Encapsulation of cesium from contaminated water with highly selective facial organic–inorganic mesoporous hybrid adsorbent

Abstract

The present work was developed an efficient mesoporous hybrid adsorbent (MHA) for selective cesium (Cs) removal from contaminated water. A novel macrocyclic ligand of di-o-benzo-p-xylyl-28-crown-8-ether (DOBPX28C8) was prepared and successfully anchored onto the mesoporous silica for the fabrication of MHA using direct immobilization approach and serving as an efficient adsorbent for Cs removal. The Cs adsorption onto the MHA was evaluated under the different experimental conditions, including initial pH solution, contact times, initial Cs concentrations, presence of high amount of potassium (K) and sodium (Na). The applicable pH range for high Cs removal was evaluated at 5.50. The Cs adsorption data were well fitted to the Langmuir adsorption model and was a monolayer adsorption with the maximum adsorption capacity of 97.63mg/g. In the presence of a high amount of K (7.69mM), the Cs adsorption was slightly affected because the hydration radius of K (3.3Å) is close to the Cs (3.25Å) than that of the other cation of Na (3.6Å). Also the Cs adsorption efficiency was more than 75% and 89% even in the presence of 1025-fold K and 1739-fold Na, respectively. The functional group of DOBPX28C8 ligand embedded onto the mesoporous silica exhibited more conformational freedom, and the benzene ring in para position was consolidated for π-electron orientation with expanding the ring size of DOBPX28C8 for easy capturing with high selectivity and adsorption ability towards the Cs. The regeneration study indicated that the adsorption process was relatively stable even after six consecutive adsorption–elution cycles. The fastest mass transports, high selectivity, adsorption capacity and reusability are to make promising of the MHA in the contaminated water remediation in Fukushima, Japan.