State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment , Nanjing University , Nanjing 210023 , China.
Research Center for Environmental Nanotechnology (ReCENT) , Nanjing University , Nanjing 210023 , China.
Environ Sci Technol. 2019 Jan 2;53(1):365-372. doi: 10.1021/acs.est.8b05177. Epub 2018 Dec 10.
Polystyrene-based nanoferric oxide composite is a representative nanomaterial successfully applied in scale-up water decontamination for arsenic and phosphorus. However, little is available on the effect of solution chemistry (for instance, the coexisting Ca) on the long-term performance of the nanocomposite. In this study, we carried out 20 cyclic runs of phosphate adsorption-desorption on a polymer-supported ferric nanocomposite HFO@201. Unexpectedly, an enhanced phosphate removal was observed in the presence of Ca, which is quite different from its adverse effect on phosphate capture by granular ferric oxide. Further mechanistic studies revealed that enhanced phosphate removal was mainly realized via the Ca-P coprecipitation inside the networking pores of HFO@201 as well as the possible formation of the multiple Fe-P-Ca-P complex. The complex formation led to a distinct increase in P adsorption, and the coprecipitation, driven by the accumulated OH in confined pores during phosphate adsorption and alkaline regeneration, favored P removal via the formation of amorphous calcium phosphate (ACP) and hydroxyapatite inside. TEM-EDS spectra indicated that coprecipitation did not occur on the surface of loaded nano-HFO, greatly mitigating its adverse effect on P adsorption on the surface of nano-HFO. Fixed-bed column study showed that the presence of Ca increased the effective treatable volume of HFO@201 toward P-containing influents by ∼70%. This study is believed to shed new insights into the effect of solution chemistry on similar nanocomposites for advanced water treatment.
基于聚苯乙烯的纳米氧化铁复合材料是一种成功应用于砷和磷规模化水净化的代表性纳米材料。然而，对于溶液化学（例如共存的 Ca）对纳米复合材料长期性能的影响，研究甚少。在这项研究中，我们在聚合物负载的铁纳米复合材料 HFO@201 上进行了 20 次循环的磷酸盐吸附-解吸实验。出乎意料的是，在 Ca 的存在下观察到磷酸盐去除的增强，这与 Ca 对颗粒状氧化铁捕获磷酸盐的不利影响完全不同。进一步的机理研究表明，磷酸盐去除的增强主要是通过 HFO@201 的网络孔内的 Ca-P 共沉淀以及可能形成的多种 Fe-P-Ca-P 络合物来实现的。这种络合作用导致 P 吸附的明显增加，而在磷酸盐吸附和碱性再生过程中，由于受限孔内积累的 OH，共沉淀有利于通过在孔内形成无定形磷酸钙 (ACP) 和羟基磷灰石来去除 P。TEM-EDS 谱表明，共沉淀没有发生在负载的纳米-HFO 表面，这极大地减轻了它对纳米-HFO 表面 P 吸附的不利影响。固定床柱研究表明，Ca 的存在将 HFO@201 对含磷进水的有效处理体积增加了约 70%。这项研究有望为类似纳米复合材料在高级水处理中的应用提供新的见解。
