【摘要】 通过共沉淀法制备得到镁铝层状双氢氧化物(LDHs),并在450℃高温下进行热改性处理(即C-LDHs)。系统性比较了上述两种材料除Cr(Ⅵ)的吸附动力学及等温线模型,并考察温度、p H、Cr(Ⅵ)初始浓度等重要因素对吸附效果的影响。使用XRD、SEM、FT-IR和TG-DTG等对两种吸附材料进行了表面特性表征。结果表明,热改性后C-LDHs的表面性质发生了巨大变化。但其吸附过程仍符合Langmuir吸附等温式。C-LDHs对Cr(Ⅵ)的最大吸附量为105.26 mg·g-1,远大于LDHs的吸附量(20.66 mg·g-1)。本文结果表明,对层状双氢氧化物进行经济方便的热改性可大幅度增强其对Cr(Ⅵ)的吸附性能,对层状双氢氧化物的工业化应用具有重要的参考价值。更多还原

【Abstract】 The pollution of hexavalent chromium(Cr(Ⅵ)) is of particular environmental concern because of its toxicity and carcinogenic effect. In this study, Mg-Al layered double hydroxides(Mg-Al LDHs) were prepared by the co-precipitation method. It was found that a thermal modification process of the Mg-Al LDHs(calcined LDHs, C-LDHs) could improve obviously the adsorption capacity of Cr(Ⅵ). The equilibrium isotherms showed that the adsorption of Cr(Ⅵ) using either LDHs or C-LDHs could be well fitted with the Langmuir model. The maximum Cr(Ⅵ) uptake capacity of C-LDHs and original LDHs was 105.26 and 20.66 mg·g-1 at 30℃, respectively. The pseudo-second-order model could be used to describe the adsorption of Cr(Ⅵ) on both C-LDHs and LDHs. Effect of important parameters such as reaction temperature, p H and initial Cr(Ⅵ) concentration was also investigated, and it was found that the reaction temperature has slight effect on the adsorption capacity of the C-LDHs. This could be ascribed to the nature of the Cr(Ⅵ) adsorption reaction by the C-LDHs. Characterizations of the LDHs and C-LDHs by XRD, SEM, FT-IR and TG-DTG evidenced that the surface properties of LDHs particles could be successfully varied by the calcined treatment of LDHs.更多还原