Highly-efficient and easy separation of hexahedral sodium dodecyl sulfonate/δ-FeOOH colloidal particles for enhanced removal of aqueous thallium and uranium ions: Synergistic effect and mechanism study

Abstract

Thallium (Tl) and uranium (U) contaminants pose serious threats to the ecological environment and human health. In this research, a cost-effective feroxyhite (δ-FeOOH) dispersed with sodium dodecyl sulfonate (SDS) was prepared and a series of experiments were optimized to explore the removal mechanism of Tl+ and UO22+ from the effluent. The SDS/δ-FeOOH exhibited highly dispersed colloidal particles and showed significantly enhanced adsorption performance on the removal of Tl and U in the presence of H2O2 and pH of 7.0. Equilibrium uptakes of 99.5% and 99.7% were rapidly achieved for Tl+ and UO22+ within 10 min, respectively. The Freundlich isotherm model fitted well with the adsorption data of Tl and U. The maximum isotherm sorption capacity of SDS/δ-FeOOH for Tl+ and UO22+ was 182.9 and 359.6 mg/g, respectively. The sorption of Tl followed the pseudo-second-order kinetic model, whereas the sorption of U followed the pseudo-first-order kinetic model. The uptake of Tl and U by SDS/δ-FeOOH was notably inhibited at Na+, K+ concentrations over 5.0 mM, and a high content of dissolved organic matter (over 0.5 mg/L). The mechanistic study revealed that ion exchange, precipitation, and surface complexation were main mechanisms for the removal of Tl and U. The findings of this study indicate that stabilizer dispersion may serve as an effective strategy to facilitate the treatment of wastewater containing Tl and U by using δ-FeOOH.