The transformations of cellulose after concentrated sulfuric acid treatment and its impact on the enzymatic saccharification

Multifunctional composite films with regenerated cellulose prepared via acid-catalytic degradation for in-situ growth of ZnO

Regenerated cellulose is extensively utilized as a natural polymer due to its actually natural piezoelectric properties as well as renewable properties, but suffers from processing difficulties and low piezoelectric constants (d33). Consequently, this work focuses on controlling the molecular weight of regenerated cellulose through pretreatment methods that promote the growth of in situ ZnO to enhance its d33. Firstly, the acid-catalyzed pulp fibers (PF) and zinc nitrate hexahydrate were added in NaOH/urea solvent to effectively prepare RC/ZnO composite film via regeneration and in-situ growth. The effects of the acid-catalytic degradation on the solubility of PF, the structure of RC, and the RC/ZnO composite film were systematically discussed. It is found that the hydrogen bond network structure in the RC/ZnO composite film prepared by 1.5 % ~ 6 h treated PF is the most regular, where the ZnO is well combined with substrate and dispersed evenly, and the d33 is up to 34.99 pm/V. Therefore, the maximum open-circuit voltage of the prepared piezoelectric generator (PEG) reaches 5 V. On this basis, a piezoelectric sensing system is developed, displaying portable and accurate detection performance to human movement. This work provides insights and ideas for the development and design of cellulose and ZnO composites.

A Study on the Preparation and Performance of Ultrafine Powder Made of Industrial Hemp Degumming Residue

Industrial hemp, one of the most widely available and extensively produced varieties, generates a substantial amount of waste in the form of hemp cellulose. This study uses a recycling method combining crushing and acid treatment to convert leftover hemp fiber into ultrafine powder. A scanning electron microscope (SEM), an atomic force microscope (AFM), Fourier transform infra-red spectroscopy (FTIR), and X-ray diffraction (XRD) were used to examine the morphology of acid-treated hemp fiber heated to 200 °C and crushed into powder. The decrease in intensity, fiber surface crystalline, and grain size was analyzed. It became apparent that fiber strength decreased, and fiber roughness significantly increased after acid treatment. The degree of crystallinity of the broken fibers decreased significantly. The proposed method was a simple and effective method for converting leftover hemp fiber into ultrafine powder. In approximately 3 to 5 min, about 1 kg of dry ultrafine powder with a particle size of 38.68 μm was produced. This production method will significantly enhance future industrial applications of hemp residue.

Surface modification of cellulose nanocrystals for biomedical and personal hygiene applications

The increasing demand for sustainable and effective materials in biomedical and personal hygiene applications has driven the exploration of cellulose nanocrystals (CNCs) derived from biomass. These nanomaterials are highly valued for their exceptional mechanical properties, biocompatibility, and renewable nature. Researchers are exploring CNCs for advancing medical and hygiene products, but surface modification is often needed to maximize their benefits. Techniques such as chemical functionalization, physical coating, and hybridization can significantly enhance CNCs dispersibility, stability, and interaction with biological systems. This versatility makes CNCs suitable for a variety of applications, including drug delivery systems, wound dressings, and personal hygiene products. Despite their advantages, maintaining the inherent properties of CNCs while integrating new functionalities through modification poses a challenge. Understanding the impact of various modification techniques on CNC performance is crucial for optimizing their effectiveness. This review aimed to consolidate current knowledge on the surface modification of biomass-derived CNCs, offering insights into different methods and their implications for biomedical and personal hygiene applications. By highlighting advancements, challenges, and prospects, it served as a crucial resource for advancing the development and application of CNCs in these critical fields.

Mechanically strong micro-nano fibrillated cellulose paper with improved barrier and water-resistant properties for replacing plastic

Replacing nonbiodegradable plastics with environmentally friendly cellulose materials has emerged as a key trend in environmental protection. This study highlights the development of a strong and hydrophobic micro-nano fibrillated cellulose paper (MNP) through the incorporation of micro-nano fibrillated cellulose fiber (MNF) and chitin nanocrystal (Ch), followed by the impregnation of polymethylsiloxane (PMHS). A low-acid, heat-assisted colloidal grinding strategy was employed to prepare MNF with a high aspect ratio effectively. Ch was incorporated as a reinforcing matrix into the cellulose fiber scaffold through straightforward mechanical mixing and mechanical hot-pressing treatments. Compared to pure MNP, the 5Ch-MNP exhibited a 25 % improvement in tensile strength, reaching 170 MPa, and showed enhanced barrier properties against oxygen and water vapor. The impregnation of PMHS rapidly confers environmentally resistant hydrophobic properties to 1 % PMHS-5Ch-MNP, leading to a water contact angle exceeding 112°, and a 290 % increase in tensile strength under wet conditions. Additionally, the paper demonstrated excellent antibacterial adhesion properties, with the adhesion rates for E. coli and S. aureus exceeding 98 %. This study successfully produced functional cellulose paper with remarkable mechanical properties and barrier properties, as well as hydrophobicity, using a simple, efficient, and environmentally friendly method, making it a promising substitute for petroleum-based plastics.

Intensifying urban imprint on land surface warming: Insights from local to global scale

Increasing urbanization exacerbates surface energy balance perturbations and the health risks of climate warming; however, it has not been determined whether urban-induced warming and attributions vary from local, regional, to global scale. Here, the local surface urban heat island (SUHI) is evidenced to manifest with an annual daily mean intensity of 0.99°C-1.10°C during 2003-2018 using satellite observations over 536 cities worldwide. Spatiotemporal patterns and mechanisms of SUHI tightly link with climate-vegetation conditions, with regional warming effect reaching up to 0.015°C-0.138°C (annual average) due to surface energy alterations. Globally, the SUHI footprint of 1,860 cities approximates to 1% of the terrestrial lands, about 1.8-2.9 times far beyond the urban impervious areas, suggesting the enlargements of the imprint of urban warming from local to global scales. With continuous development of urbanization, the implications for SUHI-added warming and scaling effects are considerably important on accelerating global warming.

Emerging horizons and prospects of polysaccharide-constructed gels in the realm of wound healing

Polysaccharides, with the abundant availability, biodegradability, and inherent safety, offer a vast array of promising applications. Leveraging the remarkable attributes of polysaccharides, biomimetic and multifunctional hydrogels have emerged as a compelling avenue for efficacious wound dressing. The gels emulate the innate extracellular biomatrix as well as foster cellular proliferation. The distinctive structural compositions and profusion of functional groups within polysaccharides confer excellent physical/chemical traits as well as distinct restorative involvements. Gels crafted from polysaccharide matrixes serve as a robust defense against bacterial threats, effectively shielding wounds from harm. This comprehensive review delves into wound physiology, accentuating the significance of numerous polysaccharide-based gels in the wound healing context. The discourse encompasses an exploration of polysaccharide hydrogels tailored for diverse wound types, along with an examination of various therapeutic agents encapsulated within hydrogels to facilitate wound repair, incorporating recent patent developments. Within the scope of this manuscript, the perspective of these captivating gels for promoting optimal healing of wounds is vividly depicted. Nevertheless, the pursuit of knowledge remains ongoing, as further research is warranted to bioengineer progressive polysaccharide gels imbued with adaptable features. Such endeavors hold the promise of unlocking substantial potential within the realm of wound healing, propelling us toward multifaceted and sophisticated solutions.