双效催化剂可见光催化与活化过硫酸盐协同修复水中二噁烷污染的效能及机理研究

1,4-Dioxane, one of the non-biodegradable organic compounds, has been widely utilized in daily chemical and food industries. 1,4-Dioxane can easily release to surface water and ground water around due to its high solubility, posing great threats to water supply, food safety and ecological security. Persulfate based advanced oxidation processes have been demonstrated as the potential and powerful technologies for the degradation of emerging organic pollutants. The catalyst from transition metal ion doping zinc ferrite possess excellent properties on visible light photocatalysis and persulfate activation, displaying promising application in persulfate utilization with solar energy for the removal of 1,4-Dioxane from water. In this project, new bifunctional catalysts cobalt doped zinc ferrite (Co-Zn ferrite), manganese doped zinc ferrite (Mn-Zn ferrite) and copper doped zinc ferrite (Cu-Zn ferrite) will be synthesized and applied for synergistic degradation of 1,4-Dioxane by a novel photocatalytic heterogeneous activation of persulfate process under visible light irradiation. The introduction of cobalt, manganese and copper on zinc ferrite are designed to improve the visible light photocatalytic ability and persulfate activation of the as-prepared bifunctional catalysts. The analysis of degradation byproducts, speculation of degradation path, detection and the exploration of active species along with electron transfer process will be detailed investigated to study the synergistic mechanism between heterogeneous activation of persulfate and visible light photocatalysis during the degradation of 1,4-Dioxane, as well as to clarify the relationship among mineralization, toxicity variation and degradation path of 1,4-Dioxane. A detailed mechanism for heterogeneous activation of persulfate together with visible-light-driven photocatalytic degradation of 1,4-Dioxane will be proposed accordingly. It is expected that the results of this project will provide theoretical guidance, technical methodology and proof-of-concept that can be applied widely for remediation of emerging organic pollutants like 1,4-Dioxane contaminated water via visible light photocatalytic persulfate process bifunctional catalysts.

二噁烷等难降解有机物被广泛用于日化、食品等行业，易迁移到附近的水环境中，是影响活动区供水安全、食品安全及生态安全的关键环境问题。过硫酸盐高级氧化技术是降解这类难降解有机物的有效途径。过渡金属离子掺杂铁酸锌材料具有性能优良的可见光催化活性和活化过硫酸盐的性能，在利用太阳能活化过硫酸盐处理水中二噁烷等难降解有机物的领域具有较好的应用前景。本项目通过过渡金属离子（钴、锰、铜）掺杂铁酸锌，调控催化剂的可见光响应，并强化对过硫酸盐的活化能力。将催化剂应用于可见光活化过硫酸盐体系，通过分析二噁烷降解和产物生成规律，推测降解路径，结合活性自由基的捕捉与检测和电子传递机制的分析，揭示活化过硫酸盐与可见光催化在降解二噁烷过程中的协同作用机制，阐明二噁烷的降解机理、矿化途径及毒性变化之间的关系。本研究有望丰富和发展可见光催化和过硫酸盐的研究理论和方法，为二噁烷类难降解有机物的污染修复创新提供基础。

光催化技术协同过硫酸盐高级氧化技术为难降解有机污染物的处理提供了一种有力方法，其应用的前提和关键是确定光催化剂在可见光（天阳能）活化过硫酸盐反应过程（或降解路径）中的催化效能和机理。本研究通过过渡金属离子（钴、铜。锰）掺杂铁酸锌制备了Co1-xZnxFe2O4、Cu1-xZnxFe2O4和Mn1-xZnxFe2O4催化材料，揭示了这3种催化剂在可见光非均相活化过硫酸盐处理难降解有机污染物橙黄II（AO7）、双酚A（BPA）及氯贝酸（CFA）的影响因素，并阐明了在可见光协同活化过硫酸盐降解AO7、BPA和CFA反应过程的作用机理。受控于催化剂的可见光响应和对过硫酸盐的活化能力，锌和过渡金属（钴、铜。锰）的比例显著影响催化剂在可见光非均相活化过硫酸盐降解有机污染物的效果，因此确定了最优的催化剂分别为Co0.2Zn0.8Fe2O4、Cu0.3Zn0.7Fe2O4和Mn0.2Zn0.8Fe2O4。这三种催化剂可见光照射下非均相活化过硫酸盐能高效处理AO7、BPA、CFA、2,4-二氯苯酚（2,4-DCP）及苯酚，表明该协同技术具备了处理水中难降解有机污染物的应用潜力。研究了4种无机阴离子（碳酸氢根离子、氯离子、硫酸根离子和硝酸根离子）和2种天然有机物（腐殖酸和富里酸）对上述可见光非均相活化过硫酸盐降解AO7、BPA和CFA效果的影响。这三种催化剂能保持良好的催化活性及稳定性，在重复利用过程中金属离子的溶出非常低，不会对环境造成二次污染。此外，本研究还重点分析了反应体系中存在的活性粒子（羟基自由基、硫酸根自由基、超氧根自由基、单线态氧、电子和空穴）对有机污染物降解的相对贡献量。本研究丰富了可见光催化和过硫酸盐活化的研究方法和理论并可供类似研究借鉴，有助于促进难降解有机污染物的修复应用。