Production of activated carbon from walnut shell by CO2 activation in a fluidized bed reactor and its adsorption performance of copper ion

Low-cost and effective activated carbon for copper ion adsorption was prepared from walnut shell by CO 2 activation in a fluidized bed. The effects of activation temperature and activation time on the specific surface area and yield were investigated. The adsorption performance of copper ion on walnut shell-derived activated carbons was examined in details. BET, SEM, FT-IR and XPS were used to determine the pore structure, morphology and surface chemistry of activated carbons obtained. Under the optimal condition (i.e., activation temperature of 900 °C and activation time of 90 min) the activated carbon with maximum specific surface area of 1011 m 2 /g and largest pore volume of 0.65 cm 3 /g with uniform micropores structure ( V micro / V Total was more than 80%) could be produced. Changes in surface functional groups of activated carbon were observed, and the contents of carboxyl groups (–COOH) increased significantly after activation process, which is very favorable for copper ion adsorption. The kinetics for copper ion adsorption followed the Pseudo-second-order model.