Hierarchical structured materials formed by combination of zeolite crystals and bacterial cellulose fibers

Hierarchical materiais integrate different kinds of porosity enhancing mass transport and diffusion within the crystals, ideally while maintaining the intrinsic zeolitic properties and can be achieved using post-synthesis methods such as zeolitization of preformed solids.1 Many adsorbents and catalysts may use this approach and, among them, the zeolites are highlighted once mass transference issues dueto densification, which limits the access of molecules to the active sites in the inner channels and consequently makes its applications difficult, can be worked. Zeolites have well-defined microporous system formed by tetrahedral silicon and aluminum atoms linked by oxygen atoms.2 Bacterial cellulose is a biomaterial with several interesting characteristics such as high water holding capacity, crystallinity and purity that have recently attracted attention, especially for composite development. lt possesses a three-dimension structure and large surface area that stabilizes adsorbed particles, enabling stable composites.3 Macro and mesopores present at the bacterial cellulose structure have been regarded as a feasible alternative to mass transference problems caused by the zeolites compaction that prevents the specific molecules access to the micropores. Thus, herein we propose the synthesis of composites by means of impregnation of zeolite crystals on bacterial cellulose forming cartridges with high surface area. Zeolite A was synthesized by hydrothermal method and then added to a suspension of functionalized cellulose prepared via bacterial route and them mixed by ultrasonification. The solids cartridges were prepared by lyophilization. Figure 1 shows sheets formed by bacterial cellulose nanofibrils entwining the zeolite crystals, evidencing no aglomerations. X-ray diffraction patterns of zeolite A, cellulose and composites are presented in Figure 2, showing that zeolite crystals are preserved in the concentrations tested.