CoFe_2O_4/MgAl-LDO吸附水中的Cr(Ⅵ)

Adsorption of Cr( Ⅵ) from aqueous solution by CoFe_2O_4/MgAl-LDO

采用水热法、共沉淀法合成Co Fe2O4/Mg Al-LDH,于高温下焙烧4 h后,制备出同时具有高吸附性能和磁分离性能的镁铝复合氧化物（Co Fe2O4/Mg Al-LDO）,研究其对水中Cr（Ⅵ）的吸附效果。采用X射线衍射（XRD）、红外光谱（FTIR）等技术对吸附剂进行表征。通过序批实验考察了焙烧温度、溶液初始p H值、吸附时间、温度等因素对Co Fe2O4/Mg AlLDO吸附Cr（Ⅵ）的影响。结果表明,当焙烧温度在450-550℃之间、溶液初始p H=2-6时,吸附剂对Cr（Ⅵ）均具有较好的吸附效果,且吸附反应在90 min内达到平衡。Co Fe2O4/Mg Al-LDO吸附Cr（Ⅵ）过程符合准二级动力学和Langmuir等温吸附模型,当温度为318 K时,理论饱和吸附容量为98.04 mg/g。热力学研究结果表明,该吸附过程为自发的、吸热反应过程。

Co Fe2O4/ Mg Al-LDH was prepared by hydrothermal and coprecipitation method,and then was calcined at high temperature for 4 h to obtain Co Fe2O4/ Mg Al-LDO which possessed good adsorption capacity and excellent magnetic separation property. Co Fe2O4/ Mg Al-LDO was applied for removal of Cr（ Ⅵ） from aqueous solution. The adsorbent was characterized by X-ray diffraction（ XRD）,Fourier transform infrared spectroscopy（ FTIR） and so on. Effects of calcination temperature,solution p H,contact time and temperature on Cr（ Ⅵ） adsorption by Co Fe2O4/ Mg Al-LDO were investigated in batch experiments. The results indicated that the adsorbent exhibited good adsorption capacity for Cr（ Ⅵ） at calcination temperature 450- 550 ℃ and initial solution p H 2- 6,and the adsorption process reached equilibrium within 90 min. Kinetic and isotherm studies showed that the adsorption of Cr（ Ⅵ） onto Co Fe2O4/ Mg Al-LDO followed the pseudo-second-order kinetic model and Langmuir model,respectively.The maximum adsorption capacity of Co Fe2O4/ Mg Al-LDO for Cr（ Ⅵ） was found to be 98. 04 mg / g at 318 K. Thermodynamics parameters revealed that the adsorption process was endothermic and spontaneous.