Ag Nanoparticle/Nanofibrillated Cellulose Composite as an Effective and Green Catalyst for Reduction of 4-Nitrophenol

Synthesis and catalytic activity of silver- reduced graphene oxide and silver- magnetite- reduced graphene oxide nanocomposites in the reduction of 4-nitrophenol

The catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is vital for environmental remediation. This study synthesizes and assesses silver-reduced graphene oxide (Ag/rGO) and silver-magnetite-reduced graphene oxide (Ag/Fe2O4/rGO) nanocomposites for 4-NP reduction. Various reducing agents-ascorbic acid (AA), hydrazine hydrate (HH), sodium borohydride (SBH), and cellulose nanofibers (NFC)-were employed under reflux (R), hydrothermal (H), and ultrasonic (U) conditions. Drying methods (oven-drying (O) and freeze-drying (F)) and CTAB as a stabilizer were explored to optimize Ag NP distribution. The nanocomposites were characterized using FT-IR, XRD, FE-SEM, EDS, TEM, BET, TGA, ICP-OES, and VSM. XRD confirmed Ag NP formation with crystallite sizes of 12-23 nm. FE-SEM and TEM showed uniform distribution of cubic Fe2O4 and spherical Ag NPs (approximately 50 nm) on GO. The Ag/Fe2O4/rGO(O)-AA-U-F nanocomposite demonstrated the highest catalytic activity, with a pseudo-first-order rate constant (k) of 1.81 min-1 and a specific activity parameter (k') of 180.77 min-1.g-1. This nanocomposite exhibited a mesoporous structure with a high specific surface area (226.9 m2/g) and uniform Ag and Fe2O4 nanoparticle distribution on rGO. The combination of ascorbic acid (AA) and freeze-drying (F) yielded nanocomposites with superior catalytic performance due to their porous structure and uniform nanoparticle dispersion.

Nanocellulose/Nanoporous Silicon Composite Films as a Drug Delivery System

Nanocellulose (NC) is a promising material for drug delivery due to its high surface area-to-volume ratio, biocompatibility, biodegradability, and versatility in various formats (nanoparticles, hydrogels, microspheres, membranes, and films). In this study, nanocellulose films were derived from "Bolaina blanca" (Guazuma crinita) and combined with nanoporous silicon microparticles (nPSi) in concentrations ranging from 0.1% to 1.0% (w/v), using polyvinyl alcohol (PVA) as a binding agent to create NC/nPSi composite films for drug delivery systems. The physicochemical properties of the samples were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The mechanical properties and drug release capabilities were also evaluated using methylene blue (MB) as an antibacterial drug model. Antibacterial assays were conducted against S. aureus and E. coli bacteria. The results show that NC/nPSi composites with 1% nPSi increased the T50% by 10 °C and enhanced mechanical properties, such as a 70% increase in the elastic modulus and a 372% increase in elongation, compared to NC films. Additionally, MB released from NC/nPSi composites effectively inhibited the growth of both bacteria. It was also observed that the diffusion coefficients were inversely proportional to the % nPSi. These findings suggest that this novel NC/nPSi-based material can serve as an effective controlled drug release system.

Synthesis of bacterial cellulose nanofibers/Ag nanoparticles: Structure, characterization and antibacterial activity

The aim of this study was to compare the characterization of bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) obtained by three different pretreatment methods of BCNs (no pretreatment, sodium hydroxide activation pretreatment and TEMPO-mediated oxidation pretreatment), which were recoded as N-BCNs/Ag nanoparticles, A-BCNs/Ag nanoparticles and O-BCNs/Ag nanoparticles, respectively. The results of scanning electron microscopy and transmission electron microscopy showed the prepared Ag nanoparticles by three different pretreatment methods were spherical and dispersed on the surface of BCNs, while the Ag nanoparticles in O-BCNs/Ag nanoparticles displayed the smallest diameter with a value of 20.25 nm and showed the most uniform dispersion on the surface of BCNs. The ICP-MS result showed O-BCNs/Ag nanoparticles had the highest content of Ag nanoparticles with a value of 2.98 wt%, followed by A-BCNs/Ag nanoparticles (1.53 wt%) and N-BCNs/Ag nanoparticles (0.84 wt%). The cytotoxicity assessment showed that the prepared BCNs/Ag nanoparticles were relatively safe. Furthermore, the O-BCNs/Ag nanoparticles had the best antioxidant and antibacterial activities as compared with the other two types of BCNs/Ag nanoparticles, where O-BCNs/Ag nanoparticles destroyed the structure of bacterial cell membranes to lead the leakage of intracellular components. This study showed that O-BCNs/Ag nanoparticles as antibacterial agents have great potential in food packaging.

