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This study investigated the use of dielectric barrier discharge (DBD) plasma as a pretreatment to extract micro and nano-cellulose fibers from walnut shells (WS). The powdered WS was subjected to plasma at 18 and 20 kV before undergoing sodium hydroxide alkaline, sodium chlorite bleaching, or both alkaline and bleaching treatments. A control sample was also prepared without plasma treatment. The extracted cellulose was then analyzed for extraction efficiency, chemical composition, color, crystallinity index, FTIR, thermal properties, microstructure, and surface composition. The results showed that the plasma pretreatment reduced the cellulose extraction efficiency from ∼26 % to ∼22 % which was accompanied by a decrease in the C-C/C-H and C-OH/C-O-C bonds. The 20 kV plasma pretreatment prior to both alkaline and bleaching treatments resulted in the conversion of microfibrils into nanofibrils, with an average diameter of 80 ± 10 nm. These changes in the fiber structure were likely caused by the disruption of hydrogen-bonding interactions in the plasma-treated samples, leading also to a reduction in crystallinity index. The plasma-treated sample exhibited a different weight loss pattern below 100 °C compared with the control, originating from changes in water absorption. Overall, the study demonstrated that plasma pretreatment can successfully produce micro and nano-cellulose fibers from WS. [Display omitted] [ABSTRACT FROM AUTHOR]

Hemicellulose is mainly distributed in the tightly packed S 2 layer of the plant cell wall and the middle lamella. This rigid microstructure of wood and interactions among hemicellulose, lignin, and cellulose jointly restrict the separation and transformation of hemicellulose in the wood matrix. To address this issue, a method combined with microwave-expanding pretreatment (MEP) and microwave-assisted extraction (MAE) with a NaOH solution was carried out. We found that the MEP could effectively create new pathways for bagasse cells in mass transferring. More specifically, 195 % of the specific surface area (m 2 /g) with 193 % of the pores (>50 nm) increased after MEP; the SEM images also confirmed that the microstructure of bagasse was modified. MAE could considerably exfoliate hemicellulose from cellulose fiber and accelerate mass transfer. Additionally, we optimized MEP and MAE by using response surface methodology (RSM). The optimal parameters were 370 K, 3.7 min, 1081 W microwave power, and 9.9 wt% NH 4 HCO 3 consumption for the MEP and 1100 W microwave power, 2.5 wt% NaOH concentration, 34.6 min reaction time for MAE, respectively. Moreover, molecular dynamics (MD) simulation suggests that NaOH could significantly lower the work needed to peel off the xylan chain from cellulose nanofibril., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The complete dissolution of starch without degradation are necessary prerequisites for starch fractionation to obtain amylose or amylopectin (AP). With the recent, continuous progress in finding efficient and eco-friendly starch-dissolving solutions, applying new solvents for starch fractionation is important. In this study, the effects of dimethyl sulfoxide (DMSO), NaOH, and CaCl 2 solutions on starch structure and AP product parameters during starch fractionation were compared with respect to the starch deconstruction effect. This study proved that the CaCl 2 solution could effectively dissolve corn starch (50 °C, solubility of 98.96 %), and promote the regeneration of starch into uniform and fine particles. Furthermore, the three solvents (DMSO, NaOH, and CaCl 2 ) changed the crystal structure of corn starch, but they were all non-derivatizing solvents. The effect of the CaCl 2 solution on the molecular structure of corn starch was the least significant of the three solvents. Finally, the extraction rate of AP from the CaCl 2 solution reached 69.45 %. In conclusion, this study presents a novel and effective method for AP extraction., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Pure cellulose has been successfully isolated from tomato peels by either acidified sodium chlorite or chlorine-free alkaline peroxide routes, at 10.2-13.1% yields. Negatively charged (ζ = -52.4 mV, 0.48 at% S content) and flat spindle shaped (41:2:1 length:width:thickness) cellulose nanocrystals (CNCs) were isolated at a 15.7% yield via sulfuric acid hydrolysis (64% H2SO4, 8.75 mL/g, 45 °C, 30 min). CNCs could be facilely assembled from dilute aqueous suspensions into highly crystalline (80.8%) cellulose Iβ fibrous mass containing mostly sub-micron fibers (ϕ = 260 nm) and few interconnected nanofibers (ϕ = 38 nm), with 21.7 m(2)/g specific surface and 0.049 m(3)/g pore volume. More uniformly nanofibers with average 42 nm width and significantly improved specific surface area (101.8m(2)/g), mesoporosity and pore volume (0.4m(3)/g) could be assembled from CNCs in 1:1 v/v tert-butanol/water mixture.

