Low-concentration alkali treatments at low temperatures facilitate the crystal transition of cellulose I to II. However, the transition mechanism remains unclear. Hence, in this study, we traced the ...transition using in situ solid-state 13C CP/MAS NMR, WAXS, and 23Na NMR relaxation measurements. In situ solid-state 13C CP/MAS NMR and WAXS measurements revealed that soaking cellulose in NaOH at low temperatures disrupts the intramolecular hydrogen bonds and lowers the crystallinity of cellulose. The dynamics of Na ions (NaOH) play a crucial role in causing these phenomena. 23Na NMR relaxation measurements indicated that the Na-ion correlation time becomes longer during the crystal transition. This transition requires the penetration of Na ions (NaOH) into the cellulose crystal and a reduction in Na-ion mobility, which occurs at low temperatures or high NaOH concentrations. The interactions between cellulose and NaOH disrupt intramolecular hydrogen bonds, inducing a conformational change in the cellulose molecules into a more stable arrangement. This weakens the hydrophobic interactions of cellulose, and facilitates the penetration of NaOH and water into the crystal, leading to the formation of alkali cellulose. Our findings suggest that a strategy to control NaOH dynamics could lead to the discovery of a novel preparation method for cellulose II.
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The nitrogen pollution control of liquid-ammonia mercerization wastewater (LMWW) is one of the typical obstacle restricting the sustainability of textile industry. In this study, a 500 kg N/day ...two-stage partial nitritation/anammox (PN/A) process containing PN reactor filled with zeolite and biofilm anammox reactors was successfully started up in 45 days and operated stably with high shock resistance over one year for LMWW treatment. The large-scale process achieved an average ammonium removal efficiency (94.3 ± 2.3%), total nitrogen removal efficiency (89.4 ± 2.7%) and nitrogen removal rate (1.003 ± 0.386 kg N/m3/day) during one year engineering operation. Simultaneous denitrification was revealed by the contribution of 5.2% total nitrogen removed. High-throughput sequencing results showed that Nitrosomonas was the most dominant genus in PN reactor, and Ca. Anammoxoglobus and Ca. Kuenenia were the functional bacteria for nitrogen removal in anammox reactors. Compared to traditional nitrification-denitrification process, the large-scale process reduced a total operational cost of 46.03 CNY/kg N for LMWW. This study revealed the proposed process was quite reliable with fast start-up and high impact resistance to overcome the obstacle of nitrogen pollution control for LMWW economically and conducive to the sustainable development for textile industry.
•500 kg N/day two-stage partial nitritation/anammox process was initiated in 45 days.•89.4 ± 2.7% TN removal was achieved at N removal rate of 1.003 ± 0.386 kg N/m3/day.•The process showed high shock resistance facing NH4+-N ranging at 1000-500 mg/L.•The large-scale process reduced a total operational cost of 46.03 CNY/kg N.
A two-stage sequential pretreatment including caustic mercerization (CM) and liquid ammonia (LA) treatment was applied to investigate the influence on dyeing performance and handle of knit cotton ...fabric, and the relationship between dye size and dyeing properties. Various techniques were applied to characterize all the treated fabrics. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses of the treated fabrics confirmed that both sequential treatments decreased the crystallinity of cotton fabric more than only the CM or LA treatment. The pattern of cellulose I was transferred to a mixed configuration of cellulose II and cellulose III after the CM/LA or LA/CM treatment. Thermal performances measured by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) techniques showed that the thermal stability of the treated cotton only marginally decreased. The wicking height increased after the sequential CM/LA treatment, indicating that the hydrophilicity of the fabric increased. The dye absorption and color uniformity were better for the reactive dye with a smaller molecular weight (Reactive Red 2) compared with the one with a larger molecular weight (Reactive Red 195). The total dye fixation efficiency (T%) increased to 72.93% and 73.24% for Reactive Red 2 dyeings of CM/LA- and LA/CM-cotton fabric from 46.75% of the untreated fabric, respectively; the T% increased to 65.33% and 72.27% for Reactive Red 195 dyeings of CM/LA- and LA/CM-cotton fabric from 35.17% of the untreated fabric, respectively. The colorfastness and dye exhaustion and fixation percentages of the samples were enhanced after the treatments. Furthermore, compared to the single CM or LA treatment, the softness handle properties were further improved after the fabrics were sequentially treated by CM/LA. The developed pre-treatment of CM/LA can be used in the textile industry to promote the dyeability, handle, and mechanical properties of knit cotton fabrics.
