Cellulose (2021) 28:10183–10201 https://doi.org/10.1007/s10570-021-04133-w (0123456789().,-volV) (0123456789().,-volV)
ORIGINAL RESEARCH
Locust bean gum adsorption onto softwood kraft pulp fibres: isotherms, kinetics and paper strength
. Rodger P. Beatson . Heather L. Trajano
Jingqian Chen
Received: 7 October 2020 / Accepted: 3 August 2021 / Published online: 1 October 2021 The Author(s) 2021
Abstract The adsorption of locust bean gum (LBG) onto Northern Bleached Softwood Kraft (NBSK) pulp improved paper tensile and burst strength and lowered refining energy by strengthening inter-fibre bonding. Adsorption kinetics and isotherms were investigated to develop a fundamental understanding of the adsorption mechanism. The adsorption rate followed pseudo-second-order kinetics and the activation energy was 99.34 kJ mol - 1 , suggesting chemisorp- tion. The adsorption rate constant increased rapidly with temperature from 25 to 45 C ( k = 1.93 to 24.03 g mg - 1 min - 1 ), but the amount adsorbed at equilibrium decreased ( q e = 1.91 to 0.48 mg g - 1 o.d. fibre). LBG adsorption to NBSK at 25 C was The online version contains supplementary material available at https://doi.org/10.1007/ s10570-021-04133-w. J. Chen H. L. Trajano ( & ) Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada e-mail: heather.trajano@ubc.ca J. Chen H. L. Trajano BioProducts Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada Supplementary Information R. P. Beatson Chemical and Environmental Technology, British Columbia Institute of Technology, 3700 Willingdon Avenue, Burnaby, BC V5G 3H2, Canada
consistent with the Langmuir adsorption model for LBG \ 2.1 wt% of o.d. fibre, suggesting reversible, homogenous adsorption to a finite number of sites on the fibre surface. Refining to 3000 rev increased the heterogeneity of the NBSK pulp surface leading to multi-layer Freundlich adsorption with adsorption constant n = 5.00, and the equilibrium constant K f = 2.57 mg g - 1 (mg L - 1 ) - 1/n at 25 C. Favorable adsorption conditions for negatively charged LBG were identified: 25 C for 10 min, low dosage level ( \ 2 wt%), lightly refined ( \ 3000 rev) NBSK pulp at low fibre consistency ( \ 0.5 wt%), high agitation rate ( [ 150 r.p.m.), acidic or neutral conditions (pH 2–7) without salt addition.
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