铜藻基载铁活性炭的制备及其对亚甲基蓝的吸附特性研究

Preparation of Sargassum Horneri based activated carbon coated with iron oxide and its adsorptive properties for methylene blue

以一种大型海藻——铜藻为原料,Fe Cl3·6H2O为活化剂,采用超声浸渍-原位合成法制备了铜藻基载铁活性炭(Fe/SAC),并以活性炭得率和亚甲基蓝吸附值为指标,通过正交法考察了活化温度、活化时间和浸渍比的影响.同时,采用X射线衍射、扫描电镜和比表面积分析仪对最优结果进行表征,并考察了Fe/SAC吸附亚甲基蓝的热力学与动力学特性.结果表明,Fe/SAC的最优制备工艺条件为活化温度600℃、活化时间1 h、浸渍比1∶1,此时的活性炭得率为39.5%,亚甲基蓝吸附值为255.67 mg·g^(-1);最优工艺条件下制得的Fe/SAC比表面积为558.31 m2·g^(-1),其负载的铁组分主要为Fe3O4和Fe O;亚甲基蓝在Fe/SAC上的吸附过程符合准二级动力学模型,Langmuir等温吸附模型能够很好地描述吸附平衡过程,该吸附是熵增加的自发吸热(ΔS>0、ΔG<0、ΔH>0)过程,升温有利于吸附.

Sargassum ttorneri based activated carbon coated with iron oxide （ Fe/SAC ） was prepared by ultrasonic immersing and in-situ synthesis method using S. Horneri as a raw material and ferric chloride hexahydrate as activating agent. Effects of activation temperature, time and impregnation ratio on the yield and the adsorption of methylene blue （MB） on Fe/SAC were investigated by using orthogonal experiments. The Fe/SAC was characterized with X- ray diffraction, scanning electron microscopy and surface area analyzer. Furthermore, the kinetics, equilibrium and thermodynamics of MB adsorption onto Fe/SAC were studied. The results indicate that the Fe/SAC yield, MB adsorption, and specific surface area could reach 39.5%, 255.67 mg·g-1 and 558.31 m2·g-1 under the optimal condition with activation temperature of 600 ℃, 1 h of activation time and impregnation ratio of 1：1. The results also show that the main components on Fe/SAC are Fe3 04 and FeO. The pseudo-second-order equation could describe the adsorption kinetics well, and the Langmuir model provided the best correlation of the equilibrium data. Calculation of AG0, AH0 and AS0 indicates that the adsorption of MB onto Fe/SAC was an entropy increasing, spontaneous and endothermic process, which was promoted by increasing process temperature.