• Novel adsorbents combined beneficial properties of modified nanocellulose. • Succinic anhydride modified merzerated nanocellulose were effective adsorbents for heavy metals. • Modified ...nanocellulose could be regenerated after ultrasonic treatment. • Porosity of the hybrid adsorbents affected the kinetics of the metal adsorption. • Adsorption isotherms depended on the type of metal.
In this study, the removal of Zn(II), Ni(II), Cu(II), Co(II), and Cd(II) ions from aqueous solutions was investigated using succinic anhydride modified mercerized nanocellulose. The modified adsorbents were characterized using FTIR and SEM analyses. FTIR results showed the bands related to carboxyl groups and SEM-images clear increase in crystallinity after modification of nanocellulose. The effects of pH, contact time, regeneration, and the concentration of metals were studied in batch mode. The maximum metal uptakes ranged from 0.72 to 1.95mmol/g following the order of: Cd>Cu>Zn>Co>Ni. Adsorption isotherms were demonstrated using Langmuir and Sips models with wet and dry weight of adsorbent. Both models were representative to simulate adsorption isotherms. Regeneration of the modified nanocellulose was accomplished using nitric acid and ultrasonic treatment.
This study evaluated the effect of sodium hydroxide mercerized bagasse fiber (BF) on the mechanical and thermal properties of polypropylene composites reinforced with hybrid BF/calcium carbonate ...(CaCO3). Samples were fabricated with a compression molding machine and characterized for tensile, flexural, and thermal properties. Hybrid composites with mercerized BF (HMC) exhibited improved mechanical properties than the unmercerized hybrid composite (UHC), single-component composite (SC) and control sample. Additionally, TGA/DTG analysis revealed that the HMC were more thermally stable in comparison with other samples. Crystallinity index of HMC was about 24% higher than UHC, as indicated by XRD analysis. SEM images showed good interfacial adhesion in the morphology of HMC compared to UHC, which contributed to the improved thermal and mechanical properties exhibited by HMC. These results indicated that mercerization treatment and reinforcement hybridization could be utilized for improving the thermal and mechanical responses of natural fiber reinforced polypropylene composites.
•Polypropylene composites containing hybrid bagasse fiber (BF)/calcium carbonate are synthesized via compression molding.•Improved interfacial and enhanced mechanical and thermal properties are realized with BF mercerized with sodium hydroxide.•Hybrid reinforcements result in improved mechanical, thermal resistance and higher crystallinity in the composites.•Hybridization and mercerization are beneficial in improving the properties of eco-friendly polypropylene composites.
Environmental pollution, such as air, water, and soil pollution, has become the most serious issue. Soil pollution is a major concern as it generally affects the lands and makes them non-fertile. The ...main cause of soil pollution is agro-waste. It may be possible to mitigate the agro-waste pollution by re-utilizing this agro-waste, namely natural fibres (NFs), by blending into polymer-based material to reinforce the polymer composite. However, there are pros and cons to this approach. Consequently, the polymer composite materials fabricated using NFs are inferior to those polymer composites that are reinforced by, e.g., carbon or glass fibres from the mechanical properties’ perspectives. The limitations of utilizing natural fibres in polymer matrix are their high moisture absorption, resulting in high swelling rate and degradation, inferior resistance to fire and chemical, and inferior mechanical properties. In particular, the NF polymer composites exhibit inferior interfacial adhesion between the fibre and the matrix, which, if improved, ultimately overcome all the listed limitations and improve the mechanical properties of the developed composites. To improve the interfacial adhesion leading to the enhancement of the mechanical properties, optimum chemical treatment such as Alkalization/Mercerization of the fibres have been explored. This article discusses the Mercerization/Alkali surface treatment method for NFs and its effects on the fibres regarding the Mercerization/Alkali surface treatment method for NFs and its effect on the fibres regarding their utilization in the polymer composites, the morphological features, and mechanical properties of composites.
