烟梗基活性炭的优化制备及对苯酚吸附动力学

Optimized preparation of tobacco stem-based activated carbon and adsorption kinetics of phenol

为了优化制备烟梗基活性炭,经Minitab软件设计2^3全因素正交实验.比表面积作为活性炭制备的评价指标。通过微孔材料吸附仪和SEM表征活性炭;采用间歇吸附实验探索苯酚在活性炭上吸附特性和机理。由结果可知影响活性炭制备的最主要因素为ZnCl2质量分数,且活性炭制备最佳条件为:活化温度500℃,ZnCl2质量分数为30%,活化时间0.2h。最佳条件下制备的活性炭比表面积为1036m^2/g,介孔占比68.9%。拟二级能更好地描述活性炭对苯酚的动力学吸附,Freundlich和Langmuir2种模型均能很好描述活性炭对苯酚的等温吸附。制备活性炭3个主因素间的交互作用既不利于活性炭制备,同时也增加耗能,活性炭的孔结构一定程度上决定其吸附速率和能力,丰富的孔结构更利于吸附。

The 2^3 factorial experiment was designed by Minitab software to optimize the preparation of tobacco stem-based activated carbons.The surface area of activated carbons was chosen as evaluation index of its preparation.The activated carbons were characterized by microporous material adsorption instrument and SEM.Batch adsorption experiments were carried out to discuss characteristics and mechanism of adsorption onto activated carbons.The results show that the most important factor affecting the preparation of activated carbons is ZnCl2 mass fraction and the optimum preparation conditions are activation temperature of 500℃,ZnCl2 mass fraction of 30%and activation time of 0.2 h.The activated carbon prepared under the optimum conditions has specific surface area of 1 036 m^2/g and mesoporosity of 68.9%.The Pseudo-second-order model was found to explain the adsorption kinetics most effectively.Both Freundlich and Langmuir models were capable of describing isothermal adsorption of phenol onto activated carbon.The interactions of three main factors had negative impacts on the preparation of activated carbon,and it also increased energy consumption.The pore structure of activated carbon determined its adsorption rate and capacity to a certain extent,and the rich pore structure was more conducive to adsorption.