Preparation of expanded graphite-based C/C composites by vacuum impregnation and its adsorption properties on formaldehyde

The expanded graphite-based C/C composites were prepared by vacuum impregnation while expanded graphite (EG), sucrose and phosphoric acid solution were selected as starting materials. The effect of phosphoric acid/sucrose mass ratio (X_p), sucrose concentration on pore structure and specific surface area surface area of the composites was investigated by SEM, nitrogen adsorption/desorption techniques, TG and TEM. The surface chemical functional groups of composite material were characterized by FTIR and Boehm titration method. And the formaldehyde adsorption ability was investigated. The results indicate that there are a lot of micropores, a certain amount of meso-and macropores. The abandant oxygen-containing functional groups on the surface of the composites are benefit to the adsorption of formaldehyde. Under the condition of X_p=1.0, 30% sucrose concentration(mass fraction), the C/C composite is obtained with the highest surface area of 2112 m²/g and total pore volume of 1.08 mL/g. The formaldehyde removal capabilities of expanded graphite-based C/C composites are 26.9% higher than that of activated carbons which were prepared under the same condition.