Highlights • A simple and sensitive FI-CL method has firstly been established for the determination of CS. The LOD is 5 ng/mL and the analytical time is just 50 s. • Compared with the reported methods so far, the established method is simple, accurate, sensitive, rapid and specific for CS determination. • The established method is suitable to the analysis of plasma samples. • This method provides new ideas and directions for the analysis of other GAGs and lays a foundation for the CS pharmacokinetic study in the future. Abstract A simple and sensitive flow injection chemiluminescence (FI-CL) method has been developed for the determination of chondroitin sulfate (CS). The method is based on the sensitization effect of enzymatic products of CS on the luminol-H 2 O 2 system. Experimental parameters affecting FI-CL method such as concentrations of luminol, H 2 O 2 and NaOH and the standing time of luminol alkaline solution were optimized. Under optimum conditions, the calibration plot between CS concentration and the change of CL intensity was linear in the range of 25 ng/mL∼250 ng/mL. The limit of detection (LOD) was 5 ng/mL and the average relative standard deviation (RSD) of CL intensity was 2.5%. The method was successfully applied to the quantitative analysis of CS concentration in drugs. Compared with the reported methods so far, the established method is simple, sensitive, accurate and rapid. [ABSTRACT FROM AUTHOR]

Highlights • Aqueous alkali exhibits fully different dissolving power for deacetylated chitin, i.e., KOH > NaOH >> LiOH for chitin (DA = 0.94–0.74), KOH ≈ LiOH ≈ NaOH for chitosan I (DA = 0.53–0.25), and inverse LiOH >> KOH > NaOH for chitosan II (DA < 0.25). • It is the first time to find the dissolution behavior of chitosan I and chitosan II in aqueous NaOH and KOH solvents are different. • In the two alkali mixed solvent, NaOH or KOH can destroy the interaction of LiOH with D9 (chitosan II region) in the order of NaOH >> KOH, but LiOH cannot destroy the interaction of KOH with raw chitin. • Metal cations is the determining factor to the inverse solubility of chitin/chitosan in alkali solvent rather than OH− ion and low temperature. Abstract The low-temperature dissolving mechanism of chitin/chitosan in the alkali (LiOH, NaOH and KOH) aqueous solvents has not been well established yet. As revealed by our XRD and NMR methods, the prepared deacetylated chitins can be categorized as chitin (DA = 0.94–0.74), chitosan I (DA = 0.53–0.25) and chitosan II (DA < 0.25). Aqueous alkali exhibits fully different dissolving power in the above three regions, i.e., KOH > NaOH >> LiOH for chitin, KOH ≈ LiOH ≈ NaOH for chitosan I, and inverse LiOH >> KOH > NaOH for chitosan II. While in the two-alkali mixed solvent, NaOH or KOH can destroy the interaction of LiOH with D9 (chitosan II region) in the order of NaOH >> KOH, but LiOH cannot destroy the interaction of KOH with raw chitin. The varied solubility of chitin/chitosan in alkali solvent is suggested to be from the cation's preferential interaction rather than OH− ion and low temperature. [ABSTRACT FROM AUTHOR]

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

We investigated the dissolution state of cellulose in NaOH/urea aqueous solution using molecular dynamics simulations. All the components, including cellulose, NaOH, urea and H 2 O were combined into one simulation. A clear and detailed description for the formation of cellulose inclusion complexes has been stated. The simulation results showed that the cellulose inclusion complexes exhibited anisotropic properties. In this system, the sodium ions and hydroxide ions located at the regions of hydroxyl and hydroxymethyl groups in cellulose molecules. However, the urea molecules occupied the faces of the hydrophobic pyranose rings. The hydrogen-bonding configuration and lifetime of hydrogen bonds in cellulose inclusion complexes were also systematically characterized. The spatial structure of inclusion complexes, the hydrogen-bonding interaction between cellulose and solvent molecules, the diffusive property of solvent molecules and the distribution of water–water angles in cellulose inclusion complexes were discussed in details. The NaOH, urea and H 2 O molecules surrounding the cellulose chain within radial distance 0.35 nm have smaller diffusion coefficients than those in bulk state. The water–water angles provide a quantitative estimate of hydrophobic effect of cellulose. [ABSTRACT FROM AUTHOR]

Cationic derivatives of konjac glucomannan (KGM) were homogeneously synthesized by reacting KGM with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) in NaOH/urea aqueous solutions. The derivatives were characterized by FT-IR, 1 H NMR, elemental analysis, thermogravimetric analysis and zeta potential analysis. The results showed that the degree of substitution (DS) of the CKGM with the value of 0.15–0.46 could be obtained by changing the molar ratio between KGM and CHPTAC. The TG/DTG revealed that the thermal stability of KGM after cationization was lower than that of raw KGM. Among a wide range of pH value, the zeta potential in CKGM solution was shown with positive charges. The flocculation capacity of the CKGM was assessed through Kaolin suspension using the light transmission test. The results exhibited that the CKGM had excellent flocculation performance and could be used as an emerging flocculant agent in the wastewater treatment. [ABSTRACT FROM AUTHOR]

