Chemistry Journal of Moldova

 

DOI: http://dx.doi.org/10.19261/cjm.2021.920

Abstract (PDF) 

Graphical Abstract: The possibilities of application of the Monte-Carlo method for simulating the consequences of pollutants emissions with specific adsorption on the underlying surface were considered. Effective methods of obtaining kinetic curves for the concentration of a pollutant for a selected square on the field and constructing contamination profiles for a specified time are analysed. The estimation of the necessary parameters of the model for obtaining high-quality kinetic curves was performed and recommendations for their optimization are given. Specific fronts for the spot propagation were obtained and visualised.


 

DOI: http://dx.doi.org/10.19261/cjm.2021.911

 

Abstract (PDF)
Graphical Abstract: This paper deals with V₂O₅ nanoparticles adsorbents which were obtained by thermal pretreatment carried out by increasing the temperature between 90 and 750°C. In order to obtain more detailed information on the surface chemistry of the newly prepared nanoparticles, the characterisation was done by X-ray diffraction and scanning electron microscopy, Fourier Transform infrared spectroscopy and thermogravimetric investigation technique. The prepared nanoparticles were tested for methylene blue (MB) removal from modelled water solutions. The obtained results indicated that increased MB removal efficiency (93%) and adsorption capacity (27 mg/g) after 40 minutes of adsorption were obtained for V₂O₅ annealed at 500°C.  The applicability and suitability of the two kinetic models were tested and the removal mechanism was proposed.
 

 

DOI: http://dx.doi.org/10.19261/cjm.2021.913

 

Abstract (PDF)
Graphical Abstract: The effect of the nature and concentration of d-metal salts attached to synthetic zeolites NaA and KA on the kinetic and stoichiometric parameters of the chemisorption-catalytic oxidation of sulphur dioxide with air oxygen at ambient temperature was studied. It was found that the adsorption capacity of NaA zeolite relative to SO₂ is 100 times higher than that of KA zeolite; the time of protective action of NaA and KA zeolites increases upon modification with transition metal salts and with an increase of their content in the compositions. It was shown that the formation of inner and outer sphere complexes and the relationship between them is determined by the nature and concentration of metal ions and by the nature of the carrier. It was proven that the chemisorption-catalytic process ends with the oxidation of SO₂ to H₂SO₄.


 

DOI: http://dx.doi.org/10.19261/cjm.2021.918

Abstract (PDF) 

Graphical Abstract: This review paper is focused on the detailed consideration of the structure, properties and reactions of H₂O₂. The paper highlights the importance of revealing these processes’ mechanisms, since they have been insufficiently studied so far, or the related data have a fragmentary and incomplete character. A special attention is given to catalytic oxidation reactions, formation and properties of intermediates, their role in the natural environment. 


 

DOI: http://dx.doi.org/10.19261/cjm.2021.885

 

Abstract (PDF)
Graphical Abstract: Two new μ3-oxo trinuclear heterometallic Fe2IIICrIII complexes with furan-2-carboxylic and salicylic acids with the composition: [Fe₂CrO(C₄H₃OCOO)₆(CH₃OH)₃]NO₃·0.5CH₃OH and [Fe₂CrO(C₆H₄(OH)COO)₇(CH₃OH₎₂]·2DMA were synthesized starting from iron(III) and chromium(III) salts mixture. The complexes structures were confirmed by elemental analysis, IR, Mössbauer spectroscopies, and X-ray analysis. The atomic absorption spectroscopy confirmed that the iron: chromium ratio is 2:1. The thermal properties of both heteronuclear complexes have been investigated in oxidizing and inert atmospheres revealing the stability of the trinuclear core up to 170 and 220°C, respectively.


 

DOI: http://dx.doi.org/10.19261/cjm.2021.854

Abstract (PDF) 

Graphical Abstract: The main problems and prospects of water disposal systems of such a megalopolis as Saint Petersburg are considered. Methods for processing sewage sludge to an ecologically safe state, as well as the use of sludge combustion ash at the Central Aeration Station (CAS) in Saint Petersburg are proposed. Special attention was paid to the issues of sludge management in the sewage system of domestic wastewater. The possibility of using ash for extinguishing and eliminating oil spills at the CAS was confirmed experimentally in comparison with similar capabilities of marshalite and fine-grained construction sand. A method for preparing dry building mixes based on Portland cement for obtaining low-water demand construction binders was proposed. 


 

DOI: http://dx.doi.org/10.19261/cjm.2021.877

 

Abstract (PDF)
Graphical Abstract: The GC-MS analysis of the essential oil from Tanacetum corymbosum revealed the presence of 38 compounds, including terpenes - germacrene D, (Z)-β-farnesene, g-elemene, β-caryophyllene, aliphatic - palmitic and linoleic fatty acids, fatty alcohol n-octadecanol, higher alkane n-heneicosane as the major constituents. The in vitro antimicrobial assessment of the ethanolic extract showed promising antibacterial/antifungal activities against five Gram-(+), Gram-(-) and phytopathogenic bacteria species and two fungi strains. The data obtained in this study may be useful both for researchers and for producers interested in new or less studied species of medicinal plants in healthcare and their biological activities.


 

DOI: http://dx.doi.org/10.19261/cjm.2021.861

Abstract (PDF)
Supplementary Material (PDF) 

Graphical Abstract: The study described the isolation of β-D-galactopyranoside seco-phytoporphyrin from Atropa belladonna and Solanum tuberosum yellow leaves. Column chromatography was applied for its isolation. The UV-Vis, mass spectrometry and NMR spectroscopy were used for the structure confirmation. The results demonstrate that the two plants that the same chlorophyll catabolite structure. 

 

DOI: http://dx.doi.org/10.19261/cjm.2021.881

Abstract (PDF) 

Graphical Abstract: The novel binuclear Zn(II) complex of general formula Zn₂(L)₄(CH₃OH)₂ where HL is N-[bis(benzylamino)phosphoryl]-2,2,2-trichloroacetamide has been synthesized from non-aqueous solution and characterized by elemental analysis, FTIR and NMR spectroscopy as well by X-ray single crystal diffraction. This complex represents the third example of binuclear complexes with this ligand within four known for today.


 

DOI: http://dx.doi.org/10.19261/cjm.2021.848

 

Abstract (PDF)
Graphical Abstract: This study was aimed to investigate the chemica l compositions and lipoxygenase inhibitory activity of the essential oil from Alstonia angustiloba growing in Malaysia. The essential oils were obtained by hydrodistillation and fully characterized by gas chromatography and gas chromatography-mass spectrometry. Analysis of the A. angustiloba essential oil resulted in the identification of twenty-five chemical components, attributed 90.8% of the total oil. The most abundant components of A. angustiloba oil were linalool (21.2%), 1,8-cineole (16.8%), α-terpineol (9.5%), terpinene-4-ol (8.5%), β-caryophyllene (6.2%), and caryophyllene oxide (5.2%). The essential oil displayed moderate activity towards lipoxygenase activity with IC₅₀ value of 45.8 μg/mL.