A large quantity of coal fly ash is generated worldwide from thermal power plants, causing a serious environmental threat owing to disposal and storage problems. In this work, for the first time, ...coal fly ash is converted into advanced and novel aerogel fibers and high-purity α-Alsub.2Osub.3. Silica–bacterial cellulose composite aerogel fibers (CAFs) were synthesized using an in situ sol-gel process under ambient pressure drying. Due to the unique “nanoscale interpenetrating network” (IPN) structure, the CAFs showed wonderful mechanical properties with an optimum tensile strength of 5.0 MPa at an ultimate elongation of 5.8%. Furthermore, CAFs with a high porosity (91.8%) and high specific surface area (588.75 msup.2/g) can inherit advanced features, including excellent thermal insulation, stability over a wide temperature range, and hydrophobicity (contact angle of approximately 144°). Additionally, Alsub.2Osub.3 was simultaneously extracted from the coal fly ash to ensure that the coal fly ash was fully exploited. Overall, low-cost woven CAFs fabrics are suitable for wearable applications and offer a great approach to comprehensively use coal fly ash to address environmental threats.
Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion re‐evaluating the safety of ...microcrystalline cellulose (E 460(i)), powdered cellulose (E 460(ii)), methyl cellulose (E 461), ethyl cellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methyl cellulose (E 464), ethyl methyl cellulose (E 465), sodium carboxy methyl cellulose (E 466), enzymatically hydrolysed carboxy methyl cellulose (E 469) and cross‐linked carboxy methyl cellulose (E 468) as food additives. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food (SCF) established an acceptable daily intake (ADI) ‘not specified’ for unmodified and modified celluloses. Celluloses are not absorbed and are excreted intact in the faeces; in addition, microcrystalline cellulose, powdered and modified celluloses could be fermented by the intestinal flora in animals and humans. Specific toxicity data were not always available for all the celluloses evaluated in the present opinion and for all endpoints. Given their structural, physicochemical and biological similarities, the Panel considered it possible to read‐across between all the celluloses. The acute toxicity of celluloses was low and there was no genotoxic concern. Short‐term and subchronic dietary toxicity studies performed with E 460(i), E 461, E 462, E 463, E 464, E 466 and E 469 at levels up to 10% did not indicate specific treatment related adverse effects. In chronic toxicity studies performed with E 460(i), E 461, E 463, E 464, E 465 and E 466, the no observed adverse effect level (NOAEL) values reported ranged up to 9,000 mg/kg body weight (bw) per day. No carcinogenic properties were detected for microcrystalline cellulose and modified celluloses. Adverse effects on reproductive performance or developmental effects were not observed with celluloses at doses greater than 1,000 mg/kg bw by gavage (often the highest dose tested). The combined exposure to celluloses (E 460–466, E 468 and E 469) at 95th percentile of the refined (brand‐loyal) exposure assessment for the general population was up to 506 mg/kg bw per day. The Panel concluded that there was no need for a numerical ADI and that there would be no safety concern at the reported uses and use levels for the unmodified and modified celluloses (E 460(i); E 460(ii); E 461–466; E 468 and E 469). The Panel considered an indicative total exposure of around 660–900 mg/kg bw per day for microcrystalline, powdered and modified celluloses.
Unlike established coating formulations, functional particulate coatings often demand the omission of polymer dispersant so as to retain surface functionality. This results in heterogeneous complex ...rheology. We take an example from a novel development for an NOx mitigation surface flow filter system, in which ground calcium carbonate (GCC), applied in a coating, reacts with NOsub.2 releasing COsub.2. Inclusion of mesoporous ancillary mineral acts to capture the COsub.2. The coating is applied as droplets to maximize gas-contact dynamic by forming a pixelated 2D array using a coating device consisting of protruding pins, which are loaded by submersion in the aqueous coating color such that the adhering droplets are transferred onto the substrate. The flow is driven by surface meniscus wetting causing lateral spread and bulk pore permeation. Filamentation occurs during the retraction of the pins. Stress-related viscoelastic and induced dilatancy in the suspension containing the ancillary mesoporous mineral disrupts processability. Adopting shear, oscillation and extensional rheometric methods, we show that the inclusion of an ancillary mineral that alone absorbs water, e.g., perlite (a naturally occurring porous volcanic glass), is rheologically preferable to one that in addition to absorbing water also immobilizes it on the mineral surface, e.g., sepiolite. When including micro-nanofibrillated cellulose (MNFC), critical for maintaining moisture to support NOsub.2 sorption, it is observed that it acts also as a flow modifier, enabling uniform coating transfer to be achieved, thus eliminating any possible detrimental effect on mineral surface activity by avoiding the use of soluble polymeric dispersant.
