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

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。

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.