Competitive adsorption of alkali metal ions onto Prussian blue

Prussian blue (PB) is an effective adsorbent for separating Cs+. However, the competitive adsorption behavior of alkali metal ions onto PB was unknown, and the Cs+ adsorption mechanism of the PB was controversial. In this work, the adsorption behaviors of alkali metal ions onto prepared PB were investigated in single-element and multi-element solutions. The equilibrium adsorption capacity was in the sequence of Cs+ > Rb+ > Na+, while Li+ and K+ were not adsorbed. Kinetic curves of Na+, Rb+ and Cs+ were all better fitted with the pseudo-second-order kinetics model. The adsorption isotherms data of Rb+ and Cs+ agreed with the Freundlich model while Na+ followed the Langmuir model. It was found that the mechanism for the adsorption of M+ (Na+, Rb+ and Cs+) onto PB was H+-exchange and K+-exchange according to ???C (M+) = ???C (K+) + ???C (H+).

Automated summary

This study investigated the adsorption behavior of alkali metal ions onto Prussian blue (PB) and found that the equilibrium adsorption capacity followed the order of Cs+ > Rb+ > Na+. The adsorption kinetics were fitted with the pseudo-second-order model for Na+, Rb+, and Cs+, while the adsorption isotherms followed the Freundlich model for Rb+ and Cs+ and the Langmuir model for Na+. It was observed that the adsorption mechanism for M+ (Na+, Rb+, and Cs+) onto PB was H+-exchange and K+-exchange.