Preparation of sulfonated graphene aerogel and its adsorption performance for alcoholamine

In the coal chemical industry, alcoholamine can be used as an effective solvent to extract phenolic compounds from coal tar, while the easy formation of hydrogen bonds between the amino group （—NH₂） of the extractant and the phenolic hydroxyl group results in residual alcoholamine in the phenolic oil. Therefore, it is necessary to develop efficient and stable solid adsorbents to remove the residual amine extractant and improve the purity of phenol oil. A compressible and resilient sulfonated graphene aerogel （SGA） was prepared by hydrothermal reaction and lyophilization using graphene oxide and diazonium p-aminobenzenesulfonate as precursors and ethylenediamine as crosslinking agent, which was used as adsorbent to remove residual amines in phenol oil via electrostatic interaction between —SO₃H and —NH₂. FT−IR and elemental analysis results confirm that sulfonation strategy can effectively graft —SO₃H on the graphene surface. The results of nitrogen adsorption and desorption test show that the average pore size of SGA is 12~14 nm, and its large mesoporous structure is conducive to the adsorption and storage of crude phenol oil. The saturation adsorption experiment reveals that the average adsorption capacity of SGA for crude phenol is 100 g/g. The sulfonated graphene aerogel （SGA2） prepared at 180 ℃ for 12 h, where the mass ratio of graphene oxide to diazonium p-aminobenzenesulfonic acid was 1:3, manifests a good adsorption effect on residual alcoholamine in phenol oil. The content of phenolic components increased from 69.02% （concentration of crude phenolic oil） to 76.41% after adsorption process. When the SGA2 was subjected to oxygen plasma treatment for 20 min, the adsorption performance for alcoholamine was further elevated with adsorption temperature of 50 ℃ and the content of phenolic components increased to 79.89%. The SGA2 demonstrates good adsorption performance for alkanolamine, providing design principles for efficient carbon-based adsorbents.