The Thomas model was used to predict adsorption breakthrough
curves, and the following conclusions were derived: (1)
the adsorption capacities of CM, PF, and SB under the examined
conditions decreased as the flow rate increased and decreased as
the solution pH increased from 4 to 6; (2) the biosorbent uptake of
metal ions occurred through both ion exchange and complexation
processes, and metal complexation was the primary adsorption
mechanism. The selected biosorbents possess carboxylic acid
groups, which function as exchangeable cation sites and facilitate
complexation, thus, increasing the capacity to adsorb heavy metal
ions; (3) among the selected biosorbents, CM had the greatest
adsorption capacity; however, PF offered the advantage of requiring a simple pretreatment process. Thus, both CM and PF
are excellent biosorbent materials.