硼酸催化制备玉米芯活性炭工艺研究

Technique research on preparation of activated carbon from corncob with boric acidcatalytic

以玉米芯为原料,磷酸为活化剂,硼酸为催化剂制备活性炭。以磷酸与玉米芯的质量比、硼酸添加量、活化温度和活化时间作为考查的4个因素,以亚甲基蓝吸附值和焦糖脱色率作为活性炭性能的参考指标,通过正交试验法,得出最佳的水平组合是磷酸与玉米芯的质量比为2∶1,硼酸的添加量为4%,活化温度为450℃,活化时间为80 min,制备出活性炭的亚甲基蓝吸附值为240 mg/g,焦糖脱色率为120%。在该水平组合下不添加硼酸作对比实验,得到活性炭的亚甲基蓝吸附值为233 mg/g,焦糖脱色率为110%。用氮气吸附法对这两种活性炭进行表征,发现添加硼酸制备出的活性炭BET比表面积、总孔容、微孔孔容和中孔孔容都有所提高,结合热重(TG)和红外光谱(IR)分析,发现添加硼酸没有改变活化过程,但能促进活化的进行。

Activated carbons were prepared from corncob by phosphoric acid activation and boric acid catalytic. An orthogonal design was conducted to analyze the effects of the mass ratio of H3PO4 / corncob,the percentage of Iq3BO3/corncob, activation temperature and activation time on the methyleneblue adsorption value and caramel de-colorization rate which are as reference indexes of theproperties of activated carbon; through orthogonal tests, the optimum condition was found as follows： H3PO4 ： corncob （mass friction） being 2 ： 1, H3BO3 / corncob addition being 4%, activation temperature 450 ℃ , activation time 80 min, the methylene blue adsorption value and caramel de-colorization rateof the activated carbon were respectively 240 mg/g and 120 %. Meanwhile, the methyleneblue adsorption value and caramel de-colorization rateof the activated carbon were 233 mg/g and 110 % without using H3BO3 catalyticcomparing with the optimum condition. The pore structureof two samples was characterized by N2 adsorption, and the results indicate that the values of BET surface area, total volume, micro-pore volume and meso-pore volume of the activated carbon using H3BO3 catalytic were raised. By combining the TG analysis and IR analysis, It was found that the addition of H3BO3 catalytic didn＇t changethe process ofactivation butcould promote the activation.