HNO_3/H_2O_2氧化修饰碳球的表征与分析

Characterization and dispersion of carbon spheres modified by HNO_3/H_2O_2 oxidization in water

为改善碳球在液相中的反应性能,采用HNO3/H2O2混合氧化剂氧化法对碳球表面进行改性,通过场发射扫描电子显微镜、X射线衍射和红外光谱法等手段分析了氧化处理条件对碳球微观结构和引入的官能团种类的影响,并采用酸碱滴定方法对氧化引入的官能团的数量进行测定,同时考察了改性后的碳球在水中的分散性。结果表明,当HNO3和H2O2体积比为1∶1时,随氧化剂浓度的增加,含氧官能团的量增加,尤以羰基最为明显;相同氧化条件下,引入的羟基量明显高于羧基和羰基;当体积比由1∶1变为1∶3时,羟基含量增大,羧基和羰基含量下降,由此得出结论:氧化性强的HNO3有利于羧基和羰基的引入,而氧化性弱的H2O2有利于羟基的引入;采用体积比为1∶1的浓HNO3和H2O2处理在碳球表面引入了尽可能多的含氧官能团,为2.164 mmol/g,其在水中具有良好的分散性和分散稳定性。因此可以通过改变氧化条件实现碳球表面的可控改性,为碳球的进一步功能化修饰和应用提供依据。

Carbon spheres （CSs） were modified by a mixture of HNO3 and H2 02 with different volume ratios and concentrations to improve their dispersability in a liquid. The morphologies and microstructures of the modi- fied CSs were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry and acid-base titration. Results show that the amount and types of oxygen-containing groups can be tuned by the concentration and ratio of HNO3/H202. HNO3 favors the formation of carboxyl and carbonyl groups while H202 introduces mainly hydroxyl. The amount of oxygen-containing functional groups in- creases with the concentration of the oxidants when the volume ratio of HNO3/H202 is 1, which is as high as 2.164 mmol/g when the concentrations of HNO3 and H202 are 16 and 8.8 mol/L, respectively. The resulting CSs have a remarkable dispersability and stability in water.