Chemistry Journal of Moldova

Physical chemistry and chemical physics

CHROMATOGRAPHIC ANALYSIS OF ORCHID EXTRACTS AND QUANTUM CHEMICAL CALCULATIONS OF INDIVIDUAL COMPONENTS INTERACTION WITH SILICA

Author(s):

Olga Kazakova, Roman Ivannikov, Iryna Laguta, Oksana Stavinskaya, Viktor Anishchenko, Olga Severinovska, Ludmila Buyun


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2020 Volume 15, no.1
Pages: 95-102
Keywords: orchid extract, phenolic compound, HPLC, fumed silica, quantum chemical calculation.
Full Text (PDF): Download

DOI: http://dx.doi.org/10.19261/cjm.2020.694

Abstract (PDF)
Supplementary Material (PDF)
Graphical Abstract: The most common phenolic components of sixteen orchid extracts were identified using high performance liquid chromatography and laser desorption/ionization mass spectrometry. The interaction between these compounds and silica silanol groups was studied using quantum chemical calculations. Results show that the strength of the interaction of phenols with silica increased in the following order: ferullic, feruloylquinic and fertaric acids <kaempferol, apingenin <<сhlorogenic and caffeic acids, rhamnetin, quercetin, luteolin, epicatechin gallate. The common feature of compounds characterized by the strongest interaction with silanol groups is the presence of phenol ring with two neighbouring hydroxyl groups.


 

Downloads: 49

ELECTROCHEMICAL STUDIES OF THIOSEMICARBAZONE DERIVATIVE AND ITS TIN(IV) COMPLEX AS CORROSION INHIBITOR FOR MILD STEEL IN 1 M HYDROCHLORIC ACID

Author(s):

Nur Nadira Hazani, Yusairie Mohd, Sheikh Ahmad Izaddin Sheikh Mohd Ghazali, Nur Nadia Dzulkifli


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2019 Volume 14, no.1
Pages: 98-106
Keywords: 2-acetylpyridine, thiosemicarbazone, tin(IV) complex, mild steel, corrosion.
Full Text (PDF): Download

DOI: http://dx.doi.org/10.19261/cjm.2019.545   

Abstract (PDF)
Graphical Abstract: The inhibitive effects of 2-acetylpyridine 4-ethyl-3-thiosemicarbazone (HAcETSc) and dichlorophenyltin(IV) 2-acetylpyridine 4-ethyl-3-thiosemicarbazone (Sn(HAcETSc)PhenCl2) for mild steel in 1 M HCl solution at different concentrations were investigated using electrochemical measurements and scanning electron microscopy analysis. The result of electrochemical measurement found that the inhibition efficiency increased with inhibitors’ concentration. Moreover, it was shown that that Sn(HAcETSc)PhenCl2 had a better inhibitive effect than HAcETSc.







Downloads: 213

STRUCTURE OF MICELLES OF SODIUM DODECYL SULPHATE IN WATER: AN X-RAY AND DYNAMIC LIGHT SCATTERING STUDY

Author(s):

Yuri Mirgorod, Alexander Chekadanov, Tatiana Dolenko


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2019 Volume 14, no.1
Pages: 107-119
Keywords: sodium dodecyl sulphate, micelle structure, small-angle X-ray scattering, wide-angle X-ray scattering, dynamic light scattering.
Full Text (PDF): Download

DOI: http://dx.doi.org/10.19261/cjm.2019.572   
 
Abstract (PDF)
Graphical Abstract: Aqueous micellar solutions of sodium dodecyl sulphate were investigated using X-ray scattering technique by a model-independent approach and dynamic light scattering in the concentration range 0.008 – 0.1 M. The obtained results are discussed in the framework of the concept of polyamorphous transition between ensembles of water clusters of low and high density levels. Polyamorphous transition accompanies the formation of dual structures of contact and separated by water micelles with different rates of diffusion.




Downloads: 107

DFT STUDY OF THE ENTIRE REACTION CYCLE OF H2O2 DECOMPOSITION AND O2 GENERATION CATALYZED BY FENTON REAGENT

Author(s):

Ion Arsene, Natalia Gorinchioy


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2019 Volume 14, no.1
Pages: 88-97
Keywords: Fenton reaction, H2O2 decomposition, DFT calculations
Full Text (PDF): Download

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 [FeIV(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.


 

Downloads: 96

APRICOT CAKE EXTRACT AS CORROSION INHIBITOR OF STEEL: CHEMICAL COMPOSITION AND ANTI-CORROSION PROPERTIES

Author(s):

Viktoria Vorobyova, Margarita Skіba


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2019 Volume 14, no.1
Pages: 77-87
Keywords: apricot cake extract, self-assembled layer, green corrosion inhibitor, steel, organic coating.
Full Text (PDF): Download

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.

Downloads: 87

EFFECT OF THE NATURE OF SURFACTANT ON THE REACTIVITY OF C,N-DIPHENYLNITRONE TOWARDS ACRYLONITRILE IN DIFFERENT MICROEMULSION SYSTEMS

Author(s):

Kahina Hamza, Abdelkader Touati, Ahmed Ait-Yahia, Michel Baltas, Christiane André Barres, Saâd Moulay


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2018 Volume 13, no.2
Pages: 82-88
Keywords: acrylonitrile, cycloaddition, isoxazolidine, microemulsion, nitrone.
Full Text (PDF): Download

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.


 

Downloads: 113

MULTICOMPONENT CRYSTALLIZATION OF KETOPROFEN-NICOTINAMIDE FOR IMPROVING THE SOLUBILITY AND DISSOLUTION RATE

Author(s):

Yudi Wicaksono, Dwi Setyawan, Siswandono Siswandono


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2018 Volume 13, no.2
Pages: 74-81
Keywords: ketoprofen, multicomponent crystallization, solvent evaporation, solubility, dissolution rate.
Full Text (PDF): Download

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.


 

Downloads: 89

ADSORPTION OF STRONTIUM IONS FROM AQUEOUS SOLUTIONS ON NUT SHELLS ACTIVATED CARBONS

Author(s):

Gheorghe Duca, Mihai Ciobanu, Tudor Lupascu, Igor Povar


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2018 Volume 13, no.2
Pages: 69-73
Keywords: activated carbon, adsorption heat, entropy, exothermic process, strontium ion.
Full Text (PDF): Download

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.


 


Downloads: 74

HYGROSCOPIC PROPERTIES OF ENOXIL-SILICA COMPOSITES

Author(s):

Oksana Stavinskaya, Iryna Laguta, Olga Kazakova, Pavlo Kuzema, Tudor Lupascu


Field: Physical chemistry and chemical physics
Type: Short communication
Issue: 2018 Volume 13, no.2
Pages: 89-92
Keywords: Enoxil, biomolecule, fumed silica, composite, hygroscopicity.
Full Text (PDF): Download

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.

 

Downloads: 55

THE POSSIBILITY OF Ce3+ AND Mn2+ COMPLEX IONS FORMATION WITH IODINE SPECIES IN A DUSHMAN REACTION

Author(s):

Iurie Ungureanu, Gheorghe Duca, Ionel Humelnicu, 
Gelu Bourceanu


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2018 Volume 13, no.1
Pages: 103-110
Keywords: Dushman reaction, cerium ion, manganese ion, iodine specie.
Full Text (PDF): Download
 
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 I3- 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 IO3-, 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.

 
 

Downloads: 66