Liang Tian, Yan Chunjie, Li Xujian, Zhou Sen, Wang Hongquan
Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China and Engineering Research Center of Nano-materials of Ministry of Education, China University of Geosciences, Wuhan 430074, China E-mail:
Water Sci Technol. 2018 Mar;77(5-6):1570-1580. doi: 10.2166/wst.2018.022.
In the development of industrial life, an enormous amount of silica fume (SF) has been accumulated and cannot be reused properly, and a large quantity of rare-earth elements in industrial wastewater has been inappropriately discharged, both of which pose a threat to human health and the environment. By using UV photocatalytic grafting technology, a polymer brush grafted from modified SF, which can be used as a high efficiency adsorbent, can solve both problems at the same time. Specifically, SF was firstly silanol-functionalized by γ-methacryloxypropyltrimethoxysilane (KH570), then grafted with polyacrylic acid brushes by UV photocatalytic grafting to finally obtain the adsorbent. Under optimal conditions, adsorption capacity of the adsorbent for dysprosium(III) (Dy) could reach 278.49 mg/g. It took 1 min for the adsorbent to reach adsorbing equilibrium at a relatively low concentration of Dy (40 mg/L), and only 3 min at a medium and high concentration (130 mg/L and 200 mg/L). After six adsorption-desorption cycles, the adsorbent still possessed high adsorption capacity for Dy (251.20 mg/g). The adsorption behavior of the adsorbent fit the Langmuir isotherm model (R > 0.97) and pseudo-second-order kinetic model (R > 0.98) well. The functional group of carboxylate anion, -COO, played a central role during the adsorption process, which was verified by Fourier transform infrared and X-ray photoelectron spectroscopy analyses.
在工业生产发展过程中，大量硅灰（SF）被积累且无法得到妥善再利用，同时工业废水中大量稀土元素被不当排放，这两者都对人类健康和环境构成威胁。通过使用紫外光催化接枝技术，由改性硅灰接枝得到的聚合物刷可作为高效吸附剂，能同时解决这两个问题。具体而言，首先用γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）对硅灰进行硅烷醇功能化，然后通过紫外光催化接枝聚丙烯酸刷，最终得到吸附剂。在最佳条件下，该吸附剂对镝（III）（Dy）的吸附容量可达278.49 mg/g。在相对低浓度的Dy（40 mg/L）下，吸附剂达到吸附平衡需1分钟，而在中高浓度（130 mg/L和200 mg/L）下仅需3分钟。经过六次吸附-解吸循环后，吸附剂对Dy仍具有较高的吸附容量（251.20 mg/g）。吸附剂的吸附行为很好地符合朗缪尔等温线模型（R > 0.97）和伪二级动力学模型（R > 0.98）。傅里叶变换红外光谱和X射线光电子能谱分析证实，羧酸根阴离子官能团-COO在吸附过程中起核心作用。