Metal–organic frameworks (MOFs) hold great potential for efficient removal of particulate matter (PM) due to their high porosity and tunable surface groups. In this work, sustainable bacterial ...cellulose (BC) was employed as a substrate for Zr-based MOF (i.e., UiO-66-NHsub.2) deposition. Specifically, the UiO-66-NHsub.2@BC aerogel exhibits a multi-level pore structure with a specific surface area of 103 msup.2/g. Pristine BC aerogels indicated a removal efficiency of 50.6% for PMsub.2.5, with a pressure drop of 22.8 Pa. While UiO-66-NHsub.2@BC aerogels showed a PMsub.2.5 removal efficiency of 96.9%. The filtration mechanism can be assigned to the following reasons: (i) the interception/impaction of PM with the fibrous and porous aerogel network; and (ii) the presence of polar amine groups that boost electrostatic interactions between PM and MOFs. Moreover, as-prepared filters can be regenerated in a facile way with good reusability and long-term stability.
In this work, regenerated cellulose textile fibers, Ioncell-F, dry-wet spun with different draw ratios, have been investigated by scanning wide-angle X-ray scattering (WAXS) using a mesoscopic X-ray ...beam. The fibers were found to be homogeneous on the 500 nm length scale. Analysis of the azimuthal angular dependence of a crystalline Bragg spot intensity revealed a radial dependence of the degree of orientation of crystallites that was found to increase with the distance from the center of the fiber. We attribute this to radial velocity gradients during the extrusion of the spin dope and the early stage of drawing. On the other hand, the fiber crystallinity was found to be essentially homogeneous over the fiber cross section. Keywords: nanofocus X-ray probe; scanning WAXS; regenerated cellulose fibers; materials science; crystallization; crystal growth; properties of solids.
There is currently considerable interest in developing stiff, strong, tough, and heat resistant poly(1actide) (PLA) based materials with improved melt elasticity in response to the increasing demand ...for sustainable plastics. However, simultaneous optimization of stiffness, strength, and toughness is a challenge for any material, and commercial PLA is well-known to be inherently brittle and temperature-sensitive and to show poor melt elasticity. In this study, we report that high-shear mixing with cellulose nanocrystals (CNC) leads to significant improvements in the toughness, heat resistance, and melt elasticity of PLA while further enhancing its already outstanding room temperature stiffness and strength. This is evidenced by (i) one-fold increase in the elastic modulus (6.48 GPa), (ii) 43% increase in the tensile strength (87.1 MPa), (iii) one-fold increase in the strain at break (~6%), (iv) two-fold increase in the impact strength (44.2 kJ/m.sup.2), (v) 113-fold increase in the storage modulus at 90degreesC (787.8 MPa), and (vi) 10.sup.3-fold increase in the melt elasticity at 190degreesC and 1 rad/s (~10.sup.5 Pa) via the addition of 30 wt% CNC. It is hence possible to produce industrially viable, stiff, strong, tough, and heat resistant green materials with improved melt elasticity through high-shear mixing.
