Classical chemical sciences
The presented work is devoted to the evaluation of important validation descriptors concerning the spectrophotometric determination of thorium using Arsenazo III and Chlorophosponazo III. In diluted hydrochloric acid the complex between Th(IV) and Arsenazo III is formed instantly and remains stable for 25 minutes with constant absorbance. Beer’s law is obeyed in the range from 0.70 to 11.64 mol · L-1. The molar absorptivity at 660 nm is equal to 9.74(±0.09)·104 cm−1 mol−1 L (data in parentheses stands for standard deviation). The relevant relative standard deviations (RSD) reached ±1.48 %, ±4.34 % and ±3.07, respectively. Thorium concentration can be quantified using Chlorophosphonazo III in media of diluted nitric acid. The linear range of the proposed method was from 1.59 to 18.10 mol L-1 of thorium(IV). The experimentally determined values of molar absorptivity reached ε691 = 3.76(± 0.05)*104 cm-1 mol-1 L. The repeatability and trueness of determination in the linear range did not exceed ±2.2% and 3.3%, respectively. Color stability of the Th(IV)- Chlorophosphonazo III complex maintained a constant value for at least two hours. LOD and LOQ values for both methods were established applying three approaches – the 3-σ, the ULA2 and the Hubaux-Vos ones.
Keywords: thorium, Arsenazo III, Chlorophosphonazo III, spectrophotometry, limit of detection (LOD).
Low temperature molten salts based on ionic liquids have received considerable attention over the last 3 decades as potential alternative solvents for aluminium reduction. Recent reports in the literature have identified 1-propyl-1-methylpiperidinium bis(trifluoromethylsulfonyl) amide ([C3mpip][NTf2]) as a promising candidate for low temperature aluminium reduction processes. The formation of aluminium metal deposition was confirmed in these studies by both visual inspection and SEM-EDX analysis in the selected mixtures with AlCl3, but little is known about the anodic processes occurring in the cell. This work presents the results of a preliminary electrochemical study of the anodic and cathodic reactions occurring in the ionic liquid mixtures 1-propyl-1-methylpiperidinium bis(trifluoromethylsulfonyl) amide ([C3mpip][NTf2]) with AlCl3 at different temperatures, concentrations and electrode materials. Analysis of voltammetric responses of [C3mpip][NTf2]-[AlCl3]x for x=0.3 indicated that the anodic process is limited by mass transport for this particular electrolyte composition. In addition, the formation of Cl2 was confirmed to take place at a dimensionally stable anode. Aluminium deposition experiments gave inconsistent results however and gas analysis indicated that the [C3mpip][NTf2]-[AlCl3]x mixture at a prolonged elevated temperature at least partially decomposes into fluoro-carbons and chloro-compounds.
Keywords: aluminium chloride, cyclic voltammetry, ionic liquids, Al electro-deposition
Materials and environmental chemistry
Toxic and radiotoxic metals of liquid wastes are sorbed by the sludge of Waste Water Treatment Plants (WWTPs) with a high efficiency.. Sludges with low toxic metals concentrations can be temporally stored or utilized as soil conditioners in agriculture. Other possible and economically acceptable way is repeated utilization of the sludge as heavy metals sorbent. Since effluents can contain several metals, it is necessary to study the simultaneous sorption of two or more metal ions and also to quantify the mutual effect of one metal on the other. In the present study, we have undertaken the study on the sorption characteristics of Dried Activated Sludge (DAS) from industrial WWTP for sorption Co2+ and Zn2+ ions from their binary aqueous system in batch experiments using radiotracers 60Co and 65Zn technique. Values of maximum sorption capacity (Qmax) of DAS at pH 6 calculated from extended Langmuir adsorption isotherm were 247 ± 15 μmol g-1 for Co2+ and 479±32 μmol g-1 for Zn2+ ions. Results revealed that the sorption capacity of DAS for both the metals increases with increased initial concentration in the range 100 – 4000 μmol dm-3 CoCl2 and ZnCl2, respectively. Presence of Zn2+ ions as co-ions caused more significant decrease of Co2+ uptake in binary Co-Zn system than vice versa. Experimental data Co and Zn sorption in binary system were well described by extended Langmuir model and affinity parameter b indicate higher affinity of DAS to Zn2+ in comparison with Co2+ ions. Prediction of total Co-Zn sorption by DAS using extended Langmuir model was less suitable due to dissimilarity of Qmax value of DAS for Co2+ and Zn2+ in single systems.
