不同活化温度对磷酸活化竹薄壁细胞活性炭理化结构与性能的影响

Effects of different activation temperatures on the physicochemical structure and properties of phosphoric acid-activated bamboo parenchymal cell activated carbon

为探究活化温度对竹薄壁细胞活性炭(PPCAC)理化性质及性能的影响,以脱除木质素的竹薄壁细胞为原料,磷酸为活化剂,在不同活化温度(400℃、500℃、600℃、700℃)下制备活性炭,通过傅里叶红外光谱(FT-IR)、比表面积及孔径分析仪、X射线衍射光谱(XRD)和X射线光电子能谱(XPS)对其孔隙结构、化学结构和晶体结构进行对比分析,并探讨不同活化温度制备的活性炭对亚甲基蓝的吸附能力,为新型竹基活性炭的开发利用提供理论依据和科学参考。结果表明:PPCAC表面的化学组成以C和O元素为主,P元素在活性炭表面的分布较均匀且含量较少;活化温度升高可使醇、酚、醚转化为石墨碳和羰基、羧基,当温度持续升高,又会发生逆反应转化回最初的含量;不同温度下活化的样品孔径以狭缝型的微孔和中孔为主,孔隙结构参数随温度的变化没有明显规律,当温度为500℃,活性炭具有最大的比表面积922.71m^(2)/g和最丰富的中孔结构0.98cm^(3)/g;不同活化温度下制备PPCAC对亚甲基蓝均表现出较好的吸附性能,其中PPCAC-700具有最高的吸附量614mg/g,表明活性炭的MB去除能力并不是完全由孔隙结构决定,也与其表面化学性质相关。

In order to investigate the effect of activation temperature on the physicochemical properties and performance of bamboo parenchymal cell activated carbon(PPCAC),the activated carbon was prepared by using lignin-removed bamboo parenchymal cell as the raw material and phosphoric acid as the activator at different activation temperatures(400℃,500℃,600℃and 700℃).The pore structure,chemical structure and crystal structure were comparatively analysed by Fourier transform infrared spectroscopy(FT-IR),specific surface area and pore size analyser(SSPA),X-ray diffraction spectroscopy(XRD)and X-ray photoelectron spectroscopy(XPS),and the adsorption capacity of activated carbons prepared at different activation temperatures for methylene blue was investigated,which provided a theoretical basis and scientific references for the exploitation of the new type of bamboo-based activated carbon.The results showed that:the chemical composition of PPCAC surface was dominated by C and O elements,and the distribution of P elements on the surface of activated carbon was more uniform and less content.The increase of activation temperature could transform alcohol,phenol and ether into graphitic carbon and carbonyl and carboxyl groups.When the temperature continued to increase,these compounds transformed back to their initial content by reverse reaction.The pore sizes of the samples activated at different temperatures were dominated by slit-type micropores and mesopores,and the change of pore structure parameters with the temperature had no obvious pattern.When the temperature was 500℃,the activated carbon had the largest specific surface area of 922.71m^(2)/g and the richest mesopore structure of 0.98cm^(3)/g.The adsorption performance of PPCAC prepared at different activation temperatures showed good adsorption performance for methylene blue,among which PPCAC-700 had the highest adsorption amount of 614mg/g,indicating that the MB removal capacity was not entirely determined by the pore structure,but also related to its surface chemical properties.