Aldehyde-functionalized porous nanocellulose for effective removal of heavy metal ions from aqueous solutions
Nanoscale sorption is a promising strategy for catalyst and purification system design. In this paper, cellulose nanofibrils (CNFs) were densely attached with aldehyde functional groups on the surface via a mild periodate oxidation process, and then applied as mesoporous sorbents to remove Cu(II) and Pb(II) from aqueous solutions. In the studied concentration range (0.6–1.0 mmol L−1), a removal capacity of 0.75 mmol g−1 for Pb(II) and 0.58 mmol g−1 for Cu(II) was obtained. It is higher than most reported results over a much broader concentration range. Furthermore, the physical chemistry of the sorption process was studied in terms of sorption kinetics, sorption isotherm study and thermodynamic study. The results showed that the sorption process is under the combined influences of reaction kinetics, film diffusion and intraparticle diffusion, and follows the Langmuir model of monolayer adsorption. The sorption is spontaneous and endothermic. This development demonstrates an ecofriendly and cost-effective method with high level effectiveness of metal ion removal.