Nanoconfined oxygen vacancies assisted highly efficient and selective Cr(VI) removal in high salinity industrial wastewaters

The carcinogenic and hard-to-dispose Cr(VI) in high-salinity industrial wastewater has caused severe environmental problems. Herein, a novel hollow spherical CuFe 2 O 4 spinel oxide with concentrated confined oxygen vacancies (HS/CuFe 2 O 4 -OVs) was developed for Cr(VI) decontamination. Such a fancy material delivers a remarkable removal rate of 0.041 min −1 , approximately-one order of magnitude higher than the commonly reported iron-based materials. The OVs in the confined space could exert dual effects on Cr(VI) removal from the aspects of enhanced stabilization via local electronic structure regulation and strengthened immobilization via electron conductivity modulation. Importantly, due to the highly sensitive response of Cr(VI) to the changed confined OVs content, the HS/CuFe 2 O 4 -OVs showed higher selectivity for Cr(VI) removal in the interference of high concentration salts than its nonhollow-structured counterpart and can successfully treat Cr(VI)-contaminated industrial wastewater with high salinity. This work opens up a new concept for rational design of robust spatial confined architectures for Cr(VI) treatment.