Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing 100083, China.
J Environ Sci (China). 2020 Mar;89:102-112. doi: 10.1016/j.jes.2019.10.005. Epub 2019 Nov 4.
Zirconium-based materials are efficient adsorbent for aqueous phosphate removal. However, current zirconium-based materials still show unsatisfied performance on adsorption capacity and selectivity. Here, we demonstrate a zirconium hydroxide encapsulated in quaternized cellulose (QC-Zr) for the selective phosphate removal. Zirconium hydroxide nanoparticles were simultaneously generated in situ with the QC framework and firmly anchored in the three-dimensional (3D) cross-linked cellulose chains. The maximum P adsorption capacity of QC-Zr was 83.6 mg P/g. Furthermore, the QC-Zr shows high P adsorption performance in a wide pH range, generally due to the electrostatic effects of quaternized cellulose. The enhanced adsorption of P was also achieved in the presence of competing anions (including Cl, NO, SO, SO) and humic acid (HA) even at a molar ratio up to 20 levels. The column adsorption capacity of QC-Zr reached 4000 bed volumes (BV) at EBCT = 0.5 min as the P concentration decreased from 2.5 to 0.5 mg/L. Mechanism study revealed that both -N(CH) groups and zirconium hydroxide were involved in phosphate adsorption via electrostatic interactions between -N(CH) and phosphate, and the formation of zirconium hydrogen phosphate (Zr(HPO)x). The P nuclear magnetic resonance (NMR) study implied that P surface-precipitated and inner-sphere complexed with zirconium hydroxide at a ratio of 3:1.
基于锆的材料是去除水溶液中磷酸盐的有效吸附剂。然而，目前基于锆的材料在吸附容量和选择性方面的表现仍不尽如人意。在这里，我们展示了一种用季铵化纤维素（QC）包裹的氢氧化锆（QC-Zr），用于选择性去除磷酸盐。在 QC 骨架中同时原位生成了氢氧化锆纳米颗粒，并牢固地锚定在三维（3D）交联的纤维素链上。QC-Zr 的最大 P 吸附容量为 83.6 mg P/g。此外，QC-Zr 在很宽的 pH 范围内都表现出高的 P 吸附性能，这主要归因于季铵化纤维素的静电效应。即使在竞争阴离子（包括 Cl、NO、SO、SO）和腐殖酸（HA）的摩尔比高达 20 倍的情况下，P 的吸附性能也得到了增强。当 P 浓度从 2.5 降至 0.5 mg/L 时，QC-Zr 的柱吸附容量达到 4000 床体积（BV），洗脱时间常数（EBCT）为 0.5 分钟。机理研究表明，-N(CH)基团和氢氧化锆都参与了磷酸盐的吸附，这是通过-N(CH)和磷酸盐之间的静电相互作用以及形成磷酸锆（Zr(HPO)x）实现的。磷核磁共振（NMR）研究表明，P 表面沉淀并与氢氧化锆以 3:1 的比例形成内络合。
