Clay minerals occur widely in nature and play a very important role in agriculture, mineral recovery and chemical manufacturing.
Among the many properties which affect clay behaviour, water binding and ion exchanging appear to be the most important. The
study of the cation exchange capacity of soils is of great theoretical and practical importance since the CEC determines in
many ways the behavior of nutrients, chemical amendments, and many toxic compounds entering the sols. Sorption interactions
with montmorillonite and other clay minerals in soils are potantially important mechanisms for attenuating the mobility of
heavy metal cations through the subsurface environment. In this work the cation exchange capacity (CEC) of montmorillonite
from west Anatolia, and sorptions with montmorillonite for attenuating the mobility of uranium were studied. The CEC value
was found to be 77 meq/100 g montmorillonite. The relative importance of test parameters e.g., contact time, particle size,
pH and U(+6) aqueous speciation was determined. The results show that sorption on montmorillonite is a funtion of pH depending
strongly on the aqueous U(+6) species. It reaches a maximum at near neutral pH(pH}7). At low and at high pH solutions the
sorption values of uranium are poor. These sorption values were attributed to the formation of aqueous U(+6) carbonate complexes
in alkaline conditions and the ionexchange process between UO2+2 species and interlayer cations on montmorillonite in acidic solutions.
The effects of the Chernobyl disaster on lichens and pines, which are widely distributed in northern and western Turkey, have been examined within the four years between 1986–1990. Analyses of the plants studied by -spectrometry and spectrophotometric techniques have shown that the highest radioactive pollution was observed in the Pseudevernia furfuracea. The effects of Chernobyl on the ecosystem have been examined by comparing different plant species from the point of view of their reception and accumulation of fallout radionuclides.
The sorption and desorption of thorium on a West Anatolian montmorillonite has been studied by application of a batch technique. Experimental procedures are outlined and results for thorium contacted with montmorillonite are reported and discussed. The thorium concentration range was between 200–4000 ppm (8.5×10–4–1.7×10–2M). The sorption and desorption coefficients varied between 1.586–0.216 ml g–1 and 0.829–0.168 ml g–1, respectively, and sorption was not fully reversible. The data could be fitted to Freundlich and Langmuir isotherms. The quantity of the sorbed thorium was much lower than its theoretical CEC. This was attributed to a blocking of montmorillonite's CEC by thorium islands in the interlayer.
The sorption and desorption of uranium on two different clay samples which are obtained from the deposit located in Turgutlu and Kula have been studied by application of a batch technique. The two types of clay materials are Ca-montmorillonite. The uranium concentration range was between 200–3000 ppm. Experimental procedures are outlined and results for uranium contacted with montmorillonite are reported and discussed. The sorption/desorption isotherms were reversible and non-linear for this concentration range. The relative importance of test parameters e.g., pH, clay particle size, temperature, ground water composition, contact — time, solid/water ratio which require definition in order to arrive at meaningful distribution coefficients were carried out. The sorption coefficients varied between 0.65–1.45 and 0.45–1.14 for Kula clay and for Turgutlu clay, respectively. The data could be fitted to Freundlich and Langmuir isotherms. The quantity of the sorbed and desorbed uranium ions was much lower than its theoretical CEC's. This was attributed to a blocking of montmorillonite's CEC by uranium islands sorbed in interlayer. The results have shown that the test parameters can have a marked effect on sorption and the present work provides further evidence of the need to take account of the presence of such materials in safety assessment modeling.
Long-lived fission radionuclides spread out after the Chernobyl accident have been measured in samples collected from the Black Sea and at the Aegean coasts of Turkey between June 15 and September 15, 1987. Nondestructive analysis was performed using high resolution -spectroscopy. The activity remaining 16 months after the event was found to be enhanced in coniferous needles as well as in lichens, while foodstuff did not show any appreciable contamination. The relatively high106Ru/134Cs and144Ce/134Cs ratios compared to those found in analogous samples from Southern Europe, might result from a fractionation between refractory and volatile elements.
