According to Equation (4), the curve of lnkc versus 1/T should be
a straight line with a slope of Ea/R when experimental data follows
Arrhenius equation. Using chemical rate constant (k2) from
chemical reaction control model fitted to the experimental data
obtained in this study lnkc values were calculated, and lnkc versus
1/T curve was plotted (Fig. 8). From the slope of the curve the
activation energy of leaching Al from WPBs was found to be
87.24 kJ mol1. The higher value of activation energy confirms that
the leaching process is controlled by chemical reaction control
model (Abdel-Aal and Rashad, 2004), and thus certain temperature
(above 40 C) is necessary for improving the recovery of Al.