Impact of the combined effect of seawater exposure with wastewater and Fe2O3 nanoparticles on Chlorella vulgaris microalgae growth, lipid content, biochar, and bio-oil production.

Microalgae is one the promising source of energy for the production of biofuel and other value-added products to replace the existing conventional fossil fuels. However, low lipid content and poor cell harvesting are the key challenges. Based on the growth conditions the lipid productivity will be affected. The current study examines the mixtures of both wastewater and NaCl on the microalgae growth was studied. The microalgae used for conducting the tests were Chlorella vulgaris microalgae. Mixtures of the wastewater was prepared under the different concentrations of the seawater, classified as S0%, S20%, and S40%. The growth of microalgae was studied in the presence of these mixtures, and the addition of Fe2O3 nanoparticles was included to stimulate the growth. The results showed that increasing the salinity in the wastewater resulted in decreased biomass production, but significantly increased lipid content compared to S0%. The highest lipid content was recorded at S40%N with 21.2%. The Highest lipid productivity was also witnessed for S40% with 45.6 mg/Ld. The cell diameter was also found to increase with increasing salinity content in the wastewater. The addition of Fe2O3 nanoparticles in the seawater was found to enhance the productivity of the microalgae extensively, resulting in 9.2% and 6.15% increased lipid content and lipid productivity respectively compared to conventional cases. However, the inclusion of the nanoparticles slightly increased the zeta potential of microalgal colloids, with no noticeable effects on the cell diameter or bio-oil yields. Based on these findings, Chlorella vulgaris was identified as a suitable candidate for treating wastewater with high salinity exposure.

Recent catalytic applications of MXene-based layered nanomaterials.

The urgent issues related to the catalytic processes and energy applications have accelerated the development of hybrid and smart materials. MXenes are a new family of atomic layered nanostructured materials that require considerable research. Tailorable morphologies, strong electrical conductivity, great chemical stability, large surface-to-volume ratios, tunable structures, among others are some significant characteristics that make MXenes appropriate for various electrochemical reactions, including dry reforming of methane, hydrogen evolution reaction, methanol oxidation reaction, sulfur reduction reaction, Suzuki-Miyaura coupling reaction, water-gas shift reaction, and so forth. MXenes, on the other hand, have a fundamental drawback of agglomeration, as well as poor long-term recyclability and stability. One possibility for overcoming the restrictions is the fusion of nanosheets or nanoparticles with MXenes. Herein, the relevant literature on the synthesis, catalytic stability and reusability, and applications of several MXene-based nanocatalysts are deliberated including the merits and cons of the newer MXene-based catalysts.

Spotlighting of the role of catalysis for biomass conversion to green fuels towards a sustainable environment: Latest innovation avenues, insights, challenges, and future perspectives.

Recently, extensive resources were dedicated to studying how to use catalysis to convert biomass into environmentally friendly fuels. Problems with this technology include the processing of lignocellulosic sources and the development/optimization of novel porous materials as efficient monofunctional and bifunctional catalysts for biomass fuel production. This paper reviews recent advancements in catalysts procedures. Besides, it offers assessments of the methods used in catalytic biomass pyrolysis. Understanding the catalytic conversion process of lignocellulosic biomass into bio-oil remains a key research challenge in biomass catalytic pyrolysis.

Mechanically strong all-chitin filaments: Wet-spinning of ß-chitin nanofibers in aqueous NaOH.

Herein, a facile wet-spinning strategy was used for the fabrication of mechanically strong all-chitin filaments from an aqueous NaOH solution using ß-chitin nanofibers (ß-ChNFs). It is hypothesized that to reach high mechanical performance it is important to preserve the crystalline structure of chitin during fabrication. To explore this possibility, ß-ChNFs were disintegrated from squid pens by a mild procedure and showed a uniform diameter of 10-25 nm, length of a few microns, and a high aspect ratio of more than 200. An interesting finding was that gel-like ß-ChNF filaments were directly formed in aqueous NaOH without using any organic or ionic agents. The gelation of ß-ChNFS under alkali treatments contributed to the construction of strong nanonetworks and thus facilitated the formation of high-strength filaments. The resulting all-chitin filaments showed a high tensile strength and Young's modulus of 251.3 ± 12.45 MPa and 12.1 ± 0.72 GPa, respectively, which were further investigated for utilization as flexible sensors. The advantages of this strategy included the lack of use of any toxic solvents and the achievement of high mechanical performance for the all-chitin filaments. We believe that this wet-spinning approach may promote the functional utilization of chitin to develop high-strength filaments in smart textiles, biosensors, and structural reinforcements.

