Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

13-18

Authors: Camila Delinski Bet, Lucas Henrique Waiga, Cristina Soltovski de Oliveira, Luiz Gustavo Lacerda, Egon Schnitzler

Avocado seeds starch was investigated after the modification with lactic acid using thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). After the modification, there was a decrease in the thermal stability of the starch, also the parameters measured by differential scanning calorimetry showed lower values. These results can be correlated with the reduction in the relative crystallinity observed by XRD. There was no difference in the morphology of the granules, which presented an oval and rounded shape. These results are important for the food industry, since lactic acid is used to optimise the properties of starches.

28-33

Authors: Inna Seifullina, Elena Martsinko, Elena Chebanenko, Eleonora Afanasenko, Viktoriya Dyakonenko, Svitlana Shishkina

Two crystalline compounds of germanium(IV) with malic acid (H3Mal) and 1,10’-phenanthroline (phen) -[Ge(HMal)2(phen)]·phen·2H2O (1) and [CuCl(phen)2][Ge(OH)(HMal)2](2) were synthesized for the first time and characterized by elemental analysis, IR spectroscopy and thermogravimetric analysis. Using single crystal X-ray diffraction, two different forms of germanium were elucidated: Ge4+ (1) and hydrolyzed GeOH3+ (2) with a distorted octahedron and pyramid surrounding geometry, respectively.

41-49

Authors: Felix Sunday Nworie, Frank Ikenna Nwabue

A new synthetic extractive protocol for the synthesis of Cu(II) and Co(III) complexes of bis(2,2/-methylylidenephenol)diaminoethane (H2BMPDE) in a single simple step was performed. The obtained data indicated the formation of complexes with 1:1 molar ratio of metal:ligand, of distorted square planar and distorted octahedral geometries. In vitro antibacterial screening revealed that the complexes were active against clinically important gram-negative bacteria (Escherichia coli, pseudomonas, and gram-positive bacterium (Staphylococcus aureus). The synthesis of the complexes was optimized to make it more suitable and efficient for industrial scale production.

58-63

Authors: Nicolay Davidenko, Irina Davidenko, Nicolay Kuranda, Elena Mokrinskaya, Valeriy Pavlov, Viacheslav Solntsev, Sergey Studzinsky, Vladimir Syromyatnikov, Vitaliy Tarasenko, Nicolay Chuprina

The growth of the diffraction efficiency and recording velocity were found in the films of the 4-[(2-nitrophenyl)diazenyl]phenyl methacrylate copolymers with octyl methacrylate at room temperature holographic recording with a plane wavefront from parallel and orthogonal orientation of polarization of light beams for copolymer with less softening temperature. The effect of strengthening the diffraction efficiency was observed when charging the surface of investigated copolymers films with the recorded hologram in corona discharge. This effect is explained by growth of amplitude of regular geometric relief of the film surface appearing during formation of the polarization hologram in the copolymer with azobenzene chromophore.

71-78

Authors: Karima Seffah, Amel Zafour-Hadj-Ziane, Abdelghani Tarek Achour, Jean-François Guillet, Pierre Lonchambon, Emmanuel Flahaut

A new material (DWCNT/iron oxide) for heavy metals removal was developed by combining the adsorption features of double-walled carbon nanotubes with the magnetic properties of iron oxides. Batch experiments were applied in order to evaluate adsorption capacity of the DWCNT/iron oxide composite for cadmium ions. The influence of operating parameters such as pH value, amount of adsorbent, initial adsorbate concentration and agitation speed was studied. The adsorption capacity of the DWCNT/iron oxide adsorbent for Cd2+ ions was 20.8 mg g-1, which is at the state of the art. The obtained results revealed that DWCNT/iron oxide composite is a very promising adsorbent for removal of Cd2+ ions from water under natural conditions. The advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

87-101

Authors: Nadiia Roik, Lyudmila Belyakova, Marina Dziazko, Iryna Trofymchuk

Macrocyclic units were introduced into the surface layer of mesoporous silica by sol-gel condensation of tetraethyl orthosilicate and β-cyclodextrin-containing silane in water-ammonium solution in the presence of a structure directing agent. Chemical and porous structure of parent and β-cyclodextrin-containing silica materials were elucidated by IR spectral and chemical analysis of surface functional groups, as well as nitrogen adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy and dynamic light scattering. It was found that the incorporation of cyclic oligosaccharide moieties into the hexagonally arranged mesoporous framework leads to the enhancement of sorption efficiency towards methyl red. Adsorption of dye from phosphate buffer solutions was studied as function of pH, contact time and methyl red concentration. Obtained results of equilibrium sorption were analyzed using Langmuir, Freundlich, Redlich-Peterson, Dubinin Radushkevich and Brunauer-Emmet-Teller isotherm models.

9-19

Authors: Gheorghe DUCA

Nowadays, our human civilization existing on Earth faces a series of top importance challenges that represent direct impact on its existence and development, both industrial and social. All the natural compartments and their components are subjected to the strong and unprecedented anthropogenic influence, including lithosphere, soil, surface and ocean water, atmosphere, vegetal and animal world. Anthropogenic activities has reached such high proportions that provoke the changes in the energy (heat) balance of certain regions and planet as a whole that can affect the climate, increase of water level in oceans and seas, flooding of large areas.

29-36

Authors: Iurie Pinzaru, Tatiana Manceva, Raisa Sircu, Ion Bahnarel, Elena Sanduleac

The incidence and the type of acute chemical poisoning in Republic of Moldova during 2011-2015 were assessed. Records show 22458 cases of poisonings, including 919 death cases. The analysis of poisoning cases involving various types of chemical substances causing the intoxication reveals that the medicines-related poisoning accounts for the highest record of cases (6971), followed by alcohol poisoning (6556 cases); gas poisoning is the third with 1860 cases, and pesticide-related poisoning with 707 cases. Age and gender characteristics of chemical poisonings and ways of exposure to chemicals are discussed.

