Potentiometric back titration as a robust and simple method for specific surface area estimation of lignocellulosic fibers

Abstract The specific surface area (SSA) of cellulosic or lignocellulosic fibers is seldom reported in the recent literature on papermaking, despite its close relation with degree refining and other key pulp properties. Amidst outdated assays (Pulmac permeability test) methods that, while accurate, are doubtful usefulness for papermaking purposes (N 2 adsorption–desorption), we suggest a methodology based cationic demand. A commonly used polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC), became adsorbed onto thermomechanical samples. Then, potentiometric back titration an anionic polyelectrolyte measured demand, expressed as microequivalents PDADMAC per gram pulp. Multiplying this value by microequivalent polymer, considering rod-like conformation case minimum ionic strength, yielded SSA Our system assumes that quaternary ammonium groups were anchored through electrostatic ion–dipole interactions. Measuring carboxyl content allowed discriminating between both kinds forces. Finally, model could be validated plotting estimated values against Schopper-Riegler degree, attaining high correlation coefficients (R ~ 0.98). Owing to molecular weight choice (107 kDa), more particularly fine-free pulps, from demand consistently lower than those dye (Congo red) sorption. Instead being drawback, limited diffusion can enable papermakers attain helpful quantification available surfaces operations low residence times.