热活化褐铁矿吸附除磷性能

Removal of Phosphate by Thermally Activated Limonite

利用X射线荧光光谱、X射线衍射、比表面积分析、场发射扫描和透射电子显微镜、热分析等表征手段研究热活化褐铁矿物相组成和形貌特征,通过静态实验研究热活化褐铁矿除磷效果的影响因素、动力学、热力学及除磷机理。结果表明:褐铁矿中的纳米–亚微米针铁矿晶体在350℃空气中热活化转化成为具有多孔结构的赤铁矿,在该温度下活化处理产物具有更高的比表面积和吸附除磷性能。热活化褐铁矿吸附除磷是自发的吸热过程,在一定pH范围内(3~9),pH值越低越有利于对磷的吸附,低浓度(1~100 mmol/L)Cl~–、NO_3~–、SO_4^(2–)对热活化褐铁矿吸附除磷基本没有影响。

The mineral phase and morphology of the thermally activated limonite were characterized by X-ray fluorescence, X-ray diffraction, specific surface area analysis, scanning electron microscopy, transmission electron microscopy and thermal analysis, respectively. The influencing factors on the removal of phosphate, dynamics, thermodynamics and phosphate removal mechanism by thermally activated limonite were investigated. The results show that the limonite with nano-submicron goethite crystals in limonite is further transformed into porous hematite after thermally activated reaction in air atmosphere at 350 ℃, and formed nano-porous-limonite has a greater surface area favoring the removal of phosphate. Furthermore, the adsorption process of phosphate by thermally activated limonite is spontaneous endothermic process. A lower pH value （i.e., 3-9） favors the adsorption of phosphate, and a lower concentration of Cl^-, NO3^- and SO4^2- （i.e., 1-100 mmol/L） almost has little effect on the removal of phosphate by thermally activated limonite.