A growth-inhibitory polysaccharide (GIPinv) was purified using size-exclusion and ion-exchange chromatography from the fourth sodium hydroxide extraction step of a fungus found in British Columbia. The fungus was genetically identified as a member of the Paxillus involutus complex. GIPinv has an average molecular weight of 229 kDa and is a heteroglycan composed of glucose (65.9%), galactose (20.8%), mannose (7.8%), fucose (3.2%) and xylose (2.3%). GC–MS methylation analysis suggests that GIPinv has mixed linkages in the backbone containing (1 → 6)-Gal (25.5%), (1 → 4)-Glc (18.3%), (1 → 6)-Glc (8.3%), (1 → 3)-Glc (5.3%) and (1 → 2)-Xyl (4.5%). GIPinv has branching points at (1 → 2, 6)-Man (8.6%) and (1 → 3, 6)-Man (4.9%) having unsubstituted fucose (8.3%) and glucose (16.3%) as terminal sugars. GIPinv had growth-inhibitory activity against several cancer cell lines and triggered apoptosis. GIPinv should be further explored as a potential anti-cancer agent and a unique polysaccharide. [ABSTRACT FROM AUTHOR]

Herein NaOH/urea aqueous solution was assisted to dissolve bamboo cellulose fibers for the fabrication of porous nanoplatelets wrapped carbon aerogel as an economic and sustainable way in application of supercapacitor. The architecture displayed favorable features, such as a large specific surface area and a great flexibility of 86% at stress of 23 kPa. The effects of the KOH activation on the morphology and porous texture of cellulose carbon aerogel were further investigated and correlated with their electrochemical behavior. In aqueous electrolyte of 6 M KOH, activated carbon aerogel exhibited a high specific capacitance of 381 F/g which was improved by 150% compared to unactivated sample. Notably, the reasonable micropores and mesopores contributed to an excellent retention rate of 90% at high scan rate of 200 mV/s. The low equivalent series resistance and small charge transfer resistance in activated carbon aerogel also suggested an inspiring capacitor behavior. [ABSTRACT FROM AUTHOR]

The development of scaffolds to mimic the gradient structure of natural tissue is an important consideration for effective tissue engineering. In the present study, a physical cross-linking chitosan hydrogel with gradient structures was fabricated via a step-by-step cross-linking process using sodium tripolyphosphate and sodium hydroxide as sequential cross-linkers. Chitosan hydrogels with different structures (single, double, and triple layers) were prepared by modifying the gelling process. The properties of the hydrogels were further adjusted by varying the gelling conditions, such as gelling time, pH, and composition of the crosslinking solution. Slight cytotoxicity was showed in MTT assay for hydrogels with uncross-linking chitosan solution and non-cytotoxicity was showed for other hydrogels. The results suggest that step-by-step cross-linking represents a practicable method to fabricate scaffolds with gradient structures. [ABSTRACT FROM AUTHOR]

Starch nanoparticles (StNPs) were previously prepared using severe mechanical, physical and/or chemical conditions that takes too long time to produce a little yield of uncontrolled large size of StNP. The current work presents a new technique for the synthesis of StNPs based on the combination between sodium hydroxide and glycerol in aqueous medium during the synthesis process while the precipitation of the StNPs is performed under homogenization at ambient conditions. The new technique is based on three assumptions: 1) the dual impact of sodium hydroxide and glycerol on the swelling and gelatinization of starch as a pre-stage of the synthesis of (StNPs1), 2) the dual impact of glycerol and cooking of starch on the swelling and gelatinization of starch as a pre-stage of the formation of (StNPs2), and 3) the precipitation under homogenization at ambient conditions and its effect on breaking the H- bonds of the starch molecule in both StNPs1 and StNPs2. The importance of this technique arises from the ease of the process, the eco-friendly chemicals and the combination between the mechanical and chemical processes. NS (native starch), StNPs1 and StNPs2 were characterized using FTIR, XRD, TGA and TEM. TEM of StNPs1 showed a well-defined round particles uniformly distributed with size of about 62.5 nm. StNPs2 showed a non-specific shape starch particles. [ABSTRACT FROM AUTHOR]

