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. Th is could result in copper-laden material whose continual disposal into the environment may lead to bioaccumulation of toxic metal ions in the ecosystems. To asses s the reversib ility of copper uptake by spent bleaching earth, the kinetics of copper recovery from regenerate d spent bleachin g earth (RSBE) was studied on a batch basis in H SO , and CaCl . The acid showed superio r 2 4 2 desorptio n efficiency than competitive effects of Ca ions. The initial solid-phase Cu concentration an d 2+ desorption re sident time were most important factors affecting copper release from RSBE. Up to 80% coppe r 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 bot h deso rbants although it was also correlated to the first order and second order models in H SO and to th e 2 4 modified Freundlich model in CaCl respectively