Search

Herein, β -cyclodextrin ( β -CD) was conjugated on the surfaces of Fe 3 O 4 particles to synthesize magnetic Fe 3 O 4 /CD nanocomposite using a novel low temperature plasma technique. The Fe 3 O 4 /CD samples were applied in the removal of radionuclides and heavy metal ions contaminations from aqueous solutions. The synthesized Fe 3 O 4 /CD nanocomposite which showed high saturation magnetization could be likely separated by using an external magnet. The adsorption performance and underlying mechanism of Fe 3 O 4 /CD nanocomposite toward nickel ions were studied using batch technique. The adsorption kinetic of nickel ions on Fe 3 O 4 /CD surfaces could be obtained within the time period of 8 h. The surface conjugated CD can obviously improve adsorption performance towards Ni(II) ions. The Fe 3 O 4 /CD samples show propitious adsorption property toward Ni(II) ions from wastewater. The experimental findings showed that Fe 3 O 4 /CD nanocomposite could be used as a highly effective adsorbent for the removal of Ni(II) ions from large volumes of aqueous solution. [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]

Abstract: Graphene has been extensively concerned in multidisciplinary research fields due to its remarkably physicochemical characteristics. Herein, magnetic graphene/iron oxides composite (Fe3O4/GO) which was synthesized from graphene using a chemical reaction approach had been employed as a novel adsorbent for the preconcentration and solidification of U(VI) ions from aqueous solutions. The sorption behavior of U(VI) on the surface of Fe3O4/GO was carried out under ambient conditions such as contact time, pH and ionic strength according to concentration of C U(VI)initial =1.12×10−4 mol/L. The Langmuir and Freundlich models were adopted to simulate sorption isotherms of U(VI) at three different temperatures relying on the concentration of C U(VI)initial =2.25×10−5 to 2.24×10−4 mol/L, the experimental results suggested that the sorption reaction was favored at higher temperature. The pH-dependent and ionic strength-independent U(VI) sorption on Fe3O4/GO demonstrated that the sorption mechanism of U(VI) was inner-sphere surface complexation at low pH values, whereas the removal of U(VI) was achieved by simultaneous precipitation and inner-sphere surface complexation at high pH values. The maximum sorption capacity of U(VI) on Fe3O4/GO at T=293K and pH=5.5±0.1 was about 69.49mg/g higher than majority of materials and nanomaterials reported. Magnetic separation has been considered as an effective and quick technique for separating magnetic particles, without filtration and centrifugation. The Fe3O4/GO can be favorably separated from aqueous solution under an applied magnetic field from large volumes of aqueous solutions. The experimental results show that the Fe3O4/GO is a promising adsorbent for the removal of radionuclides and heavy metal ions from large volumes of aqueous solution. [Copyright &y& Elsevier]

Comprehension the extent and rate of U(VI) adsorption on some mineral surfaces are significant to predict their migration and transformation properties in the environmental systems. Herein, iron oxides particles supported reduced graphene oxide composites (MRGO) were successfully synthesized by in-situ chemical precipitation approach. The MRGO composites which illustrated high saturation magnetization could be likely separated using an external magnet. The experimental data illustrated that U(VI) ions could be interacted with MRGO composites through different interaction mechanisms depending on different environmental conditions. The adsorption kinetic results can be well simulated using the pseudo-second-order pattern. The pH-dependent adsorption behavior illustrated an favorable pH value of 7.5 for removal of U(VI) ions using MRGO composites. Furthermore, the adsorption regeneration of MRGO composites in simulated wastewater disposal systems was tested. Based on above mentioned, it was clear that MRGO composites could be potentially used as adsorbent for removal of actual U(VI)-bearing wastewaters. [ABSTRACT FROM AUTHOR]