Preparation of Aqueous Dispersions of TEMPO-Oxidized Cellulose Nanofibrils with Various Metal Counterions and Their Super Deodorant Performances

2,2,6,6-Tetramethylpiperidine-l-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) with sodium carboxylate groups (TOCN-Na) were nanodispersed in water. The Na+ ions of TOCN-Na were exchanged with other monovalent, divalent, and trivalent metal (M) ions. When an aqueous metal acetate or AlCl3 solution was added to a 0.1% TOCN-Na/water dispersion or TOCN-COOH gel/water mixture under suitable conditions followed by sonication in water, individually nanodispersed TOCNs-M with divalent and trivalent metal counterions were obtained in yields of 24-87%. The amount of metal introduced into TOCN-M was approximately 20-50% of the TOCN carboxylate content when divalent and trivalent metal ions were used. These results indicate that intrafibrillar ionic linkages are selectively formed and these TOCN-M species nanodisperse at the individual nanofiber level without agglomeration in water. Filter papers with adsorbed TOCN-Cu/water and TOCN-Ag/water dispersions efficiently decomposed or adsorbed H2S and CH3SH gases, but filter papers containing fibrous TEMPO-oxidized celluloses with Ag+ or Cu2+ counterions had much lower gas-decomposition efficiencies.