Partic. vol. 27 pp. 66-71 (August 2016)
doi: 10.1016/j.partic.2016.01.005

Preparation of MnO₂–Al₂O₃ adsorbent with large specific surface area for fluoride removal

Naicai Xu^{a, b, c}, Zhong Liu^{a, *}, Shaoju Bian^a, Yaping Dong^a, Wu Li^{a, *}

liuzhong@isl.ac.cnliwu@isl.ac.cn

Abstract

MnO₂–Al₂O₃ (MOAO) binary nanocomposite with a 1:3 MnO₂ to Al₂O₃ molar ratio was synthesized by impregnation technique using mesoporous alumina (MA) precursor. The MOAO product consisted of MA and amorphous MnO₂. The manganese valence in MOAO was +4, indicative of MnO₂ being coated on the surface of MA during the impregnation process. MOAO had a large specific surface area (385.266 m²/g) and wormhole-like mesoporous structure. The average pore size, which could be precisely controlled over the range of 3.4–4.1 nm. The optimum removal of fluoride was obtained when the initial pH was in the range of 4–10. The defluorination efficiency of MOAO was far superior to that of MA when the initial fluoride concentration exceeded 40 mg/L. The large surface area and bimodal porous structure of MOAO after coating MnO₂ may be responsible for the high removal efficiency in the defluorination process.

Graphical abstract

Keywords

Alumina; MnO₂–Al₂O₃; Mesoporous structure; Structure properties; Adsorption