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Facile Synthesis of Spinel Nanocrystalline ZnFe2O4: Enhanced Photocatalytic and Microbial Applications

Abstract

Spinel ZnFe2O4 was developed successfully as a heterogeneous-Fenton catalyst for the degradation of Reactive Yellow 86 (RY 86) under UV light. The ZnFe2O4 was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and UV-diffuse reflectance spectroscopy (UV-DRS). FE-SEM reveals that the some of the particles sizes are in the range from 10 nm to 50 nm. The photocatalytic performance of ZnFe2O4 was evaluated by degradation of RY 86 dye solution under UV light. The degradation rate was highly influenced by pH, initial concentrations of H2O2 and catalyst concentration. The results indicated that ZnFe2O4 could be used as a photocatalyst for treatment of industrial coloured wastewater. The catalyst was reused for five consecutive runs without significant change in its activity. Moreover, the antibacterial effects were investigated.

Open access
Glass Formation and Crystallization in P2O5-Nb2O5-CaO-Na2O System

Abstract

There is a lack of studies on a wide composition range for calcium phosphate glasses containing transition elements, e.g. niobium. Addition of Nb2O5 increases mechanical and chemical strength of calcium phosphate glasses and glass ceramics.

Glass is formed in a wide range of compositions. CaO promotes batch melting. The oxidation state of niobium has important role in glass forming. Solid state reactions between P2O5 and Nb2O5 during batch melt change the oxidation state of niobium. Nb5+ in this system acts as an intermediate or conditional glass former (glass is yellow) while Nb4+ is a glass modifier (glass is blue). It is possible to obtain glass with Nb2O5 (Nb5+) content up to 70 mol%. The glass ceramics obtained by reheating powdered glass contained niobium in crystalline phases. The composition of crystalline phases depends on the phosphate amount.

Open access
Liquid Membrane System for Extraction and Electrodeposition of Lead(II) During Electrodialysis

Abstract

A novel method for lead(II) removal from aqueous acidic solutions is presented. The method involves electrodialysis through bulk liquid membranes accompanied by electrodeposition of metal from the cathodic solution. Solutions of di(2-ethylhexyl)phosphoric acid with admixtures of tri-n-octylamine in 1,2-dichloroethane were used as the liquid membranes. The effects of the main electrodialysis parameters as well as of the composition of the liquid membranes and aqueous solutions on the lead(II) transport rate are studied. The optimal conditions are determined. A possibility of effective single-stage transfer of lead(II) through the liquid membrane into dilute solutions of perchloric, nitric and acetic acids is demonstrated. Dense and adherent lead electrodeposits are obtained from perchloric acid solutions. Maximum extraction degree of 93 % and electrodeposition degree of ~60 % are obtained during 5 h of electrodialysis.

Open access
Mechanical and Heat Shrinkable Properties of Electron Beam Irradiated Polypropylene With Bisphenol A Dimethacrylate Crosslinker

Abstract

Radiation crosslinking of polyolefins has gained interest for the development of advanced heat-shrinkable materials. Propylene homopolymer (PP1), polypropylene-polyethylene block copolymers (PP2, PP3) and their mixtures with 3 wt.% of bisphenol A dimethacrylate (BPDMA) crosslinking agent were irradiated with 25–150 kGy of accelerated electrons and were compared for aforementioned purpose. The studied mechanical properties indicated increased elongation in the presence of BPDMA that was contributed to the crosslinked moieties of PP and the crosslinking agent. The shrinkage stresses were comparable to that of polyethylene based heat-shrinkable material.

Open access
Staicele Paint Manufactory, Ochre Deposit of Reciems: A Retrospective Journey Through the History of Staicele Paint Manufactory and Evaluation of Production Technologies

Abstract

A historical paint manufactory in Staicele, Latvia (1967), was using local resources – colour earth. Oil paint composition consisted of pigment, drying oil, varnish and siccative. It had two different tones that are obtained by using natural colour earth pigments: ochre and its burnt form (burnt umber). Pigment quality was analyzed using historical documents, modern pigment tests, and manufactory technology. Chemical composition, particle size, and pigment tone were determined, and the coating ability was calculated. A palette of oil paints based on the historical recipes for restoring Staicele oil paints was created. Properties of colour earth pigments were compared to specimens taken from the local source of iron that is located near the old paint factory. Results provide a historical and technological insight as well as insight in the properties of the basic paint composition.

