Classical chemical sciences
The pure lead zirconate (PbZrO3) and low concentrations thorium-doped samples with general formula (Pb1-xThxZrO3) where x=0.05, 0.1, 0.2, 0.25 mole were synthesized by the conventional solid state method and sintering procedures. Experimental XRD-measurements indicated that Thorium dopant can substitute successfully on the A-sites of lead zirconate without damaging the main crystal structure which found to be orthorhombic phase with Cmmm space group. Scannin electron microscopy indicated that the average grain size of thorium-doped-lead zirconate ranged in between 0.35 and 1.43 μm. A Visualized studies were made to confirm success of thorium doping in the A-sites of perovskite structure. Theoretical investigations done were concerned by matching and comparison of bond distances ,torsions on angles of investigated compound to clarify success of thorium doping on the perovskite structure. Thermal analyses TGA&DTA were also attempted and incorporated to clarify the effect of thorium doping on thermal behavior of doped perovskite. Furthermore the effect of low concentration thorium dopings on the magnetic order, grain size and vibrational modes frequencies of infrared-spectra were studied.
Keywords: Crystal Structure; Thorium-doped lead zirconate; Doping; Perovskite
A new cobalt(II) 4-hydroxobenzoate, [Co2(C7H5O3)2(NO3)2(H2O)4]2H2O was synthesized as binuclear complex and characterized by elemental analyses (CHN), spectroscopic (infrared, electronic, x-ray powder diffraction, scanning electron microscopy SEM,) studies, magnetic susceptibility measurements and thermal analysis. This complex is a new type of 4-hydroxybenzoate bridged metal complex in which the carboxylate ligand is p-hydroxobenzoic acid. Bridging co-ordination modes for the carboxylates were indicated by the presence of (νasym–νsym) vibrations in the infrared spectra nearly the same as observed for ionic compounds. The magnetic moment value of cobalt(II) 4–hydroxybenzoate determined in at 300 K is 4.45 BM which refer to octahedral geometry. Thermo gravimetric analysis (TGA) of the hydrated water molecules shows that the first degradation step is associated with the release of water molecules followed by the decomposition of the 4-hydroxobenzoate, nitrato and coordinated water molecules. According to Horowitz-Metzger (HM) and Coats- Redfern methods, the kinetic parameters for the non-isothermal degradation of this complex were calculated using thermogravimetric data.
Keywords: 4-Hydroxobenzoic acid; Cobalt(II) ions; X-ray powder diffraction; Spectroscopic data; Thermal analysis; Nanocomposites; Biological evaluation
Materials and environmental chemistry
The primary aim of the present study was to isolate and identify a number of sea phytoplanktons for biomass production and determination of carbohydrate content. Sea phytoplankton was cultivated in cultured media “Ares-chat” to multiply seeds and cultivated stocks. In the mass media cultivation, isolation and identification of sea plankton was done based on size and some specific characteristics. The measurement of temperature, salinity and pH was also done in the media. The biomass weight of the density of selected phytoplankton was done by gravimetric method and the carbohydrate content was determined by glucose with Luff School method. The isolation results indicate six different types of sea phytoplanktons: Chlorella sp., Dunaliella sp., Tetraselmis chuii, Chaetoceros calcitrans, Chaetoceros gracilis, and Chaetoceros Isocrysis galbana. The highest biomass content 0.34 gL-1 was on Chlorella sp. and the lowest 0.14 gL-1 was on Isocrysis galbana. The carbohydrate content was also varied, the highest 31.99% on Dunaliella sp. and the lowest 4.70% on Chaetoceros gracilis.