Synthesis of nanocomposites was performed using microcrystalline cellulose (MCC), MgCl 2 in PEG/NaOH solvent by a thermal-assisted method at different temperatures by varying time and the amount of MCC. Results of XRD, FTIR, and EDS mapping showed that the materials consisted of only cellulose (CL) and magnesium hydroxide (MH). According to FTIR and XRD, it was found that crystallinity of MH in cellulose nanocomposites is increased with temperature and heating time and decreased with increasing of cellulose amount. The PEG/NaOH solvent has a significant effect on cellulose and Mg(OH) 2 morphology. BET and BJH results demonstrated the effects of temperature and cellulose amount on the pore size corresponding to mesoporous materials. TG and DTG analyses showed the increased thermal stability of cellulose nanocomposites with increasing temperature. TEM and SEM analyses showed an even distribution of MH nanostructures with various morphology in the cellulose matrix. The cellulose presented as the polymer matrix in the nanocomposites. It was supposed the possible interaction between cellulose and Mg(OH) 2 . The novel synthesis method used in this study is feasible, cost-efficient and environmentally friendly. [ABSTRACT FROM AUTHOR]

We present a quantitative study, using Raman spectroscopy combined with multivariate data analysis, to determine the degree of activation of softwood sulphite dissolving cellulose pulp by aqueous sodium hydroxide. We have chosen industrially relevant conditions, including low stoichiometric ratio of NaOH/Anhydroglucose Unit (AGU) < 2 and highly concentrated caustic (≥45% w/w [NaOH]). A design of experiments is used to investigate the effects of simultaneous variation of a set of key parameters on the degree of activation ( i.e. transformation to alkali cellulose, denoted as DoA): (a) the NaOH/AGU stoichiometric ratio, denoted (r); (b) the concentration of NaOH, denoted [NaOH]; (c) temperature, denoted (T); and (d) reaction time, denoted (t). Solid-state 13 C CP/MAS NMR spectroscopy was applied to investigate the reproducibility of the experiments and to select the range for (t). According to the model, (r) is found to have a statistically significant effect on DoA (increasing from DoA = 6–30% at the lowest (r) = 0.8, to DoA = 48–87% at the highest (r) = 1.8), together with [NaOH]. The influence of [NaOH] depends strongly on (r). The other studied variables are found to be insignificant in the model and has a complicated influence on the activation. In particular, (T) is found to be unimportant in the studied range (30–60 °C), but increasing (t) from 5 to 25 min shows a positive influence on DoA, depending on both (r) and [NaOH]. A mercerisation mechanism that is controlled by diffusion is proposed to explain these phenomena. [ABSTRACT FROM AUTHOR]

Aqueous sodium hydroxide solution is one of the simplest and most environmentally friendly solvents of cellulose. Regenerated cellulose/glucomannan blends were prepared from an aqueous sodium hydroxide solution, and the mechanical properties and structure of the blends were investigated. In addition, the noodle-shaped blends were sensory evaluated as food materials. The blends exhibited porous structures, which corresponded with high water and oil absorption. The strength and modulus of the blends were markedly low, probably due to the highly porous structure. The viscoelastic measurement indicated that cellulose and glucomannan existed in a rubbery state under wet conditions. The blends had a good oral sensation, probably derived from the remarkable porous structure, high water content, low strength and modulus, and rubbery state in wet conditions. The sensory evaluation suggested that the noodle-shaped blends can be used as a food material with a texture similar to capellini pasta. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydroxyethyl cellulose (HEC) fibers with low degree of substitution were prepared by wet spinning of solutions in 8 wt% NaOH solvent, and H 2 SO 4 /Na 2 SO 4 /ZnSO 4 solution was chosen as coagulants. The influence of coagulation temperature and H 2 SO 4 concentration on structure and mechanical properties of resultant HEC fibers was examined by synchrotron X-ray measurements, scanning electron microscope and tensile tests. The results were analyzed from the perspective of coagulation kinetics by determining coagulation rate and mass transfer rate difference. It is shown that the increase of either coagulation temperature or H 2 SO 4 concentration would accelerate the diffusion and coagulation process. The lowest coagulation temperature of 20 °C or moderate H 2 SO 4 concentration around 10–15 wt%, which provided a gentle solidification process, favored the development of regular crystal and oriented structure, uniform and dense inner structure as well as cross sections closer to circular, resulting in HEC fibers with better tensile properties. [ABSTRACT FROM AUTHOR]

Chitosan/cellulose nanocrystals (CH-CN) films were obtained by casting of dispersions, and treated with NaOH for neutralization proposes. The composition of films was varied from 1 to 10 wt.% of CN. Changes in the morphology of the systems were correlated with the different properties studied. FTIR revealed the presence of a weak interaction between the polymer matrix and nanofiller, confirmed by a slightly increase in thermal stability. SEM images suggested that incorporating CN amounts higher than 3 wt.% generates phase-segregated systems, and SAXS showed that CH avoid the typical organization of CN at concentrations below 5 wt.%. Improved performance against water was obtained in composite materials comparing to the pure polymer matrix, as well as CH and CH-CN films did not show antibacterial activity demonstrating that remnant acetic acid, when no neutralization step is done, plays an important role in this property. [ABSTRACT FROM AUTHOR]

