大麻杆活性炭对染料吸附性能的研究

Adsorption studies of dyes on hemp haulm-based activated carbon

以天然大麻杆为原料,采用磷酸活化法制备大麻杆活性炭。利用低温氮吸附对样品的比表面积与孔结构进行了表征,并利用亚甲基蓝与甲基橙两种染料对活性炭在液相中的吸附行为进行了研究。结果表明,样品的比表面积与中孔孔容随着活化温度的升高而增大,在500℃时达到最大值1325.73m2/g,随后由于磷酸过度活化导致结构坍塌致使各参数有所降低;在25℃下,大麻杆活性炭对亚甲基蓝与甲基橙的吸附等温线均遵循Langmu ir方程,单层吸附量分别达到471.698mg/g和363.64mg/g,吸附量主要受微孔孔容、染料分子尺寸及染料分子与活性炭表面作用力三者的共同影响。吸附动力学能够很好的符合准二级动力学方程,且亚甲基蓝的吸附速率高于甲基橙。

Hemp haulm has been used to prepare activated carbon samples by phosphoric acid activation at different activation temperatures. The BET surface area and pore properties were characterized by using N2 adsorption isotherms. Methylene blue （MB） and methyl orange （MO） were used to investigate the liquid adsorption of the hemp haulm based-activated carbon materials. The results show that the BET surface area and mesopore volume initially increased with increasing activation temperature, with the surface area reaching a maximum value of 1325.73 m2/g at 500 ℃, and then decreased due to collapse of the structure. The adsorption equilibria of both dyes on the activated carbon materials were fitted to the Langmuir equation with the monolayer sorption capacity for MB and MO being 471. 698 mg/g and 363.64 rag/g, respectively. The adsorption capacity is determined by the micropore volume, dye molecule size and the surface force between the activated carbon and the dyes. The adsorption kinetics of the dyes can be well described by the pseudo-second-order equation, and the adsorption rate of MB is higher than that of MO.