基于聚合多巴胺的磁性碳材料的制备及其对甲基绿的吸附

Preparation of polydopamine-based magnetic carbon material and its application in methyl green adsorption

以聚合多巴胺为碳源制备碳材料包覆的磁性纳米颗粒.通过多巴胺的自聚合反应将其包覆在Fe_3O_4纳米颗粒上,在氩气保护下高温灼烧得Fe_3O_4@C复合材料.包覆碳材料后,Fe_3O_4颗粒的稳定性和分散性提高.使用扫描电镜、透射电镜、红外光谱和振动磁强计对材料进行了表征.结果表明成功地制备了核壳结构的Fe_3O_4@C复合材料.用甲基绿来考察Fe_3O_4@C的吸附性能.研究表明,溶液pH对甲基绿的吸附有显著的影响,随溶液pH的升高,甲基绿的吸附容量显著增大.用朗格缪尔吸附等温模型拟合出在纯水、湖水和自来水中Fe_3O_4@C对甲基绿的最大吸附容量分别为490.1、442.5和389.1 mg·g^(-1).热力学研究计算出吸附的吉布斯自由能为负值,说明吸附是自发过程.动力学研究表明甲基绿在Fe_3O_4@C上的吸附过程符合拟二级反应动力学方程,吸附速率较快.

Carbon coated magnetic nanoparticles were prepared using polydopamine as carbon precursor. Polydopamine was covered on Fe_3O_4 through self-polymerization of dopamine,and then carbonized at high temperature under Ar atmosphere to form Fe_3O_4@ C composites. The stability and dispersion of the material increased after coating. The Fe_3O_4@ C composites were characterized by using scanning electron microscopy,transmission electron microscopy,Fourier transform infrared spectroscopy and vibrating sample magnetometer. The results confirm that the core- shell structured Fe_3O_4@ C was successfully synthesized. In order to test the adsorption ability of the composites,methyl green was selected as model pollutants. The pH of solution has a significant effect on the adsorption of methyl green,and the adsorption capacity increased significantly along with the increase of solution pH. By using Langmuir adsorption isotherm,the maximum adsorption capacity of Fe_3O_4@ C for methyl green from pure water,lake water,and tap water were 490. 1,442. 5 and 389. 1 mg·g^（-1）,respectively. The obtained Gibbs free energy values were negative,indicating that the adsorption of methyl green is spontaneous. The kinetic study results show that the adsorption of methyl green on Fe_3O_4@ C was well fitted by pseudo-second order kinetic equation,with fast adsorption rate.