Nanocellulose extraction from acai bagasse through mixed acid hydrolysis and oxidative techniques.

Exploring new biomass sources for nanocellulose (NC) extraction is crucial in elevating the economic value of readily available renewable resources. This study compares NC extracted from acai (Euterpe oleracea) bagasse using different methods: mixed acid hydrolysis, 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) mediation, and ammonium persulfate (APS) oxidations. A comprehensive analysis investigates the impact of each treatment on the physical-chemical properties of the nanoparticles, including chemical structure, crystallinity, morphology, and thermal and suspension stability. NCs obtained through mixed acid hydrolysis exhibit the highest crystallinity (62 %) and low sulfate groups on their surfaces. Consequently, they demonstrate excellent thermal stability but poor colloidal stability in water. Oxidized NCs undergo chemical modification, converting alcoholic groups into carboxyl, resulting in NCs with zeta potentials ranging between -25.30 ± 0.81 and - 27.49 ± 1.07 mV. APS oxidation produces nanoparticles with superior thermal stability compared to TEMPO oxidation. Atomic Force Microscopy (AFM) images reveal that all nanocelluloses share characteristics of nanofibers (CNFs). This comprehensive characterization highlights the potential of acai bagasse for yielding high-added-value bioproducts suitable for versatile applications.

Mechanism of multicyclic ß-carotene impregnation into corn starch aerogels via supercritical CO2 with mathematical modeling.

ß-carotene, a natural dye renowned for its antioxidant and provitamin A activities, is hindered from direct use in food and drug products due to its susceptibility to oxidation, easy isomerization under light, heat, or acidic conditions, as well as its low water solubility and oral bioavailability. In this study, we addressed these challenges by loading ß-carotene into corn starch aerogels via supercritical carbon dioxide (sc-CO2) and assessed its loading contributions through adsorption during contact time and precipitation during depressurization. The loading process was studied under two cycles at pressure of 30 MPa, temperature of 40 °C, depressurization rate of 0.4 MPa/min, and co-solvent (ethanol) mass percentage of 1.2 %. Experiments found adsorption minimally contributed to impregnation, while precipitation became the primary loading mechanism. The subsequent work focused on a mathematical model describing ß-carotene loading into corn starch aerogels via precipitation, using the law of conservation of mass and classical nucleation theory. The model shows that using pure CO2 results in a loading efficiency of 0.10 mg ß-carotene/g aerogel, while with CO2 and 1.2 % ethanol as the co-solvent, the loading efficiency increases threefold to 0.30 mg ß-carotene/g aerogel.

Cellulose nanocrystals-based materials as hemostatic agents for wound dressings: a review.

Wound dressings are devices used to stop bleeding and provide appropriate environmental conditions to accelerate wound healing. The effectiveness of wound dressing materials can be crucial to prevent deaths from excessive bleeding in surgeries and promote complete restoration of the injury. Some requirements for an ideal wound dressing are rapid hemostatic effect, high swelling capacity, antibacterial properties, biocompatibility, biodegradability, and mechanical strength. However, finding all these properties in a single material remains a challenge. In this context, nanocomposites have demonstrated an excellent capacity for this application because of their multifunctionality. One of the emerging materials used in nanocomposite manufacture is cellulose nanocrystals (CNCs), which are rod-like crystalline nanometric structures present on cellulose chains. These nanoparticles are attractive for wound healing applications because of their high aspect ratio, high mechanical properties, functionality and low density. Hence, this work aimed to present an overview of nanocomposites constituted by CNCs for wound healing applications. The review focuses on the most common materials used as matrices, the types of dressing, and their fabrication techniques. Novel wound dressings composites have improved hemostatic, swelling, and mechanical properties compared to other pure biopolymers while preserving their other biological properties. Films, nanofibers mats, sponges, and hydrogels have been prepared with CNCs nanocomposites, and in vitro and in vivo tests have proved their suitability for wound healing.

Photocatalytic degradation of Reactive Blue 21 dye using ZnO nanoparticles: experiment, modelling, and sensitivity analysis.

This paper presents the photocatalysis, adsorption, and photolysis of C.I. Reactive Blue 21 dye using synthesized zinc oxide nanoparticles. The density, mean particle diameter, surface area, and porosity of the catalyst were 5550 kg/m3, 1.19 × 10-7, 16,830 m2/kg, and 0.08, respectively. The impact of catalyst mass per volume of solution (0.2-1.0 kg/m3) was experimentally investigated in terms of the percentage of dye degradation. Due to the small catalyst porosity, adsorption contributed little to overall degradation. However, the photolysis of the dye was around 12.5%, which occurred predominantly between 0 and 5 min. In the second part of the present study, the photocatalytic degradation of C.I. Reactive Blue 21 was modelled mathematically based on the mass conservation law in the solution and catalyst. The model had two adjustable variables: the convection mass transfer coefficient and the photocatalytic reaction rate constant. The model was solved numerically using the finite difference method and was validated with the experimental data. The validated model was employed to examine the impact of catalyst size and initial pollutant concentration on the photocatalytic degradation.

Carboxymethyl cellulose production from sugarcane bagasse with steam explosion pulping: Experimental, modeling, and optimization.

The sugarcane bagasse was used for producing carboxymethyl cellulose (CMC) and obtaining high-molecular-mass hemicellulose as co-product. To this end, the steam explosion process was employed. It was found that the optimum operating conditions are the temperature of 187.15°C, NaOH/bagasse ratio of 39% (w/w), and retention time (RT) of 10min. Next, the obtained cellulose in the optimized condition was extracted and purified, and it was subsequently converted to CMC according to Williamson etherification technique. This paper also employed response surface methodology (RSM) to model effective factors against a degree of substitution (DS). Based on it, the optimum values of independent variables are the NaOH concentration of 28.4%, MCA mass of 1.14gram, temperature of 57.85°C, and reaction time of 4.01h which the CMC had the DS of 1.085, the yield of 181.302%, purity of 71.6%, and crystallinity of 30.1% with low viscosity. Samples comparatively studied by FT-IR, TGA and XRD.