Preparation of amidoxime-functionalized mesoporous silica nanospheres (ami-MSN) from coal fly ash for the removal of U(VI).

It is usually difficult to control the microstructure of mesoporous silica materials using coal fly ash as raw materials. In this study, amidoxime-functionalized mesoporous silica nanospheres (ami-MSN) were prepared from coal fly ash using a novel interfacial cohydrolysis-condensation method in an alkane-aqueous system. Characterizations suggested a regular microstructure, high specific surface area (676 m2 /g) as well as stable and uniformly distributed amidoxime groups in the ami-MSN framework. Furthermore, ami-MSN displays a high U(VI) removal capacity in sorption experiments (98.9% removal efficiency of 50 ppm U(VI) at a dosage of 600 mg/L). The sorption showed significant pH dependence. Introducing various cations and anions showed differing effects on sorption, which can be attributed to differing complexation abilities of ions/ami-MSN/U(VI). The sorption mechanism was also studied. In pursuit of the strategy of "treating wastewater with materials derived from waste," this work suggests that ami-MSN can be an effective and low-cost sorbent for U(VI) removal.