Chemistry Journal of Moldova

2015 Volume 10, no.1

OXIDATION AND CHARACTERIZATION OF ACTIVE CARBON AG-5

Author(s):

Tatiana Goreacioc


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2015 Volume 10, no.1
Pages: 76-83
Keywords: active carbon, oxidation, surface properties, thermal analysis, infrared spectroscopy.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).11

Graphical Abstract:  
The surface chemistry of the commercial active carbon AG-5 has been modified by oxidation with concentrated nitric acid. The structural changes caused by oxidative treatment were estimated on the basis of nitrogen adsorption-desorption isotherms and thermal analysis. Boehm titration method and infrared spectral analysis have been used in order to evaluate surface chemistry characteristics of active carbon samples.

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TEMPERATURE DEPENDENCE OF 57Fe-MÖSSBAUER SPECTRA FOR A TRINUCLEAR SYSTEM

Author(s):

Dumitru Sirbu


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2015 Volume 10, no.1
Pages: 84-88
Keywords: ferrocene, terpyridine, Mӧssbauer, Debye temperature.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).12

Graphical Abstract:
 57Fe Mӧssbauer spectra were recorded for 1'-terpyridine ferrocenecarboxylic acid and [bis(1'-terpyridine ferrocenecarboxylic acid) Fe(II)]2+ in the temperature range 7 – 293 K. The temperature dependence of the Quadrupole Splitting, Isomer Shift and Debye-Waller factor are discussed. The Debye temperature, θD, for the iron nuclei in the investigated compounds was determined.

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ANTIOXIDANT PROPERTIES OF DIHYDROXYFUMARIC ACID AND ITS DIMETHYL ETHER: A COMPARATIVE DFT STUDY OF THEIR REACTIONS WITH THE STABLE RADICAL DPPH*

Author(s):

Mikhail Gorbachev, Natalia Gorinchoy, Ion Arsene


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2015 Volume 10, no.1
Pages: 89-94
Keywords: antioxidant activity, DPPH*, dihydroxyfumaric acid, dimethyl ether of dihydroxyfumaric acid, DFT calculations.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).13

Graphical Abstract:
 The preferred mechanism of the reaction of dihydroxyfumaric acid and its dimethyl ether with the free stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH*) was revealed by means of Density Functional Theory (DFT) calculations. The proposed mechanism has an ionic character and includes the formation of charge-transfer complexes as the main stage. It is also shown that the lower antioxidant activity of dimethyl ether of dihydroxyfumaric acid is caused by both its lower acidity (as compared with its precursor acid) and formation of more stable intermediates during its reaction with DPPH*. Our results allow one to rationalize the available experimental data.

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APPLICATION OF TAGUCHI OPTIMIZATION METHOD IN THE PREPARATION OF ACTIVATED CARBON BY MICROWAVE TREATMENT

Author(s):

Oleg Petuhov


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2015 Volume 10, no.1
Pages: 95-103
Keywords: activated carbon, walnut shells, microwave radiation, experimental design, analysis of variance.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).14

Graphical Abstract: 
This paper reports on the preparation of activated carbon from walnut shell. Orthogonal array experimental design method was used to optimize the preparation of activated carbon with phosphoric acid by using microwave treatment. The optimization parameters were: microwave power, activation time, phosphoric acid concentration and particle sizes of nut shells. Thermal analysis of the intact and impregnated with phosphoric acid walnut shells was used for the simulation of activation process. Activated carbon with the optimal parameters was obtained, being characterized by gas adsorption method and scanning electron microscopy.

 

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TOWARDS SCREENING THE ENHANCE OF LUMINESCENCE PROPERTIES OF MODIFIED TANNINS IN ALKALINE SOLUTION BY A FENTON-LIKE REACTION

Author(s):

Alexandru Gonta


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2015 Volume 10, no.1
Pages: 104-112
Keywords: oxidation, tannins, free radical, chemiluminescence.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).15

Graphical Abstract:
 After modification of enotannins, flavonols monomer units could be obtained with polyfunctional properties. Moreover, polyphenols are known to generate H2O2 and other ROS under alkaline conditions. ROS generation and catalytic influence of ferrous ions enhance the chemiluminescence light. Therefore in this work, Tox/Tris-Edta/Fe2+ ions have been used for screening luminescent properties of oxidized tannins.


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METHOD OF INFRARED SPECTRA REGISTRATION OF ACTIVATED CARBONS IN POTASSIUM BROMIDE PELLETS

Author(s):

Diana Shepel, Tatiana Goreacioc, Tudor Lupascu, Mihail Filippov, Maria Rusu


Field: Analytical chemistry
Type: Short communication
Issue: 2015 Volume 10, no.1
Pages: 113-115
Keywords: infrared spectroscopy, activated carbons, potassium bromide KBr pellets.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2015.10(1).16

Graphical Abstract:
 This communication is devoted to the elaboration of a new optimal technique of infrared spectra registration of activated carbons in potassium bromide pellets. Authors investigated the dependence of the intensity of the least overlapping infrared bands of activated carbons on the conditions of preparation, recording of the spectrum, and the degree of homogenization with potassium bromide.


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IN MEMORY OF ACADEMICIAN OF ACADEMY OF SCIENCES OF MOLDOVA PROFESSOR CONSTANTIN TURTA

Author(s):

Tudor Lupascu, Aculina Aricu


Field:
Type:
Issue: 2015 Volume 10, no.1
Pages: 116-117
Keywords: Constantin Turta, Mössbauer spectroscopy, coordination compounds
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DOI:
dx.doi.org/10.19261/cjm.2015.10(1).17

A dedication in memoriam of Academician Constantin Turta, Doctor habilitate in chemistry, Professor, famous scientist, world-renowned chemist, Laureate of the State Prize of the Republic of Moldova, person of a exquisite culture and noble attitude. Scientist Constantin Turta was a worldwide specialist in the field of bioinorganic and coordination chemistry. He became known in the scientific community by his fundamental pioneering work on the application of Mössbauer spectroscopy in inorganic and coordination chemistry. Merits of academician Constantin Turta were appreciated both by the scientific community and the government. He is the Knight of the Order "Labour Glory" and Medal "Dimitrie Cantemir" of the Academy of Sciences of Moldova.


Downloads: 61