Radiation Syntheses and Performance of Novel Hierarchically Macro-/Mesoporous Silica Adsorbents with Quaternary Phosphonium for the High Selective Removal of Perrhenate

Abstract

A novel quaternary phosphonium-grafted hierarchically macro-/ mesoporous silica, named as HPS-C-P, was synthesized by alkylating hierarchically porous silica with trimethylchlorosilane and a subsequent twostep radiation-induced grafting of quaternary phosphonium. Fourier transform infrared, X-ray photoelectron spectroscopy (XPS), Brunauer−Emmett−Teller, and scanning electron microscopy analyses testified that alkyl and quaternary phosphonium groups were grafted uniformly in HPS-C-P. The adsorption of HPS-C-P for ReO 4− was evaluated and it was found that the adsorption equilibrium could be achieved within 4 min, and the adsorption isotherm was fitted well by the modified Langmuir model. The maximum ReO 4 − uptake of this adsorbent could reach 140.5 mg•g −1 , which was higher than the quaternary phosphonium-grafted hierarchically porous silica synthesized by a chemical method. HPS-C-P has good radiation resistance and cyclic adsorption performance, and the adsorption selectivity of HPS-C-P toward ReO 4 − in the presence of competitive anions, including NO 3 − , SO 4 2− , Cl − , CO 3 2− , and PO 4 3− , is extremely high, which is higher than most of the adsorbents reported in recent literature studies. Infrared and XPS analysis revealed that ReO 4 − was adsorbed onto HPS-C-P through the ion-exchange mechanism. This work provided a new method to produce highly efficient silica-based adsorbents to selectively remove Re from an aqueous solution even exposed to a radiation environment.

Radiation synthesis of binary poly(ionic liquid) functionalized silica-based materials for selective adsorption of ReO4− as analogue of TcO4− from simulated radioactive wastewater

“…This is because the increase of absorbed dose increases the number of free radicals formed on the surface of the monomer and silica, which promotes the graft polymerization of the monomer. 34 The ionic liquids with different alkyl chain lengths displayed similar reaction activity.…”

“…À removal, such as cellulose, 30 silica, [31][32][33][34][35] chitosan, 36 and COFs. 15,37 All the mentioned adsorbents were functionalized by a single ionic liquid.…”

“…29 Ionic liquids exhibited excellent extraction performance towards Re and Tc in liquid–liquid extraction, but their application is restricted due to their liquid form. Therefore, ionic liquids employed as functional monomers have been grafted onto different substrates for TcO 4 − removal, such as cellulose, 30 silica, 31–35 chitosan, 36 and COFs. 15,37 All the mentioned adsorbents were functionalized by a single ionic liquid.…”