Enhancement of the heterogeneous adsorption and incorporation of uranium(VI) caused by the intercalation of beta-cyclodextrin into the green rust

The influence of intercalated anions on the structure and composition of green rusts supplies a theoretical possibility for the investigation of the structural modification of Fe-II/Fe-III (oxyhydr)oxide materials. beta-Cyclo-dextrin was intercalated into the mixed-valent iron-based hydroxide layers to synthesize new green rust materials (beta-CD GRs), pursuing high-capacity uranium (VI)(U-VI) sorption. The molar ratios of Fe-II to Fe-III and the molar ratios of beta-CD GR to Fe-II + Fe-III in had a significant effect on the synthesis of beta-CD GRs. The synthesis process was further optimized by the quadric predictor and desirability function in a central composite design in combination. Both strong acidity and alkalinity were harmful to the adsorption of beta-CD GRs towards U-VI. The pseudo-first-order kinetic model and Langmuir isotherm model were appropriate in fitting the whole adsorption process. The maximum monolayer adsorption capacity of beta-CD GRs was 2548.61 mg/g. The presence of mimic groundwater constituents explicitly deteriorated the interaction between p-CD GR and U-VI species. Nanoscale nodules and particles were formed on the beta-CD GR after the adsorption experiments. The peaks at 1159 and 609 cm(-1) vanished with the band at 1103 cm(-1) being left-shifted to 1117 cm(-1) in the FTIR spectra of beta-CD GR during the heterogeneous process. The intercalation of beta-CD brought obvious enhancement of U-VI species sorption to the GR material, which was combinedly driven by several reaction pathways and different from the unmodified GRs.

Automated summary

The intercalation of beta-cyclodextrin into green rust layers resulted in the synthesis of new materials (beta-CD GRs) with high uranium (VI) sorption capacity. The molar ratios of Fe(II) to Fe(III) and beta-CD GR to Fe(II) + Fe(III) significantly influenced the synthesis process. Both strong acidity and alkalinity adversely affected the adsorption of beta-CD GRs towards U(VI).