Effect of operating variables on selective radiostrontium separation from aqueous waste matrices using a novel crown ether-based amino-modified mesoporous silica sorbent

A new sorbent, DFDB18C6@SBA-NH2, created by grafting diformal dibenzo-18-crown-6-ether (DFDB18C6) onto amino-modified mesoporous silica (SBA-NH2) has been used for the selective removal of radiostrontium (r-Sr: Sr-90) from aqueous waste. The Sr-sorption behavior was investigated at various operating conditions, including pH, contact time, initial Sr2+ concentration, temperature, and the presence of competing ions (e.g., Li, Na, K, Rb, Ca, Mg, and Ba). Kinetic investigations showed that the sorption process followed pseudo-second order kinetics, whereas isotherm modeling demonstrated that the Langmuir model provided the most excellent fit, implying monolayer sorption. The thermodynamic study indicated that the sorption process is endothermic. The sorbent effectively removed Sr-90 (similar to 99.67 %) from Chornobyl-derived radioactive wastewater in the presence of other ions. These findings suggest the potential of DFDB18C6@SBA-NH2 as an effective tool for Sr-90 separation from aqueous waste matrices.