Adsorption capacity of Cu(II) and Pb(II) onto carbon fiber produced from wool

The potential utility of the widely available waste product, wool textiles, in the adsorption of heavy metals from industrial and other wastewater systems was investigated by proxy experimentation. Carbon fiber was prepared from dyed wool (DW) by calcination at different temperatures (400, 600, 800, and 1000 °C, referred to as DW400, DW600, DW800, and DW1000, respectively). The samples were analyzed in terms of scanning electron microscope images, percentage yield, specific surface area, pore volume, and the pH of an aqueous suspension of virgin dyed wool (V-DW) or the calcined DW. The adsorption of Cu(II) and Pb(II) from aqueous solutions was studied using the batch method, and the effect of contact time and co-existence of metal ions was investigated. Cu(II) and Pb(II) adsorption increased with increasing DW calcination temperature in the order V-DW < DW400 < DW600 < DW800 < DW1000. The maximum equilibrium adsorption of Cu (II) and Pb(II) achieved with DW1000 (79% and 57%, respectively) was reached within 6 h. Fitting of the adsorption isotherm data for Cu(II) and Pb(II) adsorption onto DW1000 to the Freundlich equation was consistent with monomolecular adsorption onto a heterogeneous surface. The rate-limiting step was determined to be chemical sorption by fitting the adsorption kinetics data to pseudo first-order and pseudo second-order models, given that the pseudo second-order model best fit our data. The study demonstrated that DW1000 was useful for purification of wastewater containing Cu(II) and Pb(II).