Adsorption Characteristics of Microporous Carbons from Apricot Stones Activated by Phosphoric Acid

Crushed apricot stone shells were impregnated with varying H3PO4 acid concentrations (20–50 wt%), followed by carbonisation at 573–773 K. The products were characterised by nitrogen gas adsorption. Analysis of the nitrogen isotherms by the DR and αs methods proved that most of the obtained carbons are highly microporous, with high surface areas (⩾1000 m2 g-1) and very low mesoporosity. Increasing acid concentration, at 573 and 673 K, increases surface area and pore volume, whereas at 733 K a small decrease in both parameters appears at higher H3PO4 concentrations. Whole apricot stones produce activated carbon of inferior porous characteristics. Development of the extensive pore structure was described in light of the effect of H3PO4 on the lignocellulosic mataerial during carbonisation.