Enhanced catalytic performance of peroxydisulfate activation for Rhodamine B degradation over a novel MIL-68(Fe)/CuBi2O4 catalyst

Abstract

The development of advanced strategy to activate persulfate for wastewater treatment is an ever-hot research topic. Herein, a high-performance composite catalyst MIL-68(Fe)/CuBi2O4(30 %) (M-CBO-30) was prepared by in-situ synthesizing MIL-68(Fe) in the CuBi2O4. The catalytic performances of M-CBO-30 as heterogeneous catalyst to activate PDS for the Rhodamine B (RhB) degradation were systematically studied. It was shown that the M-CBO-30/PDS system presented an ultrahigh RhB degradation efficiency which could remove 100 % RhB within 5 min only using 0.4 g L− 1 catalyst and 0.4 mM PDS. In addition, the M-CBO-30 could remove RhB at a wide pH range (2–10). One should note that the M-CBO-30 exhibited outstanding reusability which afforded high degradation efficiency after 5 successive recycles. And the catalyst structure remained still after being used for 5 catalytic cycles. Heavy metal ions leaching experiment indicated that Cu2+ leaching concentration of M-CBO-30 was far lower than that of the city water criterion in Europe. The RhB degradation mechanism by M-CBO-30/PDS system was proposed based on the result of electrochemical experiment, radical quenching test, electron paramagnetic resonance and XPS analysis. The RhB degradation was attributed to the oxidization of reactive oxygen species (i.e., SO4•−, •OH and 1O2). The synergistic effect of redox cycle of surface Fe, Bi and Cu were responsible for the high-efficient PDS activation. The excellent recyclability, outstanding structural stability, wide pH application range, less heavy metal leaching and superhigh RhB degradation efficiency highlights the light application prospect of M-CBO-30 in SR-AOPs-driven RhB decontamination.