Consequences of the nanoporosity of cellulosic fibers on their streaming potential and their interactions with cationic polyelectrolytes

Abstract

Electrokinetic tests, based on the streaming potential method, were used to elucidate interactions between cationic polyelectrolytes and cellulosic fibers and to reveal aspects of fibers' nanoporosity. The fibrillated and nanoporous nature of bleached kraft fibers gave rise to time-dependent changes in streaming potential, following treatment of the wetted fibers with polydiallyldimethylammonium chloride. Electrokinetic test results were consistent with an expected longer time required for higher-mass polyelectrolytes to diffuse into pore spaces, compared to lower-mass polyelectrolytes. Further evidence of the relative inability of polyelectrolyte molecules to diffuse into the pores of cellulose was obtained by switching back and forth between high and low ionic strength conditions during repeated measurement of streaming potential, after the fibers had been treated with a moderate amount of cationic polymer. By changing the concentration of sodium sulfate it was possible to switch the sign of streaming potential repeatedly from positive to negative and back again. Such results imply that a continuous path for liquid flow exists either in a fibrillar layer or within the cell walls. The same concepts also helped to explain the dosages of high-charge cationic polymer needed to achieve maximum dewatering rates, as well as the results of retention experiments using positively and negatively charged microcrystalline cellulose particles.

Cellulosic Substrates for Removal of Pollutants from Aqueous Systems: A Review. 3. Spilled Oil and Emulsified Organic Liquids

“…The presence of lumen structure, as mentioned earlier, has been considered as a contributing factor in the secure holding of oil after its collection (Abdullah et al 2010). The mesoporous structure of a cellulosic fiber, depending on its water-swollen nature (Stone and Scallan 1966;Hubbe et al 2007), also can be expected to imbibe and hold the fluid. In other words, the oil may partly or fully replace air or water already present in the pores, within which fluids are held by capillary forces (Washburn 1921;Choi et al 1993;Adamson and Gast 1997;Ribeiro et al 2000;Inagaki et al 2002b).…”

Dissolved and Colloidal Substances (Dcs) and the Charge Demand of Papermaking Process Waters and Suspensions: A Review

“…Studies have demonstrated maximum levels of fine particle retention, the best performance of dry-strength additives, and/or the fastest dewatering rates when enough of a high-charged cationic additive was added to adjust the zeta potential close to zero (Strazdins 1977;Lindström et al 1974;Horn and Melzer 1975;Stratton and Swanson 1981;Hubbe et al 2007b). Such observations provide evidence that, at least in those cases, charge interactions can play a dominant role.…”

“…The effects of very small pores in the cell walls of water-swollen cellulosic fibers, especially in the case of kraft pulp fibers, have become increasingly well known (Stone and Scallan 1968;Li et al 1993;Berthold and Salmén 1997;Alince and van de Ven 1997;Alince 2002;Hubbe 2006;Hubbe et al 2007b). One of the consequences of fibers' mesoporous nature is that low-mass cationic polymers tend to adsorb in greater amounts compared to their higher-mass analogues (Hostetler and Swanson 1974;Lindström and Söremark 1976;Petlicki and van de Ven 1994;Farley 1997;Taipale et al 2011).…”

Nanoparticulate Hollow TiO2 Fibers as Light Scatterers in Dye‐Sensitized Solar Cells: Layer‐by‐Layer Self‐Assembly Parameters and Mechanism

“…The higher deposition rate for C-LPEI on cellulose compared to C-HPEI could be related to greater adsorption of LPEI on cellulose. This can be explained by the lower diffusion rate of larger polyelectrolytes into the pore spaces of cellulose, [38] which is due to steric and electrostatic interaction of larger polyelectrolytes with the pore walls. To quantitatively investigate the effect of molecular weight on the adsorption of PEI on cellulose, the decrease in concentration of PEI by immersion of equal quantities of cellulose after 5 min was investigated by UV/Vis spectrophotometry.…”