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The hydrogel regeneration process, involving various cellulose types, results in distinct chemical bonding patterns. Even minor variations in chemical interactions among polymers during regeneration significantly impact properties like hydrogel-forming ability, hydrophilicity, and swelling capacity. This study focuses on regenerating a superabsorbent hydrogel from the interplay of native empty fruit bunch cellulose (EFBC), sodium carboxymethyl cellulose (NaCMC), and hydroxyethyl cellulose (HEC) using epichlorohydrin (ECH) as a crosslinker. The hydrogel was formed from dissolved EFBC solutions in an aqueous NaOH/urea solvent, supplemented with different NaCMC and HEC weight ratios, and ECH chemically assisted the crosslinking process. EFBC provides the hydrogel's supporting skeletal structure, while NaCMC and HEC play vital roles in enhancing forming ability and its physical and mechanical properties through diverse chemical interactions based on their electrovalent properties. Notably, NaCMC imparts hydrophilicity, while HEC indirectly improves superabsorbent properties through the enhancement of the elastic network's retraction force. Hydrogels combining NaCMC and HEC show a remarkable water absorption capacity exceeding 30,000 %, surpassing those regenerated solely with EFBC and NaCMC. The highest swelling, over 130,000 %, is achieved with 0.75 % NaCMC and 0.25 % HEC. Regarding thermal stability, hydrogels with a higher NaCMC proportion outperform those with increased HEC content. The study highlights the critical role of tailored chemical interactions in successfully regenerating an improved superabsorbent hydrogel with enhanced water absorption properties., Competing Interests: Declaration of competing interest There is no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Carbon dioxide (CO 2 ) capture has been identified as a potential technology for reducing the anthropic emissions of greenhouse gases, particularly in post-combustion processes. The development of adsorbents for carbon capture and storage is expanding at a rapid rate. This article presents a novel sustainable synthesis method for the production of chitosan/activated carbon CO 2 adsorbents. Chitosan is a biopolymer that is naturally abundant and contains amino groups (-NH 2 ), which are required for the selective adsorption of CO 2 . Spent coffee grounds have been considered as a potential feedstock for the synthesis of activated coffee grounds through carbonization and chemical activation. The chitosan/activated coffee ground composite microspheres were created using the emulsion cross-linking method with epichlorohydrin. The effects of the amount of chitosan (15, 20, and 25 g), activated coffee ground (10, 20, 30, and 40% w/w ), and epichlorohydrin (2, 3, 4, 5, 6, 7 and 8 g) were examined. The CO 2 capture potential of the composite beads is superior to that of the neat biopolymer beads. The CO 2 adsorbed of synthesized materials at a standard temperature and pressure is improved by increasing the quantity of activated coffee ground and epichlorohydrin. These findings suggest that the novel composite bead has the potential to be applied in CO 2 separation applications.

To replace traditional petrochemical-based thermal insulation materials, in this work, the chitosan (CHI)/alginate (ALG) (CA) aerogels with three-dimensional hierarchical pore network structure were constructed by compositing CHI and ALG using a synergistic strategy of hydrogen bonding dissolution and covalent crosslinking. The structure and properties were further regulated by crosslinking the CA aerogels with epichlorohydrin (ECH). The CA aerogels exhibited various forms of covalent crosslinking, hydrogen bonding and electrostatic interactions, with hydrogen bonding content reaching 79.12 %. The CA aerogels showed an excellent three-dimensional hierarchical pore network structure, with an average pore size minimum of 15.92 nm. The structure regulation of CA aerogels obtained excellent compressive properties, with an increase of stress and strain by 137.61 % and 45.05 %, which can support a heavy object 5000 times its weight. Additionally, CA aerogels demonstrate excellent thermal insulation properties and low thermal conductivity, comparable to commercially available insulation materials. More importantly, CA aerogels have good cyclic insulation stability and thermal properties, and they have a flame retardancy rating of V-0, which shows the stability of insulation properties and excellent safety. CA aerogels provide new ideas for the development of biomass thermal insulation materials and are expected to be candidates for thermal management 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 © 2024 Elsevier B.V. All rights reserved.)

