Comparison of structural, thermal and proton conductivity properties of micro- and nanocelluloses

A High-Proton Conductivity All-Biomass Proton Exchange Membrane Enabled by Adenine and Thymine Modified Cellulose Nanofibers

Nanocellulose fiber materials were considered promising biomaterials due to their excellent biodegradability, biocompatibility, high hydrophilicity, and cost-effectiveness. However, their low proton conductivity significantly limited their application as proton exchange membranes. The methods previously reported to increase their proton conductivity often introduced non-biodegradable groups and compounds, which resulted in the loss of the basic advantages of this natural polymer in terms of biodegradability. In this work, a green and sustainable strategy was developed to prepare cellulose-based proton exchange membranes that could simultaneously meet sustainability and high-performance criteria. Adenine and thymine were introduced onto the surface of tempo-oxidized nanocellulose fibers (TOCNF) to provide many transition sites for proton conduction. Once modified, the proton conductivity of the TOCNF membrane increased by 31.2 times compared to the original membrane, with a specific surface area that had risen from 6.1 m²/g to 86.5 m²/g. The wet strength also increased. This study paved a new path for the preparation of environmentally friendly membrane materials that could replace the commonly used non-degradable ones, highlighting the potential of nanocellulose fiber membrane materials in sustainable applications such as fuel cells, supercapacitors, and solid-state batteries.

Mechanochemically functionalized and fibrillated microcrystalline cellulose as a filler in silicone foam: An integrated experimental and simulation investigation

Fibrillated celluloses have gained significant attention due to their exceptional mechanical properties and eco-friendly characteristics, which make them suitable for various applications. In this study, we designed a precise approach for producing highly fibrillated microcrystalline cellulose (MCC) via ball-milling treatment using four typical silane coupling agents. The empirical data demonstrate that the fibrillization of MCC and the properties of fibrillated MCC are largely affected by the size and geometry of the functional groups of the silanes. After ball-milling, most MCC displayed enhanced e-beam tolerance and thermal stability, whereas the silane loading amount, surface area, and morphology of fibrillated MCC appeared to be random, which was exemplified by the proportional and non-proportional relationship between the loading amount and surface area of methyl silane- and phenyl silane-treated MCC, respectively. Density functional theory calculations and molecular dynamics simulations were employed to obtain the intricate details. The simulation results were in agreement with the experimental results. Finally, fibrillated MCC was incorporated into silicone foams as an additive. The thermal stability of fibrillated MCC with added silicone was greatly improved, and the tensile strength of fibrillated MCC-containing silicone foam was 44.1 and 5.4 times higher than that of the neat and MCC-containing silicone foams, respectively.

Insight into the effect of different nanocellulose types on protein-based bionanocomposite film properties

This paper investigates the effect of five different types of nanocellulose on the properties of protein-based bionanocomposite films (PBBFs) and the mechanism of action. The results show that TEMPO-oxidized nanocellulose (TNC) PBBFs have the smoothest surface structure. This is because some hydroxyl groups in TNC are converted to carboxyl groups, increasing hydrogen bonding and cross-linking with proteins. Bacterial nanocellulose (BNC) PBBFs have the highest crystallinity. Filamentous BNC can form an interlocking network with protein, promoting effective stress transfer in the PBBFs with maximum tensile strength. The PBBFs of lignin nanocellulose (LNC) have superior elasticity due to the presence of lignin, which gives them the greatest creep properties. The PBBFs of cellulose nanocrystals (CNCs) have the largest water contact angle. This is because the small particle size of CNC can be uniformly distributed in the protein matrix. The different types of nanocellulose differ in their microscopic morphology and the number of hydroxyl groups and hydrogen bonding sites on their surfaces. Therefore, there are differences in the spatial distribution and the degree of intermolecular cross-linking of different types of nanocellulose in the protein matrix. This is the main reason for the differences in the material properties of PBBFs.

