不同温度对黑碳表面官能团的影响

Effects of different temperature on surface functional groups of black carbon

在200～800℃热解水稻秸秆制备BC,以Boehm滴定和FTIR表征BC表面官能团种类和数量,研究了不同温度对BC表面官能团的影响。结果表明:温度对BC表面官能团种类和数量都将产生影响。秸秆碳化后官能团会发生一定变化,表现为醚键(C-O-C)、羰基(C-O)、甲基(-CH3)和亚甲基(-CH2)消失,仍存有羟基(-OH)和芳香族化合物。BC有相同的化学结构,都以芳环骨架为主,但所含官能团种类有一定差异,同种官能团振动形式也不同。酸性和碱性官能团数量都随温度升高先升高后降低,高温和低温不利于官能团的形成,300～600℃对应的碱性官能团含量高于酸性官能团含量。

Black carbon （BC） is a product of weathering of graphitic carbon in rocks and of incomplete combustion of fossil fuels and vegetation. BC adsorption has been paid great attention. Pyrolyzing rice straw in the range of 200-800 ℃, the effects of different temperature on BC surface functional groups were studied by Boehm titration and Fourier transform infrared spectroscopy （FTIR）. The results showed that temperature had an effect on the types and quantities of the BC surface functional groups. The change of functional groups office straw after the carbonization was that the ether（C-O-C）, carbonyl（C-O）, methyl（-CH3） and methylene（-CH2） groups disappeared, but the hydroxyl（-OH）, alkene（C-C） and aromatic compounds still existed. BC had same chemical structure, was mainly of aromatic ring skeleton-based, but the types of BC functional groups and the vibrations of same functional group were different. The numbers of acidic and basic functional groups firstly increased and then decreased with increasing temperature, to a great extent this implied that higher temperature and lower temperature was not conducive to the formation of functional groups. The numbers of basic functional groups at 300-600 ℃ were higher than the acidity.