45-52

Authors: Michal Šereš, Tereza Hnátková, Jan Vymazal, Tomáš Vaněk

Constructed wetlands were proven to be the efficient method for treatment of agricultural wastewaters in last two decades. In this study, the performance of a constructed wetland for treating wastewater from small farm was tested. The constructed wetland for 75 PE with horizontal subsurface flow at Chrámce, Central Bohemian Uplands, Czech Republic, was built in 2011. A hybrid constructed wetland combining the horizontal (HF), vertical filter (VF) and horizontal (HF) filter stages has been designed to treat wastewater from the agriculture production (processing of fruits, sheep, pigs, production of jams, spirits and wine, etc.). The mechanical pretreatment consists of two accumulation tanks (for different wastewater types) from which the wastewater is intermittently pumped into a settling tank. The treatment system consists of two horizontal flow beds and one vertical flow bed with intermittent feeding. The filters are planted with Phragmites australis, Phalaris arundinacea, Iris pseudacorus, Iris sibirica, Glyceria maxima and Lythrum salicaria. For tertiary treatment, three shallow ponds with littoral vegetation were designed. During the feed batch operation the inflow values up to 25.400 mg/L COD and 2.640 mg/L BOD5 were reduced by up to 99%. The volume of each feed batch was applied at one to five day intervals. Also, the effect of discharged water on the littoral zone of aquatic biotopes has been evaluated. This knowledge is necessary for the design of a stable, artificial water system.

61-66

Authors: Narcis Barsan, Valentin Nedeff, Antonina Temea, Emilian Mosnegutu, Alexandra Dana Chitimus, Claudia Tomozei

Development of infrastructure in sewerage systems is essential for improving the living conditions and human health. Considering this situation, research was oriented to the use of a small Sequencing Batch Reactor (SBR) treatment system as a small-scale plant in certain sewers. This type of treatment system was chosen because it can be adapted to the quantitative changes of flows. The most important advantages of SBR process include the possibility of modifying the operating cycle, the elimination of secondary clarifiers and the satisfying control of operations that constitute the treatment. Comparing the problems in Romania and Senegal, regarding wastewater treatment, the present paper aims to identify the best methods and techniques to treat the municipal wastewater in small treatment plants with sequential operation. This paper examines the possibility of using SBR process to treat the municipal wastewater characterized by low flow. This paper also presents a comparative analysis of the degree of purification achieved in a SBR wastewater treatment plant, as well as legislative regulations in Romania and Senegal. Finally, the paper identifies the possible uses of the treated wastewater in different household activities.

74-80

Authors: Olesea Cuzan

The novel N-(methylene-2-pyridine)-N,N-bis(diethoxyphosphorylmethyl)amine ligand (L) was obtained through a double Kabachnik-Fields reaction, starting from 2-(aminomethyl)pyridine (2-picolylamine). Based on the L ligand, a new palladium(II) coordination compound [Pd(L)2Cl2] has been synthesized and comprehensively characterized by spectroscopic methods (1H NMR, UV-Vis), ESI mass spectrometry and X-ray crystallography.

87-94

Authors: Delia-Andrada Duca, Mircea Laurentiu Dan, Nicolae Vaszilcsin

In this paper, the possibility to use ceftriaxone (CEFTR) active compound from expired Cefort® drug as additive in nickel electrodeposition from Watts bath has been investigated. Electrochemical behaviour of CEFTR and preliminary information about its influence on nickel electrodeposition process were obtained using cyclic voltammetry technique. Cyclic voltammograms have been drawn on platinum electrode at scan rates between 5 and 500 mV s-1. Linear voltammograms recorded at low scan rate emphasized the influence of the drug concentration in 5 g L-1 Ni2+ electrolyte solution. Kinetic parameters such as exchange current density and cathodic transfer coefficient have been calculated using Tafel polarization plots at different temperatures in the range of 25÷65°C. Further, activation energy has been determined from Arrhenius plots. Electrochemical impedance spectroscopy technique was used to study the charge transfer resistance and surface coverage degree in the same solutions at different deposition potentials.

102-109

Authors: Andreea-Floriana Enache, Mircea Laurentiu Dan, Nicolae Vaszilcsin

In this paper, anodic oxidation of sulphite ions on platinum nanoparticles modified nickel electrode (Ni–Pt NPs) in aqueous alkaline solution was investigated in order to establish the relationship between kinetic parameters and sulphite concentration. The purpose of this research is both to clarify the oxidation mechanism and to find optimal parameters for sulphite oxidation process using various electrochemical methods. Cyclic voltammetry and linear polarization have been applied to investigate the electrochemical behaviour of sulphite ions and Tafel plots method has been used in order to determine kinetic parameters. To confirm the anodic oxidation mechanism, electrochemical impedance spectroscopy studies have been performed. Furthermore, chrono-electrochemical methods (chronoamperometry, chronopotentiometry, chronocoulometry) have been used in order to obtain more information on sulphite electrooxidation process.

115-118

Authors: Saeid Taghavi Fardood, Ali Ramazani, Sajjad Moradi

Present work involves synthesis of NiO nanoparticles using Arabic gum by the sol-gel method. The synthesized NiO nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and X-ray powder diffraction (XRD). It was shown that the synthesized NiO nanoparticles of cubic phase have a spherical shape and an average size of 34 nm.