Chiral epichlorohydrin (ECH) is an attractive intermediate for chiral pharmaceuticals and chemicals preparation. The asymmetric synthesis of chiral ECH using 1,3-dicholoro-2-propanol (1,3-DCP) catalyzed by a haloalcohol dehalogenase (HHDH) was considered as a feasible approach. However, the reverse ring opening reaction caused low optical purity of chiral ECH, thus severely restricts the industrial application of HHDHs. In the present study, a novel selective conformation adjustment strategy was developed with an engineered HheC PS to regulate the kinetic parameters of the forward and reverse reactions, based on site saturation mutation and molecular simulation analysis. The HheC PS mutant E85P was constructed with a markable change in the conformation of (S)-ECH in the substrate pocket and a slight impact on the interaction between 1,3-DCP and the enzyme, which resulted in the kinetic deceleration of the reverse reactions. Compared with HheC PS , the catalytic efficiency (k cat(S)-ECH /K m(S)-ECH ) of the reversed reaction dropped to 0.23-fold (from 0.13 to 0.03 mM -1  s -1 ), while the catalytic efficiency (k cat(1,3-DCP) /K m(1,3-DCP) ) of the forward reaction only reduced from 0.83 to 0.71 mM -1  s -1 . With 40 mM 1,3-DCP as substrate, HheC PS E85P catalyzed the synthesis of (S)-ECH with the yield up to 55.35% and the e.e. increased from 92.54 to >99%. Our work provided an effective approach for understanding the stereoselective catalytic mechanism as well as the green manufacturing of chiral epoxides., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

In the realization of the goal of circular economy, cellulose as one of sustainable biomass resources, have attracted much attention because of their abundant sources, biodegradability and renewability. However, the mechanical and waterproof performance of cellulose-based materials are usually not satisfying, which limits their high-value utilization. In this study, cellulose membrane with high-performance from the aspects of mechanical properties, water-resistance ability, oxygen barrier capacity and biodegradability, was prepared from bleached hardwood pulp (HBKP) in a AlCl 3 /ZnCl 2 /H 2 O solution. The AlCl 3 /ZnCl 2 /H 2 O acted as both solvent and catalyst to dissolve cellulose and facilitate the chemical crosslinking of epichlorohydrin (EPI) with cellulose, thus improved the overall performance of the obtained cellulose membrane. The addition sequence, amount and crosslinking time of EPI during chemical crosslinking had important effects on the properties of the membranes. When 7 wt% EPI was crosslinked for 24 h, the tensile stress reached 133 MPa and the strain reached 17 %. Moreover, the membrane had excellent oxygen insulation down to (1.1 ± 0.31) × 10 -4  cm 3 /m 2 ·d·Pa, and good water-resistance ability, no obvious swelling behavior after 450 days of immersion in distilled water. Furthermore, the membrane could be degraded by microorganisms in about 20 days. This cellulose-based membrane offers a sustainable and biodegradable packaging material., 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 B.V. All rights reserved.)

Protein materials gain new functions and applicability through redesigns in protein structure and engineering confer. However, the application and development of proteins for use in flexible devices that fit in flexible devices that fit the surface of human skin is hindered by their poor wet stability. Here, we described the design of wet-stable materials based on the reconstruction of silk fibroin (SF). The combination of polyamide-amine-epichlorohydrin (PAE) was used as a traction rope to bring SF molecular chains closer to each other, to facilitate the self-assembly of SF through branching and lengthening of molecular chains, and change its crystalline structure. SF/PAE composite films that exhibited huge improvement in ductility and wet stability were combined with flexible SF substrates via patterning and ion sputtering to prepare flexible sensors. In addition, the SF/PAE sensing system equipped with a microprocessor and Bluetooth module enabled the real-time remote acquisition of human health signals such as vocal cords, joints, pulse and meridians. This reconfiguration of the SF structure will advance the systematic exploration of protein structures and the development of protein materials for intelligent device 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 © 2024 Elsevier B.V. All rights reserved.)

