Facile preparation of cellulose nanofiber/ZSM-5 zeolite/polyethyleneimine aerogel for selective adsorption of Cu2+ in wastewater

The development of a cost-effective and environmentally friendly adsorbent is essential for effectively removing heavy metals from wastewater. This study presents the preparation of a recyclable cellulose nanofiber (CNF) /ZSM-5 zeolite/polyethyleneimine (PEI) aerogel through chemical crosslinking and freeze-drying techniques. The synthesized aerogel was applied for the highly selective adsorption of Cu2+. The characterization of the as-prepared aerogel indicates that its three-dimensional network porous structure, along with the abundance of active sites, contributes to the effective adsorption of Cu2+. The adsorption capacity was found to be 134.23 mg/g. Furthermore, it was observed that Cu2+ adsorbed by the composite aerogel could be efficiently eluted using 0.2 M EDTA-2Na. The adsorption kinetics and isotherm studies revealed consistency with the pseudo-second-order model and Langmuir model, indicating that the adsorption process was primarily governed by monolayer chemisorption. Mechanism analysis further confirmed that surface complexation, ion exchange, and electrostatic interaction were the primary driving forces behind the excellent adsorption capabilities of the prepared aerogel. Remarkably, the structural integrity and selective adsorption of the composite aerogel remained largely unchanged even after undergoing five sorption-desorption cycles. These findings strongly suggest that the CNF/ZEM-5/PEI composite aerogel holds significant promise for achieving efficient and selective removal of copper ions in wastewater.