Acta Physico-Chimica Sinica

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Defluoridation of Water Using Active Alumina Derived from Single-Layer Boehmite

Jianchuan Sun1, Xuhui Wang1, Shuaiqi Chen1, Yanqing Liao1, Awang Gao1, Yuhao Hu1, Tao Yang1, Xiangyu Xu1, Yingxia Wang2, Jiaqing Song1   

  1. 1 State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China;
    2 Institute of Inorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2019-11-05 Revised:2019-12-13 Accepted:2019-12-14 Published:2019-12-20
  • Supported by:
    The project was supported by the Shanghai Key Laboratory of Green Chemistry and Chemical Processes, East China Normal University, China (H2016107).

Abstract: The preparation of high-efficiency and low-cost adsorbents for the defluoridation of drinking water remains a huge challenge. In this study, single-layer and multi-layer boehmite were first synthesized via an organicfree method, and active alumina used for fluoride removal from water was obtained from the boehmite. The advantage of a single layer is that more aluminum is exposed to the surface, which can provide more adsorption sites for fluoride. The active alumina adsorbent derived from single-layer boehmite exhibits a high specific surface area and excellent adsorption capacity. The high surface area ensures a high adsorption capacity, and the organic-free synthesis method lowers the preparation cost. The asprepared adsorbent was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption analysis. The single-layer structure of boehmite was determined from the simulated XRD diffraction pattern of single-layer boehmite. The disappearance of the (020) diffraction peak of boehmite illustrates that the dimensions in the b direction are extremely small, and according to the XRD simulation results, the single-layer structure of boehmite could be determined. Single-layer boehmite with a surface area of 789.4 m2·g-1 was formed first. The active alumina obtained from the boehmite had a surface area of 678.4 m2·g-1, and the pore volume was 3.20 cm3·g-1. The fluoride adsorption of the active alumina was systematically studied as a function of the adsorbent dosage, contact time, concentration, co-existing anions, and pH. The fluoride adsorption capacity of the active alumina obtained from the single-layer boehmite reached up to 67.6 mg·g-1, which is higher than those of most alumina adsorbents reported in the literature. The adsorption capacities of the active alumina are related to the specific surface area and the number of hydroxyl groups on the surface. Dosages of 0.6, 1.0, and 2.6 g·L-1 of active alumina were able to lower the 10, 20, and 50 mg·L-1 fluoride solutions, respectively, below the maximum permissible limit of fluoride in drinking water in China (1.0 mg·L-1), suggesting that the active alumina synthesized in this work is a promising adsorbent for defluoridation of drinking water. In addition, the fluoride adsorption is applicable in a wide pH range from 4 to 9 and is mainly interfered by SO42- and PO43-. Further investigation suggested that the fluoride adsorption of the active alumina follows the pseudo second-order model and Langmuir isotherm model.

Key words: Defluoridation, Active alumina, Single layer, High surface area, Adsorption, High adsorption capacity, Organic-free


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