Zn系LDHs覆膜改性人工湿地沸石基质除磷机制

选择Zn系层状双金属氢氧化物(LDHs),采用水热-共沉淀法合成3种不同类型的Zn-LDHs(Fe Zn-LDHs、Co Zn-LDHs和Al Zn-LDHs)并覆膜于常用人工湿地沸石基质表面;利用模拟垂直流人工湿地小试系统,对原始沸石及3种Zn-LDHs覆膜改性沸石基质进行除磷净化实验、等温吸附-解吸实验以及动力学吸附实验,通过上述实验对以Zn-LDHs覆膜改性沸石基质为代表的改性基质除磷机制进行研究.结果表明,Zn-LDHs覆膜改性沸石基质对磷素净化效果具有明显的提升功能,其中以Fe Zn-LDHs覆膜改性基质尤为突出;改性使基质的饱和吸附容量得以提高,增强了基质对磷酸盐的解吸性能,并使沸石基质对磷酸盐的主要吸附类型由物理吸附向化学吸附转换;通过对沸石基质类型及其改性方式的合理选择,可达到利用沸石人工湿地强化除磷以高效净化富营养化水体的目的.

Mechanisms of Phosphorus Removal by Modified Zeolites Substrates Coated with Zn-LDHs in Laboratory-scale Vertical-flow Constructed Wetlands

Zn-Layered double hydroxides (LDHs) were selected to carry out the experiment in present work based on the previous research results. According to the co-precipitation method, three kinds of different Zn-LDHs (FeZn-LDHs, CoZn-LDHs and AlZn-LDHs) were synthesized by ZnCl₂, FeCl₃, AlCl₃, and CoCl₃ solution in alkaline conditions and Zn-LDHs were in-situ coated on the surface of natural zeolites. With the filling of the natural and three kinds of Zn-LDHs modified zeolites in the columns, test experiments were conducted to study the removal performance of phosphorus in vertical-flow constructed wetlands. The results showed that: compared with the natural zeolites, the removal rates of phosphorus by the three kinds of Zn-modified zeolites were greatly improved, especially for FeZn-LDHs. Moreover, the maximum adsorption capacity and the desorbed performance of phosphate were enhanced by the Zn-LDHs coated modification. The adsorption type of phosphate was converted from physical adsorption to chemical adsorption. Through reasonable selection of the type of zeolite and the method of modification, Zn-LDHs modified zeolites could be used to enhance the removal of nitrogen and phosphorus for the eutrophic water.