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An organic compound adsorbent is prepared by modifying acid-activated bentonite with cetyltrimethylammonium bromide (CTAB). The physical and chemical properties of the samples before and after modification are characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and zeta potential analysis. A batch static adsorption experiment is used to study the adsorption properties of Cs+ before and after modification. Results show that the times to reach the adsorption equilibrium of bentonite before and after modification are 12 h and 2 h, respectively, and the adsorption rates are 26% and 85%, respectively. Different types of ions have different effects on adsorption. Pseudo-first-order and pseudo-second-order kinetic simulations and adsorption isotherm simulations are carried out with the data, and the adsorption capacities of the two adsorbents for Cs+ are 4.8 mg/g and 22.6 mg/g, respectively. The calculated thermodynamic parameters show that the adsorption is endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

To the chemical behavior of Pu on backfill material for high-level radioactive waste repository. Adsorption and desorption of Pu on Natural bleaching earth, Na-bentonite, GMZ-bentonite, Ca-bentonite, acid-Ca-bentonite and alk-Ca-bentonite are discussed in this paper. Data analysis shows that adsorption abilities of Ca-bentonite, alk-Ca-bentonite, Ca-bentonite are greater than GMZ-bentonite, Natural bleaching earth, Na-bentonite, and in which Na-bentonite is relatively minimal. Desorption abilities of Na-bentonite, acid-Ca-bentonite are greater than alk-Ca-bentonite, Ca-bentonite, GMZ-bentonite, Natural bleaching earth, and in which GMZ-bentonite and Natural bleaching earth are relatively minimal. When the pH of the water phase is 1 or 13, the adsorption ability of Ca-bentonite is changed obviously. One reason is that the degree of surface complex reaction has been changed. Another reason is that the compositions and structure of Ca-bentonite have been also changed after acidizing or alkalosis by H + or OH − in the water phase. [ABSTRACT FROM AUTHOR]

An organic compound adsorbent is prepared by modifying acid-activated bentonite with cetyltrimethylammonium bromide (CTAB). The physical and chemical properties of the samples before and after modification are characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and zeta potential analysis. A batch static adsorption experiment is used to study the adsorption properties of Cs+ before and after modification. Results show that the times to reach the adsorption equilibrium of bentonite before and after modification are 12 h and 2 h, respectively, and the adsorption rates are 26% and 85%, respectively. Different types of ions have different effects on adsorption. Pseudo-first-order and pseudo-second-order kinetic simulations and adsorption isotherm simulations are carried out with the data, and the adsorption capacities of the two adsorbents for Cs+ are 4.8 mg/g and 22.6 mg/g, respectively. The calculated thermodynamic parameters show that the adsorption is endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

The ability of bentonite and montmorillonite pillared by Al-oxide and mixed (Ln-Al)-oxides (Ln = La, Ce) to remove 239 plutonium solution species from water is comparatively investigated at pH 7 and pH 4. Small-angle scattering and neutron contrast variation with H 2 O/D 2 O mixtures is used to verify the ingress of water in the calcined products after hydrophilicity was introduced by an NH 3 -H 2 O vapor treatment. The size and shape of the (La/Ce)-Al oxo-hydroxy pillaring cations (2 nm spheres) is determined by small-angle x-ray scattering from the pillaring solutions. Not all of the oxide pillars improved Pu uptake compared with sodium montmorillonite. At neutral and acidic pH only (Ce-Al)-oxide pillared clays showed the ability to remove Pu over the concentration range studied (1.35 × 10 −8 –8 × 10 −8  mol dm −3 ) with distribution coefficient ( K D ) values >10 4 . XPS analysis of the (Ce-Al)-oxide pillared clays indicates the presence of Ce 4+ as cerium dioxide. The progressive improvement in sorption performance in the order of pillar type Al 2 O 3  < La 2 O 3 -Al 2 O 3  << CeO 2 -Al 2 O 3 reflects the increasing access of Pu solution species to the clay mineral layers by changes to the basal spacing and specific surface area, and also to the higher stability of the (Ce-Al)-oxide pillars. [ABSTRACT FROM AUTHOR]