Surface carboxylation of porous regenerated cellulose beads by 4-acetamide-TEMPO/NaClO/NaClO2 system |
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Authors: | Masayuki Hirota Naoyuki Tamura Tsuguyuki Saito Akira Isogai |
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Institution: | (1) Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; |
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Abstract: | A commercial regenerated bead cellulose was suspended in water at pH 4.8, and oxidized with NaClO2 used as a primary oxidant and catalytic amounts of NaClO and 4-acetamide-2,2,6,6-tetramethylpiperidinyl-1-oxyl radical. Carboxylate
groups were formed up to 1.87 mmol/g in the beads by the oxidation of C6 primary hydroxyls to carboxylates without significant
weight losses or morphological changes. The spherical shapes, highly porous surface structures consisting of nano-sized fibrils,
and the cellulose II crystal structure of the original beads were mostly maintained by the oxidation, indicating that the
carboxylate groups formed are predominantly present on the fibril surfaces. Cation-exchange behavior of the TEMPO-oxidized
cellulose beads was compared with carboxymethylated cellulose beads, showing that the former was characteristic and superior
to the latter in terms of adsorption of metal ions and cationic polymers. Especially, the TEMPO-oxidized cellulose beads had
high adsorption behavior of lead ion and high-molecular-weight cationic polymers. |
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