During the last century, the synthetic dyes have taken a pivotal role in many domains. Part of this class is the Cochenille Red dye. It can be used as such for wool, nylon, silk, inks, paper, plastics, wood stains, leather tanning and processing. But still in the above mentioned fields it is used as well or even with much better results as ligand being complexed with different metal cations.
This domain has been approached by us in previous studies in various papers. The range of use areas is extended for foods drugs, cosmetics, hematology and histology stains and last but not least, in photography, too. Due to these multiple uses, we have found it useful to study its behavior in an acidic medium in the presence of an oxidizing agent. Chromate [Cr(VI)] and azo dyes like Cochenille Red are common pollutants which may co-exist in some industrial effluents.
The degradation kinetics of the oxidation process of Cochenille Red dye using inorganic oxidizing agent (K2CrO4) have been investigated under various experimental conditions: different concentrations of H2SO4 [10-2 -5·10-1 M ] and temperatures [296 and 308 K].
A kinetic model for oxidation of Cochenille Red dye by the combination of chromate was developed based on experimental results.
The thermodynamic activation energy was calculated from the rate constants of the oxidation process of the dye, measured at two different temperatures, 296 and 308 K. We concluded that the negative value of entropies of activation indicate that the reaction occurs between ions of similar charge.
Based on our experimental and literature data , we conclude that the destruction of azo-chromophore group by the inorganic oxidizing agent (K2CrO4) is explained by the highest oxidation state of this dye.
Over the last period of time silver was considerably studied due to its lower resistivity. In the field of materials science, silver was used in applications such as: microelectronics components of high – temperature superconductiviting materials, bactericidal coatings and others domains. This study presents the process of obtaining and characterization the new complexes of silver (I) with Nhydroxy- succinimide. In the process of obtaining the new complex compounds in aqous solution, first we have to look at conductometry and UV-Vis absorbtion spectroscopy in order to determine the molar ratio silver : N-hydroxysuccinimide and the stability constants. The obtained solid coordination compounds were characterized by elemental analysis, IR spectroscopy and also was investigated of their thermostability. The X-ray powder diffraction reflects that the complexes compounds of silver (I) with N-hydroxysuccinimide are amorphous. In our further studies we want to determine if the new synthetized compounds will present the same or improuved properties as in the above mentioned silver characteristics.
In this paper, the study of obtaining new coordination compounds of Ni (II) and Co(II) using as
ligand, N-hydroxy-succinimide, was presented. Also, the stability constants of these compounds in aqueous
medium were determined.
The obtaining conditions and the stability of the new compounds were accomplished in aqueous
solutions using characteristic methods for coordination compounds: pH-metry, conductometry and UV-VIS
absorption spectroscopy. The combination ratios and the stability constants were determined with methods
characteristic for studies in solutions. From experimental data resulted that the combination ratio of central
metallic atoms with the ligand N-hydroxy-succinimide was: 1:1 and respectively 1:2. In the experiments were
used salts of NiCl2·6H2O and CoCl2·6H2O.
The optimal domain of pH stability of the studied compounds is limited between 5.74 - 5.86 for Co-
N-hydroxy-succinimide (for molar ratio 1:1 and 1:2) and respectively 5.69 - 5.87 for Ni-N-hydroxysuccinimide(
for molar ratio 1:1 and 1:2, too).
It is important to mention that these compounds were used with very good results in determination of
wastewaters from textile, metallurgical, chemical and food industry.
Complexion reactions with this ligand are very sensitive for the cations in this paper mentioned.
Therefore it is used most often with success in analytical chemistry and also it is posibil to use as sensors.
The new complex compounds has electronics transitions at λ = 517 nm for both complexes Co-N-hydroxy-succinimide at molar ratio 1:1 and 1:2 and also at the same λ = 397nm for Ni-N-hydroxysuccinimide
at molar ratio 1:1 and 1:2.
These complexes compounds was separated and recrystallized from aqueous solution.
From the spectrophotometric data it was determined the type and the nature of the electronics
transitions by Dq parameters.
Some new coordination compounds of Cr(III) using as ligand N-hydroxy - succinimide, were obtained and studied. The combination ratio, central atom: ligand were 1:1; 1:2 and 1:3. The new complex compounds were studied using UV-Vis spectroscopy, conductance and pH measurements. The studies of obtaining and of stability of the new compounds were accomplished in aqueous solutions using methods characteristic for coordination compounds: conductance and pH measurements. The combination ratios and the stability constants were determined with methods characteristic for studies in solutions.
KEYWORDS: Ions, Chemical species, Titanium, Zirconium, Oxygen, Metals, Optoelectronics, Microelectronics, Nanotechnology, Current controlled current source
In this paper, the study of obtaining new coordination compounds of Ti(IV) and Zr(IV) using as ligand: D,L-β-iso-butyric acid, is presented. Also, the stability of these compounds in aqueous medium is studied. The studies of obtaining and of stability of the new compounds were accomplished in aqueous solutions using methods characteristic for coordination compounds: conductance and pH measurements. The combination ratios and the stability were determined with methods characteristic for studies in solutions. From experimental data resulted that the combination ratio of central metallic atoms with the ligand derived from D,L-β-iso-butyric acid was 1:2. From experimental data resulted that in strong acid and strong basic mediums, the coordination compounds could not be obtained. The optimal stability of the studied compounds is limited between 3-6, pH - values. This fact is in accordance with the conditions of using these compounds in ecological leather tanning. Of great importance is that these compounds were used with very good results in tanning processes of different types of leather. This fact evidenced that the ecological alternative of tanning is better than non-ecological tanning using chrome compounds. The importance of this paper consists in obtaining new coordination compounds that can be used in ecological leather tanning.
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