Open access
Synthesis, Characterization and Synthetic Applications of Fly-ash:H3PO4 Nanocatalyst

Abstract

The solid acidic nanocatalyst fly-ash:H3PO4 was prepared and characterized by FT-IR, SEM, EDS and TEM analysis. This catalyst was utilized for aldol condensation, coupling and cyclization reaction. The effect of catalytic activity of this fly-ash:H3PO4 nanocatalyst was studied with the obtained yield of products under solvent-free conditions. In this synthetic reaction the obtained yields were more than 95 %.

Open access
Synthesis of 4-Alkylamino-2-Triazolylquinazolines

Abstract

5-Alkylamino derivatives of tetrazolo[1,5-a]quinazoline were obtained with high regioselectivity in the reaction of 5-azidotetrazolo[1,5-a]quinazoline (formally, 2,4-diazidoquinazoline) with long chain alkylamines. The obtained 5-aminoquinazoline derivatives were used in a copper catalyzed azide-alkyne 1,3-dipolar cycloaddition reaction to obtain series of 4-(alkylamino-2-(1,2,3-triazol-1-yl)quinazolines.

Open access
ZnFe2O4 Containing Nanoparticles: Synthesis and Magnetic Properties

Abstract

Solid solutions of Co1− xZnxFe2O4 and Ni1− xZnxFe2O4 (0 < x < 1) nanoparticles were synthesized by sol-gel self-propagating combustion method. The obtained single cubic phase product has a specific surface area 25 m2∙g−1 to 33 m2∙g−1 and crystallite size 25 nm to 40 nm. Lattice parameters change linearly from 8.371 A (CoFe2O4) and 8.337 A (NiFe2O4) to 8.431 A (ZnFe2O4). The saturation magnetization (Ms) changes non-linearly from 60.8 emu∙g−1 (CoFe2O4), respectively, from 35.6 emu∙g−1 (NiFe2O4) to 3.3 emu∙g−1 (ZnFe2O4) reaching maximal value 76.1 emu∙g−1 for Co0.8Zn0.2Fe2O4 and 64.9 emu∙g−1 – for Ni0.6Zn0.4Fe2O4.

Open access
Anticorrosive efficiency of alkyd resin-based coatings containing Mg–Zn–Fe mixed oxide-based pigments

Abstract

Mixed oxide-based pigments Mg–Zn–Fe with different particle morphologies were prepared by high-temperature solid phase reactions. The core shell pigments containing ferric oxide and non-isometric particles of layered silicates were also prepared. The pigments were tested in paints, the pigment volume concentrations in the modified alkyd resin based binder being 5%, 10%, and 15%. The paint properties were examined by accelerated corrosion tests and by physico-mechanical tests. The effect of the pigment particle morphology on the surface hardness of the paint films was also studied. The influence of pigment volume concentration on the coating properties, and the optimum concentrations providing the most efficient anticorrosive protection were processed. A higher anticorrosion efficiency was observed for the paints with pigments possessing the lamellar particle shape.

Open access
Atmospheric corrosion models

Abstract

A number of damage functions or dose-response equation, which are compared to the atmospheric corrosion of metals with environmental parameters, have been determined in field programs ISOCORRAG, UN ECE ICP Materials Exposure Programme and Multi-Assess. The all of these dose-response equations are derived on field exposure results performed during period 1986-1995 where the SO2 level was relative high at urban and very high at industrial test sites. Several exposure programmes, national and international, of structural metals’ atmospheric corrosion were conducted since the 1970s on Czech atmospheric test sites including on-site measurement of environmental data. All data from these exposure programs were compared with prediction models.

Open access