碳基过硫酸盐催化剂表面氧调控及其用于生化尾水深度处理的研究

Treatment of micro-concentration refractory organic contaminants in the secondary effluent has become the key issue for today’s municipal wastewater pollution control and reclamation. Persulfate decomposition activated by carbon based catalytic oxidation system has been proven to be efficient for removal of these pollutants. However, the catalytic activity and efficiency of conventional non-nanometer scale carbon material is poor. Moreover, the actual catalytic site of carbon based activator still remains ambiguous. To address the above concerns and based on the scientific hypothesis of “metal salt was able to alter the organic decomposition pathway and then orient the material structure formation and function regulation”, this proposal intends to synthesize the carbon functional material by using easily-accessed biomass as precursor via one-pot pyrolysis route. The pyrolysis characteristics of organics and carbon-oxygen structure formation mechanisms upon carbonated product surface under the metal salts addition condition will be clarified. The efficiency and mechanism of prepared carbon material for activating persulfate decomposition to degrade organic pollutants will also be explored. More important, the relation of material structure and catalytic activity will be clarified. At last, a coupled oxidation system with multi-functions of “entrapment-adsorption-catalysis” will be constructed and its feasibility and stability for treating secondary effluent, which contains refractory organics, is to be evaluated. The presented proposal would be beneficial to obtain a more explicit persulfate decomposition mechanism catalyzed by carbon material and move forward of this technology from bench-scale to practical application.

污水处理厂生化尾水中低浓度难降解有机物的处理已成为新时期下我国城市水污染防治及污水再生利用过程中的重难点，基于“碳材料催化过硫酸盐分解”的高级氧化系统是实现其深度处理的有效手段之一。然而，传统非纳米碳材料的催化效率较低且活性位点模糊不明。针对该问题，本项目在“金属盐可改变有机物热分解路径，进而实现碳材料结构与功能的定向调控”之科学假说下，拟以廉价生物质为原料，采用一步热解碳化法制备功能化碳材料；解析在金属盐掺入条件下有机分子的裂解规律及碳氧活性位点的形成机制，探讨热解碳活化过硫酸盐降解有机污染物的效能和机制，阐明材料结构与催化效能间的“构-效”关系；在上述基础上，构建“截留-吸附-催化”多功能连续流耦合氧化系统，考察其用于处理生化尾水的可行性，以期为解析碳基材料活化过硫酸盐机制、推进该技术的工程应用提供依据。

基于“碳材料催化过硫酸盐分解”的高级氧化技术是处理生化尾水中低浓度难降解有机物的有效手段之一。然而，传统非纳米碳材料的催化效率较低且活性位点模糊不明。针对该问题，本项目以廉价生物质为原料，采用金属盐辅助一步共热解碳化法制备功能化碳材料，实现了热解碳表面氧官能团的定向富集。在混合金属盐（ZnCl2：KCl=1:1）添加下，热解碳表面的酮基氧含量可达7.4%(wt.%)，金属盐有助于生物质在升温热解阶段脱氢，碳骨架缩聚，进而实现酮基碳的形成。制备得到的生物炭可在pH3.0~11.0范围内高效催化过一硫酸盐分解产单线态氧，实现有机污染物完全去除。通过将催化剂负载到多孔聚丙烯填料表面，成功实现了催化剂的固定化。在此基础上，构建了小型催化氧化装置，该装置可在连续72 h的运行时长内，有效活化过一硫酸盐实现实际污水处理厂生化尾水中四环素类抗生素的高效去除，并且可同步完成尾水中活性微生物的灭活。此外，项目成功制备了“吸附-过滤”双功能一体的多孔滤膜，实现了尾水中磷的深度脱除和回收。最后，通过将上述生物炭制备方法进行拓展应用，成功合成得到了酮基碳和Mn-Nx双功能位点的复合催化剂，实现了双氯芬酸的高效降解。本项目的研究结果为进一步研发高效安全的尾水深度处理技术提供了有力支撑。

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