Hierarchical zeolite based on multiporous zeolite A and bacterial cellulose: An efficient adsorbent of Pb²⁺

A multiporous zeolite A (A_b) was obtained by the addition of the organosilane molecule dimethyl octadecyl [3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC) in the synthesis gel and successfully dispersed in bacterial cellulose forming aerogels for Pb²⁺ adsorption. Several characterization techniques such as powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N₂ adsorption-desorption were employed to investigate physical, chemical, and textural properties of the samples. The resulting material is also compared to the conventional microporous zeolite A and shows a positive interaction between zeolite crystals and cellulose nanofibrils, specially when the mesopores are present in the crystal. Improvements are observed for the multiporous samples in both adsorption and ionic exchange processes. The selectivity for Pb²⁺ in the presence of Cd²⁺ is enhanced as a result of improved intraparticle diffusion where there is the insertion of mesopores to the structures. From the kinetic models, the pseudo-second order model fits better to the experimental data suggesting chemisorption as the governing process in adsorption and the mesopores seem to have a remarkable role on it. These multiporous materials facilitate the access of Pb²⁺ to the zeolite inner pores and therefore present high potential to be used for both Pb²⁺ adsorptive and analytical devices.