The possibilities of preparing a packing for reversed phase column chromatography from Menderes' perlite were studied. Its
physical and chemical characteristics were compared with other solid supports prepared from rocks, such as perlite and volcanic
slags. A series of chemical treatments were applied to improve the mechanical and chemical properties of perlite. The experimental
work covers the strong acid treatment, the strong base treatment and the silanization with DMCS. The raw perlite containing
70–73% SiO2 was treated with NaOH to make soluble silicates and to increase it. Thus the surface and mechanical characters of the modified
perlite were determined. The mean surface OH group density and the specific surface area were 3.2 μmol/m2 and 9.2 m2/g, respectively. The modified perlite was silanized and hydrophized to load organic complexing agents. The TBP was fixed
successfully on perlite up to 20% w/w. The packing prepared was used to study the chromatographic behavior of UO22+ Fe3+.
The sorption and desorption of uranium, thorium and mercury on a western Anatolian montmorillonite, obtained from the deposit located in Kula, were studied by application of a batch technique. The clay used is a tertiary clay originally found in a rather large geological formation of west Anatolia. It is nearly pure montmorillonite. Its cation exchange capacity (CEC) determination was performed for ammonium acetate by the Mehlich procedure. The mean CEC was found to be 83 meq/100 g, which, taking into account that CEC determinations were carried out on unfractionated material, is in good agreement with previously reported data. The concentration ranges were between 70–1500 ppm for mercury and 100–2000 ppm for thorium and uranium. The relative importance of test parameters, e.g., pH, clay particle size, groundwater composition, contact time and solid/water ratio, which determine the distribution coefficients was studied. The sorption coefficients varied between 2.7–6.4 ml/g for U, 0.22–1.59 ml/g for Th and 152.4–427.2 ml/g for Hg. The differences of distribution coefficients are discussed. The data could be fitted to Freundlich and Langmuir isotherms. The quantities of the sorbed and desorbed Th were much lower than its theoretical CEC's. This attitude was attributed to the blocking of montmorillonite by cation islands sorbed in the interlayer. Hg is sorbed most strongly. The experimental results indicate that the montmorillonites studied should be effective components of the buffer and backfill material and lead to eventual immobilization of these elements, which are environmentally dangerous.
Authors:S. Akcay, S. Tulumen, S. Oymak and H. Kaya
Monitoring of atmospheric radionuclides is an important part of avoiding or eliminating the risk of diseases to the general
public1 Gross α and gross β activities results should be important in understanding the trends of atmospheric radioactivity and for
the variation in time. Airborne particulate samples were collected monthly during the years 2003 and 2004. Radioactivities
were determined using WPC 9550 α/β counting system. The arithmetic means of gross α/β activities were 202·10−3 and 285·10−3 Bqm−3, respectively. The data obtained in this study provide a base line for evaluating possible future changes.
Authors:S. Taysi, N. Oztasan, H. Efe, M.F. Polat, K. Gumustekin, E. Siktar, E. Canakci, F. Akcay, S. Dane and M. Gul
The aim of this study was to investigate whether an 8-week treadmill training attenuates exerciseinduced oxidative stress in rat liver. Male rats were divided into untrained and trained groups. Endurance training consisted of treadmill running at a speed of 2.1 km/h, 1.5 h/day, 5 days a week for 8 weeks. To see the effects of endurance training on acute exhaustive exercise induced oxidative stress, untrained and trained rats were further devided into two groups: animals killed at rest and those killed after acute exhaustive exercise, in which the rats run at 2.1 km/h (10% uphill) until exhaustion. Acute exhaustive exercise increased malondialdehyde level in untrained but not in trained rats. It decreased the activity of glutathione peroxidase and total (enzymatic plus non-enzymatic) superoxide scavenger activity in untrained rats and catalase activity in trained rats. However, it did not affect glutathione S-transferase, glutathione reductase, superoxide dismutase and non-enzymatic superoxide radical scavenger activities in both trained and untrained rats. On the other hand, endurance training decreased glutathione peroxidase and glutathione S-transferase activities. The results suggested that endurance training attenuated exercise-induced oxidative stress in liver, probably by preventing the decreases in glutathione peroxidase and total superoxide scavenger activities during exercise.