This article deals with cationization of cotton during mercerization and its effects on trichromatic vat dyeing. If cationization is carried out during the after-treatment, regardless of cotton ...pretreatment, the reaction takes place on the surface and blocks cellulose groups, subsequently resulting in uneven coloration. However, when cationization is carried out with an epihalohydrin during the mercerization process, new cellulose is formed in which the cationic compound is uniformly distributed and trapped between cellulose chains, resulting in uniform coloration after the dyeing process. The reaction time for the process during mercerization is 24 h, thus a more favorable process was researched. Based on electrokinetic analysis, it was found that 5 h was sufficient for the reaction with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC). The cationization of cotton contributed to the processes of vat dyeing. The change in charge upon cationization resulted in very high adsorption of vat-dye anions, indicating that ionic bonding occurred in addition to van der Waals forces. The color depth improved by more than 10 times. It should be emphasized that the colors with higher chroma and targeted color hue, especially in trichromatic dyeing, were obtained on cationized cotton, in contrast to standard cotton fabrics. The color differences obtained under the different light sources indicate the occurrence of metamerism. Considering the color fastness to laundering, vat-dyed cationized fabrics of all colors may be used in hospitals or other environments where high hygiene and oxidative bleaching are required.
Valorization of wheat straw fiber/recycled polypropylene nanocomposites was investigated through studying the individual and combined effects of organically modified montmorillonite (OMMT) and alkali ...treatments on the given composites. FTIR spectra indicated the reduction of wheat straw fibers' hydroxyl groups due to hemicellulose removal resulting from alkali treatment. There were also trace diminutions in C-O peak intensities due to the degradation of little amounts of lignin. X-ray analysis revealed the intercalation of nanoclay in the polymer matrix. The improved interaction of fiber-polymer interfaces brought about by alkali treatment was also confirmed by scanning electron microscopy. The water absorption and thickness swelling properties of the nanocomposites were improved due to the barrier properties of nanoclay against water ingress. The flexural strength and modulus of elasticity increased by the individual, and likewise combined treatments. Thermogravimetric analysis demonstrated that the temperatures of first and second stages of composites' thermal degradation increased via the formation of a carbonized char layer thermally insulating the deeper composite layers. Differential scanning calorimetry showed some slight increases in the melting temperature, melting enthalpy, crystallisation temperature, crystallisation enthalpy, and crystallinity index of the treated composites due to the nucleating effect of nanofillers. The overall results showed that the combined treatment of OMMT and NaOH (vs. the individual ones) could significantly improve the overall properties of the studied composites. This was due to some interesting synergistic effects of the given treatments converting the wheat straw fiber/recycled polypropylene nanocomposites to high performance materials of choice for industry.
Therapeutic benefits of small caliber artificial blood vessels to cure cardio and cerebrovascular diseases are mainly limited by their low patency during long-term transplantation. Bacterial ...nanocellulose (BNC), as a natural polysaccharide mainly synthesized by a bacterium Komagataeibatacter xylinus, has shown great potential in small-caliber vascular graft applications due to its shape controllability, and furthermore its physical surface structure can be adjusted with different treatments. However, influences of physical surface structure and properties of BNC conduits on behaviors of vascular cells have not been investigated. In this work, mercerized BNC conduits (MBNC) with different surface roughness and stiffness were constructed by controlled alkali (NaOH) treatment. The changes of surface structures and properties significantly affected the behaviors of vascular cells and gene expression; meanwhile, the cell seeding density also affected the cell responses. After mercerization with NaOH concentration > 10 %, it was observed that the increased stiffness of MBNC decreased several functional gene expressions of human vascular endothelial cells, and the pathological transformation of smooth muscle cells was inhibited. This study demonstrates physical surface structure of MBNC conduits will critically regulate functions and behaviors of vascular cells and it also provides important designing parameters to improve the long-term patency of BNC-based conduits.
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