低温磷酸活化棉秆制备活性炭的研究

Preparation of Activated Carbons from Cotton Stalk by Low-temperature Activation Using Phosphoric Acid

以棉秆为原料,活化温度在300～450℃之间,研究了低温磷酸活化制备活性炭的可行性,并测定了活性炭的碘吸附值、亚甲基蓝吸附值和焦糖脱色率等吸附性能指标;根据氮气吸附等温线分析了活性炭的孔隙结构特征;采用Boehm滴定方法分析了活性炭的各类表面官能团。结果表明:在磷酸的低温活化过程中,活化温度的升高显著促进了活性炭的比表面积及其对亚甲基蓝吸附值和焦糖脱色率等的吸附能力。在350℃下的低温磷酸活化棉秆能够制备出比表面积达1244m2/g,表面官能团含量高达10.4mmol/g,亚甲基蓝吸附值和焦糖脱色率分别达到190mL/g和100%的孔隙结构发达和极性较强的活性炭。

In order to investigate the feasibility of preparing activated carbons under low-temperature activation using phosphoric acid, activated carbons were prepared from cotton stalk by phosphoric acid activation under activation temperature from 300 to 450℃. The properlies of activated carbons were determined by the following terms： adsorption capacities to iodine, methylene blue and caramel, pore characteristics by measuring adsorption isotherms of nitrogen at 77 K, and surface chemistry by Boehm method. Results show that the increase of activation temperature from 300 to 350℃remarkably enhanced the porosity development and the adsorption capacities to methylene blue and caramel. Low-temperature activation using phosphoric acid could prepare activated carbon with well-developed porosity and strong polarity under activation temperature of 350℃, which are visualized by its surface area of 1 244 m^2/g, content of surface functional groups of 10.4 mmol/g, adsorption capacity to methylene blue of 190 mL/g and caramel decolorization rate of 100 %.