Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

8-13

Authors: N.Ya. Tsibakhashvili, L. Mosulishvili, E. Kirkesali, T. Kalabegishvili, S. Kerkenjia, M.V. Frontasyeva, Gh. Duca, I. Zinicovscaia

Most powerful primary analytical technique, neutron activation analysis, was applied to study indigenous bacteria, namely, Arthrobacter genera which can be successfully used in detoxification and immobilization of toxic substances. In the present study the effect of Cr(VI) on the elemental content of these bacteria has been examined. The concentrations from 12 to 19 elements such as Na, Al, Cl, K, Fe, Co, Zn, As, Br, Rb, Sr, Sb, Ba, Tb, Th, U were determined in the bacterial cells. The high rate of Cr accumulation in the tested bacterial cells was shown. In bacteria treated with chromate some similarity in the behaviour of the following essential elements − potassium, sodium, chlorine − was observed. Such non-essential elements as Ag, As, Br and U were determined in all bacteria and have to be considered by cells as toxins.

24-27

Authors: Ludmila Kiriyak, Natalia Cecoi, Tatiana Cazac, Mihail Revenco

The polarographic behavior of the complex formed by V(V) and 2,3–dihydroxybenzaldehyde (2,3–DHBA) in the solution containing acetate buffer (pH 5,2) has been investigated. By means of a.c. polarography, chronovoltammetry and other techniques, it has been shown that the electrode process is complicated by the adsorption of 2,3-DHBA and its vanadium complex. The kinetic and adsorption parameters of the electrode process have been determined: adsorption equilibrium constant B= 1,32⋅105 mol-1⋅dm3, the attraction constant γ = 1,2, the maximum surface concentration Гmax = 9,10⋅10-11 mol⋅ cm-2; the share of the electrode surface occupied by one particle of the adsorbed complex S = 1,81 nm2 and the free adsorption energy ΔG = - 39,1 kJ· mol-1.

34-39

Authors: Olga Covaliova

The problem of preventing the heavy metals and other toxic substances release in environment due to the discharges of untreated plating and rinsing solutions is actual from both ecologic and economic point of view. It is crucial to prevent the environmental pollution and uncontrolled losses of resources (metals and other substances). The treatment technologies used today are not always efficient and cost saving and in some cases they may even provoke the secondary pollution of environment. Electrochemical treatment of industrial waste waters is one of the most promising technologies as it implies the same principles as the main technological processes and does not require introducing of chemicals into the treated solution. However, until now this method was given insufficient attention, although there are certain publications in this field [1]. The electrochemical behaviour of some d-metal complexes was studied and discussed from the viewpoint of water treatment requirements. The studies performed in the model plating solutions of Zn, Ni, Cu ammonia and pyrophosphate complexes, polynuclear Cr complexes have shown that the application of conventional reagent waste water treatment methods for such solutions would be inefficient. Examination of potentio-dynamic polarization curves registered in studied solutions have shown, that due to the formation of series of Zn ammonia complexes, alkaline treatment will not ensure Zn removal from such solutions, and application of electrocoagulation treatment method will not be efficient enough. It was also found that in case of Ni-, Crcontaining solutions electrochemical treatment can be used for Cu removal, whereas for the effective Cr(VI) removal the electrocoagulation would be required, which entails the redox processes resulted in the formation of hydroxides. The research has shown that the approach on the heavy metal removal from the used plating solutions may be different depending on the plating bath composition.

44-49

Authors: Boris Găină, Rodica Sturza, Violeta Bejan, Constantin Bodean

The basic objective of this work is studying the content of ochratoxin A (OTA) in grapes, grape juice, and wine. This is an analysis of their origin, the conditions of contamination and ways decontamination, toxiconogenes mushrooms, toxicity, world and European regulations. It was estimated the methods of detection of mycotoxins in wine products. It has examined the contents of OTA in the moldavian juice/wine from different varietals at different stages of winemaking and obtained by different proceeds winemaking.

60-67

Authors: Silvia Melnic, Denis Prodius, Sergiu Shova, Helen Stoeckli-Evans, Yurii Simonov, Alexander Feher, Maria Gdaniec, Constantin Turta

Nine new complexes with the general formula {[Ln2Ba(α-Fur)8(H2O)4]}n, where Ln = Nd3+, Sm3+, Eu3+, Pr3+, Gd3+, Tb3+, Ho3+, Er3+ and La3+; α-Fur ≡ C4H3OCOO, were synthesized and characterized by IR spectra, magnetism, X-ray single crystal and powder diffractions. The X-ray diffraction analysis reveals that all titled compounds are isostructural and possess 1D architecture with Ln ion in an eight-coordination geometry formed by six oxygen atoms from furoate and two oxygen atoms from water molecules. The magnetic behaviour of several synthesised complexes as well as {[Gd2Sr(α-Fur)8(H2O)4]}n was investigated in the temperature range of 1.8-300 K. The magnetic data were interpreted in the HDVV approximation with the exchange coupling constant J = - 0.014 cm- 1 that indicates antiferromagnetic interaction in {Gd2Sr}, whereas a ferromagnetic one J = + 0.007 cm-1 for {Gd2Ba}.

78-81

Authors: Oleg Radul, Alexandru Gudima, Fliur Macaev

New effective synthesis of the chiral chinchoninic acids form (-)-α-pinene has been elaborated. It has been shown that, the considerable increase of the yield and purity of chiral acids is achieved applying the method of under phase transfer catalysis.

86-93

Authors: Oleksandr Shkurenko, Kinga Suwinska, Florent Perret, Katia Sigaud, Antoine Leydier, Said Jebors and Anthony W. Coleman

Diamino-bicycloundecane mono-deprotonates H-calix[4]arene and the solid-structure of the resulting salt has been determined by X-ray crystallography. Two different complexes are present in the structure with the Diamino-bicycloundecane cation held in the calix[4]arene cavity by CH-p interactions. In the packing there is a hydrogen-bonded polymeric chain. Both the complexes formed layered structures with differing inter-layer distances.

100-104

Authors: Anca-Dana Bendrea, Ana-Maria Catargiu and Mircea Grigoras

Mesoporous SBA-15/conducting polymers composites, type SBA- polithiophene, SBA-polyaniline, respectively were synthesized and their physical properties were investigated. Polymers molecules were synthesized by chemical oxidative polymerization inside the pores of the mesoporous material by a post-synthesis process. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, thermal analysis and infrared spectroscopy.

116-117

Authors: Felix Shepel, Diana Shepel, Fliur Macaev

The increase of yield up to 63% of ethyl 5-hydroxy-1,2-dimethyl-1H-3-indolecarboxylate was obtained via the interaction of p-benzoquinone with N-methyl-β-aminocrotone ether in mixture of glacial acetic acid/ethyl acetate.