Authors:D. Nistor, N. Miron, G. Surpateanu, and A. Azzouz
The present work tries to emphasize the effect of acid/basis properties of montmorillonite type clays by ion exchange with
cations of different natures. The acidity and basicity measuring was made by thermo programated desorption (TPD)1,2, using
ammonia like basis agent and carbon dioxide like acid agent. With TPD method we can determine acid/basis proprietes by measuring
of the quantity of the ammonia and carbon dioxide termodesorbed. Clays are crystalline aluminosilicates, similar with the
zeolyts, who presents the property of ion exchanging. That propriety can be applicated for pollutants cations from aquatic
solutions. Ion exchanging propriety depends of a lot of factors: the cation nature, the valence and the ionic ray of the cation
present in the impregnated solution. That's an advantage for depollution process of heavy metals by fixing of these metals
by montmorillonite structure. By using TPD metod we can obtaine a caracteristic diagram.
Authors:A. Azzouz, A. Kotbi, P. Niquette, T. Sajin, A. Ursu, A. Rami, F. Monette, and R. Hausler
Ion-exchanged montmorillonite-rich materials (ca. 96% purity) like NaMt, Fe(II)Mt, Co(II)Mt, Ni(II)Mt and Cu(II)Mt showed
catalytic activity in the ozonation of oxalic acid in water at room temperature, in the pH range 3.4–6.0. The conversion of
oxalic acid exceeds 95% after 180 min of ozone bubbling in the presence of Fe(II)Mt. The oxalic acid removal efficiency was
found to increase swiftly with the acid character of the clay surface up to a certain level, but decreases gently with excessive
surface acidity. The pH exerts a strong influence on the catalyst efficiency, because it induces changes in the composition
of both the liquid media and catalyst. The synergic action of ozone and clay catalysts at acidic pH seems to involve ozone
adsorption and interaction between cation and adsorbed oxalate. The negative effect of increasing pH between 3.44 and 6.0
is discussed in terms of a decrease in the amount and mobility of the cation in the vicinity of the clay surface, and of a
decay in the clay surface area available to ozonation.
Authors:H. Ilbaği, A. Çitir, A. Kara, M. Uysal, and F. Azzouz Olden
Yellow dwarf viruses (YDVs) are economically destructive viral diseases of cereal crops, which cause the reduction of harvested yield and quality of grains. Up to now the identification of such viruses was limited to monocotyledonous Poaceae weed hosts, and was not investigated in dicotyledons. In this study, using DAS-ELISA and RT-PCR methods, 6 dicotyledonous weed species, collected from Trakya, Turkey, were examined for the presence of the YDVs pathogens BYDV-PAV, BYDV-MAV, BYDV-RMV, BYDV-SGV and CYDV-RPV. The screening tests revealed certain samples of Geranium dissectum L. and Juncus compressus Jacq. were infected with BYDV-PAV, while other samples of the same species were positive for BYDV-MAV. Additionally, RT-PCR tests of both weed species revealed cases of mixed infection by BYDV-PAV and BYDV-MAV. Transmission experiments using the aphid species Rhopalosiphum padi L. showed that BYDV-PAV was transmitted persistently from Geranium dissectum to barley cv. Barbaros seedlings. To our knowledge, this is the first report of Geranium dissectum and Juncus compressus as possible plant hosts of BYDV-PAV and BYDV-MAV in Turkey.
Authors:Denisa Nistor, P. Dron, Georgiana Surpăţeanu, Ilie Siminiceanu, N. Miron, and A. Azzouz
This study presents the improved method of smectite
type clays pillaring, using aluminum salts. To achieve this goal, natural
clay with a percentage of more than 95% montmorillonite was used. In order
to analyze the pillaring process, a thermal procedure was used (thermal programmed
desorption). The results of the pillaring process show that a controlled distance
between the foliar band structures as long as 18·10–10
m can be obtained. The clays modified by pillaring can be used as molecular
sieves in microfiltration processes or as agents in residual water chemical
depolluting processes. They also have zeolite properties which make them reusable.
Authors:A. V. Ursu, G. Jinescu, F. Gros, I. D. Nistor, N. D. Miron, G. Lisa, M. Silion, G. Djelveh, and A. Azzouz
Ca–bentonite originating from a Romanian deposit was leached in 0.5–8.0 M HCl solution at 90 °C for 4 h. This material was fully characterized through BET, thermogravimetry, X-rays diffraction, and elemental analysis. The acid treatment at high temperature altered the crystallinity, but produced an increase in the surface area and thermal stability. The resulting acid-treated bentonite turned out to be an efficient adsorbent in both liquid and gaseous media. The changes of the clay mineral properties were discussed in terms of structural modification of the bulk material and increase in the number of edge terminal aluminol and silanol sites. The kinetic parameters of first dehydration step, reaction order (n), apparent activation energy (Ea) and pre-exponential factor (ln A) were calculated by the Freeman–Carroll method.