Keywords: Types of sea phytoplankton, Biomass production, Carbohydrate content, Phytoplankton culture, Arschat medium
An accepted practice is the use of inhibitors in the corrosion control of metals and its alloys which are in contact with any aggressive medium such as sea water. Inorganic and organic compounds have been studied for their corrosion control potential; these studies reveal that the inhibitors especially with the polar atoms such as P, N, S and O showed excellent inhibition efficiency (IE). The inhibitors adsorbed on the metal surface through the polar atoms; protective films are formed. The protective films have been analyzed by surface characterization studies such as UV, fluorescence spectra, FTIR, SEM, EDX, Raman spectroscopy, Auger electron spectroscopy, XRD, XPS and AFM. Adsorption of the inhibitors obeys various adsorption isotherms. The IE has been investigated by electrochemical studies such as polarization, impedance spectroscopy, open circuit potential and cyclic voltammetry, etc. The conclusion of this article gives vivid account of both inorganic and organic compounds which are used as corrosion inhibitors for various metals and its alloys in natural/artificial sea water medium.
Keywords: corrosion, FTIR, SEM, AFM, inhibitor, sea water.
The Cd and Cr fractions (mobile: 1M NH4NO3-soluble, mobilisable: ammonium acetate + EDTA-soluble, “total”: cc. HNO3 + cc. H2O2- soluble) of the experimental soils and the Cd and Cr contents of spring barley grain and straw were examined in a pot experiment to investigate the effect of applying industrial-communal sewage sludge with metal contents exceeding the permissible limit. The four experimental soils were acidic sand, calcareous sandy, calcareous chernozem loamy and brown forest soil or acidic loam. The sludge was applied at rates of 0, 2.5, 5, 10 and 20 g sludge D.M. /kg air-dry soil in four replications. The mobile fraction of both elements changed only on sandy soils significantly. Regression analysis on the soil Cr and Cd fractions and the barley grain and straw element contents revealed that in the case of Cd the soil mobile fraction is the most suitable to predict the plant concentration. The changes in plant Cr concentrations were not coherent, thus the regression with soil Cr concentration did not give reliable results. Only a negligible proportion of the elements added with the sludge appeared in mobile form in the soil. This ratio is smaller in the case of Cr where only 0.02 % of the sludge Cr content can be found in the soil mobile Cr fraction. Since Cd is more mobile element therefore, 2.5 % of the added Cd can be found in the mobile fraction. Our results indicated that in case of sewage sludge application on field it is important to consider not only the element contents, but also other parameters (pH, texture, organic matter), as these may influence the dissolution of contaminants. The Cd and Cr content of the investigated sludge may cause adverse effects mainly on light textured soils.
Keywords: element mobility, soil contamination, heavy metal
The effect of 0, 30, 90 and 270 kg·ha-1 rates of microelements on alfalfa was examined on a calcareous sandy soil during the year 2004 - 2008 in Őrbottyán, Hungary. The salts of the microelements were applied on a single occasion at the start of the experiment in spring 1995 in the form of Cr2(SO4)3, K2Cr2O7, CuSO4, Pb(NO3)2, Na2SeO3 and ZnSO4. The 24 treatments (6 elements×4 application rates) in 3 replications gave a total of 72 plots. The location was prone to drought and was poorly supplied with NPK macronutrients. The ploughed layer contained 0.7–1.0% humus and 2–3% CaCO3, and the groundwater was located at a depth of 5–10 m. The whole experiment was given 100 kg·ha-1 each of N, P2O5 and K2O active ingredients as basal fertilizer each year. The favourable precipitation contributed to the advantageous development and yield of alfalfa during the 5 years period. Pb and Cu loads remained in the ploughed layer. The 0.2-0.4 mg·kg-1 Pb-content of the control alfalfa hay increased to 0.5-1.4 mg·kg-1 on the treated soil on average. Cu concentration rose from 5-7 mg·kg-1 to 9-10 mg·kg-1 due to high Cu load. Se showed an extreme 3 orders of magnitude accumulation in hay, i.e. from under 1 mg·kg-1 detection limit to 200-400 mg·kg-1. The hay became unsuitable for feeding. However alfalfa can be utilized in phytoremediation. During the 5 years the total yield of 45.5 t·ha-1 alfalfa hay took up 6-12 kg·ha-1 Se. In 2006 after the 12th year of the experiment the leaching zone of Cr(VI) exceeded 3 meters, and that of Se exceeded 4 meters in 270 kg·ha-1 treatments. Vertical movement could not be verified in the case of Cr(III), Pb, Zn, Cu.