Keywords: sorption, activated sludge, Co-Zn system, Co, Zn
In January and March 2000 two tailings dam failed in Baia Mare (Nagybánya) and Baia Borsa (Borsabánya) which resulted cyanide and metal pollution in the Lápos - Szamos - Tisza and metal pollution in the Visó - Tisza rivers, respectively. The main aim of this study was to evaluate the long term effects of pollution on environment. Samples of easily available metal contents were collected in year 2011 from these floodplains and pastures along the Tisza (Tivadar, Vásárosnamény, Rakamaz, Tiszacsege) and were investigated and compared with our earlier results. It was noticed that during an 11 year span the easily available Cd, Cu, Zn and Pb contents of the floodplain soils have increased. This may be due to the periodical floods and the mobilization of the pollutants. Furthermore, high concentration of Zn and Pb contents – crossing the natural background values of available metal content – were also observed in the soils studied.
Keywords: Tisza River, heavy metal pollution, Lakanen-Erviö extraction
A temperature controlled carbonization process (5-800 °C for 1-4 h) of metal forms of various types of partially or completely saturated sulphonated styrene-divinylbenzene copolymer based ion-exchangers loaded with various valence state metal ions has been evaluated. The effect of temperature, nature and valence of metal ions, cross-linking and other parameters on the composition and properties of the synthesised composites have been evaluated. Depending on the ionic form and the degree of saturation of the ion exchangers the sulphur content of the ion-exchangers can partially transform into metal sulphides, SO3 or SO2. Ni(II), Mn(II) and Zn(II) forms of the ionexchangers resulted the appropriate MIIS type metal sulphides (NiS, MnS or ZnS), while copper(II) resulted metallic copper formation at 500 °C in 2 h. Both iron(II) and iron(III) forms of sulphonated styrene-divinylbenzene copolymers resulted Fe0.95S and -Fe formation at 800 °C for 2 h, however, the ratio of these compounds depended on the valence state of iron and were found to be 8:1 and 7:2 in the case of Fe(III) and Fe(II)-forms, respectively. The shape of the so formed carbon particles are bead-like and the hardness of the formed carbon beads proportional with the divinylbenzene content of the starting polymer. The higher divinylbenzene content the harder beads of carbon forms. All the beads have a leakage path due to evolution of gases which emitted at the weakest part of ball-like bead. The ball-like metalcontaining activated carbon beads have low hydrodynamic resistance towards fluid streams and this carbonisation method can be used as an environmentally friendly way for processing of waste ion-exchangers into industrially usable carbon based metallic containing composites.
Keywords: metal-containing activated carbons; waste ion-exchangers; carbonization; metal/metal compound-carbon composites; sulphonated styrene-divinylbenzene copolymers
Biochemistry, molecular biology and biotechnology
In the present study, the interaction of inhalational and oral exposure to manganese and lead was investigated. Young adult male Wistar rats (2 x 10 per group) were treated orally with MnCl2 (15 and 60 mg/kg b.w.) or Pb acetate (80 and 320 mg/kg) for 3 or 6 weeks. Then, one half of the groups was further treated by intratracheal instillation of nanoparticulate MnO2 (2.63 mg/kg) or PbO (2 mg/kg) for an equal period of time. Body weight gain and signs of general toxicity were regularly checked. Finally, the rats’ motor behavior was tested in an open field box, and their spontaneous and evoked cortical electrical activity was recorded in urethane anesthesia. MnO2 nanoparticles caused disproportionately strong reduction of body weight gain but with Pb the weight effect was more dependent on dose. In the open field test, Mn caused hypomotility, more strongly after 6 weeks oral plus 6 weeks intratracheal than after 6 weeks oral treatment. Pb-treated rats showed increased ambulation but less rearing and somewhat longer local activity. Spontaneous cortical activity was shifted to higher frequencies after oral Mn application, but this change was not intensified by subsequent nanoparticle application. Oral Pb had an opposite effect. Cortical evoked potentials showed latency lengthening. In several cases, the effect of Mn and Pb was about as strong after 3 weeks oral plus 3 weeks intratracheal as after 6 weeks oral administration, although the summed dose was ca. two times lower in the former case. There can be a more-than-additive interaction between the amounts of heavy metals entering the organism in different routes and chemical forms.
