School of Petroleum and Environmental Engineering, Yan'an University, Yan'an, 716000, PR China.
School of Petroleum and Environmental Engineering, Yan'an University, Yan'an, 716000, PR China.
J Environ Manage. 2022 Jan 15;302(Pt B):114120. doi: 10.1016/j.jenvman.2021.114120. Epub 2021 Nov 15.
Green, simple and high value-adding technology is crucial for realizing waste batteries recycling. In this work, the magnetically recyclable MnZnFeO@ZnMnO (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 ZnMnO 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 ZnMnO. Especially, the staggered bandgap alignment of MnZnFeO and ZnMnO 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 ZnMnO, P25 TiO and MnZnFeO, 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.
绿色、简单且附加值高的技术对于实现废电池回收至关重要。在这项工作中，通过绿色的生物浸出和样品共沉淀法，从废锰锌电池中制备了可回收磁的 MnZnFeO@ZnMnO（MZFO@ZMO）异质结。所制备的具有不同 ZnMnO 重量百分比（25%、50%和 75%）的催化剂在结构、光学、光电化学和光催化活性方面进行了全面表征。表征结果表明，具有核壳结构的 MZFO@ZMO 异质结在可见光区域表现出优异的吸收强度，优于单独的 ZnO 和 ZnMnO。特别是，MnZnFeO 和 ZnMnO 的能带隙交错排列极大地增强了二元异质结体系中的电子转移和电荷分离。优化后的 MZFO@50%-ZMO 在可见光照射下对亚甲基蓝（MB）表现出最高的光降解性能，在 90 分钟内 20mg/L 的 MB 的光降解效率达到 99.7%，其反应动力学常数分别比 ZnMnO、P25 TiO 和 MnZnFeO 高约 7.2、10.8 和 21.7 倍。通过捕获剂和 5,5-二甲基吡咯啉-N-氧化物（DMPO）自旋捕获电子顺磁共振（ESR）实验研究了 MB 的光催化机制，并确定 h 和 *O 是 MB 降解的主要活性物质。此外，MZFO@50%-ZMO 在经过六次连续循环后仍具有良好的可重复使用性和高磁分离性能。这种新材料表明了低成本、简单再利用和巨大应用潜力的优势。
