| Author (s): |
IONESCU, Lavinel G.
|
| Title: |
ANDRÉS MANUEL DEL RIO, DISCOVERER OF VANADIUM |
| Abstract: |
Andres Manuel Del Rio was born in Madrid in 1764 and died in Mexico City in 1849. He studied mineralogy, geology, metallurgy, and mining engineering at the Royal Academy of Mines of Almaden and the Patriotia Seminary of Vergara. In 1871, with a stipend from the Spanish Crown, he continued his studies in Paris, Freiberg, Chemnitz, and other scientific centers throughout Europe, particularly in metallurgy. In 1794 at the invitation of Don Fausto Delhuyar, who together with his brother Juan Jose Delhuyar discovered tungsten in 1783, Andres Manuel Del Rio went to Mexico where he was a professor at the SahooZ of Mines for more than fifty years, until his death. In 1801, while analyzing a lead mineral from Zimpan, Hidalgo, Mexico, he discovered a.mew element that he called pancuronium or erythronium, because of the red colors, aharaateris·tia of its salts. In 183Z, the Swedish chemist NiZs Gabriel Sez>fstz>IJm z>edisaovered erythronium in an iron ore from Taberg, Smaland, Sweden, and named it vanadium in honor of the Scandinavian goddess Vanadis.
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| Keywords: |
History of Chemistry, Vanadium, Erythronium, Panchromium, Discovery of the Elements.
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| Year: |
1997
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| Initial page: |
1
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| Final page: |
6
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.4_1997.pdf |
|
|
| Author (s): |
Haidi D. Fiedler; Manuel Carneiro; Elba C. Teixeira
|
| Title: |
STUDY OF SOME ENVIRONMENTAL IMPLICATIONS DUE TO THE DISPOSAL OF ASHES FROM THE SÃO JERÔNIMO POWER STATION - RS |
| Abstract: |
The residues (ash agglomerates from combustion) generated at the São Jerônimo Power Station (UTSJ) were characterized with the main objective of evaluating, in pre-established conditions, the release of Cd, Co, Cu, Pb, Ni, Zn, Mn, Al, and Fe to the environment. Results revealed that, at different pH values, Fe, Zn, Mn, and Al were present in higher contents. In surface waters, for all sites analyzed, Fe and Al surpass the environmental standards imposed by Brazilian Legislation for class II surface waters. Surface sediments at the sites studied are basically composed by ashes from UTSJ, and a cumulative effect of deposition of the metals on the river sediments was verified. The experimental results are strongly indicative of an imperative need for a change in criteria in relation to the final disposal of residues from UTSJ. Otherwise, there is a high risk that the environmental impact in the short term will irreversibly damage the environment.
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| Keywords: |
Residue analysis, coal ash, extractable metals, surface waters, sediments. .
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| Year: |
1997
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| Initial page: |
7
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| Final page: |
19
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.10_1997.pdf |
|
|
| Author (s): |
Tudor ROSU, Lidia PARUTA, Mirela CALINESCU, Anca EMANDI
|
| Title: |
X-RAY STUDIES ON Tl2HgI4, PbHgI4, CdHgI4 AND Au2HgI4 INORGANIC COMBINATIONS |
| Abstract: |
The parameters of the crystalline elementary cells were calculated starting from the diffraction X-ray spectra obtained on microcrystalline powders of compounds with thermocbromic and semiconductor properties. The respective cell units belong to the tetragonal system and have the following values: a=6.450 A, c=1.14 A for the Tl2HgI4 compound; a=6.875 A, c=13.110 A for the PbHgI4 compound; a=6.40 A, c=13.12 A for the Au2HgI4 compound. The wet synthesis method is described for the CdHgI4 compounds.
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| Keywords: |
X-Ray diffraction, tetraiodomercurates, thermocromik properties, semiconductor properties, cell parameters..
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| Year: |
1997
|
| Initial page: |
21
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| Final page: |
34
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.23_1997.pdf |
|
|
| Author (s): |
Arnaldo D. S. Júnior; Rosangela B. Garcia; Dina G. Rodrigues; Jorge Nozaki
|
| Title: |
SOLID SUBSTRATE FERMENTATION OF CACTUS PULP BY ASPERGILLUS NIGER |
| Abstract: |
A new method of culture is described to study the growth of Aspergillus niger on cactus pulp in the solid-state. After extraction of viscous polyelectrolytes, employed in water treatment, the pulp of Cereus peruvianus was used as a substrate for solid-state fermentation by a wild strain of A. niger . The good conditions for A. niger growth were 60 % moisture, initial pH 3.0, 35 °C, a nitrogen source made of 11 % ammonium and 2 % urea (on a nitrogen basis), 5 % potassium phosphate, and 3.2 g spores/100 g substrate. Related to the dry pulp, maximum fungal growth was observed after 120 hours of fermentation with 14 % of protein production.
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| Keywords: |
solid-state fermentation, protein, Aspergillus, agricultural wastes, cactus.
