Novel Biomass‐Derived Adsorbents Grafted Sodium Titanium Silicate with High Adsorption Capacity for Rb+ and Cs+ in the Brine

Abstract

AbstractTwo biomass‐derived adsorbents (BCA@STS, CBCA@STS) modified with sodium titanium silicate (STS) were synthesized through a hydrothermal deposition method and tested to adsorb Rb+ and Cs+ from aqueous solution and brine. The BET characterization results showed that the adsorbents had mesoporous structures and excellent adsorption capacity for Rb+ and Cs+ with the maximum adsorption amounts as high as 2.07 mmol g−1 and 1.47 mmol g−1, respectively. XRD and XPS analyses of the adsorbents before and after adsorption revealed that the high adsorption capacity is attributed to the Na+ located in the adsorbents and ion exchange between Na+ and Rb+ or Cs+ is the key mechanism. The chemical composition of functional substance is the mixture of (HNa)O⋅SiO2⋅2TiO2⋅2H2O and Na2Ti3O7. The adsorption amounts increase with increasing of pH, and decrease with the increase of NaCl concentration due to the competitive adsorption between H+/Na+ and Rb+/Cs+. The adsorption kinetics of both these two adsorbents were well fitted to the pseudo‐second order kinetic model indicating that the chemisorption was dominant throughout the adsorption process. Apart from the excellent adsorption properties of Rb+ and Cs+ from aqueous solution, both BCA@STS and CBCA@STS can be used for the adsorption of Rb+ and Cs+ from the brine, and the maximum adsorption rate is up to almost 100%, showing promising application for extracting of Rb+ and Cs+.