为此，本研究提出了一种简单实用且经济高效的方法（采用尿素辅助法）来改性Mn₃O₄的结晶度，显著提升了材料产率。我们深入探究了不同结晶结构的氧化锰如何影响过碘酸盐的活化、PI活化降解污染物的机制，以及催化剂在不同结晶程度下的生物毒性。值得注意的是，体系内非自由基性1O2与自由基性•OH的高选择性生成，显著提升了污染物去除效率并增强了环境抗性。本研究揭示了结晶度在增强氧化剂活化以实现高效污染物清除中的关键作用，为推进过碘酸氧化工艺在水处理领域的应用奠定了坚实的理论基础。
Fig. 1. (a) Overview of PI-AOPs challenges and crystallinity modification methods. (b) Approach Mn3O4 crystallinity modification. SEM images of (c) Mn3O4, (d) C1-Mn3O4, (e) C2-Mn3O4, (f) C3-Mn3O4 and (g) C4-Mn3O4, respectively. TEM images of (h-i) Mn3O4, (j-k) C3-Mn3O4, and (l-m) C4-Mn3O4, respectively. (n-q) EDS maps of C3-Mn3O4, illustrating elemental distribution.
Fig. 2. (a) XRD spectra for different Mn3O4 crystallinities. (b) SMX degradation across various systems. (c) Change in kobs correlating with crystallinity variations. (d) Influence of catalyst and oxidant dosage on kobs. (e) SMX degradation efficiency at varying pH levels. (f) SMX degradation amidst varying ionic interference. (g) Degradation of SMX and PI utilization under continuous conditions with a single PI addition. (h) TOC removal efficiencies across systems. (i) Comparative degradation of various organic pollutants by different systems.
Fig. 3. (a) Impact of scavengers on SMX degradation. (b) Transmission results for DPBF in the C3-Mn3O4 + PI system. (c) Degradation patterns for nitrobenzene across different systems. (d) PMSO conversion in the C3-Mn3O4 + PI system. (e) ESR signals in the C3-Mn3O4 + PI system. (f) LSV curves and EIS results for each catalyst. (g) i-t curves depicting electron transfer upon PI and SMX introduction. (h) In-situ Raman spectroscopy findings for different system interactions.
Fig. 4. Structural representations of (a) Mn3O4 and (b) C3-Mn3O4. (c-d) Two-dimensional charge density comparisons between Mn3O4 and C3-Mn3O4. Work functions of (e) Mn3O4 and (f) C3-Mn3O4. d-PDOS analysis for Mn in (g) Mn3O4 and (h) C3-Mn3O4. (i) Summary of properties comparing higher and lower crystallinity Mn3O4.
Fig. 5. (a) Optimized molecular structure of SMX. (b) Electron cloud distribution on SMX. (c-d) HOMO and LUMO of SMX. (e) Calculated Fukui indices and charge density differences. (f) Proposed SMX degradation pathways in the C3-Mn3O4 + PI system. Observational growth studies of (g) E. coli, (h) wheat seeds, and (i) zebrafish embryos in different treated solutions.
Fig. 6. (a) Cyclic stability of catalysts. (b) Large device diagram of medical wastewater treatment. (c) TOC removal efficiency of medical wastewater. (d) Continuous flow apparatus setup and performance results. (e) The result of LCA. (f) Environmental sustainability diagram illustrating the application of low crystallinity Mn3O4 in PI-AOPs.本研究提出了一种可扩展且经济高效的策略，通过调控Mn₃O₄的结晶度显著提升其在聚异氰尿酸（PI）基高级氧化工艺中的催化性能。我们发现降低Mn₃O₄结晶度可增加其比表面积，从而提供更多活性反应位点并改善电子传输。这促进了催化剂与污染物之间更高效的相互作用，使反应速率较高结晶度样品提升七倍。通过调节锰的价态，将d带中心向费米能级靠近，这一关键改性促进了氧化剂的配位复合，并加速了共存自由基（•OH）与非自由基（1O2）活性物种的生成。该创新体系设计显著提升了催化活性与环境适应性，确保在连续流应用中保持稳定的高性能表现。此外，本研究通过全面毒性评估确保降解产物生态安全性，证实未产生有害碘副产物。计算与实证毒性研究均表明反应后毒性显著降低，证实产物对水生生物无毒性。
这些发现填补了催化剂结晶度影响AOPs效率的关键认知空白，为设计更高效环保的水处理技术提供了重要依据。通过探究不同晶体结构在多种环境条件下的长期稳定性与适应性，本研究为AOPs的实际应用奠定了基础理论。此外，这种简便且可扩展的结晶度调控策略不仅能提升现有催化系统的效率，更拓展了其潜在应用领域——尤其在高价值化学品生产与转化方面。该方法为优化各工业领域的催化剂性能开辟了全新路径。
Xin-Tong Huang, Chang-Wei Bai, Lu-Lu Long, Fei Chen, Optimizing metal oxide crystallinity to amplify radical and non-radical pathways for efficient organic wastewater treatment, Chemical Engineering Journal, 2025, https://doi.org/10.1016/j.cej.2025.165371
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