The extraction of non-steroidal anti-inflammatory drugs (NSAIDs) from water bodies is imperative due to the potential harm to humans and the ecosystem caused by NSAID-contaminated water. Quaternary amino-functionalized epichlorohydrin cross-linked chitosan fibers (QECFs), an economical and eco-friendly adsorbent, were successfully prepared using a simple and gentle method for efficient diclofenac (DCF) adsorption. Additionally, the optimized factors for the preparation of QECFs included epichlorohydrin concentration, pH, temperature, and (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHTAC) concentration. QECFs demonstrated excellent adsorption performance for DCF across a broad pH range of 7-12. The calculated maximum adsorption capacity and the amount of adsorbed DCF per adsorption site were determined to be 987.5 ± 20.1 mg/g and 1.2 ± 0.2, respectively, according to the D-R and Hill isotherm models, at pH 7 within 180 min. This performance surpassed that of previously reported adsorbents. The regeneration of QECFs could be achieved using a 0.5 mol/L NaOH solution within 90 min, with QECFs retaining their original fiber form and experiencing only a 9.18% reduction in adsorption capacity after 5 cycles. The Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy were used to study the characterization of QECFs, the preparation mechanism of QECFs, and the adsorption mechanism of DCF by QECFs. Quaternary ammonium groups (R 4 N + ) were well developed in QECFs through the reaction between amino/hydroxyl groups on chitosan and CHTAC, and approximately 0.98 CHTAC molecule with 0.98 R 4 N + group were immobilized on each chitosan monomer. Additionally, these R 4 N + on QECFs played a crucial role in the removal of DCF., 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. Published by Elsevier Ltd.)

Hydrogels based on natural polysaccharides have received special attention in the last decade due to their interesting features, such as availability, biocompatibility, biodegradability and safety. Such characteristics may make them sustainable and eco-friendly materials for water and wastewater treatment, meeting the concept of circular economy. In this study, a novel double-cross-linked alginate-based hydrogel has been successfully synthesized using epichlorhydrin and sodium trimetaphosphate (STMP) as cross-linker agents and then used for the removal of methylene blue (MB) dye under different operating conditions. The obtained hydrogel was deeply characterized by using various analytical techniques, namely Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Experimental results showed that the synthesized double cross-linked hydrogel with relatively high STMP concentration (0.26 M) has promising structural and textural properties. This material exhibited excellent removal ability towards MB with a maximum adsorption capacity of about 992 mg/g for an initial pH of 10. The kinetic and isotherm modeling study revealed that the pseudo-second-order and Freundlich models fitted well the measured adsorption experimental data. The MB adsorption process onto the synthesized hydrogel is exothermic, feasible and spontaneous. It mainly includes electrostatic interaction and hydrogen bonds. These findings suggest that double-cross-linked alginate-based hydrogel can be considered as an attractive and potential adsorbent for an effective cationic dye removal from aqueous environments. The use of such a green adsorbent for the treatment of organic-pollutants-rich industrial wastewaters promotes sustainability and circular economy concepts., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The potential applications of cellulose nanofibril-based foam materials can be expanded by their enhanced water durability. This study proposes two crosslinking methods to improve the water durability of the oven-dried carboxymethylated cellulose nanofibril (CMCNF) foam. The first method involves the addition of a crosslinker, polyamideamine epichlorohydrin. The second method is the self-crosslinking of CMCNFs via heat treatment at 140 °C for less than an hour, which is a simple way to crosslink CMCNF-based materials. Both crosslinking methods resulted in excellent water durability and wet resilience of the foams, which also exhibited high water absorbency. Furthermore, neither method affected the structural nor mechanical properties of the oven-dried CMCNF foams. In particular, self-crosslinking by heat treatment proved to be as effective as using a crosslinking agent. Compared to the freeze-dried foam, the oven-dried foam exhibited slower methylene blue (MB) dye adsorption but a higher maximum adsorption capacity (238-250 mg/g), attributed to the closed pore structure and a larger specific surface area. In addition, the isotherm and reusability of the foam for MB adsorption were investigated. These crosslinking processes expanded the potential use of oven-dried CMCNF foams as adsorbents for cationic dyes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationship that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

A composite aerogel with good mechanical properties and adjustable physical properties was synthesized by a sol-gel technique on the base of gelatin for the boron adsorption from water solution. The adsorption key variables, for instance, initial boron concentration (C 0 ) (900-1100 mg/L), the contact time (t) (8-9 h), and pH (9-11), were optimized using central composite design to obtain improved boron adsorption performance of epichlorohydrin-modified gelatin (EMG)/N-methyl-d-glutamine (NMDG) aerogel loaded with hydroxylated carbon nanotubes (EMG@NMDG). The adsorption followed the pseudo-second-order and Freundlich model. At pH of 10, C 0 of 1000 mg/L and t of 10 h, the largest adsorbed amount of EMG@NMDG was 85.79 mg/g. Regeneration experiments were carried out by eluting the adsorbent using HCl. The analysis showed that the adsorption in actual brine was 62.65 mg/g. Therefore, the developed EMG@NMDG aerogel has potential value for the boron extraction from brine and wastewater., 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 B.V. All rights reserved.)

