粉煤灰/氧化石墨烯复合材料吸附Hg(Ⅱ)

Adsorption of Hg(Ⅱ) ions on fly ash/graphene oxide composite

利用売聚糖(CS)将氧化石墨烯(GO)交联到粉煤灰颗粒上,制备出粉煤灰/氧化石墨烯(FCGO)复合吸附材料。扫描电子显微镜(SEM)、漫反射红外光谱(DRIFT)和X射线电子光谱(XPS)对FCGO的研究表明GO被成功负载到粉煤灰上。静态吸附实验表明pH值接近中性时有利于FCGO对Hg(Ⅱ)的吸附,共存阴离子促进而阳离子抑制对Hg(Ⅱ)的吸附。动力学研究表明FCGO吸附Hg(Ⅱ)符合Elovich方程模型,饱和吸附量高达42.2 mg·g^(-1)1。非线性Redlich-Peterson模型比Langmuir和Freundlich模型更适合描述吸附过程。热力学参数△H^0=12.20 kj·mol^(-1),△S^0=48.92 J·(mol K)^(-1),△G^0=-4.09kJ·mol^(-1)(333K)表明吸附过程是吸热且自发进行的。分析吸附前后FCGO的DRIFT和XPS光谱,推测对Hg(Ⅱ)的吸附主要是静电吸引作用。

A novel composite（FCGO） adsorbent prepared by the cross-linking of fly ash with chitosan and graphene oxide was characterized by scanning electron microscopy,diffuse reflectance infrared Fourier transform（DRIFT） spectroscopy,and X-ray photoelectron spectroscopy（XPS）.The results indicated that GO was successfully grafted on the fly ash particles.The resulting FCGO adsorbent was able to effectively remove Hg（Ⅱ） at neutral pH.Adsorption of Hg（Ⅱ） was facilitated by the vast majority of the coexisting anions but hindered by the coexisting cations.The adsorption kinetics of Hg（Ⅱ） by FCGO follow the Elovich kinetic model.The adsorption process also satisfactorily fits the Redlich-Peterson model,with a maximum adsorption capacity of 42.2 mg·g^-1The thermodynamic parameters △H-0=12.20 kJ·mol^-1,△S-0=48.92 J·（mol·K）^-1,and △G-0=-4.09 kJ ·mol^-1 at 333 K indicate that the adsorption process is spontaneous and endothermic.The DRIFT and XPS spectra of FCGO and FCGO-Hg reveal that the adsorption of Hg（Ⅱ） occurs mainly by electrostatic attraction.