热还原石墨烯的制备及其对重金属Pb~(2+)的吸附性

利用瞬时加热还原氧化石墨的方法制备石墨烯,将热还原的石墨烯用于吸附水中的重金属Pb2+,研究接触时间和pH值对吸附的影响。结果表明:pH值很大程度上影响了石墨烯的吸附性能,pH值大于7时吸附量显著增加,并在5min内达到平衡。透射电子显微镜和扫描电子显微镜分析表明石墨烯的片层很薄,层数较少。采用Langmuir和Freundlich吸附等温式拟合实验数据,Langmuir吸附等温式计算出的最大理论吸附量为86.5mg/g,相关系数R2为0.9982,Langmuir常数KL为10.7,与实验结果更接近。表明石墨烯具有超强的吸附能力,以单分子层的化学吸附为主。吸附动力学符合准二级动力学模型。

Preparation of Graphene via Thermal Reduction and Its Adsorption Capacity for Heavy Metal Pb2+

Graphene (GR)was obtained by reduced graphite oxide (GO)by instantaneous heating. Thermal reduced graphene was used to adsorb heavy metal Pb2 + ions in water to study the effect of ad-sorption time and pH value on the adsorption.The results show that the pH value greatly affects the adsorption capacity of graphene.When pH value is higher than 7,the adsorption capacity obviously increases.And the equilibrium reaches within five minutes.The analysis by scanning electron micro-scope (SEM)and transmission electron microscope (TEM)shows that graphene flake is very thin and with less layers.Experimental data are fitted by Langmuir and Freundlich adsorption isotherms mod-el.According to the Langmuir adsorption isotherms model,the maximum theoretical adsorption ca-pacity of Pb2 + is 86.5mg/g,the correlation coefficient R 2 is 0.9982,and Langmuir constant K L is equal to 10.7.The Langmuir model agrees well with experimental data.It demonstrates that the ad-sorption reaction is a fast single molecular layer chemical process.The adsorption kinetics is better fit-ted to the pseudo-second-order kinetic model.