bentonite composite adsorbent

The algae-clay composite adsorbent was tested for its ability to recover U(VI) from diluted aqueous solutions. Macro marine algae (Ulva sp.) and clay (Na bentonite) were used to prepare composite adsorbent. The ability of the composite adsorbent to adsorp uranium(VI) from aqueous solution has been studied at different optimized conditions of pH, concentration of U(VI), temperature, contact time. Parameters of desorption were also investigated to recover the adsorbed uranium. The adsorption patterns of uranium on the composite adsorbent followed the Freundlich and Dubinin-Radushkevich isotherms. The thermodynamic parameters such as the enthalpy Delta H, entropy Delta S and Gibbs free energy Delta G were calculated from the slope and intercept of lnK(d) vs. 1/T plots. The results suggested that the Ulva sp.-Na bentonite composite adsorbent is suitable as sorbent material for recovery and biosorption/adsorption of uranium ions from aqueous solutions.C1 Pamukkale Univ, Fac Arts & Sci, Dept Chem, Denizli, Turkey.Ege Univ, Inst Nucl Sci, TR-35100 Bornova, Turkey

Chapter 16 - Biosorption of Uranium and Thorium by Biopolymers

Biosorption can be defined as the removal of substances, such as metal or metalloid species, compounds, and particulates from solution by biological material or their products, especially bacteria, algae, yeast, and fungi by physicochemical binding. Among these biosorbents, biopolymers have been preferred over other materials because of their advantages, including biodegradability, hydrophilicity, and presence of carboxylic groups. The increase in the nuclear industry and other anthropogenic activities has intensified environmental pollution, with the accumulation of radioactive elements as uranium and thorium. Therefore, it is very important to identify potential effective and environmentally safe adsorbents for the removal and recovery of uranium and thorium. This chapter reviews the state of art of biosorption of uranium and thorium by biopolymers and compares the results found in the literature and the biosorption results on uranium and thorium by Ca-alginate biopolymer beads. © 2014 Elsevier B.V. All rights reserved

Biosorption of uranium(VI) by bi-functionalized low cost biocomposite adsorbent

This paper presents biosorption properties of U(VI) by bi-functionalized biocomposite adsorbent consists of macro marine algae (Jania rubens) and yeast (Saccharomyces cerevisiae) immobilized on silica gel. Removal of U(VI) from aqueous solution by biosorption on biocomposite in a single component system with pH, initial concentration of U(VI), various contact time and temperature was investigated. Experimental equilibrium biosorption data was analyzed by five two-parameter equations, namely; Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin and Flory-Huggins isotherms. Among these isotherm models, the Temkin model fits better with the experimental data compared to others. Thermodynamic parameters, such as the enthalpy (δH°), entropy (δS°) and Gibbs free energy (δG°) were calculated from the slope and intercept of logK d vs. 1/T plot. Results suggested that the bi-functionalized low cost biocomposite adsorbent is a suitable biosorbent material to remove uranium ions from diluted aqueous solutions. On the other hand, immobilization of algae and yeast on silica gel was found to improve their interaction properties with uranium ions in biosorption process. © 2011 Elsevier B.V

Adsorption and thermodynamic behavior of uranium on natural zeolite

WOS: 000221298200018Adsorptive behavior of natural clinoptilolite-rich zeolite from Balikesir deposites in Turkey was assessed for the removal of uranium from aqueous Solutions. The uranium uptake and cation exchange capacities of zeolite were determined. The effect of initial uranium concentrations in solution was studied in detail at the Optimum conditions determined before (pH 2.0, contact time: 60 minutes, temperature: 20 degreesC). The uptake equilibrium is best described by Langmuir adsorption isotherm. Some thermodynamic parameters (DeltaHdegrees, DeltaSdegrees, DeltaGdegrees) of the adsorption system were also determined. Application to fixation of uranium to zeolite was performed. The uptake of uranium complex on zeolite followed Langmuir adsorption isotherm for the initial concentration (25 to 100 mug/ml). Thermodynamic values of DeltaGdegrees, DeltaSdegrees and DeltaHdegrees found show the spontaneous and exothermic nature of the process of uranium ions uptake by natural zeolite

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

Actinides-97 Conference -- SEP 21-26, 1997 -- BADEN BADEN, GERMANYWOS: 000074686200166The 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 Delta H degrees values for U(VI) on zeolite X were -29.5147 kT 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 Delta G degrees show the spontaneous values for U(VI) that become less negative at higher temperatures, which shows that sorption is less favoured at higher temperatures. (C) 1998 Elsevier Science S.A