Chemistry Journal of Moldova

https://doi.org/10.19261/cjm.2023.1063   

Abstract (PDF)

Graphical Abstract: In this paper the process of reagent desalination of mineralized mine waters was studied. Reagents 5/6 aluminum hydroxochloride and sodium aluminate were used during liming. Complex processing of waste generated during reagent water treatment allows to create a low-waste technology for the purification of mineralized water. 

DOI: https://doi.org/10.19261/cjm.2021.854

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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.2021.793

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Graphical Abstract: The purpose of this study was to investigate the physicochemical particularities of the regeneration processes that occur in spent sulphate copper-zinc solutions using the reagent methods of crystallization, cementation, and sedimentation. A comparative analysis of the results of the studies of regeneration processes has shown that the content of the extraction of Cu²⁺ and Zn²⁺ ions by the crystallization method makes up to 97.2% and 49.7%, respectively; by the contact displacement method to 99.9% and 95.4%, respectively; and by the deposition method it makes up to 99.9% and 99.9%, respectively. The presented study can be used for improvements in the electroplating productivity.


 

DOI: https://doi.org/10.19261/cjm.2021.779

Abstract (PDF) 

Supplementary Material (PDF)
Graphical Abstract: A modified Scheffe's simplex lattice design method is proposed to study the properties of multicomponent materials. This modified Scheffe's method allowed determining the optimal compositions of cordierite and corundum based ceramic materials that are used as catalyst carrier for gas purification equipment. The obtained material (0.63-1.25 mm weight fraction of cordierite of 0.35 mass% fraction; <0.63 mm weight fraction of cordierite of 0.35 mass% fraction; <0.06 mm weight fraction of corundum of 0.2 mass% fraction; 1.25-2.5 mm weight fraction of cordierite of 0.2 mass% fraction) was used successfully for the manufacturing of catalytic neutralizers of gas emissions. 

DOI: https://doi.org/10.19261/cjm.2020.775

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Graphical Abstract: This paper presents the development and optimization of a new approach which combines the utilization of activated carbon and glucose oxidase enzyme for decolourisation of beet sugar syrup. The combining of the physical adsorption with the enzymatic reaction was managed to improve the decolourisation of beet sugar syrup from 35.29 to 83.68% compared to the basic adsorption by activated carbon after 120 min of operation under the optimum conditions. The maximum decolourisation efficiency by the coupled process was achieved at glucose oxidase dosage of 0.07 g, glucose concentration of 20 mM, and solution pH 7 at the temperature of 30ºC using 0.01 g of activated carbon particles. Given the high effectiveness, reusability, and the eco-friendly nature of the process, the proposed method can serve as an alternative to ordinary decoloursation techniques.



 

 

DOI: https://doi.org/10.19261/cjm.2020.717   

 

Abstract (PDF)
Supplementary Material (PDF)

Graphical Abstract: This paper tackles the potential uses of agricultural wastes (sawdust, sunflower seed shells, pumpkin seed shells, cherry pits, walnut shells, and green walnut shells) for the production of pellets. Combustion heat was determined for these wastes and their thermal decomposition in an air atmosphere was analysed. Five types of mini-pellets were made from different combinations of available wastes and their thermal behaviour was analysed by the microscale combustion calorimetry method.
 

 

DOI: http://dx.doi.org/10.19261/cjm.2019.585 

Abstract (PDF)

Graphical Abstract: This paper presents an overview of the various innovative methodologies used in the recovery of valuable metals and critical raw materials from secondary sources. The review also highlights the used varieties of application on large scale in real situations and hopes to provide insights into valorization of spent sources.

DOI: http://dx.doi.org/10.19261/cjm.2018.516   

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Graphical Abstract: The article presents the results of studies regarding the improvement of the qualitative characteristics of blast furnace coke obtained from modified coal blend in industrial conditions of Avdeevka Coke Plant. Inorganic corundum powders are applied to modify the coal blend, namely electrocorundum (α-Al2O3) and carborundum (α-SiC). The introduction of a specific quantity (0.25 wt %) of non-clinkering additives allows the modification of the processes that occur when the coal blend is plastic, with consequent improvement in coke strength.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.502   

Abstract (PDF) 

Graphical Abstract: The features of the cement clinker when rice husk is used are investigated. The dependence of the raw mixture composition on the set product burning characteristics has been analysed using the software “CLINKER”. The mixture compositions have been identified on the basis of the chalk–clay–rice husk system, with the introduction of man-made stock of 6.0–18.0 mass %. The features of the phase composition and the binder properties, by varying the rice husk content, mixture ratio and burning temperature are shown.


 

DOI: dx.doi.org/10.19261/cjm.2017.407 

 

Abstract (PDF)
Graphical Abstract: The effect of phase and chemical composition of natural quartz sand, binder and burnable additives was studied. The conditions of application of the membrane and biocide layers on the formation of porous ceramic and microfiltration membranes were investigated. It is shown that a crystalline oxide of Si(IV) is determinant for obtaining the ceramic materials. The presence of carbonates (calcite, dolomite, aragonite, etc.) and crystalline aluminosilicates (microcline, albite, phlogopit, etc.) leads to a decrease in mechanical strength of ceramics. The biocide coating designed to protect the ceramic membrane surfaces from biofouling was applied and its anti-bacterial activity was shown.