In the last decades, the production of value-added products from lignocellulosic biomass (LCB) has gained relevance. Xylans, which are the main hemicellulose compounds in LCB, may be extracted by alkaline pretreatment and employed for xylooligosaccharide (XOS) production. However, xylan extraction currently works as a black box due to the lack of characterization of the involved streams. Therefore, the appropriate operational conditions often remain unclear, especially in hardwoods. In this study, alkaline/thermal pretreatments at different operational conditions were evaluated for xylan extractions from Chilean Nothofagus species sawdust, determining the chemical compositions of the fractions at each step of the process. Results indicated that increasing alkali concentration (NaOH) leads to a higher xylan extraction, but also to high salt production during the acid neutralization step, decreasing xylan's purity and therefore XOS production. In this context, decreasing NaOH concentration and neutralizing it by membrane filtration, allow extracting xylans (62.5 %) of higher-purity (77 %)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

We address the limited solubility and early onset of gelation of aqueous sodium hydroxide to position it as a preferred green solvent for cellulose. For this purpose, we expand the concentration window (up to 12 wt%) by using a CO 2 -depleted air and adjusting the time the dope remains in the given atmosphere, before further processing (holding time) and regeneration conditions. Cellulose solutions are extruded following characteristic (rheology and extrusion) parameters to yield aligned filaments reaching tenacities up to 2.3 cN·dtex -1 , similar to that of viscose. Further material demonstrations are achieved by direct ink writing of auxetic biomedical meshes (Poisson's ratio of -0.2, tensile strength of 115 kPa) and transparent films, which achieved a tensile strength and toughness of 47 MPa and 590 kJ·m -3 , respectively. The results suggest an excellent outlook for cellulose transformation into bioproducts. Key to this development is the control of the gelation ensuing solution flow and polymer alignment, which depend on CO 2 absorption, cellulose concentration, and holding time., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Here we report an efficient strategy to separate and recycle acid blue 93 (AB93) from mixed anionic dyes selectively within sodium hydroxide activated A/CS adsorbent (N-A/CS). This work broke the common sense that the larger the specific surface area, the better the adsorption property is, which provided an alternative strategy to separate dyes. The adsorption equilibrium of AB93 could be achieved approximately within 1-2 min, and the maximum adsorption capacity was up to 2500 mg/g. Besides, it can be activated continuously and reused at least 15 times. In mixed anionic dyes, the adsorption selectivity of N-A/CS on AB93 in the mixture of AB93 and acid fuschin (AF) reached up to 99.7 %. Molecular dynamics simulation revealed that the trend of adsorption energy for dyes qualifies well with the experimental order of adsorption capacities and molecular sizes among five anionic dyes based on molecular matching effect. Thus, N-A/CS is a low-cost, easily-preparable, significantly-effective-and-reusable adsorbent, providing a promising "size-matching" strategy to adsorb multi-component dye systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Degree of polymerization (DP) is an important factor which is affected by purification process. In this study, a new purification process is proposed in which cellulose DP is preserved. Response surface methodology (RSM) was used for optimizing the purification conditions. Purification process of biomass at 100 °C in 10 g/L sodium hydroxide and 30 g/L sodium dithionite, is reported as the optimum condition of this treatment. DP, purity, weight reduction and yellowness index were 6012, 98.10%, 8.46% and 25.22 respectively. TGA, IR, XRD and SEM techniques were used to compare both this new approach and conventional purification treatments. The results showed that this proposed purification process can produce cellulose with higher degree of polymerization compare to the conventional method. [ABSTRACT FROM AUTHOR]

In the present study, we decorated chitosan (©) with Fe 3 O 4 nanoparticles followed by cross-linking with GO to prepare Fe 3 O 4 supported chitosan-graphene oxide composite (Fe 3 O 4 ©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4–12), time (0–80 min), Fe 3 O 4 ©-GO dosage (2–10 mg), initial dye concentration (2–30 μg mL̄ 1 ) and temperature (303, 313, and 323 K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (Δ G 0 ), enthalpy (Δ H 0 ) and entropy (Δ S 0 ). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account. [ABSTRACT FROM AUTHOR]

