On the use of microwave pretreatment to assist zero-waste chemical-free production process of nanofibrillated cellulose from lime residue

The influence of residual pectin composition and content on nanocellulose films from ramie fibers: Micro-nano structure and physical properties

In this study, cellulose nanofibril (CNF) films from ramie fibers were prepared with different pectin compositions and contents, and the influence of residual pectin on the overall performances of CNF films was evaluated. There was no significant effect of the residual pectin composition on the properties of obtained CNF films. However, when the content of residual pectin was increased from 0.45 % to 9.16 %, the surface area and water absorption of CNF films were increased from 0.2223 to 0.3300 m2/g, and from 93.51 % to 122.42 %, respectively. Pectin covers the CNF surface and act as a physical barrier between the cellulose fibrils; thus the nanocellulose films with high pectin content will have a loose and porous structure, resulting in a high surface area and a high water absorption. Besides, with the residual pectin content decreasing from 9.16 % to 0.45 %, the UVA light transmittance and tensile strength of CNF films were increased from 30.6 % to 59.9 %, and from 37.67 to 100.26 MPa, respectively. After removal of amorphous pectins in CNFs, the low pectin containing CNFs are able to pack more compactly to form a strong and thin film. This paper provides guidance for the preparation of CNF films with different performance requirements.

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.

Production of salad dressings via the use of economically prepared cellulose nanofiber from lime residue as a functional ingredient

Production of cellulose nanofiber (CNF) via the use of a more economical and less energy-intensive means is desirable. Once formed, it is necessary to determine whether or not the prepared CNF would be capable of forming a Pickering emulsion as in the case of traditionally prepared nanofiber. In the present study, oil-in-water emulsions, namely, salad dressings, with CNF as a functional ingredient, were prepared. Lime residue powder as the source of dietary fiber was subject to high-shear homogenization to form CNF suspension, which was then mixed with other ingredients. Different contents of fat (20%-40%), egg yolk (0%-4%), and lime residue powder (0%-4%) were tested. The formed CNF successfully acted as a Pickering emulsifier and allowed the production of salad dressings with desirable characteristics at 30%-40% fat, 2% egg yolk, and 2% lime residue powder. The dressings exhibited adequate physicochemical properties and remained stable throughout the storage period of 28 days. PRACTICAL APPLICATION: The presently proposed means would allow the industry to produce cellulose nanofiber (CNF) in a more economical and less energy-intensive manner. The so-produced CNF exhibits comparable properties as traditionally prepared nanofiber and can be used as a stabilizer in food emulsions.

Microwave-assisted synthesis of polyethylenimine-grafted nanocellulose with ultra-high adsorption capacity for lead and phosphate scavenging from water

Herein, polyethylenimine-grafted nanocellulose (PEI_MW@NC_MW) was synthetized through microwave-assisted synthesis, which was employed for Pb(II) and phosphate scavenging from water. Characterization results exhibited that the original pomegranate peel-derived cellulose could be transformed to nanometer level by microwave radiation and the amino groups were successfully grafted on the nanocellulose evenly. The adsorption performance of PEI_MW@NC_MW possessed outstanding improvements over that of original nanocellulose with maximum adsorption capacities reaching 916.02 mg/g for Pb(II) and 278.89 mg/g for phosphate. Furthermore, the PEI_MW@NC_MW had high tolerance to various co-existing ions and could maintain over 94% removal efficiency during four regeneration cycles. Additionally, the Pb(II) uptake onto PEI_MW@NC_MW was associated with electrostatic attraction, complexation and pore-filling, whereas high phosphate capture was achieved via H-bonding, complexation and electrostatic attraction. In summary, PEI_MW@NC_MW was deemed as a potential adsorbent with excellent adsorption capacity for remediation of Pb(II) and phosphate polluted water.

Micro- and nanocelluloses from non-wood waste sources; processes and use in industrial applications

In addition to renewability and abundance, nanocellulose materials have tremendous (and variable) properties for different applications, ranging from bulk applications, such as paper and packaging reinforcement, to emerging high added-value applications, such as substrates for optoelectronics. Lignocellulosic biomass from agricultural and industrial waste sources is readily available and shows great promise as an inexpensive and sustainable raw material for nanocellulose production. However, the understanding of the potential of using non-wood based biowaste sources is not established and systematic comparisons of versatile agricultural and industrial waste sources can elucidate this complex topic. Here we present an overview of the most studied and most promising sources from agro-industrial waste, the processes to convert them into nanocellulose, some of the established and emerging applications, and discuss the advancements that are still needed for large-scale production. Sugarcane bagasse and oil palm empty fruit bunch have been the most researched waste-based sources for nanocellulose production and demonstrate the most promise due to availability and access. Industrial sources seem to have advantages over agricultural sources in collectability and ease of access. This work gives insight on the potential and the challenges of nanocellulose production from waste sources and discusses how the criteria set for nanocellulose materials in different applications can be met, thus opening new routes for circular economy.

Interest of Pickering Emulsions for Sustainable Micro/Nanocellulose in Food and Cosmetic Applications

In the present review, natural and non-toxic particles made of micro/nanocellulose were specifically targeted as stabilizers of emulsions located at dispersed and continuous phases interfaces (called Pickering Emulsions, PEs). PEs are biphasic systems stabilized by solid particles with a recent interest in food and cosmetic domains. PEs have been more and more studied in the last ten years due to their advantages compared to conventional emulsions with surfactants. PEs have already been stabilized with various types of particles and particularly cellulose. Even if some studies showed that PEs were more stable when cellulose was chemically modified, numerous other recent studies showed that unmodified micro/nanocellulose is also promising biomaterial to stabilize PEs. Micro/nanocelluloses can be extracted by various green processes from numerous agricultural wastes and co-products, as banana peels, corncob, ginkgo seed shells, lime residues, mangosteen rind, oil palm empty fruit bunches, pistachio shells, as well as wheat straw. Main green processes used to treat cellulose are grinding, high pressure homogenization, microfluidization, enzymatic hydrolysis, subcritical water, extrusion, electron beam irradiation, cryocrushing, microwaves or sonication. PEs formulated with cellulose clearly participate to a global sustainable development but, additional studies will be necessary to better understand PEs stability and improve properties.

Towards an eco-friendly deconstruction of agro-industrial biomass and preparation of renewable cellulose nanomaterials: A review

There is an array of methodologies to prepare nanocellulose (NC) and its fibrillated form (CNF) with enhanced physicochemical characteristics. However, acids, bases or organosolv treatments on biomass are far from green, and seriously threaten the environment. Current approach to produce NC/CNF from biomass should be revised and embrace the concept of sustainability and green chemistry. Although hydrothermal process, high-pressure homogenization, ball milling technique, deep eutectic solvent treatment, enzymatic hydrolysis etc., are the current techniques for producing NC, the route designs remain imperfect. Herein, this review highlights the latest methodologies in the pre-processing and isolating of NC/CNF from lignocellulose biomass, by largely focusing on related papers published in the past two years till date. This article also explores the latest advancements in environmentally friendly NC extraction techniques that cooperatively use ball milling and enzymatic hydrolytic routes as an eco-efficient way to produce NC/CNF, alongside the potential applications of the nano-sized celluloses.