The sorption of monovalent cations onto wood flour and holocelluloses of Norway spruce: molecular interactions during LiCl impregnation

Abstract

Active functional groups and interactions involved in the sorption of Li+ ions from an aqueous LiCl solution onto the Norway spruce sapwood (sW) flour have been investigated. To this purpose, sW was delignified by peracetic acid (PAA) treatments and the resulting holocelluloses (HC6 h, HC24 h, HC51 h, HC72 h, where the lower case data indicate the PAA treatment time) with various lignin contents were immersed in aqueous solution of LiCl and the sorption effects were studied by flame atomic emission spectroscopy (FAES), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The Brunauer- Emmett-Teller (BET) specific surface area increased from 1.5±0.0 m2g−1 to 2.4±0.1 m2g−1 for HC6 h, and from 1.6±0.03 m2g−1 to 2.7±0.6 m2g−1 for HC72 h upon LiCl treatment. It was found that Li+/Cl− retention occurs predominantly via O-containing functionalities and the carbohydrate-rich samples sorbed more Li+. Upon LiCl treatment, the mobility and accessibility of the wood matrix was enhanced, possibly by interference of the introduced ions with the existing intermolecular bonds.

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“…[25][26][27] The retention of Li + /Cl − occurs mainly through the action of O-containing reactive functional groups, especially the carbon-hydrated substrate can adsorb more Li + and Cl − . [28] Immersion of CNL hydrogels into Gly to remove excess free water from the hydrogel by solvent replacement, and the hydrogel weight also decreased with increasing immersion time and stabilized after 12 h (Figure S1a-c, Supporting Information). The effectiveness of the replacement process was further conducted by monitoring the weight changes of CNLG organohydrogels during vacuum drying process (Figure S1d-f, Supporting Information).…”

“…[ 29–31 ] Furthermore, Li + may also be reduced by ion‐exchange with OH groups and H 2 O molecules. [ 28 ] The strength of CN 1 L hydrogels decreased with increasing LiCl after the concentration of LiCl exceeded 1 wt.%, probably because excessive Li + /Cl − interfered and weakened the intermolecular hydrogen bonds. [ 28,29 ] For this reason, if not specified the concentration of LiCl is 1 wt.% in the following part.…”