physical Chemistry | Ida L.-C.,University of Belgrade | Suznievic D.Z.,Serbian Institute of General and Physical Chemistry
Journal of Agricultural and Food Chemistry | Year: 2010

A novel antioxidative assay based on direct current polarography has been developed. Quantification of antioxidative (AO) activity has been based on a decrease of hydrogen peroxide anodic current in the presence of antioxidants. An efficient experimental procedure, without any special pretreatment of analyzed samples, has been applied. Antioxidative activity of different kinds of commercial beers (dark, blond, and alcohol-free), some small-scale made special beers with medicinal herbs and mushroom extracts, extracts themselves, as well as individual phenolic components present in beer has been measured. In addition, changes of AO activity during the full-scale industrial process of beer production have been monitored. A strong correlation between results obtained and total phenolics content has been observed. The assay can be recommended for application in brewing industry, either to survey a process with the aim to optimize relevant technological factors or to analyze quality of final product. © 2009 American Chemical Society.


Gorjanovic S.Z.,Serbian Institute of General and Physical Chemistry | Alvarez-Suarez J.M.,Marche Polytechnic University | Novakovic M.M.,Serbian Institute of Chemistry | Pastor F.T.,University of Belgrade | And 3 more authors.
Journal of Food Composition and Analysis | Year: 2013

Hydrogen peroxide scavenging (HPS) activity of honey of different floral sources and its constituents such as predominant honey flavonoids, phenolic acids, amino and organic acids, and carbohydrates have been assessed by direct current (DC) polarographic assay. The assay was based on decrease of anodic current of hydrogen peroxide complex, formed in alkaline solution, at the potential of mercury dissolution. High correlations between honey HPS activity, its total phenolic content (FC-GAE), antioxidant activity measured by four standard methods (DPPH, TEAC, FRAP and ORAC), and also the relative antioxidant capacity index, were obtained. Statistical evaluation by ANOVA and F-test further confirmed the assay validity. The results for individual compounds showed that HPS activity of honey reflects an integrated action of a wide range of constituents, both phenolics and non-phenolics. The polarographic assay applied is a fast, reliable and low cost alternative to spectrophotometric antioxidant assays commonly applied in analysis of honey and can serve as an indicator of honey quality. © 2013 Elsevier Inc.


Stanislava G.,Serbian Institute of General and Physical Chemistry
Journal of the Institute of Brewing | Year: 2010

Pathogenesis-related proteins (PRs) are involved in the protection of dormant and germinating cereal seeds against pathogenic microorganisms and pests. Moreover, barley grain PRs have considerable technological importance in the brewing of beer. The compact structure of PRs allows them to survive the hostile conditions of the extracellular compartments, where they are usually localized, and enables the endurance of certain classes of PRs during the harsh conditions of the technological steps of beer production. Beer proteome maps reveal a dominant presence of PRs and facilitate association between particular proteins and specific beer quality traits. Current knowledge on the influence of PRs on the various aspects of beer quality has been summarized in this review. © 2010 The Institute of Brewing & Distilling.


Gorjanovic S.Z.,Serbian Institute of General and Physical Chemistry | Novakovic M.M.,Serbian Institute of Chemistry | Potkonjak N.I.,Serbian Institute of General and Physical Chemistry | Suznjevic D.Z.,Serbian Institute of General and Physical Chemistry
Journal of Agricultural and Food Chemistry | Year: 2010

Antioxidant (AO) activity of various red and white wines of different origin as well as some individual phenolic compounds present in wine has been assessed using a polarographic assay. Direct current polarography has been used to survey hydrogen peroxide scavenge (HPS) upon gradual addition of tested samples. Results expressed as reciprocal value of wine volume required for 50% decrease of anodic limiting current of hydrogen peroxide have been validated through correlation with Folin-Ciocalteau and DPPH assays. All wines exhibit HPS activity analogous with total phenolic content and DPPH scavenge. Reliability and accuracy, low cost, and rapid and direct experimental procedure open a wide area for application of this assay, making it a good alternative to standard, widely accepted AO assays. © 2010 American Chemical Society.

Loading Serbian Institute of General and Physical Chemistry collaborators
Loading Serbian Institute of General and Physical Chemistry collaborators