Preparation of mesoporous activated carbon fiber by steam activation in the presence of cerium oxide and its adsorption of Congo red and Vitamin B12 from solution

Activated carbons are widely used in separation and purification processing, and as catalysis supports [1, 2]. Activated carbon fibers (ACFs) as a new type of activated carbon have an excellent adsorptive property due to large specific surface area, pore volume, and uniform microporosity. Generally, the micropore in ACF cannot meet some special demands, such as adsorption of bulky molecules from solution and catalyst supports for macromolecule reaction [3]. So, it is desired to increase the mesopore and macropore content in ACF and exploit its new applications. Polymer additives or catalyst was added to the carbon source and carbonized to obtain mesoporous carbon fiber; but it was difficult to eliminate the catalyst from the mesoporous carbon fiber matrix [4–6]. The transition metal and rare earth metal compounds can promote the development of mesopores in activated carbon [7–9]. The activation reaction takes place in the immediate vicinity of metal/oxide particles, leading to the formation of mesopores and macrospores by pitting holes into the carbon matrix [10]. Potassium hydrate can promote the mesopore development, but it needs higher loading amount if the post-treatment is complex. Yttrium acetylacetonate [Y(acac)3] was added to the precursor of carbon and used as catalyst to increase the mesopore content of ACF, but the cost was high [11]. Cerium oxide showed certain activity due to its role in the oxidization–reduction cycle [12] and it could promote the mesopore development in activated carbon with scatter pore size distribution due to the original property of activated carbon [13]. In the current work, cerium nitrate was selected to investigate its catalytic effect on the mesopore development of commercial ACF with steam activation. The commercial ACF was first impregnated with the aqueous solution of cerium nitrate. The loadings of cerium nitrate on the basis of activated carbon were 2.0 wt%. The samples were then dried at 110 ◦C for