Adsorption kinetics and mechanisms of copper ions on activated carbons derived from pinewood sawdust by fast H 3 PO 4 activation

Abstract

Two kinds of pinewood sawdust activated carbon adsorbents were prepared by fast activation with H₃PO₄ in a spouted bed, and the application in adsorption of copper ions was investigated. With only 3 min of activation time, the BET surface area of activated carbons reached 1537.5 m²/g for impregnation mass ratio of H₃PO₄ to sawdust at 1:1 and activation temperature of 500 °C (IR1-500), whereas it was 1750.7 m²/g for the impregnation ratio at 4:1 and activation temperature of 800 °C (IR4-800). The pseudo second-order reaction kinetics well describes the experimental adsorption of copper ion in this study, indicating chemisorption dominated in the process. By the C_1s spectrum, activated carbons from IR1-500 contained more carboxyl groups (-COOH) and carbonyl groups (C=O), which played an important role in copper ions adsorption. In addition, it was found that the P-containing groups (metaphosphates) also involved in the adsorption of copper ion.