Novel TEMPO-oxidized cellulose nanofiber/polyvinyl alcohol/polyethyleneimine nanoparticles for Cu2+ removal in water

In this study, environmentally friendly TEMPO-oxidized cellulose nanofiber (TO-CNF)/polyvinyl alcohol (PVA)/polyethyleneimine (PEI) nanoparticles were obtained by assembling PEI into TO-CNF/PVA aerogel, which was prepared by freeze-drying method with the help of glutaraldehyde. FTIR results showed that PEI likely assembled into the TO-CNF/PVA aerogel due to appearances of bending vibration of the TO-CNF/PVA/PEI nanoparticles at 1615 cm−1. BET results further demonstrated that PEI have successfully assembled into the aerogel since the specific surface area (22.93 m2 /g) of TO-CNF/PVA /PEI nanoparticles was lower than that (56.37 m2 /g) of TO-CNF/PVA aerogel. SEM results also showed that PEI could obviously regulate the morphology of TO-CNF/PVA aerogel. TGA indicated that TO-CNF/PVA/PEI nanoparticles were structurally stable at 216.4 °C. The adsorption kinetics of the TO-CNF/PVA/PEI nanoparticles for copper ion (Cu2+) removal presented good correlations with the Pseudo-second-order kinetic and Langmuir model (R2 > 0.99). Its maximum adsorption capacity for Cu2+ according to Langmuir model was 156.8 mg/g. The adsorption equilibrium could reach in near one hour, and the adsorption efficiency could still maintain more than 80% after 3 cycles.