Sixteen cultivars (three resistant species and thirteen susceptible cultivars to cochineal insects) were included in the experiment to evaluate their nutritional and chemical compositions and to ...determine the in vitro digestibility of cladodes of the Opuntia species. Cultivars showed highly significant (p < 0.001) differences in their chemical composition. The cultivars' content of ash, crude protein (CP), dry matter (DM), organic matter (OM), in vitro dry matter digestibility (IVDMD), in vitro organic matter digestibility (IVOMD), acid detergent fiber (ADF), neutral detergent fiber (NDF) and Cell (cellulose) varied, with ranges of 8.18-22.75%, 3.19-10.40%, 86.40-91.88%, 77.45-91.82%, 68.25-87.3%, 55.81-78.95%, 14.88-26.15%, 29.66-67.05% and 10.99-19.92%, respectively. The ash content showed a significant highly negative correlation with OM (r = −1.00; p < 0.001), IVDMD (r = −0.603; p < 0.001) and DOMD (r = −0.904; p < 0.001), respectively. The Garao, Aloqa and O. robusta var. X11 cultivars showed the highest similarities, as they are found close to the first branch of the dendrogram. In total, 90% of the variation among the nutritional traits was attributed to the first four PCs, with 55.97% to the first two principal components (PCs). The nutritional composition of the resistant species was greater than or equal to the susceptible ones.
Cellulose-grafte-poly(L-lactide) (C-g-PLLA) copolymers synthesized in a COsub.2-switchable solvent are proposed for use as effective compatibilizers for the preparation of cellulose-PLLA composites ...with enhanced interfacial compatibility. The effect of the molar substitution (MSsub.PLLA) of the grafted PLLA side chain in the C-g-PLLA copolymer and the feeding amount of this copolymer on the mechanical and thermal properties and hydrophilicity of the composites was investigated. The composites had a largely increased impact strength with the incorporation of the compatibilizer. With the increasing of MSsub.PLLA and the feeding amount of the copolymer, the resulting composites had an increased impact strength. When 5 wt% C-g-PLLA with MSsub.PLLA of 4.46 was used as a compatibilizer, the obtained composite containing 20 wt% cellulose presented an impact strength equal to that obtained for the neat PLLA. The composites had a slightly decreased melting temperature and thermal decomposition temperature, but increased hydrophilicity due to the incorporation of the compatibilizer. This work suggests an effective method to improve the interfacial compatibility between cellulose and PLLA for the fabrication of fully bio-based composites with high performance.
► Interest for microfibrillated cellulose (MFC) is exponentially increasing. ► Nano-scale dimensions and ability to form a strong entangled nanoporous network. ► New sources, new mechanical ...processes, new pre- and post-treatments induce new types of MFC materials for industrialization. ► Focus on the barrier properties of MFC used as films, in nanocomposites or in paper coating is then proposed.
Interest in microfibrillated cellulose (MFC) has been increasing exponentially. During the last decade, this bio-based nanomaterial was essentially used in nanocomposites for its reinforcement property. Its nano-scale dimensions and its ability to form a strong entangled nanoporous network, however, have encouraged the emergence of new high-value applications. In previous years, its mode of production has completely changed, as many forms of optimization have been developed.
New sources, new mechanical processes, and new pre- and post-treatments are currently under development to reduce the high energy consumption and produce new types of MFC materials on an industrial scale. The nanoscale characterization possibilities of different MFC materials are thus increasing intensively. Therefore, it is critical to review such MFC materials and their properties. Moreover, very recent studies have proved the significant barrier properties of MFC. Hence, it is proposed to focus on the barrier properties of MFC used in films, in nanocomposites, or in paper coating.
Nowadays, skin biocompatible products are fast-growing markets for nanocelluloses with increasing number of patents published in last decade. This review highlights recent developments, market ...trends, safety assessments, and regulations for different nanocellulose types (i.e. nanoparticles, nanocrystals, nanofibers, nanoyarns, bacterial nanocellulose) used in skincare, cosmetics, and healthcare. The specific properties of nanocelluloses for skincare include high viscosity and shear thinning properties, surface functionality, dispersion stability, water-holding capacity, purity, and biocompatibility. Depending on their morphology (e.g. size, aspect ratio, geometry, porosity), nanocelluloses can be used as formulation modifiers, moisturizers, nanofillers, additives, membranes, and films. Nanocellulose composite particles were recently developed as carriers for bioactive compounds or UV-blockers and platforms for wound healing and skin sensors. As toxicological assessment depends on morphologies and intrinsic properties, stringent regulation is needed from the testing of efficient nanocellulose dosages. The challenges and perspectives for an industrial breakthrough are related to optimization of production and processing conditions.
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