拜耳法赤泥吸附废水中Mn^2＋和NH4^＋的研究

Studies of Adsorbing Mn^(2+) and NH_4^+ from Wastewater Using Bayer Red Mud

以拜耳法赤泥为吸附剂,研究了赤泥对Mn2+和NH4+的吸附性能及动力学关系,分析了p H、温度、赤泥投入量、吸附时间对吸附效率的影响,以及吸附前后赤泥的矿物学特征。结果表明:在20 m L,p H为5.60的溶液中,投加0.5 g赤泥,50℃,吸附时间为120 min时,赤泥吸附Mn2+和NH4+的效率分别达到99.3%、94.7%,单位质量赤泥吸附量分别为4.05、3.79 mg/g。温度、赤泥投入量、吸附时间的增加有助于提高赤泥对Mn2+和NH4+的吸附效率。赤泥吸附Mn2+和NH4+的过程符合Freundlich吸附等温式,吸附Mn2+符合准二级动力学模型,吸附NH4+符合准一级动力学模型。赤泥吸附Mn2+和NH4+是化学吸附和交换吸附2种作用方式。

Application of Bayer red mud for adsorbing Mn^2＋ and NH4^＋ from wastewater was studied in the laboratory, focusing on adsorptive properties and kinetics and mineralogical characteristics before and after the red mud adsorption. Effects of pH, temperature, dosage of the red mud and adsorptive time on the absorptive rates were investigated. The laboratory study showed that the absorptive rates were 99.3%, 94.7% for Mn^2＋ and NH4^＋ and adsorptive capacities for Mn^2＋ and NH^＋ were 4.05, 3.79 mg/g, respectively under the conditions of 20 mL solution of pH 5.60, red mud dosage of 0.5 g, temperature 50 ℃ and absorptive time 120 rain; and increases of temperature, dosage of red mud and adsorptive time promoted Bayer red mud adsorption of Mn^2＋ and NH4^＋. The adsorptive process fitted the Freundlich adsorption isotherm equation and the kinetic model of Mn^2＋ adsorbing followed the pseudo second order kinetic equation, while NH4^＋ adsorbing followed the pseudo first order kinetic equation. In addition, process of Bayer red mud adsorption of Mn^2＋ and NH4^＋ involved two modes including： chemical adsorption and exchange adsorption.