气凝胶负载水镁石和镁铝水滑石纳米粒子的制备及对铅离子吸附性能研究

Synthesis and Pb²⁺ Adsorption Properties of Aerogel Supported Brucite and Mg-Al Hydrotalcite

摘要: 本文以低成本高比表面的商用SiO₂气凝胶为负载基底，通过一步(共)沉淀法制备了负载水镁石及负载水滑石，用作高效的Pb²⁺吸附剂。采用TEM, SEM, XRD及ICP等对制备的负载水镁石及负载水滑石的织构性能进行表征，结果显示制备的负载型水滑石和负载水镁石具有小的粒径、薄的厚度，弱的结晶。对Pb²⁺的吸附性能研究表明，两吸附剂对Pb2+的吸附与假二次动力学模型和Langmuir等温线模型拟合良好(R2 ≥ 99.0%)，表明负载水镁石和负载水滑石对Pb²⁺的吸附是一个表面化学吸附过程。通过Langmuir等温线模型计算的饱和吸附容量为442.5 mg/g和246 mg/g，与实验测得的值相一致，高于文献报道的水滑石基Pb²⁺吸附剂。

Abstract: Low-cost and high surface area commercial silica aerogel supported brucite and Mg-Al hydrotalcite were synthesized as adsorbents for Pb²⁺ removal. The textural properties of the supported brucite and Mg-Al hydrotalcite were characterized by TEM, SEM, XRD and ICP, and the results showed supported brucite and Mg-Al hydrotalcite with small size, weak crystallization and thin thickness. In the adsorption experiments, the adsorption rates were fast in the first 60 min, then slowed down and finally reached equilibrium for both the adsorbent. The adsorption data fitted well with pseudo-second-order kinetic model and Langmuir isotherm model, indicating monolayer chemisorption process. The saturated adsorption capacities of the supported brucite and Mg-Al hydrotalcite are 442.5 mg/g and 246 mg/g, respectively, higher than that of reported hydrotalcite-based adsorbents.