Chemistry Journal of Moldova

DOI: http://dx.doi.org/10.19261/cjm.2018.543   

Abstract (PDF)
Graphical Abstract: The reaction cycle of H₂O₂ decomposition and O₂ generation catalyzed by Fenton reagent was studied using density functional theory calculations. A four-stage mechanism for the oxygen production and the Fe²⁺ regeneration in the Fenton reaction is proposed based on the obtained results. It is shown that the O-O bond cleavage of coordinated H2O2at the first step of reaction does not lead to a free HO^● radical. Instead, a highly reactive intermediate [Fe^IV(H₂O)₄(OH)₂]²⁺ with two HO^● radicals “trapped” in the complex is formed. The result of the next two reaction steps is the formation of the two HO₂^● radicals which can react on the triplet energy surface in order to produce O₂ and a H₂O₂.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.525

Abstract (PDF)

Graphical Abstract: The protection performance of self-assembled layers (SALs) formed by apricot cake extract (ACE) on the surface of steel has been studied. It was revealed that the protection ability of the SALs is determined by the time of film formation on the steel surface. The maximal corrosion inhibition efficiency (about 93%) was obtained after 48 h process of film formation in the vapour phase of the apricot cake extract. The results of the electrochemical analysis revealed that the ACE modified steel showed better corrosion protection in conditions of periodic condensation of moisture.

protection in conditions of periodic condensation of moisture.

DOI: http://dx.doi.org/10.19261/cjm.2018.522   

Abstract (PDF) 

Graphical Abstract: The present work provides an insight into the effect of the nature of surfactant (cationic, anionic), a component of water- and oil-borne microemulsions, on the reaction rate of 1,3-dipolar cycloaddition of C,N-diphenylnitrone with acrylonitrile. The electrostatically attractive character of the cationic surfactant, would bring the reactants closer to each other; hence, a rate enhancement would ensue, particularly within the water-rich zone. Besides the fact that acrylonitrile played a dual role, as a component of the microemulsion and a dipolarphile in the cycloaddition reaction, made the work-up advantageously sound. Additionally, the increase in reagents molar ratio was found to promote higher reactivity.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.493   

Abstract (PDF) 

Graphical Abstract: The study was aimed at increasing solubility and dissolution rate of ketoprofen by using multicomponent crystallization approach with nicotinamide as additional material. The multicomponent crystallization was carried out by solvent evaporation method using 2-propanol as solvent. The solubility and dissolution test showed that the ketoprofen-nicotinamide multicomponent crystal has solubility and dissolution rate significantly higher than the solubility and dissolution rate of the pure ketoprofen.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.494

Abstract (PDF)

Graphical Abstract: The adsorption of strontium ions from aqueous solutions on nut shells activated carbons (samples CAN-7 and CAN-8) at different temperatures has been studied. The isotherm of adsorption of strontium ions from aqueous solutions on activated carbon CAN-7 has two inflection points at relatively small and high equilibrium concentrations. As the temperature increases, the adsorption values decrease, which indicates that the adsorption process is exothermic.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.487   

Abstract (PDF)
Graphical Abstract: Enoxil-silica composites with various Enoxil-to-silica ratios were prepared by mechanical mixing of the biologically active Enoxil and fumed silica powders. The hygroscopic properties of the composites were studied by the gravimetric method. . It was found that hygroscopicity is reduced by 30÷40% when the Enoxil-to-silica mass ratio in the composites is 0.15÷0.35.

 Holding time in desiccators: 92 (1), 141 (2) and 365 (3) days.

 

 

DOI: http://dx.doi.org/10.19261/cjm.2017.464

Abstract (PDF) 

Graphical Abstract: This contribution presents investigations into possible effects of Ce³⁺ and Mn²⁺ on the reduction of UV-spectral signal for I^₃- observed e.g. in the Dushman reaction. The potential of the metal ions to form complexes with iodine-containing species was analysed. It was shown that no complex ions are formed between Ce³⁺ and Mn²⁺ metals ions with IO^₃-, I^-, I₂ species. Only the formation of a very weak CeI₃²⁺ complex ion was found to occur. An effect of a complex formation on the studied systems could be excluded.

 
 

DOI: http://dx.doi.org/10.19261/cjm.2017.461  

Abstract (PDF) 

Graphical Abstract: Green synthesis of silver nanoparticles (AgNPs) using Lantana camara yellow flower extract via microwave irradiation and ultrasound methods was conducted. The research was aimed at evaluating the effect of the synthesis method and also the time of treatment during synthesis on the particle size and antioxidant and antibacterial activities of the AgNPs. Analysis of the nanoparticles was performed using UV-Vis spectroscopy, transmission electron microscope (TEM), particle size analyzer, and Fourier transform infrared spectroscopy (FTIR). The present results support the advantages of plant extract and the green method for the production of nanoparticles for further potential applications.

DOI: http://dx.doi.org/10.19261/cjm.2017.459  

Abstract (PDF) 

Graphical Abstract: The state of water in a polyacrylamide (PPA) gel has been studied by the 1H NMR spectroscopy. It is shown that the PAA gel can serve as a container for prolonged retention of the Enoxil preparation without changing its chemical composition. At the same time, the molecular structures of Enoxil bind strongly to polymer chains, probably due to the formation of hydrogen-bound complexes with amino and imino groups.