Preparation And Characterization Of Al₂O₃/C Hybrid Aerogels And Al₂O₃ Aerogels

In this paper, the black monolithic Al2O3/C hybrid aerogels with high specific surface area and low density were firstly prepared by sol-gel, supercritical n-hexane drying and carbonization using Al(NO3)3·9H2O as Al2O3 source, resorcinol (R) and furfural (F) as carbon precursor, alcohol as the solvent and propylene oxide (PO) as gelation initiator.The white powder Al2O3 aerogels were prepared by burning the Al2O3/C hybrid aerogels at 600℃for 6h in air to remove carbon.The effects of various factors on formation,porous properties,crystalline nature feature and microstructure of the hybrid aerogels were investigated by a series of characterization methods.And the performance of the hybrid aerogels for adsorption/desorption of fluorine ion when the Al2O3/C hybrid aerogels were used as the electrode material in electroadsorption process were preliminarily studied.The preliminarily results of the paper are as follows:Al2O3/C hybrid aerogels are amorphous, constituted byγ-type Al2O3 and amorphous carbon and they mixed uniformity in the nanoscale. The crystallinity of Al2O3 aerogels was improved after the burning and the main composition areγ-type Al2O3.The Al2O3/C hybrid aerogels and Al2O3 aerogels are all typical mesoporous materials. The BET surface area of Al2O3/C hybrid aerogels can reach to 520m2/g.The mesopore volumes are between 1.08-2.3 cm/g and mesopore sizes are between 10-60nm. The mesopore volumes and the mesopore sizes of Al2O3 aerogels increased after buring,but the specific surface area decreased.It was found that the BET surface areas,mesopore volumes,and mesopore sizes all increased with the increase of PO/Al molar ratios or the decrease of the R+F contents at the PO/Al ratios of 5 and 6, but increased with the decrease of R+F concentrations at the PO/Al ratios of 4 in the experiment range. The total mass loss of Al2O3/C hybrid aerogels are about 50.9%,and have a good thermal stability. The thermal stability was improved with the increase of the concentrations of Al(NO3)3·9H2O.The capacity of Al2O3/C hybrid aerogels as the electrode material in electrosorption of fluorine ion reaches 18.23 mg/g, desorptionrate reaches 98.0%.