活化赤泥的除氟性能

以成本低的铝工业废矿渣（赤泥）为原材料,通过高温煅烧和酸化处理对赤泥进行活化,制备了除氟吸附剂。研究了反应时间、投加量、初始氟浓度、溶液温度、共存阴离子和pH值对活化赤泥除氟效果的影响。结果表明,接触反应时间为18 h时,吸附接近平衡。活化赤泥对氟离子的吸附符合Lagergren二级吸附动力学方程。另外,初始浓度越高,吸附容量越大。与Freundlich相比,Langmuir吸附等温模型可以更好地描述氟离子的吸附特性,最大吸附量可达2.71 mg/g。SO24-、Cl-和NO3-存在时（〈1 000 mg/L）,对氟离子的吸附几乎没有影响,然而,HCO3-、PO34-和氟离子共存时,会对氟吸附造成不利影响。活化赤泥在pH值3.5～11.0时,具有较好的吸附稳定性。活化赤泥是一种吸附容量高、性能稳定的环境友好型除氟材料,具有应用潜力。

Adsorption characteristics of activated red mud for fluoride removal

Red mud, a waste tailing from alumina production, was activated with calcination and acid treatment for fluoride removal from water solution. Factors affecting fluoride adsorption on activated red mud were investigated, including reaction time, dosage of adsorbent, initial fluoride concentration, temperature, coexisting anions, and pH. Results showed that fluoride adsorption onto activated red mud generally achieved equilibrium at about 18 h. The kinetic data revealed that adsorption kinetics agreed well with the expression of Lagergren second-order rate. The higher the initial fluoride concentration, the greater the adsorption capacity was. The adsorption isotherm can be better described by Langmuir isotherm model, in comparison with Freundich isotherm model. Its maximum adsorption capacity was up to 2.71 mg/g. In addition, the coexistence of SO₄^2-, Cl^-, and NO₃^-(< 1 000 mg/L) had no significant effects on F^- adsorption. However, HCO₃^- and PO₄^3- showed negative effects on fluoride removal. It demonstrated that fluoride adsorption was relatively independent on pH between 3.5 and 11.0. In summary, the activated red mud is an environmental-friendly fluoride adsorbent with high and stable adsorption capacity, which is of great advantage in practical application.