Mahmoud A.A. Aslani

Sorption characteristics of uranium onto composite ion exchangers

The composite ion exchangers were tested for their ability to remove UO22+ from aqueous solutions. Polyacrylonitrile (PAN) composites having natural zeolite, clinoptilolite, and synthetic zeolite, zeolite X, were used as an adsorbents. The influences of pH, U(VI) concentration, temperature and contact time on the sorption behavior of U(VI) were investigated in order to gain a macroscopic understanding of the sorption mechanism. The optimum adsorption conditions were determined for two composites. The sorption behaviors of uranium on both composites from aqueous systems have been studied by batch technique. Parameters on desorption were also investigated to recover the adsorbed uranium.

Removal of uranium from aqueous solutions by diatomite (Kieselguhr)

In this study, the removal of uranium from aqueous solutions by diatomite earth (Kieselguhr) fine particules has been investigated. Diatomite earth is an important adsorbent material in chromatographic studies. Uranium adsorption capacity of four different types of diatomite was determined. The adsorption of uranium on the chosen diatomite sample was examined as a function of uranium concentration, solution pH, contact time and temperature. The adsorption of uranium on diatomite followed a Langmuir-type isotherm.

Distribution of uranium on zeolite X and investigation of thermodynamic parameters for this system

Abstract The sorption of U(VI) from aqueous solutions on zeolite X has been studied by a batch technique. Distribution coefficients ( K d ) were determined for sorption systems as a function of sorbate concentration, pH, contact time and temperature. The sorption isotherm was formed according to the Langmuir isotherm. Thermodynamic parameters have been determined at different temperatures. The Δ H ° values for U(VI) on zeolite X were −29.5147 kJ mol −1 at 313 K at pH 3 and −19.8705 kJ mol −1 at 303 K at pH 9. The sorption of U(VI) on zeolite X is an exothermic in nature. Negative values of Δ G ° show the spontaneous values for U(VI) that become less negative at higher temperatures, which shows that sorption is less favoured at higher temperatures.

Activity concentration of caesium-137 in agricultural soils.

In this study, we measured 137Cs activity concentrations in the soil samples taken from agricultural lands in the Buyuk Menderes Basin in Turkey in 1997 and 1998. The soil samples were collected from 42 sites in this Basin. The activity concentration of 137Cs was found to range between 2.81+/-0.17 Bq.kg(-1) and 20.75+/-0.29 Bq.kg(-1). The effect of organic matter, clay, silt and sand contents and pH of the soil on the relative adsorption of the 137Cs on the soil surface were also studied.

Separation of thorium from aqueous solution using silk fibroin

In this study we investigate the basic features of thorium adsorption from aqueous systems by silk fibroin. Our previous study showed that this biopolymer has high efficiency for U(VI) adsorption. It is well-known that thorium, which is a tetravalent metal, is a more reactive element than uranium. Thorium(IV) adsorption proves to be very rapid and dependent on pH, temperature, retention time, concentration of ion, amount of fibroin, volume of solution and volume-to-mass ratio.

Vertical distribution of 226Ra and 210Po in agricultural soils in Buyuk Menderes Basin, Turkey

The vertical distribution of (226)Ra and (210)Po was investigated in the cultivated soils of the Buyuk Menderes Basin in Turkey. Five soil cores down to a depth of about 50 cm were taken from each site and divided into strata of 2-3 cm intervals. The samples were analyzed for their (226)Ra and (210)Po activity concentrations using radioanalytical methods. Down-core concentration profiles of (226)Ra and (210)Po in the soil cores from five sites are obtained. The activity concentrations of soil cores range from 80 to 1170 Bq kg(-1) for (226)Ra and from 10 to 870 Bq kg(-1) for (210)Po with the depth. Analysis of the vertical soil profiles indicate that the activity concentrations of (226)Ra and (210)Po for soil strata at all the sites have not extremely changed with depth.

Activity concentration of radium-226 in agricultural soils

Fourty two soil samples were collected to a depth of 20 cm from the Aegean Region of Turkey. The activity concentrations of 226Ra in the samples were determined by a radioanalytical method. The radiochemical yield for pure 226Ra was found to be 90.02±2.74%. The average concentration of 226Ra was 0.150 Bq.g-1 and its distribution fitted a normal curve. The average absorbed dose rate was found to be 61 nGy.h-1. The data were evaluated to explain of 226Ra distribution in the agricultural area and compared with other results in the literature.

