改性稻壳焦对糠醛的吸附特性

Adsorption mechanism of furfural onto modified rice husk charcoals

摘要:

为了探索生物质焦对糠醛的吸附脱除特性，利用流化床快速热解制得稻壳焦，研究N2、CO2气氛下高温改性方式对稻壳焦孔隙特征与表面性质的影响，以及稻壳焦对糠醛的吸附脱除特性。采用元素分析、N2等温吸脱附、傅里叶红外、Boehm滴定等方法对稻壳焦的孔隙结构与表面化学特性进行表征。结果表明：原始的稻壳焦残留大量有机基团，孔隙结构较差；经N2和CO2高温改性后，稻壳焦表面的含氧酸性官能团大量分解，碱性官能团增加，比表面积和孔结构得到较好的扩充和优化，稻壳焦与糠醛的π-π色散力作用力增强。综合考虑π-π色散力和表面吸附位点的作用，CO2改性的稻壳焦表现出了最好的吸附效果。

Abstract:

To evaluate the absorptive characteristics of furfural onto biomass charcoals derived from rice husk pyrolysis, we studied the information of the structure and surface chemistry properties of the rice husk charcoals modified by thermal treatment under nitrogen and carbon dioxide flow and adsorption mechanism of furfural. The modified samples are labeled as RH-N2 and RH-CO2. Fresh rice husk charcoal sample (RH-450) and modified samples were characterized by elemental analysis, nitrogen adsorption-desorption isotherms, Fourier-transform infrared spectroscopy and Boehm titration. The results show that fresh rice husk charcoal obtained at 450 °C had a large number of organic groups on its surface and poor pore structure. After the modification under nitrogen and carbon dioxide flow, oxygenic organics in rice husk charcoals decompose further, leading to the reduction of acidic functional groups on charcoals surface, and the increase of the pyrone structures of the basic groups. Meanwhile, pore structure was improved significantly and the surface area was increased, especially for the micropores. This resulted in the increase of π-π dispersion between the surfaces of rice husk charcoals and furfural molecular. With making comprehensive consideration of π-π dispersion and pore structure, the best removal efficiency of furfural was obtained by rice husk charcoal modified under carbon dioxide flow.