Selective removal of Cs plus from aqueous solution by ion flotation using SDBS and the flotation mechanism

The coexistence of Cs+ with alkali metal ions in aqueous environments presents a significant challenge to the selective removal or extraction of Cs+ from water bodies. In this study, sodium dodecyl benzene sulfonate (SDBS) was employed as the collector, enabling the selective removal of Cs+ from solution through ion flotation. The underlying adsorption mechanism was subsequently investigated. The micro-flotation experiment results demonstrated that the maximum removal rate of Cs+ by ion flotation was 78.42 %. Furthermore, the removal of Cs+ was not significantly affected by other alkali metal ions. The order of removal of SDBS to alkali metal ions was as follows: Cs+ > Rb+ > K+ > Li+. The separation factors (SF) of Cs+ with Li+, K+ and Rb+ were 3.90, 3.70 and 3.38, respectively. The foam analysis results showed that the presence of ions made the foam more stable. The flotation kinetic showed that the removal of Cs+ was controlled by a pseudo-second-order kinetic model. The mechanism analysis indicated that SDBS was capable of removing Cs+ through two primary mechanisms: electrostatic adsorption and ion exchange. The DFT calculation showed that the adsorption energies of SDBS for Li+, K+, Rb+, Cs+ and H+ were-8.23,-17.32,-24.39,-46.61 and-6.36 eV, respectively, among which the adsorption energy of Cs+ was the highest, which was the reason why SDBS had the selective removal ability for cesium ions. The process of collecting Cs+ by ion flotation was finally depicted through the use of molecular dynamics simulations. The findings offer a promising strategy for the selective removal and extraction of Cs+ from complex ionic solutions.