改进Hummers法制备氧化石墨烯及其吸附铜离子研究

Preparation of graphene oxide by modified Hummers method and its adsorption performance on Cu^(2+)

为了探明氧化石墨烯吸附重金属离子的特性,采用改进的Hummers法,制备了氧化石墨烯(GO),采用FTIR、Raman、XRD、XPS和AFM对其进行了表征。对比了不同溶液初始p H值、Cu2+初始浓度、吸附时间、反应温度和离子强度下,GO对Cu2+的吸附效果。结果表明,氧化处理后,GO含有羧基、羟基和环氧基等含氧官能团,C、O质量比达到2.0,厚度约为1.0 nm,层间距约为0.97 nm。GO对Cu2+的吸附在90 min内达到平衡,其吸附容量在p H值小于6.0时随p H值的升高而升高,随温度的升高而升高,随Cu2+初始浓度的增大而增大。在298 K,p H值为5.5,Cu2+初始质量浓度为50 mg/L时,GO对Cu2+的平衡吸附容量为91.6 mg/g。GO对Cu2+的吸附过程符合Langmuir等温吸附模型和准二级动力学模型,是均匀的单分子层吸附且由化学反应控制,GO对Cu2+的吸附是自发的吸热过程。

In order to study the adsorption performance of graphene oxide （GO） on heavy metal ions, it was prepared by modified Hummers method and characterized by FTIR, Raman, XRD, XPS and AFM. The adsorption capability of GO on Cu2＋ under different pH values, initial Cu2＋ concentrations, adsorption time, reaction temperature and ionic strength conditions was investigated. The results showed that, oxygen-containing groups（i.e., epoxy, hydroxyl and carboxyl） were generated following oxidation. The C/O mass ratio was 2.0; the interlayer spacing and the thickness of GO were 0.97 and 1.0 nm respectively. The adsorption equilibrium of GO on Cu2＋ was obtained in 90 min, under the condition that the pH value was lower than 6.0, the adsorption capacity increased with the increasing pH value, temperature and initial Cu2＋ concentration. When the reaction temperature was 298 K, the pH value was 5.5, the initial mass concentration of Cu2＋ was 50 mg/L, the equilibrium adsorption capacity of GO on Cu2＋ was 91.6 mg/g. The process of GO adsorbing Cu2＋ fit Langmuir isothermal adsorption model and pseudo-second-order kinetic model. It was indicated that, the adsorption of GO on Cu2＋ was a homo- geneous monolayer chemisorption, which was also an endothermic and spontaneous process.