Photocatalytic activity of peg-modified catalysts

This work is focused on the influence of polyethylene glycol (PEG) onstructural, textural and photocatalytic properties of titanium dioxide (TiO2)catalyst. Catalysts were synthesized by sol-gel method using PEG withdifferent molecular weight (600 and 10000) as pore generating agent. Theresults showed that PEG enhances not only porous structure but also changeanatase to rutile ratio. The photocatalytic activity of the synthesized catalystwas measured by decomposition of phenol. The order of catalystphotoactivity was: TiO2/P600>TiO2/P10000>TiO2.The difference in catalystphotoactivity is attributed to their surface area and anatase fraction, ratherthen pore size

Photocatalytic activity of peg-modified catalysts

This work is focused on the influence of polyethylene glycol (PEG) on structural, textural and photocatalytic properties of titanium dioxide (TiO2) catalyst. Catalysts were synthesized by sol-gel method using PEG with different molecular weight (600 and 10000) as pore generating agent. The results showed that PEG enhances not only porous structure but also change anatase to rutile ratio. The photocatalytic activity of the synthesized catalyst was measured by decomposition of phenol. The order of catalyst photoactivity was: TiO2/P600>TiO2/P10000>TiO2.The difference in catalyst photoactivity is attributed to their surface area and anatase fraction, rather then pore size

Synthesis of crystaline silicon oxynitride composites

Silicon oxynitride / silicon nitride (Si2N2O/Si3N4) ceramics have been prepared from Si3N4 powder and amorphous silica (SiO2) by hot pressing at different temperature. It was found that material sintered at lower temperature exhibit fine composite structure composed of equiaxed α-Si3N4 grains and Si2N2O crystals. At higher temperature the growing of Si2N2O particles as well as phase transformation from α-Si3N4 to β-Si3N4 phase take place.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Radioactivity measurements in soils surrounding four coal-fired power plants in Serbia by gamma-ray spectrometry and estimated dose

The study of spatial distribution of activity concentration of U-238, Ra-226, (210)pb, Th-232, K-40 and Cs-237 radionuclides in the surface soil samples (n = 42) collected in the vicinity of four coal-fired power plants in Serbia is presented. Radioactivity measurements in soils performed by gamma-ray spectrometry showed values [Bqkg(-1)] in the range: 15-117 for U-238, 21-115 for Ra-226, 33-65 for (210)pb, 20-69 for Th-232, 324-736 for K-40, and 2-59 for Cs-137. Surface soil radioactivity that could have resulted from deposition of radionuclides from airborne discharges or resuspension of ash from disposal sites showed no enhanced levels. It was found that variation of soil textural properties, pH values, and carbonate content influenced activity levels of natural radionuclides while radiocesium activities were associated with soil organic matter content. Modification of some soil properties was observed in the immediate vicinity ( lt 1 km) of power plants where the soil was more alkaline with coarser particles (0.2-0.05 mm) and carbonates accumulated. Calculated average values of the absorbed gamma dose rate and annual external effective dose originating from the terrestrial radionudides were 69.4 nGy/h and 0.085 mSv, respectively

Preparation of biomorphic SiC ceramics

This paper deals with a new method for producing non-oxide ceramic using wood as a template. SiC with a woodlike microstructure has been prepared by carbothermal reduction reactions of Tilia wood/TEOS composite at 1873K. The porous carbon preform was infiltrated with TEOS (Si(OC(2)H(5))(4)), as a source of silica, without pressure at 298K. The morphology of resulting porous SiC ceramics, as well as the conversion mechanism of wood to SiC ceramics, have been investigated by scanning electron microscopy (SEM/EDS) and X-ray diffraction analysis (XRD). Obtained SiC ceramics consists of beta-SiC with traces of alpha-SiC