This paper reports a synergic binding technique of dye and cadmium/lead ions onto freeze-dried modified chitosan beads (GCCS), in this work modified chitosan beads was applied in binary solution. Chitosan beads (CS) composite was produced and polyethyleneimine was grafted onto the backbone of the developed composite. The beads were analyzed utilizing different analytical techniques such as Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The model applied in pH equilibrium was found to justify the adsorption of pollutants onto the adsorbent. The model was established from 2 equilibrium calculations, one justifying the acid-base attributes of the modified beads, the other elucidating the adsorption of the adsorbates onto the beads, and a mass balance of the various arrangement of nitrogen in the adsorbent. The excellent fit of the Pseudo-second order and intra-particle diffusion kinetic model shows that chemical binding might be the rate-limiting step. The adsorption isotherms were well represented by the Langmuir and Temkin models at a temperature of 45 °C. The maximum binding capacities (Q max ) from the Langmuir model were observed to be 390, 315 and 278 mg/g for the adsorption of dye, lead and cadmium ions respectively`. However, it was found to be higher in the binary system with the same applicable conditions. The correlation was analyzed utilizing various models and lines of best fit were obtained. Synergic effect was observed from the experimental results acquired from the adsorption of Rhodamine B (RHB) and adsorbates. These findings show the formation of fresh binding sites during simultaneous binding process., Competing Interests: Declaration of competing interest The corresponding author confirms on behalf of all authors that there have been no involvements that might raise the question of bias in the work reported or in the conclusions, implications, or opinions stated., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Epichlorohydrin-modified chitosan-Schiff base composite (CS/24Cl/ECH) prepared via the one-pot reaction as characterized by Fourier transform Infra-Red spectroscopy (FT-IR), X-ray powder diffraction (XRD), Differential scanning calorimetry (DSC) and Scanning electron microscope (SEM). Its removal ability of Pb(II) ions from aqueous solution was investigated. The adsorption of Pb(II) ions carried out at different initial pH, dose of CS/24-Cl/ECH, contact time and co-existing ions. The maximum adsorption capacity of Pb(II) ions was 170 mg/g. Finally, based on the absorption results, the adsorption of Pb(II) ions was fitted by single-layer Langmuir isotherm model and the pseudo-second-order (PSO) kinetics model. The absorption mechanism of Pb(II) ions was controlled by chemical coordination Pb(II) ions with the active sites on the surface of CS/24Cl/ECH composite. Also, CS/24Cl/ECH showed excellent recyclable efficiency up to 5 cycle and potential sorbent for other heavy metal ions., 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 The Authors. Published by Elsevier B.V. All rights reserved.)