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| Year: |
1997
|
| Initial page: |
35
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| Final page: |
42
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.37_1997.pdf |
|
|
| Author (s): |
Tudor ROSU, VioreL CARCU, Maria NEGOIU, Ovidiu MAIOR, Niculina BADICU
|
| Title: |
SOME NEW N-BENZOYL-N-SUBSTITUTED PHENYL THIOUREA COMPLEXES OF COPPER(II) |
| Abstract: |
The new N-benzoyl-N-substituted phenyl thiourea ligands have been used to p1·cpare copper(ll) complexes [Cu(L)2Cl2]. The novel complexes were characterized by ESR, IR, NIR, electronic spectroscopy and conductivity measurements, Tentative geometry of the complexes involves four-coordinate environments (tetrahedral distorted D2d) for the copper ion and a monodentate behavior for ligands. In all these complexes N, N-substituted thiourea is sulphur-bonded to the copper ion.
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| Keywords: |
thiourea, copper(II), complexes, ESR spectra.
|
| Year: |
1997
|
| Initial page: |
43
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| Final page: |
49
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.45_1997.pdf |
|
|
| Author (s): |
Paulo Cesar Pereira das Neves; Percio de Moraes Branco; Paulo Anselmo Matioli
|
| Title: |
THE PERCIO DE MORAES BRANCO COLLECTION OF RARE MINERALS OF THE UNIVERSIDADE LUTERANA DO BRASIL (ULBRA) |
| Abstract: |
The Mineral Collection of the Lutheran University of Brazil is one of the most valuable mineral collections of the South American Continent and consists of approximately 500 cataloged minerals, of which about 200 can be classified as rare or very rare. The majority of them are present in paragenesis with other minerals in the form of euhedric, subhedric, and anhedric crystals. The minerals come from different mineralogic provinces, including Denmark, the United States of America, Canada, Italy, Romania, Russia, Sweden, Brazil, Mexico, Chile, Slovenia, Germany, Algeria, England, and others. The Collection is organized in mineralogical classes with the exception of meteorites, organic compounds, and mineraloids and is found on permanent display and open to visitors in the Laboratory of Mineralogy, Building I, Central Campus of ULBRA in Canoas, RS, Brazil.
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| Keywords: |
Rare Minerals, Mineralogic Provinces, Mineralogical Classes, Meteorites..
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| Year: |
1997
|
| Initial page: |
51
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| Final page: |
66
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.52_1997.pdf |
|
|
| Author (s): |
Tudor ROSU, Angela KRIZA, Viorel CARCU, Anca NICOLAE
|
| Title: |
TRANSITION METAL COMPLEXES OF THE FORMYL VANILLINE DERIVATIVES LIGAND FAMILY |
| Abstract: |
Divalent 3d metal complexes with formyl-vanilline derivatives, of lite type ML2 or ML2X2 (M = Cu(II), Co(II); X = Cl), were sythesized by reaction of the corresponding metal(II) chlorides with 1-[3-formyl-4-methoxy-6-hidroxybemilydene]-2-phenazinoyllhydrazine, (FDFH), 1-benzilydene-2-phenazinoyhydrazine, (BFH), and 3-formyl-5,6-dihydroxybemilydenc-2-nitro-1--methylaniline, (FBAH). The novel complexes were characterized by ESR, IR, electronic spectroscopy, molar electric conductibility measurements and magnctk studies. These compounds appear to bn hexacoordinated.
|
| Keywords: |
phenazinolhydrnzine, copper(II), cobalt(II), hydroxybenzilydene, IR spectra.
|
| Year: |
1997
|
| Initial page: |
67
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| Final page: |
77
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.68_1997.pdf |
|
|
| Author (s): |
TINCA ONOFREI; CECILIA ARSENE; CARMEN MITA
|
| Title: |
SORPTION AND SEPARATION OF Cu(II), Co(II) AND Ni(II) ON 1(4-AZOBENZYLCELLULOSE)-2-NAPHTOL |
| Abstract: |
The mechanism of Cu(ll), Co(ll), and Ni(ll) sorption on 1(4-azobenzylcellulose)-2-naphthol has been investigated along with the possible chromatographic separation of the three elements on this chelating sorbent. The data obtained from the dependence of the distribution coefficients on pH and from isotherms, as well, have evidenced that physical sorption of the three elements is accompanied by chemical sorption, adsorption being predominant for Co(ll) and chemosorption for Ni(ll) and Cu(ll) being much more pronounced for the last element. The modifications in IR and diffuse reflectance spectra lead to the conclusion that chemical sorption involves the formation of chelates. The sorbent may be employed for the separation of Co(ll)-Ni(ll)-Cu(ll) through successive elution with 0.01 N HCl, 0.1 N HCl, and 1 N HCl.
