Adsorption of thorium (IV) ions using a novel borate-based nano material Ca3Y2B4O12: Application of response surface methodology and Artificial Neural Network.

Since nuclear wastes are the most important wastes in terms of health and the environment, they are evaluated differently within nuclear reactors as well as in terms of their use in medical and industrial applications. In some cases, emergency intervention is necessary due to the amount of radioactivity or the physical and/or chemical conditions. . The purpose of this study is to investigate the adsorption properties of nano Ca3Y2B4O12 (CYBO) material synthesized by the sol-gel combustion method for the adsorption of Thorium (IV) from an aqueous medium. We tested how pH (3-8), the concentration of Th (IV) (25-125 mg/L), amount of adsorbent value (0.005-0.08 g) and temperature (20-60 °C), affect adsorption efficiency. The best possible combinations of these parameters were examined by Response Surface Methodology (RSM) and Artificial Neural Network (ANN). R2 values for RSM and ANN were 0.9964 and 0.9666, respectively. According to the models, the adsorption capacity under the optimum conditions determined for the RSM and ANN model was found to be 134.62 mg/g and 125.12 mg/g, respectively.

Sorption of Ce(III) on magnetic/olive pomace nanocomposite: isotherm, kinetic and thermodynamic studies.

Used for various high-tech applications, cerium is an important rare earth element (REE), and its sorption on various solids also is important considering purification and environmental and radioactive waste disposal. In view of the industrial and environmental terms, it is important to remove Ce3+ ions from an aqueous solution. Magnetite and magnetic olive pomace nanocomposite were thus fabricated by a partial reduction co-precipitation approach. The structure and morphological properties of the prepared nano-material and nanocomposite were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), vibrating sample magnetometry (VSM), and BET surface area analysis. The effects of parameters such as solution pH, contact time, initial Ce(III) concentration, and temperature on the sorption efficiency were studied. The maximum sorption capacities of the magnetite (MNP) and magnetic olive pomace nanocomposite (MOP) for Ce(III) ions were found to be 76.92 and 90.90 mgg-1, respectively. The sorption data fitted well with Dubinin-Radushkevich isotherm model and the pseudo-second-order kinetic model. Thermodynamic parameters indicated that the sorption was non-spontaneous and endothermic. This paper reports the preparation of MNP and novel MOP and their application as efficient, sustainable adsorbents alternative to commercial ones for adsorption of cerium ions from aqueous solution.

The use of sea shell (Donax trunculus) powder to remove Sr(II) ions from aqueous solutions.

This study aimed to investigate and explore the possibility of using ground sea shell powder (Donax trunculus) (SSP) for sorption of Sr(II) ions from aqueous solutions. The maximum removal of Sr(II) removal in SSP was 60% at initial Sr(II) concentration of 25 mg/L, at pH 6.0, contact time 120 min, temperature 25 °C and volume/mass ratio equivalent to 500. Sorption data were interpreted considering the adsorption isotherms and thermodynamic parameters calculated. The maximum Sr(II) adsorption on SSP was 25.45 mg/g at pH 6.0. Freundlich isotherm and Dubinin-Radushkevich models were seen to be more compatible with the sorption equilibrium. The nature of the process was spontaneous and exothermic. The results suggest that SSP could be used as an efficient and cost-effective adsorbent to remove strontium ion.

Development of an Amperometric Glucose Biosensor Based on the Immobilization of Glucose Oxidase on the Se-MCM-41 Mesoporous Composite.

A new bioenzymatic glucose biosensor for selective and sensitive detection of glucose was developed by the immobilization of glucose oxidase (GOD) onto selenium nanoparticle-mesoporous silica composite (MCM-41) matrix and then prepared as a carbon paste electrode (CPE). Cyclic voltammetry was employed to probe the catalytic behavior of the biosensor. A linear calibration plot is obtained over a wide concentration range of glucose from 1 × 10-5 to 2 × 10-3 M. Under optimal conditions, the biosensor exhibits high sensitivity (0.34 µA·mM-1), low detection limit (1 × 10-4 M), high affinity to glucose (Km = 0.02 mM), and also good reproducibility (R.S.D. 2.8%, n=10) and a stability of about ten days when stored dry at +4°C. Besides, the effects of pH value, scan rate, mediator effects on the glucose current, and electroactive interference of the biosensor were also discussed. As a result, the biosensor exhibited an excellent electrocatalytic response to glucose as well as unique stability and reproducibility.

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 (238)U, (232)Th and (40)K 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 (238)U, (232)Th and (40)K 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.

Sorption of uranium(VI) from aqueous solutions by akaganeite.

Removal of U(VI) ions from aqueous solutions was investigated using synthetic akaganeite-type nanocrystals. Nanocrystals of iron oxyhydroxides were synthesized with two different methods and then compared their adsorption capacities. Akaganeite (beta-FeOOH) was synthesized in the laboratory by precipitation from aqueous solution of Fe(III) chloride and different precipitating agents. The relative importance of test parameters like solution pH, contact time, temperature and concentration of adsorbate on adsorption performance of akaganeite for U(VI) ion were studied. Typical adsorption isotherms (Langmuir, Freundlich, Dubinin-Raduskevich) were determined for the mechanism of sorption process. Also the thermodynamic constants (DeltaH degrees , DeltaS degrees and DeltaG degrees ) were calculated. The product materials were examined by powder X-ray diffraction for crystalline phase identification and scanning electron microscope (SEM).