Synthesis and Application of a Novel Sorbent (Tannic Acid-Grafted-Polyethyleneimine Encapsulated in Alginate Beads) for Heavy Metal Removal

A sorbent was produced by chemical modification (tannic acid grafting) of polyethylenimine (PEI) and encapsulation in alginate gel beads. The sorbent was characterized by SEM-EDX and FTIR analyses before being used for the sorption of Cu(II), Zn(II) and Ni(II). The influence of pH was tested and sorption isotherms have been determined: the Langmuir equation fits well experimental data; for Cu(II), the bi-site Langmuir equation was preferred. Metal sorption capacity exceeds 1 mmol metal g^?1 and amine groups (with hydroxyl groups of tannic acid or carboxylic groups of alginate) contribute to metal binding. The pseudo second-order rate equation fits kinetic profiles well.