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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.

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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.

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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.

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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.

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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.

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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 %.

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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.

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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.

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Allelopathic activity of Nepeta nuda L. subsp. nuda water extracts

Abstract

Nepeta nuda subsp. nuda is a medicinal plant growing wild in Bulgaria. Different species of Nepeta genus have been reported to possess allelopathic potential. The present study was conducted to observe its phytotoxic effects on T. aestivum and C. sativus L. seeds in laboratory conditions. Nepeta water extracts (NWE) prepared from aerial parts of plants at concentrations 2, 4, 6, 8, 10, 12 and 14 g/l were tested. The rate of seed germination, the root and shoot length, fresh and dry weight of seedlings were observed after treatment with NWE. As a control served seeds treated with distilled water. Germination was not affected, but NWE showed deterioration in seedling growth. Roots were more affected than shoots. The fresh and dry weights were reduced upon treatment with the extracts tested. These negative effects were dose-dependent. The overall results indicate presence of water soluble allelochemicals in Nepeta nuda subsp. nuda.

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Climate Change, Risks and Natural Resources didactic issues of educational content geography of Bulgaria and the world in 9th and 10th grade

Abstract

The purpose of this paper is to follow “Climate change, risks and Natural Resources“ in the curriculum of Geography of Bulgaria and the world in 9th and 10th grade and to interpret some didactic aspects.

Analysis of key themes, concepts and categories related to the environment, events and approaches to environmental protection and the environmentally sound development of sectors of the economy is didikticheski targeted. Considering the emergence and development of geo-ecological issues, their scope and their importance to the environment, systematize some species and some approaches to solving them.

Geography education in grade 9 and 10 involves acquiring knowledge, developing skills and composing behaviors of objective perception and assessment of the reality of globed, regional and local aspect.

The emerging consumer and individualistic culture snowballing globalization, are increasingly occurring global warming, declining biodiversity form new realities which education must respond appropriately.

The objective, consistency, accessibility and relevance in real terms are meaningful, logical accents. Whether and how reproduced in the study of Geography of Bulgaria and the world is the subject of research study in this report.

Geoecological structuring of topics, concepts and categories can be done in different signs. In terms of their scope are local, national or regional, and global. Matter and interdisciplinary approach, which is to reveal the unity of the “man-society-nature” to clarify the complexity of their character with a view to forming a harmonious personality with high Geoecological consciousness and culture, and the activities carried out in their study.

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