Mg-Al层状双金属氢氧化物的制备及其吸附性能研究

Study on Synthesis and Adsorption Characteristics of Mg-Al Layered Double Hydroxides

通过共沉淀法制备了Mg-Al层状双金属氢氧化物(LDHs)并对其进行Cr6+吸附性能的研究。动力学实验结果表明:Mg-Al水滑石对Cr6+的吸附效果明显,在2 h的时候就可以达到95%的去除率;热力学实验结果表明Mg-Al水滑石对Cr6+的吸附量随Cr6+浓度的增加初期快速上升而后趋于稳定。Mg-Al水滑石对Cr6+的等温吸附数据符合Langmuir方程。在25℃时Mg-Al水滑石对Cr6+的饱和吸附量高达68 mg·g-1;而后主要对吸附影响因素进行分析,结果表明Mg-Al水滑石受p H影响较大,溶液为中性时效果最佳;溶液中的无机阴离子会大大降低Mg-Al水滑石的吸附能力。

Mg-Al layered double hydroxides（ LDHs） were synthesized by co-precipitation and its adsorption capacity on Cr^6＋was studied. Kinetics experiment result showed that Mg-Al LDHs were effective in Cr^6＋adsorption and the removal ratio reached 95% within 2 h. Thermodynamics experiment result showed that the quantity of Cr^6＋sorption increased rapidly with the raise of Cr^6＋concentration at the initial stage and then approached to a constant level in later period. The Cr^6＋sorption of the Mg-Al LDHs fitted well with the Langmuir isotherm. The saturated adsorption capacity of Cr^6＋on the Mg-Al LDHs was found to be 68 mg · g^-1on 25 ℃,indicated that the Mg-Al LDHs was a fine adsorbent material for removing Cr^6＋from the aqueous solution. Comparing adsorption efficiency of different adsorption conditions,the result showed that the adsorption capacity influenced by solution p H value and the neutral solution was the best adsorption condition in Cr^6＋removal. Besides,the anions in aqueous solution will reduce the Cr^6＋adsorption capacity of Mg-Al LDHs.