石墨烯气凝胶的制备及其对水中油分的吸附特性

Facile synthesis of graphene aerogels as high-performance adsorbents for diesel removal

以改性Hummers法制备出的氧化石墨(GO)为原料,乙二胺(EDA)为交联剂,通过液相化学交联法制备出以石墨烯为主体的多孔网状气凝胶(EGA)。利用电子扫描电镜(SEM)、电子透射电镜(TEM)及选区电子衍射(SAED)对其进行表征。以水中柴油为研究对象,考察所制EGA样品对水中柴油的吸附脱除效果。结果表明,石墨烯气凝胶对柴油的吸附量在前5 min上升迅速,在30 min左右达到吸附平衡。吸附过程遵循准二级动力学模型,且吸附速率随温度的升高而增加,体系的表观活化能E_a=23.94 k J·mol^(-1)。颗粒内扩散模型拟合结果表明,EGA对水中柴油的吸附分为表面孔道吸附、气凝胶内部孔道扩散以及石墨烯片层间小孔道扩散。石墨烯气凝胶对柴油的吸附等温线与Freundlich模型较为吻合。

Three dimensional（3D） graphene aerogels（EGA） with interconnected networks were fabricated from graphite oxide（GO） and ethylenediamine（EDA） via chemical crosslinking method. The properties of EGA were characterized by scanning electron microscope（SEM）, transmission electron microscope（TEM） and selected area electron diffraction（SAED）. Adsorption performance of the aerogel in removing diesel oil in water was investigated. The results showed that the EGA adsorption capacities rose quickly in the first 5 min, and reached adsorption equilibrium in 30 min. The kinetic analysis indicated that the EGA adsorption behavior can be accurately fitted with a pseudo second-order model, and the adsorption rate increased with the increase of temperature. The activation energy（Ea）, determined by Arrhenius law, was 23.94 k J·mol-1, suggesting physical adsorption dominated the adsorption of diesel oil onto aerogels. The intraparticle diffusion model（IPD） fitting results revealed that the adsorption sites for aerogels consisted of external surface, large inner pore spaces and small-size pore spaces between the graphene sheets. The adsorption isotherms were well fitted with Freundlich model.