RESUMEN
A multilevel factorial design of 23 with 12 experiments was developed for the preparation of cellulose nanocrystals (CNC) from Agave tequilana Weber var. Azul bagasse, an agro-industrial waste from tequila production. The studied parameters were acid type (H2SO4 and HCl), acid concentration (60 and 65 wt% for H2SO4, 2 and 8N for HCl) temperature (40 and 60 °C for H2SO4, 50 and 90 °C for HCl), and hydrolysis time (40, 55 and 70 min for H2SO4; and 30, 115 and 200 min for HCl). The obtained CNC were physical and chemically characterized using dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XDR) techniques. The maximum CNC yield was 90 and 96% for HCL and H2SO4, respectively, and the crystallinity values ranged from 88-91%. The size and morphology of A. tequilana CNC strongly depends on the acid type and hydrolysis time. The shortest CNC obtained with H2SO4 (65 wt%, 40 °C, and 70 min) had a length of 137 ± 68 nm, width 33 ± 7 nm, and height 9.1 nm, whereas the shortest CNC obtained with HCl (2 N, 50 °C and 30 min) had a length of 216 ± 73 nm, width 69 ± 17 nm, and height 8.9 nm. In general, the obtained CNC had an ellipsoidal shape, whereas CNC prepared from H2SO4 were shorter and thinner than those obtained with HCl. The total sulfate group content of CNC obtained with H2SO4 increased with time, temperature, and acid concentration, exhibiting an exponential behavior of CSG=aebt.
RESUMEN
Global environmental pollution issues caused by synthetic materials and the lack of practical utilization of the local industrial lignocellulosic waste, force Mexican researchers to produce new biobased sustainable materials that use industrial waste as a source of components. Herein, we show the preparation and characterization of environmentally friendly starch-based nanocomposites reinforced with cellulose nanofibrils (CNF) extracted from Agave tequilana Weber. Tensile, bending and impact mechanical properties of dried and hydrated nanocomposites were studied. Moreover, the water absorption capacity of the nanocomposites were measured and evaluated. The mechanical properties improved because of the presence of a small amount of CNF (1 wt%). This work demonstrates the importance of the addition of a natural biomodifier in a starch matrix to achieve better mechanical properties. Most importantly, this study highlights that lignocellulosic waste from the tequila industry can have a practical application, which is being a source of natural nanoreinforcements for preparation of all-biobased sustainable materials.