Natural radioactivity of riverbank sediments of the Maritza and Tundja Rivers in Turkey

This article represents the first results of the natural radionuclides in the Maritza and Tundja river sediments, in the vicinity of Edirne city, Turkey. The aim of the article is to describe the natural radioactivity concentrations as a baseline for further studies and to obtain the distribution patterns of radioactivity in trans-boundary river sediments of the Maritza and Tundja, which are shared by Turkey, Bulgaria and Greece. Sediment samples were collected during the period of August 2007–April 2010. The riverbank sediment samples were analyzed firstly for their pH, organic matter content and soil texture. The gross alpha/beta and 238U, 232Th and 40K activity concentrations were then investigated in the collected sediment samples. The mean and standard error of mean values of gross alpha and gross beta activity concentrations were found as 91 ± 11, 410 ± 69 Bq/kg and 86 ± 11, 583 ± 109 Bq/kg for the Maritza and Tundja river sediments, respectively. Moreover, the mean and standard error of mean values of 238U, 232Th and 40K activity concentrations were determined as 219 ± 68, 128 ± 55, 298 ± 13 and as 186 ± 98, 121 ± 68, 222 ± 30 Bq/kg for the Maritza and Tundja River, respectively. Absorbed dose rates (D) and annual effective dose equivalent s have been calculated for each sampling point. The average value of adsorbed dose rate and effective dose equivalent were found as 191 and 169 nGy/h; 2 and 2 mSv/y for the Maritza and the Tundja river sediments, respectively.

A correlative study between 99mTc-ESTCPTA and 99mTc-MIBI in rats.

Tissue distribution of the 99mTc labeled derivative of the estrogen compound 3,17-alpha-estradiolyl propyl 1,4,8,11-tetraazacyclotetradecanyl-l-(4-methylbenzoic acid) ester (ESTCPTA), which has an 3,17-alpha-estradiolyl propinol coupled to l-(4-methylbenzoic acid)1,4,8,11-tetraazacyclotetradecane (CPTA), was compared to 99mTc-MIBI (methoxyisobutyl isonitrile) in female Albino Wistar rats. Tissues of interest included lung, liver, heart, kidneys, spleen, stomach, intestines, pancreas, muscle, blood, breast, ovary, fat, and uterus. 99mTc-ESTCPTA uptake by the uterus and ovary, as ER-rich tissues, was highly selective. Maximum uptakes for 99mTc-MIBI and 99mTc-ESTCPTA are 90 min in breast, ovary and uterus. The pancreas also showed significant receptor saturated and unsaturated ratios for 99mTc-ESTCPTA. Results are sufficiently encouraging to generate further evaluation of these and related compounds as possible estrogen receptor based tumor imaging and therapeutic agents in estrogen-rich tissues.

Assessment of reaction between thorium and polyelectrolyte nano-thin film using Box–Behnken design:

Sandwich type polyelectrolyte nano-thin films (PENTFs) were prepared by using polyallylamine hydrochloride and polyacrylic acid from layer-by-layer assembly process with spin coating system. Their nanostructures have been studied by scanning electron microscope, atomic force microscope, and attenuated total reflectance Fourier transform infrared spectroscopy. In order to understand the effects of the initial concentration of thorium, initial solution pH, temperature, and contact time on the reaction between thorium and PENTF, an experiment data set was designed according to Box–Behnken model. The analysis of variance calculations for regression model were carried out in 95% confidence level and were checked for fitting experimental data and predicted values. The correlation coefficient value (R2) obtained as 94% showed that there was a correlation between the predicted and the observed values. The optimum pH, temperature, initial concentration of thorium, and interaction time in studied ranges were found as 2.81, 35℃, 160 mg·L−1, and 120 min, respectively. At these conditions thorium (IV) ions adsorption yield was obtained as 89 ± 2%. The Freundlich, Langmuir, and Dubinin–Radushkevich isotherms were used to investigate the characteristics of the process. These characteristics data imply that the Freundlich model fits better than the Langmuir model for the Th (IV) sorption onto PENTFs with KF and n values were found to be 20.6 mg·g−1 and 1.08 L·mg−1, respectively. The thermodynamic parameters were also computed as negative ΔH value suggest that adsorption of Th (IV) is exothermic nature. The calculated negative and positive values of ΔG indicate that the sorption process is favorable (energetically) while running below 40℃ and over this point the process status change to non-spontaneous, respectively.