用稻壳制备亚甲基蓝高吸附容量的超高比表面积活性炭

活性炭因具有高比表面积和丰富的孔结构而被广泛应用于吸附水处理中的污染物。稻壳具有独特的组成和微观结构, 是制备活性炭的优质碳源。以稻壳为原料, 利用过饱和KOH溶液的预活化和活化双重作用, 在不同温度下制备出超高比表面积活性炭。随着活化温度的升高, 活性炭的比表面积和总孔容逐渐增大。900 ℃下制得的活性炭具有超高比表面积, 达到3600 m²/g, 总孔容为3.164 cm³/g, 明显优于商用活性炭(YP-80, 比表面积为1310 m²/g, 总孔容为0.816 cm³/g)。具有最高比表面积的稻壳活性炭对亚甲基蓝的最大吸附量达到983 mg/g, 几乎是YP-80 (525 mg/g)的两倍。通过吸附动力学拟合, 吸附亚甲基蓝的过程与拟二级动力学模型一致, 表明该过程为化学吸附。

Ultra-large Specific Surface Area Activated Carbon Synthesized from Rice Husk with High Adsorption Capacity for Methylene Blue

Activated carbon with high surface area and abundant pore structure is widely used for contaminant adsorption in wastewater treatment. Rice husks (RHs) with unique composition and microstructure are often used as carbon source to prepare activated carbon. Herein, ultra-large specific surface area activated carbon was synthesized from rice husks with pre-activation and activation by supersaturated KOH solution at different temperatures. With the increase of activation temperature, the specific surface area and total pore volume of activated carbon gradually increase. The activated carbon obtained at 900 ℃ shows the largest specific surface area of 3600 m²/g and the maximal total pore volume of 3.164 cm³/g, which are significantly superior to those of the commercial activated carbon (YP-80, the specific surface area of 1310 m²/g and the total pore volume of 0.816 cm³/g, respectively). The highest maximum adsorption capacity for methylene blue was found for the activated carbon with the largest specific surface area, namely, 983 mg/g, which is almost twice as high as that of YP-80 (525 mg/g). By adsorption kinetics fitting, the results are consistent with pseudo-second-order model which indicates that the process of adsorbing methylene blue is chemical adsorption.