Composite optimization and characterization of dietary fiber-based edible packaging film reinforced by nanocellulose from grapefruit peel pomace

The development of edible packaging films was motivated due to resource waste and environmental damage caused by chemically produced plastic packaging. The development of edible packaging film based on grapefruit peel pomace dietary fiber has significant technological and functional potential because grapefruit processing waste is a potential source of high-quality dietary fiber. In this study, the first successful development of an edible packaging film based on dietary fiber using grapefruit soluble dietary fiber (GSDF) from grapefruit peel pomace as a substrate and nanocellulose (GNCC) as a filler was developed. Principal component analysis, membership function synthesis, and response surface methods were used to determine the optimal process to prepare the edible packaging films, and the impact of GNCC on this material was analyzed. The results showed that the overall performance score of the edible packaging film with 1 wt% GNCC was 0.764. The maximum pyrolysis temperature increased from 226.36 °C to 227.10 °C, the melting temperature (Tm) increased by 5.54 °C, the crystallinity increased by 2.95 %. The film solution exhibited non-Newtonian characteristics and a solid-like property. Our results showed that the edible packaging film developed from grapefruit peel pomace and dietary fiber could have several potential applications in the food packaging field.

Interaction of the lignin-/cellulose-derived char with volatiles of varied origin: Part of the process for evolution of products in pyrolysis

The interaction between volatiles and homologous and/or heterologous char is almost inevitable during the transfer or diffusion of volatiles from inner core to outer surface of a biomass particle in pyrolysis. This shapes both composition of volatiles (bio-oil) and property of char. In this study, the potential interaction of lignin- and cellulose-derived volatiles with char of varied origin was investigated at 500 °C. The results indicated that both the lignin- and cellulose-char promoted polymerization of the lignin-derived phenolics, enhancing production of bio-oil by ca. 20%-30%, generating more heavy tar but suppressing gases formation, especially over cellulose-char. Conversely, the char catalysts, especially the heterologous lignin-char, promoted cracking of the cellulose-derivatives, producing more gases while less bio-oil and heavy organics. Additionally, the volatiles-char interaction also led to gasification of some organics and also aromatization of some organics on surface of char, resulting in enhanced crystallinity and thermostability of the used char catalyst, especially for the lignin-char. Moreover, the substance exchange and formation of carbon deposit also blocked pores and formed fragmented surface dotted with particulate matters in the used char catalysts.

Understanding Nanocellulose-Water Interactions: Turning a Detriment into an Asset

Modern technology has enabled the isolation of nanocellulose from plant-based fibers, and the current trend focuses on utilizing nanocellulose in a broad range of sustainable materials applications. Water is generally seen as a detrimental component when in contact with nanocellulose-based materials, just like it is harmful for traditional cellulosic materials such as paper or cardboard. However, water is an integral component in plants, and many applications of nanocellulose already accept the presence of water or make use of it. This review gives a comprehensive account of nanocellulose-water interactions and their repercussions in all key areas of contemporary research: fundamental physical chemistry, chemical modification of nanocellulose, materials applications, and analytical methods to map the water interactions and the effect of water on a nanocellulose matrix.

Sustainable Plant-Based Biopolymer Membranes for PEM Fuel Cells

Carboxycellulose nanofibers (CNFs) promise to be a sustainable and inexpensive alternative material for polymer electrolyte membranes compared to the expensive commercial Nafion membrane. However, its practical applications have been limited by its relatively low performance and reduced mechanical properties under typical operating conditions. In this study, carboxycellulose nanofibers were derived from wood pulp by TEMPO oxidation of the hydroxyl group present on the C6 position of the cellulose chain. Then, citric acid cross-linked CNF membranes were prepared by a solvent casting method to enhance performance. Results from FT-IR spectroscopy, ¹³C NMR spectroscopy, and XRD reveal a chemical cross-link between the citric acid and CNF, and the optimal fuel cell performance was obtained by cross-linking 70 mL of 0.20 wt % CNF suspension with 300 µL of 1.0 M citric acid solution. The membrane electrode assemblies (MEAs), operated in an oxygen atmosphere, exhibited the maximum power density of 27.7 mW cm^-2 and the maximum current density of 111.8 mA cm^-2 at 80 °C and 100% relative humidity (RH) for the citric acid cross-linked CNF membrane with 0.1 mg cm^-2 Pt loading on the anode and cathode, which is approximately 30 times and 22 times better, respectively, than the uncross-linked CNF film. A minimum activation energy of 0.27 eV is achieved with the best-performing citric acid cross-linked CNF membrane, and a proton conductivity of 9.4 mS cm^-1 is obtained at 80 °C. The surface morphology of carboxycellulose nanofibers and corresponding membranes were characterized by FIB/SEM, SEM/EDX, TEM, and AFM techniques. The effect of citric acid on the mechanical properties of the membrane was assessed by tensile strength DMA.

