One-step fabrication of oxygen vacancy-enriched Fe@Ti/C composite for highly efficient degradation of organic pollutants through persulfate activation

In this work, cost-effective, magnetic carbon-supported Fe@Ti composite (Fe@Ti/Cs) with abundant active sites was synthesized by one-step carbothermal reduction of ilmenite with the assistance of microwave oven and utilized as a highly efficient persulfate (PS) activator for the wastewater purification. The coexistence of Fe 0/2+/3+ , Ti 3+/4+ and oxygen vacancies on Fe@Ti/Cs was found to favor for the electron transfer to PS, which facilitate the generation of reactive oxygen species (ROS). Catalytic experiment results showed that the Fe@Ti/C-4 produced from ilmenite/carbon with a mass ratio of 4:1 exhibited the best catalytic activation performance towards PS for the degradation of Rhodamine B (RhB). Usage of merely 0.12 g/L Fe@Ti/C-4 enabled the removal of 94.01% RhB (200 mg/L) within 30 min in the PS containing system, significantly outperforming ilmenite + PS (29.29%) and carbon + PS (49.91%) systems tested under the same conditions. The physico-chemical properties of the produced Fe@Ti/Cs before and after the reaction were carefully characterized. Radical scavenging experiments and electron paramagnetic resonance (EPR) analysis were carried out to better understand the underlying mechanism. The results indicate that oxygen vacancies in Fe@Ti/C-4 promoted the electron transfer and participated in the transition metal redox cycle to generate ROS in the PS-containing system, which was highly efficient for degrading RhB into small molecules and finally enabling mineralization. This work offers a new perspective for designing highly efficient and stable PS activators with long life derived from natural ore for environmental remediation.