Keywords: Manganese, lead, neurotoxicity, cortical activity, open field, nanoparticles, rat
History reveals that heavy metals have been used since ancient times. The human body contains about 80 mg copper, which can be present mostly in eyes, brain, liver, heart, kidneys and musculature. In our study we determine the adsorption capacity of copper in five different concentrations and in four different soil types: brown forest soil, chernozem, meadow and sand with humus. In our method we prepared soil columns, in which we put 50 g experimental soil samples and poured on copper solutions of known concentrations. The concentrations of runoff filtrates were determined by titration methods. The adsorption capacity of soil samples were calculated from the two different concentration values.
Keywords: copper, root zone, soil, adsorption, pollution
Cobalt (Co) is an essential trace element and its accumulation affects the concentrations of other elements also. Co(II) is shown to compete with iron (Fe) for the transferrin receptor and to form a stable complex with haemoglobin thus affecting haematopoiesis. There are lack of data regarding the effect of chronic exposure to Co compounds on Fe content in spleen and liver of mice. The study deals with the effect of long-term treatment with cobalt-EDTA (Co-EDTA) on iron content in the spleen and liver of immature mice. Pregnant ICR mice were subjected to chronic treatment with daily dose of 75 mg/kg Co-EDTA which continued until day 25pnd of the newborn pups. Results show accumulation of Co(II) and altered Fe content in the spleen and liver of treated mice compared to age-matched controls with significantly increased Fe concentration in the livers of treated mice. The changes could explain impaired haematopoiesis and immune responses of exposed to Co(II) immature mice.
Keywords: Co-EDTA, iron content, in vivo model, immature mice, spleen, liver
Trace elements are essential for maintenance and production of farm animals, but most of the feeding stuffs do not contain adequate amount of most of them, therefore to supplement them in complete feed with trace elements is necessary. However, the rate of absorption and tissue deposition of trace elements from different complexes is also different which may have food safety aspects because of the maximum level of some trace minerals. The present review, based on scientifically proved results, discussions about the rate of absorption and deposition of different metal (Cu, Zn, Fe and Mn) proteinates, amino acid chelates (e.g. lysine, methionine, methyl-hydroxy-methionine) and humic acid complexes of trace elements. The results showed that metal proteinates have higher rate of tissue accumulation as compared to inorganic salts, and additionally some metal-proteinates (e.g. copper-proteinate) also improves the tissue deposition of manganese. Metal propionates, as possible new trace element supplements have positive effects on the rate of absorption which was proved by the higher blood serum levels. In the case of humic acid chelates there are some results about their positive effects on bioavailability of trace minerals but those were not scientifically proved. In conclusion it can be stated that organic metal complexes have better bioavailability than their inorganic counterparts, in particular modern farm animal genotypes with higher requirement level and also in stress conditions.
Keywords: Copper, zinc, iron, manganese; metal complexes, feed additives, deposition
Industrial and engineering chemistry
Effects of different reaction conditions on the synthetic method of n-butyl acetate have been reviewed in the present paper. Different catalysts consisting inorganic salt like (Ce(S2O8)2/SBA-15, NH4Fe(SO4)2·12H2O) and oxide (MoO3/SiO2) have also been introduced. Kinetics equations have also been applied on n-butyl acetate system. The results showed that kinetic equations may predict the distribution of product and the experimental data are in agreement with the quantitatively analytical conclusions drawn from the calculated data.
Keywords: reaction conditions; kinetics; n-butyl acetate; synthesis