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In this work, novel microbial yeast-decorated zeolitic imidazolate framework-8 (ZIF-8/yeast) composites were successfully synthesized by an in situ growth method and applied in the efficient elimination of Eu(III) from a water medium. The adsorption performances and interaction mechanisms of Eu(III) by ZIF-8/yeast were determined by macroscopic experimental tests under diverse water chemistry conditions. The experimental results indicated that the adsorption performance of Eu(III) on ZIF-8/yeast hybrids could reach equilibrium within 15 min, which conformed to the pseudo-second-order kinetic pattern. The maximum adsorption capacity was 1.09 × 10−3 mol g−1, which was higher than that of a series of adsorbents reported in previousliterature. The interaction mechanism between ZIF-8/yeast composites and Eu(III) was primarily revealed by electrostatic attraction, cation exchange and surface complexation. According to the research, the ZIF-8/yeast is considered a preferable adsorbent for the highly efficient purification and elimination of trivalent lanthanides from radioactive wastewater. [ABSTRACT FROM AUTHOR]

To better understand the application of kaolinite as an adsorbent for the decontamination of Ni(II) from radionuclide contaminated aqueous systems, herein, the sorption behavior of radionuclide Ni(II) on kaolinite as a function of contacting time, pH, coexistent electrolyte ions, adsorbent concentration, fulvic acid and humic acid was investigated using batch technique. At low pH values, ion exchange and/or outer-sphere surface complexation was the main mechanism of Ni(II) sorption on kaolinite, whereas, the sorption of Ni(II) was dominated by inner-sphere surface complexation at high pH values. The presence of different electrolyte ions can enhance or inhibit the sorption of Ni(II) on kaolinite to some extent. The Langmuir and Freundlich models were used to simulate the sorption isotherms of Ni(II) at three different temperatures of 288, 313 and 338 K. The thermodynamic parameters (i.e., Δ S°, Δ H°, and Δ G°) calculated from the temperature-dependent sorption isotherms indicated that the sorption reaction of Ni(II) on kaolinite was endothermic and spontaneous. The findings in this present study demonstrates that the kaolinite can be used as a cost-effective adsorbent for the solidification and pre-concentration of Ni(II) from large volumes of aqueous systems. [ABSTRACT FROM AUTHOR]

In this study, the removal of radionuclide Co(II) from wastewater by Ca-rectorite was studied as a function of various environmental parameters such as contact time, pH, ionic strength, coexisting electrolyte ions, humic substances (HS) and temperature under ambient conditions. The results indicated that the sorption of Co(II) on Ca-rectorite was strongly dependent on pH and ionic strength. The Langmuir and Freundlich models were used to simulate the sorption isotherms of Co(II) at three different temperatures of 298.15, 318.15 and 338.15 K. The thermodynamic parameters ( $$ \Updelta H^{0} ,\,\Updelta S^{0} $$ and $$ \Updelta G^{0} $$) calculated from the temperature-dependent sorption isotherms indicated that the sorption process of Co(II) on Ca-rectorite was spontaneous and endothermic. At low pH, the sorption of Co(II) was dominated by outer-sphere surface complexation and ion exchange with Ca/H on Ca-rectorite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, it is possible to conclude that Ca-rectorite has good potentialities for cost-effective disposal of radiocobalt bearing wastewaters. [ABSTRACT FROM AUTHOR]