Micronized cellulose from citrus processing waste using water and electricity only

Along with a water-soluble fraction rich in pectin, the hydrodynamic cavitation of citrus processing waste carried out in water demonstrated directly on semi-industrial scale affords an insoluble fraction consisting of micronized cellulose of low crystallinity ("CytroCell"). Lemon and grapefruit CytroCell respectively consist of 100-500 nm wide cellulose nanorods, and of 500-1000 nm wide ramified microfibrils extending for several μm. These findings establish a technically viable route to low crystallinity micronized cellulose laying in between nano- and microcellulose, using water and electricity only.

Recycling of Brewer's Spent Grain as a Biosorbent by Nitro-Oxidation for Uranyl Ion Removal from Wastewater

Developing biosorbents derived from agro-industrial biomass is considered as an economic and sustainable method for dealing with uranium-contaminated wastewater. The present study explores the feasibility of oxidizing a representative protein-rich biomass, brewer's spent grain (BSG), to an effective and reusable uranyl ion adsorbent to reduce the cost and waste generation during water treatment. The unique composition of BSG favors the oxidation process and yields in a high carboxyl group content (1.3 mmol/g) of the biosorbent. This makes BSG a cheap, sustainable, and suitable raw material independent from pre-treatment. The oxidized brewer's spent grain (OBSG) presents a high adsorption capacity of U(VI) of 297.3 mg/g (c 0(U) = 900 mg/L, pH = 4.7) and fast adsorption kinetics (1 h) compared with other biosorbents reported in the literature. Infrared spectra (Fourier transform infrared), 13C solid-state nuclear magnetic resonance spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis were employed to characterize the biosorbents and reveal the adsorption mechanisms. The desorption and reusability of OBSG were tested for five cycles, resulting in a remaining adsorption of U(VI) of 100.3 mg/g and a desorption ratio of 89%. This study offers a viable and sustainable approach to convert agro-industrial waste into effective and reusable biosorbents for uranium removal from wastewater.

Spin diffusion transfer difference (SDTD) NMR: An advanced method for the characterisation of water structuration within particle networks

HYPOTHESIS

The classical STD NMR protocol to monitor solvent interactions in gels is strongly dependent on gelator and solvent concentrations and does not report on the degree of structuration of the solvent at the particle/solvent interface. We hypothesised that, for suspensions of large gelator particles, solvent structuration could be characterised by STD NMR when taking into account the particle-to-solvent ¹H-¹H spin diffusion transfer using the 1D diffusion equation.

EXPERIMENTS

We have carried out a systematic study on effect of gelator and solvent concentrations, and gelator surface charge, affecting the behaviour of the classical STD NMR build-up curves. To do so, we have characterised solvent interactions in dispersions of starch and cellulose-like particles prepared in deuterated water and alcohol/D₂O mixtures.

FINDINGS

The Spin Diffusion Transfer Difference (SDTD) NMR protocol is independent of the gelator and solvent concentrations, hence allowing the estimation of the degree of solvent structuration within different particle networks. In addition, the simulation of SDTD build-up curves using the general one-dimensional diffusion equation allows the determination of minimum distances (r) and spin diffusion rates (D) at the particle/solvent interface. This novel NMR protocol can be readily extended to characterise the solvent(s) organisation in any type of colloidal systems constituted by large particles.

