氧化锆磁性吸附剂的制备及其磷吸附研究

Preparation of Magnetic Zirconia Adsorbent and Study on Phosphorus Adsorption

摘要: 以球磨后的粉煤灰磁珠(MS)为磁核，通过一步化学沉淀法，制备了氧化锆包覆的粉煤灰磁珠(MS@ZrO₂)磁性磷吸附剂。系统的结构与磁性分析表明，ZrO₂均匀地包覆在磁珠表面，样品中ZrO₂质量百分比约为23%。MS@ZrO₂的比磁化强度为17.25 emu/g，可借助外磁场高效分离回收。利用MS@ZrO₂对20 mg/L含磷污水进行的吸附实验表明，在最优条件：MS@ZrO₂投加量为0.4 g/L，pH为2时，磷的比吸附量可达18.80 mg/g，与Langmuir等温方程计算得出最大吸附量19.05 mg/g接近。吸附热力学和吸附动力学实验结果表明，MS@ZrO₂对磷的吸附过程符合Langmuir模型和准二级动力学模型，说明磷吸附以单分子层化学吸附为主。磷吸附机理可以用ZrO₂表面羟基化–离子交换模型解释。

Abstract: A magnetic phosphorus adsorbent coated with zirconia magnetic fly ash (MS@ZrO₂) was prepared by one-step chemical precipitation method using magnetic fly ash (MS) as magnetic nucleus after ball milling. The structure and magnetic analysis of the system showed that ZrO₂ was uniformly coated on the surface of the magnetic beads, and the mass percentage of ZrO₂ in the sample was about 23%. The specific magnetization of MS@ZrO₂ is 17.25 emu/g, which can be efficiently separated and recovered by external magnetic field. The adsorption experiments of 20 mg/L phosphorous wastewater by MS@ZrO₂ show that the specific adsorption capacity of phosphorus can reach 18.80 mg/g under the optimal conditions: MS@ZrO₂ dosage is 0.4 g/L and pH is 2, which is close to the maximum adsorption capacity of 19.05 mg/g calculated by Langmuir isothermal equation. The experimental results of adsorption thermodynamics and kinetics showed that the adsorption process of MS@ZrO₂ for phosphorus was in accordance with Langmuir model and quasi-second-order kinetic model, indicating that the adsorption of phosphorus was dominated by mono-molecule chemisorption. The mechanism of phosphorus adsorption can be explained by ZrO₂ surface hydroxylation and ion exchange model.