Journal of the University of Chemical Technology and Metallurgy, XXXVII, 2002, Book 4

CHEMISTRY

 

SYNERGISTIC SOLVENT EXTRACTION OF Ce (III) WITH MIXTURES OF CHELATING EXTRACTANT AND QUATERNARY AMMONIUM SALT
I. Dukov, M. Atanassova

DIELECTRIC PROPERTIES OF (1-x)BaTiO3.xMgTiO3 OBTAINED BY PEROXOMETHOD
V. Parvanova

IR SPECTROSCOPY INVESTIGATION OF METAL AMORPHOUS NANOPARTICLES
I. Markova - Deneva, K. Alexandrova, G. Ivanova, I. Dragieva

RELATIONSHIP BETWEEN THE CHEMICAL SOIL CONTENT AND THE PRESENCE OF TERMITES
G. M.Taha, M. A. Hoda

INVESTIGATION OF THE KINETICS OF AGING OF CHEMI-MECHANICAL
PULP FROM POPLAR WOOD
E. Valcheva, R. Boeva, E. Petkova, Z. Litovski

 

SYNERGISTIC SOLVENT EXTRACTION OF Ce (III) WITH MIXTURES OF CHELATING EXTRACTANT AND QUATERNARY AMMONIUM SALT
I. Dukov, M. Atanassova

 

The influence of the quaternary ammonium salt anion on the synergistic extraction of Ce (III) with mixtures of thenoyltrifluoroacetone (HTTA) and 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HP) and Aliquat 336 as synergistic agent in chloride (QCl) and perchlorate (QClO4) forms in C6H6 has been studied. The formation of mixed anionic complexes of type Q+[Ln(TTA)4]- and Q+[LnP4]- have been determined. The values of the equilibrium constants have been calculated. It was found that the change of the anion of the salt from Cl- to ClO4- exerted a considerable influence on the metal extraction.
Keywords: Synergistic extraction, lanthanoids, thenoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, quaternary ammonium salt.

DIELECTRIC PROPERTIES OF (1-x)BaTiO3.xMgTiO3 OBTAINED BY PEROXOMETHOD
V. Parvanova

 

The system (1-x)BaTiO3.xMgTiO3 (x=0,1; 0,2; 0,3 and 0,4 mol at.) is obtained by peroxometod. Temperature dependence of the permittivity (er) and dielectric losses (tgd) at frequency 1 kHz from calcination temperatures of ceramics Tcal = 1250, 1300 and 1400°C are studied. Ceramic material with compound 0,6BaTiO3.0,4MgTiO3 calcinated at 1400°C have TKer ® 0 for temperature interval - 40 to 140°C, er = 3500, and low dielectric losses tgd = 35.10-4. Those values make it suitable for production of thermal stability capacitors as well as capacitors with low dielectric losses working at high frequencies.
Keywords: Titanates, (1-x)BaTiO3.xMgTiO3, dielectric properties

IR SPECTROSCOPY INVESTIGATION OF METAL AMORPHOUS NANOPARTICLES
I. Markova - Deneva, K. Alexandrova*, G. Ivanova*, I. Dragieva*

 

IR spectroscopy investigations of metal amorphous nanoparticles with composition such as (M1, M2)xByHz (where M1 and M2 may be Co, Fe, Li, Mg, Sm) in a wide frequency region of 4000 - 400 cm -1 on IR Spectrophotometer with Fourier transformation (Bruker EQUINOX 55) have been carried out. The IR spectra of the (Li, Fe)xByHz nanoparticles, synthesized by the T - method, and prepared with and without the presence of a hydrophobic agent have been taken. An IR spectroscopy study of the amorphous (Co, M)xByHz nanoparticles (where M = Fe, Li, Mg, Sm) and (Li, Fe)xByHz particles prepared by the Y method as well as of ( Li, Fe)xByHz particles, prepared by the T - method has been performed too. The IR spectra of MH electrodes based on these nanoparticles have been taken down before and after an implementation of charge - discharge tests as electrodes (a positive pole) in 6M KOH electrolyte in a Ni - MH electric battery. The creation of chemical bonds between boron and oxygen atoms and the formation of BO3 and BO4 groups has been proved. The hydrophobic agent used during the borohydride reduction process has limited the access of the oxygen from the surroundings and the possibility of Fe and Li to be oxidized and has stimulated the formation of BO3 groups. The electrochemical tests in a KOH electrolyte of the MH electrodes based on the metal nanoparticles investigated have proved the creation of chemical bonds between boron and oxygen atoms in BO3 and BO4 groups and between metal and oxygen in complex metal oxides as well as the presence of O - H bonds in free and linked OH groups and in adsorbed molecules of H2O on the MH electrode surface.
Keywords: infrared spectra, (Co, M)xByHz and ( Li, Fe)xByHz nanoparticles, borohydride reduction process, Ni - MH electrodes

 

RELATIONSHIP BETWEEN THE CHEMICAL SOIL CONTENT AND THE PRESENCE OF TERMITES
G. M.Taha*, M. A. Hoda**

 

*Chemistry Department, Aswan Faculty of Science, South Valley University, Aswan, Egypt,E-mail: gmtaha@hotmail.com**Zoology Department, Aswan Faculty of Science, South Valley University, Aswan, Egypt

Received 21 May 2002Accepted 12 June 2002

 

Unprecedented trials were performed to find a relationship between the physicochemical characteristics, major and trace element content of a soil and the existence of termites under its surface "at 40 cm depth". For this purpose, twenty soil samples under the roots of both the infested and sound trees "ten each" were collected from Kima district, Aswan, Egypt. All the collected samples were analyzed for pH, conductivity, organic matter (OM), loss on ignition (LOI), Ca, Cl, CO32-, HCO3-, Mg, NO-2 and NO-3 content in the soil:water extract. The acids mixture containing HCl, HNO3 and HF was used for the complete attack of the samples. The resulting clear solutions were analyzed for Cd, Co, Cr, Cu, Fe, K, Mn, Pb and Zn content. The resulting data were then statistically treated.
Keywords: soil insect pests, wood eating insects, capillary pore space, non-capillary pore space.

 

INVESTIGATION OF THE KINETICS OF AGING OF CHEMI- MECHANICAL PULP FROM POPLAR WOOD
E. Valcheva, R. Boeva, E. Petkova, Z. Litovski

 

University of Chemical Technology and MetallurgyKl. Ohridski 8, Blvd., 1756 Sofia, Bulgaria

Received 18 October 2002 Accepted 28 October 2002

 

Aging of high yield fiber materials is a complicated physico-chemical process which depends on a lot of factors: temperature, time, humidity and oxygen presence, irradiation, etc. As a result of aging the optical and physico-mechanical properties of the materials are degraded. The kinetics of aging of chemi-mechanical pulp (CMP) from poplar wood is examined in this paper. Samples from unbleached and bleached with hydrogen peroxide and sodium hydrosulfite CMP which have been subjected to artificial thermal aging at temperatures of 363, 378 and 393 K are used. The change in the brightness W(%) is traced.
It is found out that the kinetics of the process is best described by an exponential kinetic equation, which is applicable to processes taking place over an energetically uniformly inhomogeneous surface. The values of the heterogeneous coefficient are computed and is determined that it slightly depends on the temperature and the method of CMP bleaching. The values of the activation energy and the pre-exponential factor are determined. The presence of a compensatory effect is ascertained. The presence of general a compensatory effect in the process of aging of various samples of CMP shows that the method of bleaching does not influence the process mechanism.
Keywords: chemi-mechanical pulp, bleaching, hydrogen peroxide, hydrosulfite, aging, pre-exponential factor.