不同合成条件对ZnAl-LDHs覆膜改性生物陶粒除磷效果的影响

采用3种Zn~(2+)/Al~(.+)金属浓度比的ZnCl_2和AlCl_3溶液,在两个不同pH值条件下,利用水热-共沉淀法对生物陶粒基质进行层状双金属氢氧化物(LDHs)覆膜改性.将生成的不同类型ZnAl-LDHs覆膜改性基质与原始生物陶粒基质分别填充于实验柱中,构建模拟垂直流人工湿地小试系统;对改性前后的7种基质进行磷素净化效果、等温吸附实验和解吸附实验研究,通过实验数据结合主成分分析,探讨ZnAl-LDHs覆膜改性生物陶粒除磷效果提升的影响因素.结果表明,pH=11的ZnAl-LDHs改性方式对磷素净化效果具有更为明显的提升功能;其中ZnAl-LDHs(pH=11,1∶1)改性生物陶粒基质相比于原始基质,对TP、TDP、SRP平均去除率的增幅超过70%,其最大理论吸附量达到原始生物陶粒的3倍.合成ZnAl-LDHs时的pH值和Zn~(2+)/Al~(3+)金属浓度比对改性生物陶粒的结构形态与覆膜效果有着不同程度的影响,其中合成时的pH值是ZnAlLDHs覆膜改性生物陶粒除磷效果的主要影响因素.通过合理调控制备ZnAl-LDHs覆膜改性生物陶粒时的pH值及Zn~(2+)/Al~(3+)金属浓度比,可以达到有效提高ZnAl-LDHs覆膜改性生物陶粒除磷效果的目的.

Influencing Factors for Phosphorus Removal by Modified Bio-ceramic Substrates Coated with ZnAl-LDHs Synthesized by Different Modification Conditions

Under different pH conditions, the hydrothermal and co-precipitation method was used to synthesize layered double hydroxides (LDHs) coated on bio-ceramic substrates with three different Zn²⁺/Al³⁺ molar ratios. Applying the original and six kinds of modified bio-ceramic substrates coated with ZnAl-LDHs (bio-ceramic/ZnAl-LDHs) in simulated vertical-flow constructed wetlands, experiments for phosphorus removal and isothermal adsorption were conducted to analyze the mechanism and effect of each synthesis factor. The results showed that ZnAl-LDHs (pH=11) had a more obvious effect on phosphorus removal, especially for bio-ceramic/ZnAl-LDHs (pH=11, 1:1), whose average removal rates of TP, TDP and SRP were enhanced over 70%. Its maximum adsorption capacity for phosphorus was three times higher than that of the original bio-ceramic. Both pH and Zn²⁺/Al³⁺ molar ratio affected the configuration and coating properties of bio-ceramic/ZnAl-LDHs at the time of synthesis, and pH was the main synthesis factor for phosphorus removal efficiency of bio-ceramic/ZnAl-LDHs. Through reasonable regulation of pH and Zn²⁺/Al³⁺ molar ratio when bio-ceramic/ZnAl-LDHs was synthesized, the phosphorus removal efficiency could be improved effectively.