Structural, optical and photocatalytic properties of magnetic recoverable Mn 0.6 Zn 0.4 Fe 2 O 4 @Zn 0.9 Mn 0.1 O heterojunction prepared from waste Mn-Zn batteries

• Published in: Journal of environmental management Vol. 302; no. Pt B; p. 114120
• Main Authors: Huang, Hua, Feng, Wanting, Niu, Zhirui, Qin, Xiaoqian, Liu, Xianfan, Shan, Baoqin, Liu, Yu
• Format: Journal Article
• Language: English
• Published: England 15.01.2022
• Subjects: Catalysis; Electric Power Supplies; Light; Zinc; Photocatalytic activity; Mn doped ZnO; MB degradation; Magnetic photocatalyst; Mn-Zn ferrite
• ISSN: 1095-8630

Green, simple and high value-adding technology is crucial for realizing waste batteries recycling. In this work, the magnetically recyclable Mn Zn Fe O @Zn Mn O (MZFO@ZMO) heterojunctions are prepared from waste Mn-Zn batteries via a green bioleaching and sample co-precipitation method. The as-prepared catalysts with different Zn Mn O weight percentage (25%, 50% and 75%) have been comprehensively characterized in structure, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that MZFO@ZMO heterojunctions with the core-shell structure, demonstrates excellent absorption intensity in the visible light region, outperforming that of individual ZnO and Zn Mn O. Especially, the staggered bandgap alignment of Mn Zn Fe O and Zn Mn O greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@50%-ZMO shows the highest photodegradation performance toward methylene blue (MB) under the visible light irradiation, with a 99.7% of photodegradation efficiency of 20 mg L of MB within 90 min, and its reactive kinetic constants is about 7.2, 10.8 and 21.7 times higher than that of Zn Mn O, P25 TiO and Mn Zn Fe O , respectively. The MB photocatalytic mechanism is investigated in the scavenger and 5,5-dimethylpyrroline-N-oxide (DMPO) spin-trapping electron spin resonance (ESR) experiments, and h and *O are identified as the major active species for MB degradation. In addition, MZFO@50%-ZMO also exhibits a good reusability and high magnetic separation properties after six successive cycles. This new material indicates the advantages of low costs, simple reuse and great potential in application.