Removal of Co, Sr and Cs from aqueous solution using self-assembled monolayers on mesoporous supports

Sorptive removal of Co, Sr and Cs from aqueous solution by SAMMS was investigated. The single-solute sorption data were well fitted by the Freundlich, Langmuir and Dubinin-Radushkevich models (R²>0.95). The maximum sorption capacities (q_mL) of the Langmuir model were in the order of Cs (1. 14 mmol/g)>Co (0. 20 mmol/g)≈Sr (0. 195 mmol/g). The bi-solute competitive sorption of the metals was analyzed by the Langmuir, competitive Langmuir, modified extended Langmuir and P-factor models. The sorption of one metal was suppressed by the presence of competing metals. Sorptions of Co and Sr were strongly dependent on the initial solution pH but that of Cs was not. The calculated thermodynamic parameters such as ΔH⁰, ΔS⁰ and ΔG⁰ showed that sorption of Co onto SAMMS was endothermic, whereas those of Sr and Cs were exothermic. The negative ΔG⁰ values indicated all the sorption processes were spontaneous in nature.