碳纳米管-石墨烯气凝胶制备及其对水中乳化油的吸附特性

Facile synthesis of carbon nanotubes-graphene aerogels and its adsorption property for emulsified oil in water

以改进的Hummers-Offeman法制备出的氧化石墨(GO)与羧基化多壁碳纳米管(CNTs—COOH)为原料,聚乙烯吡咯烷酮(PVP)为交联剂,乙二胺(EDA)为还原剂,水热还原法制得羧基碳纳米管-石墨烯复合气凝胶(CGA)。调整GO与CNTs—COOH的质量比获得密度在8.40~14.42 mg·cm^(-3)之间的气凝胶,并确定在GO:CNTs—COOH=3:1(质量)时得到的气凝胶的机械强度最优。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)对所制备的CGA进行表征,得知GO与CNTs—COOH已成功还原组装成多孔状三维气凝胶结构。以水中乳化柴油作为研究对象,考察CGA样品在不同温度下对乳化柴油的吸附特性。结果表明,CGA的吸附量在前6 min迅速上升,在30 min左右达到吸附平衡,且平衡吸附量随温度升高而增加。吸附过程遵循准二级动力学模型,体系表观活化能为7.10 k J·mol^(-1)。利用颗粒内扩散模型分析得出,CGA对乳化油的吸附分为外表面吸附过程和内部孔道吸附过程(内部大孔道吸附、中孔道和微孔道内扩散3个阶段)。

Graphene oxide(GO)was prepared by an improved Hummers-Offeman’s method.The GO and carboxylated multi-walled carbon nanotubes(CNTs-COOH)was used as raw materials,polyvinyl pyrrolidone(PVP)as crosslinking agent and ethylenediamine(EDA)as the reducing agent.Hydro-thermal method was adopted in the preparation of carbon nanotubes-graphene aerogel(CGA).The density was between 8.40 mg·cm-3 and 14.42 mg·cm-3 for CGAs under different mass ratios of GO to CNTs-COOH.The mechanical strength of the composite aerogel under the mass ratio of GO:CNTs-COOH=3:1 is optimal.The characterized results by scanning electron microscopy(SEM),X ray diffraction(XRD),X ray photoelectron spectroscopy(XPS)showed that GO and CNTs-COOH have been successfully assembled into reducing porous aerogel structure.The study on CGA sample adsorption characteristics of emulsified diesel oil in water at different temperatures showed that the adsorption capacity of CGA increased rapidly in the first 6 min.The adsorption equilibrium was achieved in about 30 min.With the increase of temperature,the equilibrium adsorption capacity increased gradually.The adsorption process follows pseudo-second order kinetics model.The apparent activation energy is 7.10 kJ·mol-1.Through the particle diffusion model analysis,it is found that the adsorption process of CGA is divided into an outer surface adsorption and pore adsorption processes,which include large inner pore adsorption,mesopore adsorption and small-size pore adsorption.