CoFe_2O_4/氧化石墨烯吸附材料的制备及对Cr吸附

Preparation of Magnetic Graphene Oxide Composite and Its Adsorption of Cr(Ⅵ)

通过低温水热法将铁酸钴负载到氧化石墨烯(GO)上,得到磁性氧化石墨烯复合材料(CFGO)吸附剂,用漫反射红外光谱(DRIFT)、X射线衍射(XRD)和X光电子能谱(XPS)分析方法对吸附剂进行测试,并对其吸附Cr(Ⅵ)性能进行了研究。CFGO对Cr(Ⅵ)的静态吸附试验表明,p H值为2~11,随着p H值增大,Cr(Ⅵ)去除率逐渐减小,在p H值=2时达到最高,去除率>98%。CFGO吸附Cr(Ⅵ)过程符合Langmuir等温模型,属于优惠吸附,吸附动力学符合准二级动力学模型。XPS研究表示吸附Cr(Ⅵ)后的CFGO表面含有Cr(Ⅵ)和Cr(Ⅲ),结合吸附前后CFGO的DRIFT光谱,推测吸附Cr(Ⅵ)过程主要是静电吸引作用和配位作用。吸附过程的ΔH=3.943 k J/mol,ΔS=23.561 J/(mol·K),ΔG=-3.903 k J/mol(333 K),表明吸附过程是吸热且自发进行的。

Magnetic graphene oxide adsorbent （CFGO） was prepared by graphene oxide （GO） and cobalt ferrite with low temperature hydrothermal method, and characterized by diffuse reflectance infrared spectroscopy （DRIFT）, X-ray diffraction （XRD） and X-photoelectron spectroscopy （XPS）. And its adsorption capacity was determined by the static adsorbing test. The results showed that the removal rate of Cr（VI） gradually decreased with the initial pH value increasing from of 2 to 11, and reached the highest removal ratio of 98% at the initial pH value of 2. The adsorption process of Cr（VI） by CFGO agreed with the Langmuir adsorption isotherm and its adsorption kinetics well fitted with the pseudo-2nd-order kinetic model. The results of Cr（VI） and Cr（III） existing on the surface of the CFGO adsorbent determined by XRP analysis confirmed the reduction of Cr（VI） during adsorption. The removal process of C r（VI ） by CFGO mainly attributed to the electrostatic attraction and the complexation reaction. The thermodynamic parameter AH value of 3.943 kJ/mol, AS value of 23.561 J/（mol·K）, and AG value of -3.903 kJ/mol（333 K） indicated that the adsorption process was endothermic and spontaneous.