Keywords: microelement, alfalfa, soil pollution, element composition, toxicity
Biochemistry, molecular biology and biotechnology
Magnesium participates in numerous enzymatic reactions in the human body and it has an essential role in maintaining the antioxidant system. Our purpose was to investigate the effect of magnesium on element content in blood. Male Wistar rats were divided into four groups. The animals in group ND were fed with normal diet, the animals in group ND+Mg. were fed with normal diet and treated with magnesium polygalacturonate (200 mg Mg/kg body weight ad libitum daily). The animals in group FD were fed with fat rich diet containing cholesterol (2.0% w/w), sunflower oil (20% w/w) and cholic acid (0.5% w/w) added to the control diet. The animals of group FD+Mg were fed with fat-rich diet and magnesium polygalacturonate. The rats were kept on the diets for 9 days. The element concentration (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Ni, P, Pb, S, Si, Sn, Sr, Ti, V, Zn) of blood samples was determined with an ICPOES after digestion with a mixture of nitric acid and hydrogen peroxide. The results show that the concentration of several elements changed significantly in both magnesium-treated groups, nevertheless the alteration was different in the control and hyperlipidemic groups. It has been concluded that high amount of magnesium supplementation alters the metal ion homeostasis in short time experiment. Although some favourable effects were found in the hyperlipidemic group by magnesium polygalacturonate treatment, it is worth to note that supplementation with magnesium should be carried out carefully especially in metabolic diseases like fatty liver.
Keywords: magnesium supplementation, rat, essential elements, metabolic alteration, hyperlipidemia
Industrial and engineering chemistry
The properties and classification of wax phase change materials (WPCMs) such as melting point, fusion heat, density, thermal conductivity and specific heat capacity have been reviewed in the present article. Three types of packaging wax methods have also been discussed such as the direct mixing method, the soaking and absorption method and the container packing method. The complete development of WPCMS has been resulted in good economic and social benefits.
Keywords: overview; wax; phase change; materials
Nowadays a few synthetic methods of n-butyl acetate using different catalysts such as inorganic salt like (Ce(S2O8)2, FeNH4(SO4)2·12H2O, LaSO4/SiO2, KHSO4 and SnCl4/C), HZSM-5, oxide (MoO3/SiO2), I2, heteropolyacid (H2(PW12O40)·nH2O), quaternary ammonium salt ionic liquid and nanometer ZnO have been reviewed. The yields of n-butyl acetate are improved by the addition of above catalysts. These methods are having the advantages of simple process and low investment costs.
Keywords: overview; synthetic study; n-butyl acetate; catalysts
Radiochemistry and isotopes
The compounds with general formula Bi2SrV2-xThxO9, where (x=0.05, 0.1, 0.2, 0.3, 0.6) were carefully synthesized and processed by using mixed techniques solid state reaction and solution routes with sintering temperature at 880 °C for 20 h. XRD – analysis of the prepared samples proved that thorium(IV)-dopant can substitute successfully until x=0.55 mole on the Bi-layered perovskite crystal structure without damaging the original perovskite structure . It was observed that Th-dopings have slight to moderate effects on both ESR-signals and conduction mechanism of Th-doped Bi-Sr-V-O regime. Electrical measurements indicated that the energy gap Eg and number of electrons in conduction band Ncb increase as the ratio of Th doping increases from x=0.05 till x=0.6 mole respectively due to the increasing of paramagnetic character of thorium than vanadium .
Keywords: Thorium doping; Perovskite; Th-doped 212-vanadate ceramics