Reactive dyes are most preferred dyes for dyeing of cellulosic fibres as they are chemically bonded to the fibre which is being dyed and also inexpensive to apply. But the application of reactive dyes onto the cellulosic materials requires a very high concentration of salt since fibre and dyes are anionic in nature. Even with required amount of salt only 65–70% of reactive dyes are exhausted, remaining 25–30% of dyes are removed as a coloured effluent after dyeing. The present work aims to eliminate salt usage in the reactive dyeing of cellulosic material, especially in cotton hosiery fabrics dyeing industry. In this study, the cationization of cotton fabric was carried out by varying concentration of cationic agent from 20 to 60 g/L by an exhaust method with the goal to achieve 100% dye utilization and fixation during the salt-free reactive dyeing process. All the dyes taken for the study showed excellent dye exhaustion, fixation and colour strength properties on the cotton fabrics. [ABSTRACT FROM AUTHOR]

Presented study deals with the pre-treatment of cellulose fibres with the aim to activate their surface and to enlarge their pore system, leading to an enhancement of fibres’ affinity for subsequent functionalization processes. Swelling of fibres in aqueous solutions of sodium hydroxide opens their fibrillar structure, while freezing and freeze-drying retain this enlargement of the pore system, in contrast with conventional air or elevated temperature drying. Effect of different pre-treatment procedures on fibres’ supramolecular structure, enlargement of their pore system, surface topography, zeta potential and mechanical properties was investigated. Degree of enhancement of the pore system depends on the concentration of sodium hydroxide and type of freezing; higher alkali concentrations are more effective, but at the cost of extensive deterioration of mechanical properties. Swelling of fibres in lower concentrations of NaOH, in combination with freeze drying, offers an acceptable compromise between enhancement of the fibres’ pore system, changes in surface potential and tensile properties of treated fibres. Design of a suitable regime of swelling and drying of cellulose fibres results in an effective procedure for controlled tuning of their surface topography in combination with an increase of the available internal surface area and pore volume. [ABSTRACT FROM AUTHOR]

Hydroxypropylation is a significant industrial process for diverse applications of polysaccharides. In the present study hydroxypropylation of Cassia gum derived from ruderal Cassia tora species was investigated using Taguchi's L'16 orthogonal array design of experiments. The optimized reaction conditions comprised: reaction temperature 50 °C, time 240 min, sodium hydroxide (0.015 mol), propylene oxide (0.0755 mol) and 60% aq. propane-2-ol. The maximum hydroxypropyl content, 8.43 and 7.71% were achieved using chromic acid titration and 1H NMR spectroscopic analysis respectively in the optimized product. The chemical shift values of substituted hydroxypropyl groups for methyl, methine and methylene protons at 0.98, 3.87 & 3.41 ppm along with respective carbons at δ 18.23, 69.41 & 79.13, and other assignments, 1H and 13C signals, were confirmed by COSY and HSQC correlation spectral analysis. The substituted hydroxypropyl groups, C 6 of the β-D-1, 4-linked-Manp unit, were established at 66.18 ppm. [Display omitted] • Taguchi L'16 array design was used to prepare hydroxypropyl derivative of Cassia tora gum • Chromic acid titration method is an appropriate method to determine the hydroxypropyl content • Derivative and substituted hydroxypropyl group at C-6 of the β-D-1, 4-linked-Manp unit were studied by NMR techniques [ABSTRACT FROM AUTHOR]

Upon heating and subsequent solvent displacement with pure water, the cold chitosan solution with aqueous alkaline/urea as solvent readily transforms into a hydrogel which is substantially stronger than traditional chitosan hydrogels regenerated from acidic solutions. In this work, we have systematically studied the effects of the treatment parameters in this two-step basic route and found that thermal gelation was the crucial step that dictated the structure and properties of the final gels. We hypothesized that the primary network formed in the thermal gelation step served as a template for the deposition of chitosan chains during solvent displacement, leading to a homogenous and compact structure. The primary network also provides crystalline seeds to facilitate the crystallization of the chitosan chains, leading to higher degree of crystallinity. This study provided a guideline for the preparation of chitosan hydrogels with high mechanical properties which is very meaningful to relevant research and applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In this study, graphene oxide reinforced regenerated cellulose/polyvinyl alcohol (GO–RCE/PVA) ternary hydrogels were successfully prepared via a repeated freezing and thawing method in NaOH/urea aqueous solution. The effect of GO content on the mechanical properties, swelling behavior, water content of composite hydrogels was investigated. It was found that the mechanical properties of GO–RCE/PVA ternary hydrogels were largely enhanced relative to RCE/PVA hydrogels. With the addition of 1.0 wt% GO, the tensile strength was increased by 40.4% from 0.52 MPa to 0.73 MPa, accompanied by the increase of the elongation at break (from 103% to 238%). Meanwhile, GO–RCE/PVA ternary hydrogels performed the excellent pH-sensitivity, and the higher pH leaded to higher swelling ratio. With 0.8 wt% GO loading, the swelling ratio of GO–RCE/PVA ternary hydrogel was improved from 150% (pH = 2) to 310% (pH = 14). In addition, a slight increase in the water content of the ternary hydrogel was achieved with increasing concentrations of GO. It is believed that this novel ternary hydrogels is a promising material in the application of biomedical engineering and intelligent devices. [ABSTRACT FROM AUTHOR]

