氧化镁基稀土复合脱氟剂的制备与成型

Preparation and Molding of A Rare Earth Magnesia Composite Fluorine Adsorbent

摘要:

以Mg(NO3)2·6H2O和La(NO3)3·6H2O为原材料，采用共沉淀法制备了含有少量稀土金属镧的氧化镁基稀土复合脱氟剂。以聚乙烯醇（PVA）和聚偏氟乙烯（PVDF）为粘合剂，利用挤出成型法制备出直径0.5cm左右的颗粒状复合脱氟剂。利用XRD、SEM和FTIR对制备的复合氧化物脱氟剂进行了表征分析，评价了粉末状及颗粒状复合脱氟剂对水中氟离子的脱除性能。结果表明：复合脱氟剂对水溶液中氟离子的最大平衡吸附量为142.85mg/g，pH=4~10时吸附效率最高，200 min内达到吸附平衡。25℃下，复合脱氟剂对氟离子的吸附符合Langmuir等温吸附模型和伪二级动力学模型。

Abstract:

The fluorine adsorbent of a magnesia based lanthanum composite was synthesized by co-precipitation method using magnesium nitrate and lanthanum nitrate as main materials. The composite powder was further molded into grains with polyvinyl alcohol (PVA) and polyvinylidene fluoride (PVDF) with a di-ameter of around 0.5cm by using extrusion molding. XRD, SEM and FTIR were used to characterize and analyze the prepared composite adsorbents. The performance of the powdered and granular composite adsorbents on the absorption of F- in aqueous solutions was tested and analyzed respectively. The results showed that the maximum adsorption of F- could reach 142.85mg/g with the powdered composite adsor-bent. The best pH for F- adsorption was found in the range of 4~10, and the adsorption equilibrium could be reached within 200min. At 25℃, the adsorption of F- with the magnesia/lanthanum composite adsor-bent was well fitted by the Langmuir isothermal adsorption model and the adsorption kinetics could be well described by the pseudo-second-order kinetic model.