Zwitterionic peptide-functionalized highly dispersed carbon nanotubes for efficient wastewater treatment

Multi-walled carbon nanotubes (MWCNTs) have displayed great potential as catalyst carriers due to their nanoscale structure and large specific surface area. However, their hydrophobicity and poor dispersibility in water restrict their applications in aqueous environments. Herein, the dispersibility of MWCNTs was significantly enhanced with a chimeric protein MPKE which consisted of a zwitterionic peptide unit and a mussel adhesive protein unit. The MPKE could be easily attached to MWCNTs (MPKE-MWCNTs) by a simple stirring process due to the versatile adhesion ability of mussel adhesive unit. As expected, the MPKE-MWCNTs displayed outstanding dispersibility in water (>7 months), as well as in alkaline solutions (pH = 12) and organic solvents (DMSO and ethanol) due to the hydrophilicity of the zwitterionic peptide unit. Moreover, the MPKE-MWCNTs were used as silver nanoparticle carriers for the reduction of 4-nitrophenol in wastewater, with the normalized rate constant k_nor up to 32.9 s^-1 mmol^-1. Meanwhile, they also exhibited excellent biocompatibility and antibacterial activity, which were favorable for wastewater treatment. This work provides a facile strategy for MWCNT modification, functionalization and applications in aqueous environments.

Evaluation of the multifunctional activity of silver bionanocomposites in environmental remediation and inhibition of the growth of multidrug-resistant pathogens

Imperata cylindrica cellulose supported Ag bionanocomposites purified industrial water and controlled the contagious diseases with high potential activity.

Carboxylcellulose hydrogel confined-Fe3O4 nanoparticles catalyst for Fenton-like degradation of Rhodamine B

Facile preparation of functional hydrogel materials for environmental catalysis is a hot research topic of soft materials science and green catalysis. In this study, a carboxylcellulose hydrogel confined Fe₃O₄ nanoparticles composite catalyst (Fe₃O₄@CHC) with magnetic recyclability has been synthesized by taking the advantages of the newly developed cellulose solution in tetramethyl guanidine/DMSO/CO₂ through in situ acylation using mixed cyclic anhydrides and ion exchange reaction. The achieved Fe₃O₄@CHC hydrogel catalyst was shown to be an more efficient and better Fenton-like catalyst for decomposition of the organic dye rhodamine B (RhB) in the presence of hydrogen peroxide, with almost complete decomposition occurring within 180 min, in comparison with Fe₃O₄@cellulose hydrogel (CH) with excellent recyclability. This work provided a facile strategy for the preparation of hydrogel-based functional composite green catalytic materials, which has potential applications in green catalysis.

Chronicle of Nanocelluloses (NCs) for Catalytic Applications: Key Advances

Nanocellulose (NC) is a biomaterial with growing interest in the field of nanocomposites and sustainable materials. NC has various applications including biodegradable materials, reinforcing agents, packaging films, transpiring membranes and medical devices. Among the many applications, the use of NC functionalized with organic and inorganic groups has found wide use as a catalyst in chemical transformations. The goal of this review is to collect the current knowledge on its catalytic applications for chemical groups conversion. We have chosen to organize the manuscript according to subdivision of NC into Bacterial Nanocellulose (BNC), Cellulose Nanocrystals (CNCs), and Cellulose Nanofibers (CNFs) and their role as inorganic- and organic-functionalized NC-catalysts in organic synthesis. However, in consideration of the fact that the literature on this field is very extensive, we have decided to focus our attention on the scientific productions of the last five years.