Adsorption kinetics and mechanisms of copper ions on activated carbons derived from pinewood sawdust by fast H3PO4 activation

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 m(2)/g for impregnation mass ratio of H3PO4 to sawdust at 1:1 and activation temperature of 500 degrees C (IR1-500), whereas it was 1750.7 m(2)/g for the impregnation ratio at 4:1 and activation temperature of 800 degrees 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.