Effects of aqueous suspension properties on the atomization and dispersibility of spray dried cellulose nanocrystallite granules

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Canada is a major global forest products country and leads the commercialization of next generation high-value added wood derived products:cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF). To accelerate the commercialization process of wood based nanofibers and maintain global leadership, Canadian forest industries leading research organization, FPInnovations identified six (6) main challenges to be solved. One of them is the dispersion of cellulose nanocrystals in aqueous media which is addressed in this proposal. CNC is typically produced first by milling and then acid hydrolyzing of kraft pulp cellulose. Employing concentrated (65%) sulfuric acid removes the amorphous regions and releases homogenous and defect free cellulose nanocrystals (CNC). The produced slurry is first centrifuged, filtrated and then CNC dispersion slurry is spray dried. Thus, CNC particles are recovered in the form of free flowing dry granular material. In spray drying, evaporation of water often causes an irreversible aggregation of CNC particles. CNC in powder state must be redispersed in aqueous solutions for accurate end product applications. Hence, proper control of aggregation during drying is needed to preserve individual particles sizes and surface properties of CNC particles after the redispersion processes.This proposal deals with how electrolytes, surfactants and polymers in aqueous CNC suspensions influence the droplet formation and the morphology of dried CNC granules during the spray drier operations and their dispersibility in aqueous media. The objective of this research is to understand how CNC suspension properties after filtration influences the spray drying and morphologies of dried CNC granules. This in turn contributes to the formation of aggregates and redispersion of CNC granules in water. Spray drying of CNC suspensions will be carried out at various CNC suspension concentrations, electrolyte (NaCl), surfactant (non-ionic linear secondary alcohol with 12-14 carbon chain), and deflocculant (ammonium polyacrylate) presence and operating at different spray dryer operating conditions.