One-step extrusion was developed to prepare starch sodium dodecenyl succinate (SSDS). Effects of screwing speed, reaction temperature, moisture content, sodium hydroxide amount (as catalyst), and dodecenly succinic anhydride (DDSA) amount on the degree of substitution (DS) were investigated. Optimum conditions were determined and found to be as follows: screwing speed, 110 rpm; temperature, 120 °C; moisture content, 30%; sodium hydroxide amount, 0.5%; DDSA amount, 3%. Under these conditions, the DS of SSDS was 0.014%, and the reaction efficiency was 78%. The structure of SSDS prepared by one-step extrusion was partially characterised. Infrared absorption spectra showed peaks of ester bond and carbonyl group at 1707 and 1564 cm −1 , respectively, indicating that dodecenyl succinic groups were introduced into starch molecule backbone by esterification agent. X-ray diffraction analysis showed that compared with native starch, the particle morphology of SSDS prepared by extrusion became irregular, and its crystallinity was partially destroyed. [ABSTRACT FROM AUTHOR]

Cellulose I, cellulose II and cellulose I/II hybrid fibers were prepared from energycane bagasse using NaOH and NaClO 2 treatments. The definitive defibrillation effect with an average width of 12 ± 5 μm was observed for the fibers treated with 20 wt% NaOH for 10 h and NaClO 2 for 2 h. The ribbon shaped cellulose I fibers were converted to a swollen state with a rougher surface by 20 wt% NaOH treatment for 10 h. The percentage of cellulose I decreased from 100% to 5%, and the corresponding CI values increased from 58.2% to 68.8% during the conversion from cellulose I to II. After further NaClO 2 treatment, the CI values were decreased because of partial destruction of hydrogen bond network. XRD, NMR and FTIR results present the same trend in the degree of crystallization for all the samples. [ABSTRACT FROM AUTHOR]

In this paper, we examine the significance of treatment with NaOH on chitosan (CH) film structure to obtain biodegradable materials for several applications. In order to determine the structure of the films, an analysis based on SEM, FTIR spectroscopy and X-ray diffraction data was performed. In addition, the consequences of this treatment were evaluated by swelling index measurements and mechanical testing. As result of FTIR and X-ray analysis, three effects were identified: the deprotonation and phosphate extraction, which allowed new hydrogen bonds to form, and a higher CH deacetylation. These studies also revealed that two hydrated and anhydrous polymorphs were present in the CH–NaOH films. Moreover, the new hydrogen bond and the reduction of N -acetyl groups produced films with a more compact and disordered structure, reducing their swelling characteristics and increasing their brittleness. The introduction of a mild NaOH treatment is a versatile tool to obtain chitosan films with interesting and tunable properties. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCG), obtained during the processing of coffee powder with hot water to make soluble coffee, are the main coffee industry residues and retain approximately seventy percent of the polysaccharides present in the roasted coffee beans. The purpose of this study was to extract polysaccharides from SCG by using an alkali pretreatment with sodium hydroxide at 25 °C, and determine the chemical composition, as well as the antioxidant and antimicrobial properties of the extracted polysaccharides. Galactose (60.27% mol) was the dominant sugar in the recovered polysaccharides, followed by arabinose (19.93% mol), glucose (15.37% mol) and mannose (4.43% mol). SCG polysaccharides were thermostable, and presented a typical carbohydrate pattern. Additionally, they showed good antioxidant activity through different methods and presented high antimicrobial percent inhibition against Phoma violacea and Cladosporium cladosporioides (41.27% and 54.60%, respectively). These findings allow identifying possible applications for these polysaccharides in the food industry. [ABSTRACT FROM AUTHOR]

This study focused on the effect of cellulose crystal type on the dissolution of cellulose in aqueous NaOH/urea. Cellulose I, II, III I , and IV I were prepared and characterized. Subsequently, the solubility of these cellulose samples in aqueous NaOH/urea was tested and the mechanism was determined by a combination of 1 H NMR spectroscopy and differential scanning calorimetry (DSC). The results indicated that, compared with the degree of polymerization (DP) and crystallinity index of cellulose, the cellulose crystal type had greater impact on cellulose dissolution. Specially, the solubility of the cellulose I, II, and III was progressively decreased, probably due to different hydrogen bond network and packing energy in it. The ability of cellulose I, II, III, and IV to form hydrogen bonds with sodium hydroxides was nearly the same, while gradually increased when cellulose preparations were associated with urea. Moreover, all the cellulose solutions showed good thermal stability. [ABSTRACT FROM AUTHOR]

