Dynamic adsorption and desorption behaviors of rosin colloids onto and from cellulose nanofibers in aqueous media

The dynamic adsorption and desorption behaviors of rosin colloids onto and from CNFs and TOCNFs in aqueous media were investigated using QCM-D measurements. Gum rosin colloids (GR-C) were well adsorbed onto CNFs, but not well adsorbed onto TOCNFs. Maleic anhydride modification of GR had little effect on the surface charge but contributed to particle size reduction, an increase in the glass transition temperature (Tg) and an enhancement of the colloids' stability. The adsorption of GR-maleic anhydride adducts colloids (GRM-C) was not affected by the surface charge of the cellulose nanofibers in the aluminum sulfate (Alum)-free system, but was significantly affected by that in the Alum-containing system. Maleic anhydride modification contributed to an increase in the adsorption rate of the rosin colloids in the system of CNFs with Alum. On the other hand, using an anionic surfactant contributed to increasing the particle size and ionicity of the rosin colloids. The adsorption of GR-maleic anhydride adducts with anionic surfactant colloids (GRMS-C) was higher than that of GRM-C in the system of CNFs with and without Alum, suggesting that using an anionic surfactant contributed to increasing the adsorption of the rosin colloids onto CNFs. By contrast, GRMS-C was not entirely adsorbed on TOCNFs in the Alum-free system but was adsorbed in the Alum-containing system. The adsorption and desorption behaviors of GRMS-C was also affected by the pH of GRMS-C solution. Thus, dynamic adsorption and desorption behaviors of rosin colloids onto and from cellulose fibers are complicated and influenced by the rosin modification method, using an anionic surfactant or Alum addition.

Automated summary

The dynamic adsorption and desorption behaviors of rosin colloids onto and from CNFs and TOCNFs in aqueous media were investigated using QCM-D measurements. The effects of maleic anhydride modification, anionic surfactant, and Alum addition on the adsorption were studied. The results showed that maleic anhydride modification contributed to particle size reduction, an increase in Tg, and enhanced stability, while using an anionic surfactant increased the particle size and ionicity. The adsorption of rosin colloids was affected by the surface charge of CNFs and the presence of Alum.