Chemistry Journal of Moldova

https://doi.org/10.19261/cjm.2022.895   

 

Abstract (PDF)
Graphical Abstract: A facile, one-pot, and solvent-free synthesis was developed to obtain a thermally stable chitosan biopolymer. The bifunctional isocyanate by interaction with chitosan formed urea and urethane bonds between chitosan chains. Subsequently, the designed chemistry facilitated the formation of carbodiimide bonds between chitosan chains via dehydration of the urea bond. The modified chitosan was proved to be superior in thermal properties and could be used as a thermally stable bio-filler. This synthetic methodology is a facile route to achieve improved thermal stability in biopolymers.

 

https://doi.org/10.19261/cjm.2021.902   

 

Abstract (PDF)
Graphical Abstract: An environmentally friendly method for phosphogypsum processing into N,Ca,S,P-fertilizers is proposed. Thus, was obtained a complex liquid N,Ca,S,P-fertilizer with the content of nutrients (% wt.) N:Ca:S:P = 56:26:12:6 in the dry product, and 16.8:3.6:7.8:1.8 in the liquid phase. The obtained fertilizer increased the yield of radish by 7.16% compared to the control. The advantage of the proposed method is reducing the cost of the fertilizer, increasing its nutritional value, and obtaining useful products from the waste.


 

DOI: https://dx.doi.org/10.19261/cjm.2021.859   

 

Abstract (PDF)
Graphical Abstract: On the basis of a new model of chemical dissolution, an analysis of the kinetic parameters obtained using the modified V.V. Dolivo-Dobrovolsky equation was carried out. It shows that the change in parameters during the transition from one mineral to another is subject to a compensation effect. Additionally, calculations based on the new dissolution model made it possible to distinguish between the systemic and individual properties of minerals of the same nature in the process of dissolution. These minerals differ from each other by the concentration of ac tive surface complexes, and are combined into a system by a single transmission coefficient and the same value of the lifetime of the active complex.
  

 

Abstract (PDF)
Graphical Abstract: The detailed mechanism of the interaction of the radical cation ABTS^•+ with a number of food acids (gallic, ferulic, caffeic, vanillic, cinnamic, syringic, p-coumaric) is revealed by means of the DFT calculations. It is shown that the interaction between the neutral molecules of the studied food acids and ABTS^•+ does not lead to any charge transfer from these molecules onto ABTS^•+. The almost complete conversion of the ABTS radical cation into its diamagnetic derivative occurs due to the interaction of one of the sulphonic groups of ABTS^•+ with the acid anions through the formation of the corresponding intermolecular hydrogen bond.

 

DOI: https://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: https://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: https://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: https://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: https://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: https://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.