ABSTRACT
The photocatalysts for hexavalent uranium (U(VI)) reduction suffered from the low uranium uptake capacity and weak long-wavelength light absorption. Herein, we synthesized the CdSxTe1-x nanobelts capped by ethylenediamine (EDA), which provided amino groups as the adsorption sites. With the increase of the Te content, the amino groups on the CdSxTe1-x nanobelts decreased because of the variation of the electron density of Cd2+, whereas the light adsorption was enhanced due to the narrowed bandgap. In photocatalytic reduction of U(VI), the CdS0.95Te0.05-EDA nanobelts exhibited a considerable U(VI) removal ratio of 97.4% with a remarkable equilibrium U(VI) extraction amount on per weight unit of the adsorbent (qe) of 836 mg/g. The bandgap structure and Fourier transform infrared spectroscopy (FT-IR) spectra analysis revealed that the optimum photocatalytic activity of CdSxTe1-x nanobelts was achieved at a 5% of Te2- doping, which balanced the factors of amino groups and bandgap. This adsorption-photoreduction process offers an ultrahigh uranium extraction capacity over wide uranium concentrations.
ABSTRACT
In this paper, nano-montmorillonite (nano-MMT) was introduced into the microbial mineralization system of strontium carbonate (SrCO3). By changing the nano-MMT concentration and the mineralization time, the mechanism of mineralization was studied. SrCO3 superstructures with complex forms were acquired in the presence of nano-MMT as a crystal growth regulator. At low concentrations of nano-MMT, a cross-shaped SrCO3 superstructure was obtained. As the concentration increased, flower-like SrCO3 crystals formed via the dissolution and recrystallization processes. An emerging self-assembly process and crystal polymerization mechanism have been proposed by forming complex flower-like SrCO3 superstructures in high concentrations of nano-MMT. The above research indicated that unique bionic synthesis strategies in microbial systems could not only provide a useful route for the production of inorganic or inorganic/organic composites with a novel morphology and unique structure but also provide new ideas for the treatment of radionuclides.