Isocratic HPLC was used in conjunction with conductometric titration to quantitatively examine the modification of cotton cellulose by citric acid (CA)/sodium hypophosphite (SHP). CA/SHP had been extensively used as a green crosslinking agent for enhancement of cellulose and other carbohydrate polymers without in-depth understanding of the mechanisms. The current study investigated all identifiable secondary polycarboxylic acids from CA decomposition in the CA/SHP-cellulose system under various curing conditions. It was found that CA decomposition was more sensitive to temperature compared with the desirable esterification reaction. Two crosslinking mechanisms, namely ester crosslinking and SHP crosslinking were responsible for the observed improvement in crease resistance of CA/SHP treated cotton fabrics. An oligomer of citraconic acid (CCA) and/or itaconic acid (IA) was identified as a possible contributor to fabric yellowing. Finally, the crease resistance of fabrics correlated strongly with CA preservation in polyol-added CA/SHP crosslinking systems. The dosage of polyol should be held below an inflexion point to keep the undesirable competition against cellulose minimum. The combination of HPLC and conductometric titration was demonstrated to be useful in studying the CA/SHP-cellulose crosslinking system. The findings have implications for better application of CA/SHP in polysaccharide modifications in general. [ABSTRACT FROM AUTHOR]

Cationization of cotton fabric form was effected by reacting the cellulose with 3-chloro-2 hydroxypropyl trimethyl ammonium chloride in presence of sodium hydroxide as per the pad dry cure method. Thus obtained cationized cotton cellulose was reacted with a reactive copolymer, namely, reactive β-cyclodextrin grafted with polyacrylic acid (MCT-βCD-g-PAA).Bridging of another copolymer, namely, β-cyclodextrin grafted with polyacrylic acid (βCD-g-PAA) to the cationized fabric using epichlorohydrin crosslinker was also performed. Inclusion of Ag nanoparticles in these three cotton substrates via treatment of the latter with colloid of Ag nanoparticles or through in situ formation of the former was exercised. Characterization of cotton fabric before and after being chemically modified was carried out using FTIR, XRD and SEM. Bacterial examination of the cationized cotton containing either (MCT-βCD-g-PAA) or (βCD-g-PAA) incorporated with Ag nanoparticles showed these substrates function against G+ve and G−ve bacteria. Ability of (MCT-βCD-g-PAA) modified cotton to include hydrophobic molecules was examined. [ABSTRACT FROM AUTHOR]

A group of 12 polysaccharide extracts were prepared from the tips, stem and roots of an Indian halophyteSalicornia brachiataRoxb. obtained by sequential extractions with cold water (CW), hot water (HW), aqueous ammonium oxalate (OX) and aqueous sodium hydroxide (ALK) solutions. Monosaccharide composition analysis revealed that all the polysaccharide extract samples consisted primarily of rhamnose, arabinose, mannose, galactose, glucose, whereas ribose and xylose were present only in some of the extracts. All the extracts exhibited low apparent viscosity (1.47-2.02cP) and sulphate and contained no prominent toxic metal ions. Fucose was detected only in OX extract of the roots. These polysaccharides were found to be heterogeneous and highly branched (glycoside linkage analysis, size-exclusion chromatography,13C-NMR, FT-IR, circular dichroism and optical rotation data). Physico-chemical analyses of these polysaccharides including uronic acid, sulphate and protein contents were also carried out. This constitutes the first report on the profiling ofSalicorniapolysaccharides. [ABSTRACT FROM AUTHOR]

In this article, the manganese-containing cellulose nanocomposites were obtained using microcrystalline cellulose and Mn(CH3COO)2·4H2O in the NaOH/urea aqueous solutions by a efficient microwave-assisted method. The effects of the heating time and Mn(CH3COO)2·4H2O concentration on the cellulose nanocomposites were investigated. It was found that the microcrystalline cellulose pretreated with NaOH/urea aqueous solutions played an important role in the phase, shape, and thermal stability of manganese-containing cellulose nanocomposites. Well-crystalline phases of manganese oxides were not observed in the manganese-containing cellulose nanocomposites. Furthermore, well-crystalline phases of manganese oxides were not also observed by thermal treatment of the manganese-containing cellulose nanocomposites at 600 °C for 3 h. These results could be attributed to the restrain effect of cellulose treated with NaOH/urea aqueous solutions. It was supposed the possible mechanism during the phase transformation of cellulose nanocomposites. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three adsorbents, sodium hydroxide activated carbon, calcium alginate and a composite of both were prepared. [•] Effect of adsorbent dosage, pH, time, temperature and initial concentration of methylene blue were studied. [•] Thermodynamic studies show the spontaneous and endothermic nature of overall adsorption process. [ABSTRACT FROM AUTHOR]