Structural, optical and photocatalytic properties of magnetic recoverable Mn0.6Zn0.4Fe2O4@Zn0.9Mn0.1O heterojunction prepared from waste Mn–Zn batteries. (15th January 2022)

• Record Type: Journal Article
• Authors: Huang, Hua; Feng, Wanting; Niu, Zhirui; Qin, Xiaoqian; Liu, Xianfan; Shan, Baoqin; Liu, Yu
• Is Part Of: Journal of environmental management. Volume 302:Part B(2022)
• Publication Date: 2022-01-15
• Subjects: Mn-Zn ferrite -- Mn doped ZnO -- Magnetic photocatalyst -- MB degradation -- Photocatalytic activity; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2021.114120
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Green, simple and high value-adding technology is crucial for realizing waste batteries recycling. In this work, the magnetically recyclable Mn0.6 Zn0.4 Fe2 O4 @Zn0.9 Mn0.1 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 Zn0.9 Mn0.1 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 Zn0.9 Mn0.1 O. Especially, the staggered bandgap alignment of Mn0.6 Zn0.4 Fe2 O4 and Zn0.9 Mn0.1 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 −1 of MB within 90 min, and its reactive kinetic constants is about 7.2, 10.8 and 21.7 times higher than that of Zn0.9 Mn0.1 O, P25 TiO2 and Mn0.6 Zn0.4 Fe2 O4, 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 *O2 − 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. Highlights: Mn0.6 Zn0.4 Fe2 O4 @Zn0.9 Mn0.1 O heterojunctions are prepared from waste batteries. The effect of Zn0.9 Mn0.1 O weight percentage in heterojunctions are investigated. MB can be rapidly and thoroughly degraded by the as-prepared heterojunction. The active radicals generated during photocatalytic process are identified.