Abstract:
This study investigated the kinetics and thermodynamics of copper(II) removal from aqueous
solutions using spent bleaching earth (SBE). The spent bleaching earth, a waste material from edible oil
processing industries, was reactivated by heat treatment at 370
o
C after residual oil extraction in excess methyl-
ethyl ketone. Copper adsorption tests were carried out at room temperature (22±3 ºC) using 5.4 x 10
-3
M metal
concentrations. More than 70% metal removal was recorded in the first four hours although adsorption continued
to rise to within 90% at 42 hours. The pH, adsorbent dosage and initial concentrations were master variables
affecting RSBE adsorption of Cu(II) ions. The adsorption equilibrium was adequately described by the DubininRadushkevich
(D-R) and the Temkin isotherms and the maximum sorption capacity derived from the D-R
isotherm was compared with those of some other low cost adsorbents. The adsorption process was found to follow
Lagergren Pseudo-second order kinetics complimented by intra-particle diffusion kinetics at prolonged periods of
equilibration. Based on the D-R isotherm adsorption energy and the thermodynamic adsorption free energy ∆G, it
was suggested that the process is spontaneous and based on electrostatic interactions between the metal ions and
exposed active sites in the adsorbent surface.
KEY WORDS
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KEY WORDS
KEY WORDS: Kinetics, Thermodynamics, Copper adsorption isotherms, Spent bleaching earth