Fabrication of Worm-Like Mesoporous Silica Monoliths as an Efficient Sorbent for Thorium Ions from Nitrate Media

Mesostructured silica monoliths were synthesized using a simple reproducible strategy of an instant direct templating with nonionic Brij-35 copolymer surfactant and C12 alkane (dodocane). The synthesized silica monoliths were first immobilized with 3,3-glycidoxypropyltrimethylsilane (GPS), which was followed by the reaction with ethylenediamine (EDA) to produce SiO 2 @GPS-EDA worm-like mesoporous silica monoliths. SiO 2 @GPS-EDA was characterized by SEM, SEM-EDX mapping, HR-TEM, EDS, elemental analysis, zeta potential, nitrogen adsorption/desorption isotherms, and pore size distribution measurements. Our results show that Brij-35/dodocane can be used to fabricate uniformly mesochannel pores of silica monoliths. EDS, SEM-EDX mapping, and elemental analysis of SiO 2 @GPS-EDA demonstrate the presence of C (16.25%), H (1.75%), and N (5.45%) embedded into the silica pore surface frameworks. Batch adsorption experiments were carried out to evaluate the sorbent efficiency. The SiO 2 @GPS-EDA mesoporous adsorbent efficiently removes thorium ions from aqueous solutions. The highest adsorption of Th(IV) ions, 94.8 mg g –1 , was observed at pH 4.0 (equilibration time 120 min). The adsorption of Th(IV) ions onto the sorbent follows the Langmuir, pseudo-second-order, intraparticle diffusion, and Dubinin–Radushkevich models. The adsorbed Th(IV) ions were eluted and recovered with 0.1 M HNO 3 . The absorbent was successfully applied to Th(IV) extraction from the monazite leach liquor. The prepared porous organic-inorganic hybrid sorbent showed sensitivity, selectivity, reusability, and fast kinetics in Th(IV) adsorption from aqueous solutions.