Electrochemical Behavior of H3pw12o40/Acid-Activated Bentonite Powders

Electrochemical behavior of 12-tungstophosphoric acid (HPW)/acid-activated bentonite (AAB) powders with various loadings of HPW was investigated. The physicochemical properties of the prepared powders were examined by X-ray powder diffraction, nitrogen adsorption-desorption isotherms, atomic force microscopy and cyclic voltammetry measurements. The results indicated that the prepared powders are composed mainly of oriented domains of large rock blocks, probably resulting from a preferable deposition of bentonite particles having a face-to-face interaction. The particles had a mainly disordered mesoporous structure with a pore volume that varied according to the pore size in the range of 2-50 nm. In addition, the particles had crystallite size between 4.9 and 9.0 nm. The electrocatalytic activities of prepared HPW/AAB electrodes were studied in the oxidation of NO2- and the results revealed that the electrodes possessed relatively higher nitrite oxidation currents than AAB electrode. The best electroactivity was observed for HPW3/AAB electrode (AAB + + 20 wt % HPW) and the limit of detection (3 sigma) was determined as 8 mu M

Bioethanol production by immobilized Sacharomyces cerevisiae var. ellipsoideuscells

Bioethanol can be produced by fermentation of sugars from various waste agricultural materials. Whichever system for bioethanol production is chosen, the attention must be paid to the overalleconomics and energy consumption. The aim of the present study was to investigate the immobilization of Sacharomyces cerevisiae var. ellipsoideus yeast cells for bioethanol production fromcorn meal hydrolyzates. For this purpose the biocompatible polymers such as polyvinil alcohol (PVA) and Ca-alginate were assessed. The parameters of ethanol fermentation, such as inoculumconcentration in different carriers and the choice of a convenient carrier for the efficient ethanol production were studied. The maximum ethanol concentration of 10.05% (w/w) was obtained in the fermentation of corn meal hydrolyzates by 5% (v/v) of inoculum concentration of the yeast immobilized in Ca-alginate using a method of electrostatic droplet generation. The repeated batch fermentation with the yeast immobilized in Ca-alginate indicated that alginate gels degraded after the second fermentation cycle. PVA carrier exhibited better mechanical properties and stability; however lower ethanol concentrations were achieved during the fermentation

Novel and highly potent antitumour natural products from cnidarians of marine origin

This article covers the 2003-2012 literature published for marine natural products from the phylum Cnidaria. The focus is on new and highly potent antitumour substances, together with details related to the organism sourced. It describes 12 promising bioactives isolated from 7 species

Further in vitro evaluation of antiradical and antimicrobial activities of phytol

The antiradical activity of phytol was evaluated by electron paramagnetic resonance towards hydroxyl radical (root OH), superoxide anion radical (), methoxy radical (root CH2OH), carbon-dioxide anion radical (), as well as towards nitric-oxide radical (root NO) and 2,2-diphenyl-1-picrylhydrazyl (root DPPH) radical. It reduced the production of all tested radicals showing more promising activity against , root CH2OH and root DPPH radicals (56\%, 50\% and 48\%, respectively) in comparison with root NO, and root OH radicals (38\%, 23\% and 15\%, respectively). The antimicrobial activity of phytol was evaluated by the microdilution method against eight bacterial and eight fungal strains. To varying degrees, it was proven to be active against all tested bacteria and fungi (MIC 0.003-0.038mg/mL and MBC 0.013-0.052mg/mL, MIC 0.008-0.016mg/mL and MFC 0.090-0.520mg/mL, respectively). According to the obtained results, medical foods containing phytol may support development of new therapies for heart disease.Ministry of Education, Science and Technological Development of the Republic of Serbia {[}41005, 173017, 173032, 173040

The paramagnetic pillared bentonites as digestive tract mri contrast agents

The increased use of imaging techniques in diagnostic studies, such as MRI, has contributed to the development of the wide range of new materials which could be successfully used as image improving agents. However, there is a lack of such substances in the area of gastrointestinal tract MRI. Many of the traditionally popular relaxation altering agents show poor results and disadvantages provoking black bowel, side effects of diarrhea and the presence of artifacts arising from clumping. Paramagnetic species seem to be potentially suitable agents for these studies, but contrast opacification has been reported and less than 60% of the gastrointestinal tract magnetic resonance scans showed improved delineation of abdominal pathologies. The new solution has been proposed as zeolites or smectite clays (hectorite and montmorillonite) enclosing of paramagnetic metal ions obtained by ion-exchange methods. However, such materials have problems of leakage of paramagnetic ions causing the appearance of the various side-effects. In this study we show that Co(+2) and Dy(+3) paramagnetic-pillared bentonites could be successfully used as MRI digestive tract non-leaching contrast agents, altering the longitudinal and transverse relaxation times of fluids in contact with the clay minerals

