These pectin-like compounds can be
ionized with an alkaline treatment generating negative charges
that may bind the metallic cations. Banana cortex contains higher
amounts of starch and cellulose (Khalil et al., 2006) than lemon or
orange cortexes as well as more pectin-type compounds (Yapo
et al., 2007). This difference between banana and citric cortex does
not means significant difference for biosorption of Pb, but it is
important for Cd and Cu in agreement with data collected.