棉秆炭吸附糠醛机理研究

Adsorption Mechanism of Furfural onto Cotton Stalk Charcoals

以不同热解温度(400℃、600℃、800℃)制得棉秆炭(棉-400、棉-600、棉-800),研究热解温度对棉秆炭孔隙特征与表面性质的影响,以及棉秆炭对糠醛的吸附特性。结果表明:棉-400表面含有大量有机基团,孔隙结构较差;随着热解温度的提高,含氧有机成分进一步分解,棉秆炭表面酸性官能团逐渐减少,而类吡喃酮结构的碱性官能团不断增加,孔结构得到改善;棉秆炭中氢碳摩尔比、表面酸碱官能团含量是影响其对糠醛吸附的主要因素;随着炭化程度的提高,酸性官能团含量减少,碱性官能团含量增加,使得棉秆炭表面石墨层与糠醛分子间的π-π色散力作用增强,所以棉-800对糠醛脱除率最高。

Charcoals were derived from cotton stalk pyrolysis in a fixed-bed reactor at different temperatures （400℃ , 600℃ , 800℃ , the samples are labeled as CS- 400, CS- 600, CS- 800, respectively）. The charcoals were characterized by elemental analysis, nitrogen adsorption-desorption isotherms, Boehm titration and Fourier-transform infrared spectroscopy. The results show that cotton stalk charcoal obtained at 400℃ has a large number of organic groups on its surface and poor pore structure. With the increase of pyrolysis temperature, oxygenic organics in cotton stalk decompose further, which leads to the reduction of acidic functional groups on charcoals surface, and the increase of the pyrone structures of the basic groups, meanwhile, pore structure is improved significantly and the surface area is increased, especially for the micropores. The H/C mole ratio, surface acid and basic functional groups of cotton stalk charcoals are the main factors that influence the removal efficiency of furfural. The increase of pyrolysis temperature promotes removal of furfural onto cotton stalk charcoal. With the increase of carbonization degree, the basic functional groups increase, while the acidic functional groups decrease, which results in the increase of 7r - rr dispersion between the surfaces of cotton stalk charcoals and furfural molecular, therefore the best removal efficiency of furfural is obtained by cotton stalk charcoal pyrolyzed at 800℃.