纳米零价铁@氢氧化镁的合成、活化机制及其在印染废水深度处理中的应用研究

Nanoscale zero-valent iron（nZVI） have been successfully used for the remediation of contaminated groundwater. However, the limitations include the aggregation of nZVI and decreasement of activity. Hence, nZVI has been not widely used in environmental remediation. Currently, the aggregation of nZVI has been solved by formation of the supported-nZVI or of the core-shell structure, but the the activity reduction resulting from the susceptibility of oxidation is still a problem. Therefore, in this proposal, we intend to synthesize the flower-like Mg(OH)2 used as the support materials to reduce both the aggregation and the oxidation, where will based on the aspect: similar to the surface of the mineral, ion exchange reaction occur between Mg2 + and the oxidized surface of nZVI since Mg(OH)2 have a appropriate solubility in aqeous solution (Ksp=10-11). The genernated H+ by ion excxhange damage the oxidized layer of nZVI. Conseqently, the regerenation of reactivity and stablity of nZVI is possible. We will understand the interaction beween nZVI and Mg(OH)2 , the way of damaging oxidized layer , the stablity of nZVI@ Mg(OH)2, and their application in treatment of printing and dyeing waste water. The outcomes from this proposal is not only a sigficantly improving the nZVI application on contaminated site remedation, but also delivering the scientific issues such as understanding the Mg(OH)2 interacted with nZVI and their funcations.

纳米零价铁(nZVI)在环境修复和污染治理方面有广阔应用前景。然而，其易团聚及活性随使用时间而迅速降低的缺点成为其应用的瓶颈问题。已有研究通过负载或核壳结构成功解决材料的团聚问题，但nZVI因易氧化而引起的氧化层包覆导致的材料活性降低，依然是研究的难点和热点。本研究拟借鉴矿物表面的离子交换原理，以自支撑氢氧化镁负载适量nZVI作为研究对象，通过分析nZVI与氢氧化镁的结合方式，及微溶于溶液中mM量级的Mg2+破坏nZVI的表面氧化层的途径，阐明氢氧化镁既降低nZVI的团聚又提高活性的机理；同时基于氢氧化镁对水中低浓度的有机物和重金属有较强的吸附能力，及nZVI高效的还原和降解能力，拓展nZVI@Mg(OH)2在印染废水的生化出水(含低浓度有机物和重金属)处理中的应用，并阐明相关科学问题。此研究不仅对于理解nZVI的活性和使用周期具有重要意义，同时对印染废水的深度处理提出新的潜在解决方案。

本项目针对纳米零价铁(nZVI)易团聚及活性随使用时间而迅速降低的缺点，设计以花状氢氧化镁作为支撑材料来分散nZVI以解决上述缺点。首先采用简单的化学沉淀法在表面活性剂存在的情况下合成花状氢氧化镁，然后采用原位合成的方法将nZVI负载其花瓣状的纳米片上，获得了花状氢氧化镁的宏量合成的方法。最终以铅离子和各种不同种类的染料作为典型的目标污染物来研究nZVI@ Mg(OH)2复合材料的活性及去除效果。研究表明该种复合材料不但对模拟的含铅废水有很好的去除效果，对于实际的铅锌矿的浸出液中的铅离子也表现出高达99%的去除效果；同时对其去除机理进行了深入的研究；该复合材料对于大部分的染料均表现出较高的脱色率并对其机理进行了分析。本研究的开展对于解决nZVI在实际应用过程中的问题具有一定的指导意义，获得了宏量合成花状氢氧化镁的合成方法。项目研究期间共发表SCI论文3篇，申请国内发明专利两项，参加项目研究的硕士生4名，其中两名已经顺利毕业。