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| Keywords: |
Sorption, Separation, Copper, Nickel, Cobalt, Chelating cellulose.
|
| Year: |
1997
|
| Initial page: |
79
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| Final page: |
85
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.79_1997.pdf |
|
|
| Author (s): |
Adalgiza Ciobanu, Fiorica Zalaru, D. Albinescu, Christina Zalaru
|
| Title: |
COORDINATION COMPOUNDS OF Cu(II) AND Ni(II) WITH SCHIFF BASES DERIVED FROM FORMYLCARVONE AND o,p-AMINOBENZOIC ACID |
| Abstract: |
Copper(II) and nickel(II) complexes employing the Schiff bases derived from formylcarvone and ortho and para aminobenzoic acid (L) have been prepared. The complexes of general formula CuL2.2H2O and Nil2.2L have been characterized by elemental analysis, infrared, visible and EPR spectra, and thermodifferential analysis. The metallic ion has determined the type of the complex.
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| Keywords: |
Coordination compounds of Cu(II) and Ni(II), Schiff bases derived from formylcarvone.
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| Year: |
1997
|
| Initial page: |
87
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| Final page: |
95
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.86_1997.pdf |
|
|
| Author (s): |
Dan Cascaval, Radu Tudose, Comeliu Oniscu
|
| Title: |
REACTIVE EXTRACTION OF DICARBOXYLIC ACIDS I. MECHANISM, LIMITING STEPS AND KINETICS |
| Abstract: |
In this paper the reactive extraction of some dicarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) have been studied. These acids have been extracted by Amberlite LA-2 in butyl acetate using a modified extraction cell of the Lewis type. Mechanism, limiting steps, and kinetic of the mass transfer process have been settled.
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| Keywords: |
dicarboxylic acids, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, reactive extraction, Amberlite LA-2.
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| Year: |
1997
|
| Initial page: |
97
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| Final page: |
110
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.95_1997.pdf |
|
|
| Author (s): |
Chim Rodica-Mariana ION, Cristina MANDRAVEL
|
| Title: |
THE PHOTODEGRADATION REACTION OF SOME PORPHYRINS |
| Abstract: |
One of the most important but undesirable properties of the porphyrins is their oxidative photodegradation which can occur in non-polar solvents, under irradiation, and in the presence of molecular oxygen. The mechanism of this oxidative photodegradation implies singlet oxygen and different radical species. This paper is concerned with the mechanism of the photodegradation of some meso-tetra(4-X-phenyl)porphyrins(TXPP) and meso-tetra(4-X-1-naphtyl)porphyrins(TXNP), where X could have different organic structures (-NH2,-N02,-S03H,-OH,-OCH3,-CH3). Based on different spectral methods (UV-Vis and IR absorption spectroscopy, emission spectroscopy, X-ray diffraction, electronic microscopy, and mass spectrometry, we propose a photodegradation mechanism, and we evaluated the effect of some scavengers (2,6-di-tert-butyl-phenol (DTBF) for radical species, 1,3-diphenylisobenzofuran (DPBF) for singlet oxygen and nitro-blue tetrazolium (NBT) for superoxide anion) during the porphyrin photodegradation.
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| Keywords: |
porphyrins, photodegradation, spectral analysis, meso-substitution..
|
| Year: |
1997
|
| Initial page: |
111
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| Final page: |
129
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.109_1997.pdf |
|
|
| Author (s): |
Dumitru Fatu; Maria Muscalu
|
| Title: |
CHARACTERIZATION OF SOME NODULAR CAST IRONS BY THERMAL ANALYSIS |
| Abstract: |
In this study, thermal analysis has been used to characterize thermal behavior and oxidation resistance of some nodular cast iron. One has studied samples of nodular cast iron, in several stages of elaboration, with different chemical compositions. The samples have been heated in air, in the temperature range: 18-1000 °C, and the thermal (TG, DTG, and DTA) curves have been recorded. A group of samples with low silicon content shows similar behavior: a continuous increase of weight, some peaks, and exothermal effect up to 850 °C. The thermal peaks correspond to iron oxides (Fe304, FeO, Fe203) formation. At high temperatures (T>850 °C), one can see a decrease of weight and an endothermal effect. A superficial decrease of carbon content by combustion ("decarburization" effect) takes place in the range of high temperatures. The two effects: oxidation-decarburization, depend on the structural changes of cast iron, wich takes place at high temperatures. The decarburization process has been modeled, and the kinetical parameters have been determined (reaction order n=0.76; activation energy E=l41.5 kJ). Kinetical study of the oxidation process has been achieved by nonisothermal methods using two mechanisms: bidimensional transport -for low temperatures and three-dimensional transport through a sphere for high temperatures. The activation energies have been calculated: 67.7 kJ for low temperatures and 122.5 kJ for high temperatures.
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| Keywords: |
TG, DTG, DTA, thermal behavior and oxidation resistance, nodular cast iron.
|
| Year: |
1997
|
| Initial page: |
131
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| Final page: |
141
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v5.n5.1997.128_1997.pdf |
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