Kinetics of Copper Desorption from Regenerated Spent Bleaching Earth

Abstract

Recent studies have shown that spent bleaching earth (SBE), a clayey waste from edible oil refineries, could be used to remove Cu from aqueous solutions. This could result in copper-laden material whose continual disposal into the environment may lead to bioaccumulation of toxic metal ions in the ecosystems. To assess the reversibility of copper uptake by spent bleaching earth, the kinetics of copper recovery from regenerated spent bleaching earth (RSBE) was studied on a batch basis in H SO , and CaCl . The acid showed superior 2 4 2 desorption efficiency than competitive effects of Ca2+ ions. The initial solid-phase Cu concentration and desorption resident time were most important factors affecting copper release from RSBE. Up to 80% copper recovery was realized in 1-hour agitation period but longer contact time reduced the fraction of metal recovery from the adsorbent. The desorption process was consistent with the parabolic diffusion kinetics in both desorbants although it was also correlated to the first order and second order models in H SO and to the 2 4 modified Freundlich model in CaCl respectively