氧化程度对氧化石墨结构与阳离子交换容量的影响

通过改进hummers法制备了不同氧化程度的氧化石墨。采用XRD、FTIR及XPS等对不同氧化程度氧化石墨样品的结构特征、含氧官能团种类与含量及阳离子交换容量进行表征。结果表明,石墨经氧化后结构层上键入羟基(C-OH)、环氧基(C-O-C)和羧基(-COOH)等含氧官能团;随氧化程度的增加,石墨结构逐渐全部转化为氧化石墨结构,C-O-C和-COOH的含量逐渐增大,而C-OH的含量先增大后略有减小,阳离子交换容量也表现为先增大后减小,对应的最大值分别为1.70、3.80和4.50 mmol·g-1;氧化石墨碳平面上C-OH发生去质子化反应在层间产生H+,其他阳离子与之交换进入GO层间域,C-OH的含量是影响氧化石墨阳离子交换容量的主要因素,随C-OH含量的增加,氧化石墨样品的阳离子交换容量增大。

Effect of Oxidation Degree on Structure and Cation Exchange Capacity of Graphite Oxide

The graphite oxide samples with different oxidation degree were prepared by modified Hummuers method. The kinds and content of oxygen containing functional groups, structure and cation exchange capacity for the experiment process samples were characterized by XRD, FTIR and XPS. The results show: graphite structure layer oxidized have various oxygen-bearing functional groups such as hydroxyl group (C-OH), carboxy group (-COOH) and epoxy group (C-O-C); with the increase of the degree of oxidation, graphite structures gradually and completely converted to the structure of graphite oxide. The content of C-O-C and-COOH increases gradually, and the content of C-OH first increases then decreases. With the increase of the oxidation degree, the cation exchange capacity of graphite oxide samples also increase firstly and then decrease, corresponding to the maximum value of 1.70, 4.50 and 3.80 mmol·g^-1. The C-OH in the carbon basal plane is protonated and H⁺ is generated at the same time. The H⁺ can exchange with other cations in the interlayer of graphite oxide. The content of C-OH is the main factor affecting the cation exchange capacity of graphite oxide, and the cation exchange capacity of graphite oxide samples increase with the increase of the content of C-OH.