石墨烯对四环素的吸附热力学及动力学研究

为了研究石墨烯(graphene, GR)与四环素(tetracycline, TC)之间的吸附作用,采用氧化还原法制备GR,并利用X射线衍射、透射电镜等手段对其形态结构进行表征,结果表明成功制备出比表面积较高的片状GR。应用平衡吸附法研究了pH值、吸附时间及温度条件对GR与TC相互作用的影响,并对其吸附动力学方程和吸附等温线进行模型拟合。结果显示,吸附反应过程的最佳pH为4.0～7.0;吸附在20min内达到平衡状态,吸附动力学符合伪二级动力学模型;在293,303,313K条件下, GR对TC的最大吸附量分别为172.1, 278.2，467.6mg／g,吸附等温线符合Freundlich模型;热力学分析说明该吸附作用是自发进行的吸热反应。GR对TC的吸附机理主要包括静电吸附、范德华力和π-键作用。

Kinetic and thermodynamic studies on the adsorption of tetracycline onto graphene

The graphene(GR) was prepared via a facial oxidation reduction method, and its adsorption behavior with tetracycline(TC) was also studied. The characterization results, such as X-ray diffraction and transmission electron microscopy (TEM) observations, showed that the synthesised GR possessed laminated structure and high surface area. The effects of pH, adsorption time and temperature on the interaction between TC and GR were investigated by the equilibrium adsorption method. The results were fitted by the equation of adsorbent kinetics and isothermal curve. The optimal pH condition for the adsorption process ranged from 4.0 to 7.0. The adsorption reached at the balanced state in 20 minutes and the adsorption process could be well described by the pseudo second order model. The maximum adsorption capacity was respectively 172.1, 278.2, 467.6mg／g at 293, 303, 313K. The adsorption process was spontaneous and endothermic in nature, which could be described well by Freundlich isotherm. The electrostatic interaction, van der Waals forces and π-based interaction might be the adsorption mechanisms of TC adsorption on GR.