La3+活化空心介孔氧化硅球的微结构调控及其高效除磷机理

The excessive presence of phosphorous in natural water bodies has become one of the major causes to eutrophication. The development of high-performance adsorbent materials has been regarded as the most promising strategy to control and reduce the level of phosphate in wastewater. In this proposal, a series of functionalized hollow mesoporous silica spheres (HMS) will be designed and synthesized by grafting of amino-functional groups on the surfaces of mesopores within the shells of HMS; followed by the immobilization of La3+ as active sites for phosphate removal. These fabricated adsorbents will integrate both superior adsorption capacity and excellent mass transformation rate, derived from the high density of active sites inside the mesopores and from their inner macropores, respectively. Moreover, their phosphate removal performances will be optimized by tailoring their hierarchical structures, such as the sizes of macroporous cores and the thickness of mesoporous shells, along with the loading of the functional groups on the surface of mesopores. Afterwards, XRD, SEM/EDX, TEM, nitrogen adsorption-desorption and FT-IR spectroscopy will be adopted to investigate the structural properties and surface chemistry of as-prepared adsorbents in detail. The batch phosphate adsorption will be studied to figure out the effect of structure on their phosphate removal performance and deduce the possible phosphate adsorption mechanisms. Finally, the recyclability and safety of our developed novel adsorbents will also be evaluated, which will provide experimental basis for developing new-generation highly efficient phosphate adsorbents.

磷污染是导致天然水体富营养化的主要原因，研发高效吸附除磷新材料是控制和消除污水磷污染的有效手段。针对官能团负载量增大导致有序介孔吸附剂的孔道堵塞这一缺点，本项目拟制备具有空心大孔-壳层有序介孔结构的氧化硅球，进而以La3+配位形式在乙二胺嫁接后的孔道表面构建高密度活性吸附位点，改善其壳层的介孔孔道微结构和表面特性，获得兼具高吸附容量和快速吸附速率的新型除磷吸附剂。基于XRD、SEM/EDX、TEM、BET和FTIR等测试结果，调控其空腔直径、壳层厚度等微结构参数及其影响机制；调节壳层介孔孔道表面乙二胺负载量及其对模拟废水中吸附除磷的“构-效”关系，并揭示其影响规律。综合吸附数据的相关模型拟合结果，从吸附剂的微结构和分子水平表面特征上揭示其吸附除磷机理，从而实现新型空心介孔吸附剂的可控构筑和性能优化。此外，考察与评价吸附剂的再生性能和安全性能。

磷污染是导致水体富营养化的关键因素之一，吸附法能够实现废水中磷的深度去除。可控制备吸附容量高、吸附速度快并且易于再生的新型介孔吸附剂对实现废水中磷污染的高效去除具有重要的研究意义。针对负载量增大导致介孔孔道堵塞这一问题，本项目在介孔材料中引入空心大孔结构和次级介孔结构，并通过调控介孔孔径等手段提高其负载容量，进而在其孔道中嫁接乙二胺官能团，调控其与La(III)配位以及负载等，获得La活化空心介孔微球、La和La/Fe负载花状分级结构介孔微球和La活化大孔径介孔纳米球等吸附剂。通过调控孔道表面官能团和活性位点的负载量，研究了微结构和组成对其在废水除磷中的构效关系和影响规律。探索实验条件，如：温度、pH值、干扰离子等对吸附性能的影响并掌握最优化实验条件。综合表征数据和吸附模型的拟合结果，揭示了介孔孔道表面的活性位点对磷酸根的吸附机理。本项目所研发的新型介孔微球吸附剂能够保留介孔孔道的有序性，有效发挥其作为传质通道的作用，提高磷离子在孔道内的传输速率并被活性位点捕获，从而获得具有快速吸附速率和高吸附容量的介孔吸附剂。此外，引入磁性内核，获得磁性空心介孔吸附剂以提高其循环再利用效率。本研究对新型功能化介孔吸附剂的可控设计及其在污水除磷方面的应用提供理论指导和实验依据。