For orange cortex, results were similar than lemon reaching up to 96% removal of Pb,
84% of Cu and 36% of Cd when the sample was reloaded three times (Fig. 4). The capacity of biosorption was calculated using Eq. (1) for every cortex and the results are shown in Table 1 As shown, banana
cortex was capable to adsorb around 65 mg of Pb and Cd per
gram but only 36 mg of Cu per gram. For lemon and orange, the best retention rate was for Pb (77.6 and 76.8 mg/g) then Cu (70.4 and 67.2 mg/g) and finally Cd (12 and 28.8 mg/g).