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

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.

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

Carbon coated magnetic nanoparticles were prepared using polydopamine as carbon precursor. Polydopamine was covered on Fe₃O₄ through self-polymerization of dopamine, and then carbonized at high temperature under Ar atmosphere to form Fe₃O₄@C composites. The stability and dispersion of the material increased after coating. The Fe₃O₄@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 Fe₃O₄@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 Fe₃O₄@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 Fe₃O₄@C was well fitted by pseudo-second order kinetic equation, with fast adsorption rate.