Surface-modified activated carbon with β-cyclodextrin--Part II. Adsorption properties.

Sorption properties of surface modified activated carbon (AC) with p-nitrophenol (PNP) and methylene blue (MB) in aqueous solution were investigated. The calculated surface areas for AC and surface modified AC were compared using nitrogen sorption and a dye-based method. The surface areas of AC and the surface modified AC with glutaraldehyde (AC-β-CD) (1:10:10⁹) and 1,4-phenylene diisocyanate (ACPDICD) measured by nitrogen sorption were 1,269 m²/g, 103 m²/g, and 95 m²/g, respectively (Langmuir model) and 956 m²/g, 74 m²/g, and 69 m²/g (BET model), respectively. However, the calculated surface areas for the dye-based method (PNP; pH 6.00) for AC, AC-β-CD(1:10:10⁹), and ACPDICD was 1,035 m²/g, 814 m²/g, and 76 m²/g (Langmuir model), respectively and 1,491 m²/g, 1,669 m²/g, and 92 m²/g (BET model), respectively. The corresponding surface areas for the dye-based method (MB; pH 8.40) for AC-β-CD(1:10:10⁹) and ACPDICD was 263 m²/g and 171 m²/g (Langmuir model), respectively and 1019 m²/g and 182 m²/g (BET model), respectively. The sorption capacity (Q(m)) and binding affinity characteristics [K(F)(L/g), K(L)(g/mol), and K(BET)(L/g)] were estimated at room temperature at equilibrium conditions using several sorption isotherm models.