Strong, Water-Resistant, and Ionic Conductive All-Chitosan Film with a Self-Locking Structure.

Renewable and biodegradable natural polymeric materials are attractive candidates for replacing nonbiodegradable plastics. However, it is challenging to fabricate polysaccharide-based materials (such as cellulose and chitin) that can be used in humid or even watery environments due to their inferior stability against water. Here, a self-locking structure is constructed to develop a strong, water-resistant, and ionic conductive all-chitosan film without other additives. The densely packed self-locking structure introduces strong interactions between chitosan nanofibers, preventing the fibers from disentangling even in watery environments. The resulting film exhibits outstanding tensile strength of ∼144 MPa, superior wet strength of ∼54.3 MPa, and high ionic conductivity of 0.0012 S/cm at 10-4 M KCl, which are significantly higher than those of conventional polysaccharide-based materials and many commercially used plastics. Additionally, it also possesses outstanding flexibility, excellent thermal stability, good antimicrobial ability, and biodegradability, which make it a promising eco-friendly alternative to plastics for many potential applications, such as packaging bags, drinking straws, and ion regulation membranes.

A Comparative Study on the Characterization of Nanofibers with Cellulose I, I/II, and II Polymorphs from Wood.

Polymorphic changes in cellulose nanofibers (CNFs) are closely related to their properties and applications, and it is of interest to investigate how polymorphic changes influence their properties. A comparative study on the properties of CNFs with cellulose I, I/II, and II polymorphs from wood was conducted herein. CNFs were obtained by chemical extraction combined with a simple and efficient mechanical treatment (one pass through a grinder). This process resulted in a relatively high yield of 80⁻85% after a simple grinding treatment. The polymorphic changes in the CNFs and the chemical composition, morphology, tensile performances, and thermal properties were systematically characterized and compared. The X-ray diffraction and FTIR analyses verified the existence of three types of purified pulps and CNFs with cellulose I, cellulose I/II, and cellulose II polymorphs (CNF-I, CNF-I/II, CNF-II). Morphological observations presented that these three types of CNFs all exhibited high aspect ratios and entangled structures. Tensile testing showed that the CNF films all exhibited high tensile strengths, and the fracture strains of the CNF-I/II (11.8%) and CNF-II (13.0%) films were noticeably increased compared to those of the CNF-I film (6.0%). If CNF-II is used as reinforcing material, its larger fracture strain can improve the mechanical performance of the CNF composites, such as fracture toughness and impact strength. In addition, CNF-I, CNF-I/II, and CNF-II films showed very low thermal expansion in the range 20⁻150 °C, with the coefficient of thermal expansion values of 9.4, 17.1, and 17.3 ppm/K, respectively. Thermogravimetric analysis (TGA) revealed that the degradation temperature of CNF-I and CNF-II was greater than that of CNF-I/II, which was likely due to increased α-cellulose content. This comparative study of the characterization of CNF-I, CNF-I/II, and CNF-II provides a theoretical basis for the application of CNFs with different polymorphs and could broaden the applications of CNFs.

A three-dimensionally chitin nanofiber/carbon nanotube hydrogel network for foldable conductive paper.

We reported a highly conductive nanocomposite made with multiwalled carbon nanotubes (MWCNTs) and chitin nanofibers (ChNFs). The MWCNTs were dispersed into ChNFs by the simple process of vacuum-filtration, forming a three-dimensional network structure. In this approach, MWCNT acted as a filler to introduce electron channel paths throughout the ChNF skeleton. And then, a hybrid hydrogel system (20 wt.% NaOH, -18 °C) was applied to prepare the ChNF/MWCNT gel-film followed with drying process. It is found that the resultant ChNF/MWCNT gel-film exposed much more MWCNT areas forming denser structure due to the shrinking of ChNFs after the gelation treatment. Compared with ChNF/MWCNT film, the one treated under hydrogel system (ChNF/MWCNT gel-film) exhibited almost twice higher conductivity (9.3S/cm for 50 wt.% MWCNTs in gel-film; whereas 4.7S/cm for 50 wt.% MWCNTs in film). Moreover, the facile and low-cost of this conductive paper may have great potential in development of foldable electronic devices.