Guo Yanping, Rockstraw David A
Department of Environmental Engineering and Science, Clemson University, 342 Computer Court, Anderson, SC 29625, USA.
Bioresour Technol. 2007 May;98(8):1513-21. doi: 10.1016/j.biortech.2006.06.027. Epub 2006 Sep 14.
Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part.
以磷酸活化法由山核桃壳制备活性炭。采用氮气吸附、 Boehm滴定和傅里叶变换红外光谱（FTIR）技术对这些活性炭的孔结构和酸性表面基团进行了表征。表征结果表明，在250℃时孔结构的发展较为明显，在500℃时分别达到1130m²/g和0.34cm³/g。活化温度下的浸渍比和浸泡时间也会影响最终碳产物的孔发展和孔径分布。在浸渍比为1.5时，在400℃下可获得BET表面积和微孔体积分别高达861m²/g和0.289cm³/g的活性炭。本研究制备出了微孔活性炭。低浸渍比（小于1.5）和活化温度（小于300℃）有利于酸性表面官能团的形成，这些官能团由温度敏感型（高温下不稳定）和温度不敏感型（高温下稳定）两部分组成。温度敏感型基团在300℃时显著消失；而温度不敏感型基团即使在500℃时也很稳定。FTIR结果表明，温度不敏感部分主要是含磷基团以及一些含羰基基团，而含羰基基团是温度敏感部分的主要贡献者。