Methanol electrooxidation on PtRu modified zeolite X

Zeolite NaX (faujasite type) was used as a support for platinum-ruthenium catalyst. A procedure for thermal decomposition of noble metal acetylacetonates to deposit noble metal clusters on the surface of solid support was adapted by authors to introduce noble metal clusters in zeolite cavities. The effectiveness of this composite material for methanol electrooxidation from alkaline solution was investigated by cyclic voltammetry. The influence of the concentration of supporting electrolyte, scan rate and rotation rate on the reaction of methanol oxidation was investigated. The obtained activity was compared with literature data for similar catalysts.Zeolit NaX (fožazitnog tipa) korišćen je kao nosač za platina-rutenijumski katalizator. Autori su prilagodili proceduru termalne dekompozicije plemenitih metalnih acetilacetonata kojom su nanošeni klasteri plemenitih metala na površinu čvrste podloge, kako bi se klasteri plemenitih metala su uveli u šupljine zeolita. Efikasnost ovih kompozitnih materijala za reakciju elektrooksidacije metanola je ispitana cikličnom voltametrijom. Ispitan je uticaj koncentracije inertnog (osnovnog) elektrolita, brzine polarizacije i brzine rotacije elektrode na reakciju oksidacije metanola. Dobijena aktivnost je upoređena sa literaturnim podacima za slične katalizatore

Organo-inorganic bentonite for simultaneous adsorption of Acid Orange 10 and lead ions

Partial substitution of the interlayer cations of a local bentonite (Bogovina) by hexadecyl trimethylammonium ions (HDTMA) was performed to prepare adsorbents able to simultaneously adsorb toxic metal cations and organic pollutants. Acid Orange 10 adsorption increased with increasing HDTMA addition, while the adsorption of Pb2+ decreased with increasing organophilicity. The adsorption of the dye and Pb2+ and their mixture onto Na-rich bentonite and HDTMA-bentonites, regardless of adsorbents' organophilicity, obeyed the pseudo-second-order kinetics model. (C) 2009 Elsevier B.V. All rights reserved

Synthesis and characterization of self-assembled polyaniline nanotubes/silica nanocomposites

Self-assembled semiconducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of colloidal silica particles of an average diameter ∼12 nm, without added acid. The electrical conductivity of polyaniline nanotubes/silica nanocomposites is in the range (3.3-4.0) × 10-3 S cm-1. The presence of paramagnetic polaronic emeraldine salt form of polyaniline and phenazine units in nanocomposites was proved by FTIR, Raman, and EPR spectroscopies. The influence of the initial silica/aniline weight ratio on the morphology of polyaniline/silica nanocomposites was studied by scanning and transmission electron microscopies. Nano-composites synthesized by using the initial weight ratio silica/aniline ≤0.2 contain polyaniline nanotubes which have a typical outer diameter of 100-250 nm and an inner diameter of 10-80 nm, and nanorods with a diameter of 60-100 nm, accompanied with polyaniline/silica nanogranules, while the nanocomposite synthesized at weight ratio silica/aniline ∼2 contains polyaniline/silica nanogranules with an average diameter of 35-70 nm. The evolution of molecular and supramolecular structure of polyaniline in the presence of colloidal silica is discussed

Properties of Zirconia/Polyaniline hybrid nanocomposites and their application as photocatalysts for degradation of model pollutants

A serie of novel ZrO2/Polyaniline (PANI) hybrid nanocomposite powders were successfully synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate (APS) in water, in the presence of ZrO2 nanoparticles. Syntheses were performed at initial ZrO2/aniline mole ratios 50,100 and 150 to produce ZP-50, ZP-100 and ZP-150. The morphological, structural, and optical properties of the synthesized nano composites were studied using Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Raman, UV-Vis and Electron-paramagnetic resonance (EPR) spectroscopies. EPR spectra of ZP-50 and ZP-100 nanocomposites showed the presence of intensive peak at the g-values comparable to that for free electrons (2.0023) indicating the presence of oligo/poly (semiquinone radical cations), i.e. polarons as charge carriers in PANI part; ZP-150 showed weak polaron peak of PANI, and peak that can be assigned to defects in zirconia matrix (Zr3+, oxygen vacancies). The monoclinic crystal structure of ZrO2 nanoparticles in all nanocomposites was confirmed by XRD and by Raman spectroscopy. The photocatalytic activities of ZP nanocomposites were evaluated using the photocatalytic degradation of trichlorophenol (TCP) and Rhodamine B model compounds and compared with the activity of bare ZrO2 nanoparticles. Enhanced degradation efficiencies of nanocomposites regarding TCP degradation were observed. (C) 2017 Elsevier B.V. All rights reserved