title: Surface adsorption and self-assembly of Cu(II) ions on TEMPO-oxidized cellulose nanofibers in aqueous media.
abstract: TEMPO-mediated oxidized cellulose nanofibers (TOCNFs) have shown potential in the bioremediation of metal ions from contaminated water due to their interaction with positively charged metal ions via electrostatic interactions involving surface carboxyl groups. Copper is one of the most common pollutants in industrial effluents and is thus the target metal in the current study. The specific surface adsorption of Cu(II) was similar for TOCNFs with different degrees of functionalization and directly impacted the zeta potential. SEM imaging of the TOCNF after Cu(II) adsorption revealed interesting nanostructured clusters that were attributable to Cu(II) ions first being adsorbed by carboxylate groups on the TOCNF and subsequently being reduced and self-assembled to Cu(0) nanoparticles (NPs) or copper oxide NPs by microprecipitation. TOCNF turned superhydrophilic and resulted in faster water filtration after copper adsorption due to the stronger polarity of the copper ions or the self-assembled Cu(0) NPs creating voids or highly water-permeable channels at the interface between the interconnected TEMPO-oxidized nanofibers. Thus, the adsorption of Cu(II) ions and self-assembly into the Cu NPs on TOCNF favors a faster water purification process and provides a viable route to reuse/recycle TOCNFs studded with Cu nanoparticles as biocidal materials.
authors.affiliation: Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden.
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.affiliation: Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden.
authors.forename: Kristiina
authors.initials: K
authors.lastname: Oksman
authors.affiliation: Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden; Division of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden. Electronic address: aji.mathew@ltu.se.
authors.forename: Aji P
authors.initials: AP
authors.lastname: Mathew
mesh_terms: D000327:Adsorption; D002413:Cations, Divalent / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry*; D057139:Nanofibers / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D003497:Cyclic N-Oxides; D014867:Water; D003300:Copper; D002482:Cellulose; C003959:TEMPO
keywords: Adsorption; Cellulose nanofibers; Metal ions; Self-assembly; TEMPO modification; Water purification