Recovery of platinum from waste effluent using polyethyleneimine-modified nanocelluloses: Effects of the cellulose source and type.

Nanocellulose is a promising biosorbent for the recovery of precious metals from waste streams. A variety of nanocelluloses exhibit significant different properties that depend on the natural source and type. In this study, cellulose nanofibrils(P-CNF) and cellulose nanocrystals(P-CNC) obtained from hard wood pulp and CNF from tunicates(T-CNF) were evaluated for their ability to recover platinum(Pt) after modification with polyethyleneimine(PEI). The PEI grafting density on each nanocellulose was distinct, resulting in significant variations in the Pt adsorption performance. The Pt adsorption capacity of the PEI-modified nanocelluloses followed the order T-CNF>P-CNC > P-CNF. The inherent characteristics of T-CNF, that is, the negative charge and high surface area caused by open porous structure, were found attributed to the grafting of ≈40% PEI and the excellent Pt adsorption capacity(≈600 mg/g). Also PEI-modified T-CNF exhibited high selectivity towards Pt in the presence of other metals. Finally, PEI modified T-CNF was applied for Pt recovery from simulated spent automobile catalyst leachate to prove feasibility in a real application.