Zearalenone and ochratoxin A: adsorption by kaolin modified with surfactant

Octadecyldimethylbenzyl ammonium chloride (OA) was used as a surfactant for the preparation of organokaolin. The natural kaolin (from a plant for production of quartz sand in Rgotina, Serbia) was modified with a surfactant in amount equal to 90% of the kaolin cation exchange capacity (CEC). FTIR spectroscopy was used for characterization of the new product. FTIR spectra confirmed the presence of OA ions at the kaolin surface. Adsorption of mycotoxins – zearalenone (ZEN) and ochratoxin A (OCHRA) was studied by organokaolin at different amounts of adsorbent and pHs. Results showed that the presence of organic cations in the kaolin structure increased adsorption of both ZEN and OCHRA. Adsorption of the mycotoxins by organokaolin increased with increasing amounts of adsorbent and, at the lowest amount of solids in suspension, adsorption of ZEN and OCHRA was slightly higher at pH 7 and 9

Synthesis of silver doped fluoroapatite as perspective filler for food package

Proceeding

Synthesis, characterization and cytotoxicity of a palladium(II) complex of 3-[(2-hydroxybenzylidene)amino]-2-thioxoimidazolidin-4-one

The polydentate ligand 3-[(2-hydroxybenzylidene)amino]-2-thioxoimidazolidin-4-one was synthesized in the intermolecular cyclocondensation reaction of 2-hydroxybenzaldehyde thiosemicarbazone and ethyl chloroacetate. A novel palladium(II) complex was obtained from cis-[Pd(DMSO)(2)Cl-2] by nucleophilic substitution of both DMSO ligands with the iminic nitrogen and the thiolactamic sulfur from the ligand. The structures of the compounds were characterized based on their spectral data. The cytotoxic activities of the ligand and the palladium(II) complex were studied on the tumor cell lines: human colon carcinoma HCT-116 and SW-480 cells using the MTT viability test. The results showed that the investigated palladium(II) complex had a significantly greater cytotoxic effect compared to that of the ligand

Mineralogy and crystallographic properties of heu-type zeolitic tuff from the novakovic deposit, Bosnia and Herzegovina

This paper presents mineralogical and crystallographic characterization of the zeolitic tuff from the Novakovic deposit, Republic of Bosnia and Herzegovina. The zeolitic tuff is of a whitish color composed of Ca-clinoptilolite and an amorphous phase (volcanic glass and amorphous SiO 2 ). The zeolitic tuff was analyzed by X-ray diffraction of the polycrystalline sample (XRPD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), and differential thermal and thermogravimetric (DTA/DTG) methods. According to the results obtained, it can be concluded that the studied zeolitic tuff is composed of Heu-type minerals. Based on the chemical analysis, thermal treatment and XRPD analysis it was determined that this is a mineral Ca-clinoptilolite. Thermal analysis in the temperature range from 300 up to 700°C showed that the examined zeolite minerals from the Novaković deposit are stable up to the temperature of 600°C. The crystal structure of Ca-clinoptilolite has been refined in the centrosymmetric space group C2/m (S.G. 12) with disordered distribution of Al and Si in the tetrahedral framework. The unit-cell parameters are as follows: a = 17.662 Å, b = 17.874 Å, c = 7.402 Å, β = 116.32° and V = 2122.73 Å 3 . The basic structural motif is represented by four channels. Three channels are composed of eight-membered rings, and one of ten-membered rings. The ten-membered (channel A) and one eight-membered channel (B) are parallel to the crystallographic axis c, and the other eight-membered channel is parallel to the a-axis. Ca-clinoptilolite comprises approximately 90 % of the studied zeolite tuff while the rest 10 % is the amorphous phase. The overall cation exchange capacity (CEC) amounts to 187 mmolM + / 100 g, and calcium represents the most abundant cation in the studied sample. The atomic ratios of Si/Al, Na + /(Na + +K + ), and Ca 2+ /(Ca 2+ +Mg 2+ ) are as follows: 4.36, 0.14, and 0.55, respectively. The zeolite tuff is both thermally and structurally stable and has applications in various areas of industry and agriculture. © 2018, Association of Chemists and Chemical Engineers of Serbia. All rights reserved