Protection of agarwood essential oil aroma by nanocellulose-graft-polylactic acid

Essential oil products are often volatile, and their aromas cannot be effectively preserved over long periods of time. In this study, nanocellulose crystals were modified, and an amphiphilic copolymer was prepared by ring-opening polymerisation to produce wall materials. A nanocellulose crystal-grafted polylactic acid copolymer was successfully synthesised and characterised using nuclear magnetic resonance spectrometry, Fourier transform infrared spectrometry, X-ray diffraction, and thermogravimetric analysis. Because of the amphiphilic properties of the synthesised copolymer, an agarwood essential oil nanoemulsion system was prepared. Using transmission electron microscopy and dynamic laser light scattering, the nanoemulsion was observed to have an apparent shell-core structure. The nanoemulsion was uniformly distributed, and the system had good stability. Finally, the electronic nose results showed that the nanocellulose crystal-grafted polylactic acid copolymer micelle effectively protected agarwood essential oil aromas.

Direct ink writing of aloe vera/cellulose nanofibrils bio-hydrogels

Direct-ink-writing (DIW) of hydrogels has become an attractive research area due to its capability to fabricate intricate, complex, and highly customizable structures at ambient conditions for various applications, including biomedical purposes. In the current study, cellulose nanofibrils reinforced aloe vera bio-hydrogels were utilized to develop 3D geometries through the DIW technique. The hydrogels revealed excellent viscoelastic properties enabled extruding thin filaments through a nozzle with a diameter of 630 μm. Accordingly, the lattice structures were printed precisely with a suitable resolution. The 3D-printed structures demonstrated significant wet stability due to the high aspect ratio of the nano- and microfibrils cellulose, reinforced the hydrogels, and protected the shape from extensive shrinkage upon drying. Furthermore, all printed samples had a porosity higher than 80% and a high-water uptake capacity of up to 46 g/g. Altogether, these fully bio-based, porous, and wet stable 3D structures might have an opportunity in biomedical fields.

Preparation and characterization of carboxymethyl cellulose-based composite films reinforced by cellulose nanocrystals derived from pea hull waste for food packaging applications

Pea hull is a renewable, readily available and abundant agricultural waste whose high-value utilization deserves more attentions. This work aimed at the isolation of cellulose nanocrystals (CNC) from pea hull and evaluation its reinforcement capability for carboxymethyl cellulose (CMC) film. The obtained CNC displayed needle-like shapes with length of 81-286 nm, diameter of 8-21 nm, aspect ratio of 16 and crystallinity index of 0.77. The effects of CNC content on the morphologies, optical, mechanical, water vapor barrier and thermal properties of CMC/CNC films were investigated. SEM images showed that the CNC was evenly distributed in the CMC matrix to form homogenous films when the content of CNC was ≤5 wt%. The CMC/CNC composite films showed improved UV barrier, mechanical strength, water vapor barrier and thermal stability. Compared with pure CMC film, an increase of 50.8% in tensile strength and a decrease of 53.4% in water vapor permeability were observed for 5 wt% CNC-reinforced composite film. Furthermore, 5 wt% CNC-reinforced composite film was used for red chilies packaging, which is very effective at reducing weight loss and maintaining vitamin C compared with uncoated red chilies. These results indicated that the CMC/CNC composite film may have promising application potential as edible food packaging material.

Investigation of the thermal and conductive properties of oxalic acid salts with planar and undulating proton-conducting layers

The physical properties of two proton conductors 1H-1,2,4-triazol-4-ium hydrogen oxalate (TriOX) and 1H-imidazol-3-ium hydrogen oxalate (ImiOX) were investigated.

Nanocellulose applications in sustainable electrochemical and piezoelectric systems: A review

Recent studies advocate the use of cellulose nanomaterials (CNs) as a sustainable carbohydrate polymer in numerous innovative electronics for their quintessential features such as flexibility, low thermal expansion and self-/directed assembly within multiphase matrices. Herein, we review the contemporary advances in CN-built electrochemical systems and highlight the constructive effects of these nanoscopic entities once engineered in conductive composites, proton exchange membranes (PEMs), electrochromics, energy storage devices and piezoelectric sensors. The adopted strategies and designs are discussed in view of CN roles as copolymer, electrolyte reservoir, binder and separator. Finally, physiochemical attributes and durability of resulting architectures are compared to conventional materials and the possible challenges/solutions are delineated to realize the promising capabilities. The volume of the up-to-present literature in the field indeed implies to nanocellulose overriding importance and the presented angles perhaps shed more lights on prospect of the biosphere's most dominant biomaterial in the energy-related arena that deserve attention.