Chitosan/bentonite beads (CsB) composites were prepared from chitosan (Cs) and bentonite (B) and cross-linked with epichlorohydrin for removal of reactive orange 16 (RO16) and methylene blue (MB). The adsorption results have shown that the (Cs20B80), 20 % wt of (Cs) and 80 % (B), was selected as the best adsorbent for (MB) and (RO16) dyes. SEM, EDX, FTIR, BET, and pHpzc were implemented to investigate the features of Cs, B, and Cs20B80 samples. The influence of contact time (0-72 h), initial RO16 concentration (15-300 mg/L), temperature (30, 40, and 50 °C), the quantity of adsorbent (1-4 g/L), ion strength (0.1-1 M), and solution pH (3-10) on RO16 adsorption onto Cs20B80 were explored. The pseudo-second-order and the Langmuir models fit adequately the adsorption kinetic results and the isotherms ones respectively. Also, the maximal monolayer capacities calculated using the non-linear form of the Langmuir isotherm are 55.27, 55.29, and 70.80 mg/g, at 30, 40 and 50 °C. Based to the statistical physics model, the RO16 could be retained on the surface of Cs20B80 through a non-parallel orientation. The RO16 adsorption process is endothermic and natural, as demonstrated by thermodynamic studies. After three regeneration cycles, the Cs20B80 composite has shown an adsorption capacity of around 20 % compared to the initial one. The adsorption energy of RO16 onto Cs, B, and Cs20B80 examined using the Monte Carlo simulation method (MC) ranged from -164.8 to -303.7 (kcal/mol), showing the potential of the three adsorbants for RO16 dye. Also, the process of adsorption of RO16 dye on the surface of Cs20B80 composite indicates several kinds of physical interactions, involving electrostatic interaction, hydrogen bonding, and π-π interactions, this finding was proved theoretically via molecular dynamic simulations., Competing Interests: Declaration of competing interest There are no known competing interests to declare., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This paper presents a binary reinforcement system of polyamide polyamine epichlorohydrin with nanocellulose (PAE-NC) for effectively modification of the reclaimed fibres for paper production, and based on the improvement of physical and mechanical properties of cellulosic fibres together with PAE-NC self-crosslinking networks, the strengthening mechanisms of recycled papers are examined. The PAE-NC binary system was applied directly to old corrugated container (OCC) and softwood bleached kraft pulp (SWBKP), and handsheets are prepared with varying amounts of PAE/NC/PAE-NC, namely 0.05, 0.1, 0.3, 0.5, 0.75, 1.0, 1.5, 2.0 wt% (dry pulp). The results showed that the studied additives improved the performance of recycled fibres, whether SWBKP or OCC pulp, and handsheets in solely or combined mechanisms except for the air permeability of the handsheets. The treatment of PAE-NC combination was significantly more effective than those of PAE or NC alone for both OCC and SWBKP, although the combined PAE-NC treatment results in better performance enhancement for OCC than SWBKP handsheets, and the NC alone is more effective than PAE for SWBKP recycled paper and conversely for OCC recycled paper. SEM observations further confirmed that the combined PAE-NC addition treatment imparted a relatively uniform surface structure to the handsheet., 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. Published by Elsevier B.V.)

Chitosan (Ch, a natural polymer) and kaolin (K, a natural mineral) composite (Ch-K) was produced with the help of two crosslinkers, epichlorohydrin and tripolyphosphate, and then moulded into uniform beads in tripolyphosphate solution. The synthesis was proved by the analyses involving FT-IR and SEM-EDX. The beads were then used as the natural adsorbent for removal of the auramine O (AO), a frequently-used industrial dye, in aqueous solutions. Adsorbent performance of the Ch-K composite for AO dye molecules was optimized: 500 mg L -1 at pH 7.5 at 25 °C. The Langmuir model found 0.118 mol kg -1 for the maximum adsorption capacity of the Ch-K and the D-R isotherm model showed that the nature of the adsorption process was physical. Kinetics of the adsorption could be explained by using both IPD (intraparticle diffusion) and PSO (pseudo second order) models. Thermodynamic parameters demonstrated that the behaviour of the adsorption was an endothermic and spontaneous. The activity of the composite adsorbent was recovered (88%) after the five sequential adsorption/desorption cycles. Supported by experimental findings, the results obtained from in silico modeling at M06-2X/6-31+G (d,p) level helped hypothesise a mechanism for the formation of the Ch-K composite, and shed some light onto the adsorption behaviour of AO dye by assuming several favourable intermolecular interactions., (Copyright © 2022. Published by Elsevier B.V.)

Curcumin (Cur) is an anti-inflammatory polyphenol that can be complexed with polymeric cyclodextrin (CD) to improve solubility and bioavailability. The aim of the present work was to prepare a CurCD hydrogel to treat inflammatory skin conditions. Epichlorohydrin-β-CD (EpiβCD) was used as polymeric CD. To characterize the binary system, solid-state and in-solution studies were performed. Afterwards, an experimental design was performed to optimize the hydrogel system. Finally, the CurEpiβCD hydrogel system was tested for anti-inflammatory activity using a HaCat psoriasis cell model. Co-grinded Cur/EpiβCD binary system showed a strong interaction and Curcumin solubility was much improved. Its combination with Pluronic ® F-127/hyaluronate hydrogel demonstrated an improvement in release rate and Curcumin permeation. After testing its anti-inflammatory activity, the system showed a significant reduction in IL-6 levels. Hydrogel-containing CurEpiβCD complex is a great alternative to treat topical inflammatory diseases.

A series of lignin-based epoxy resins (LEPs) were prepared by the reaction of epichlorohydrin with lignin oligomers derived from partial reductive depolymerization of lignin. To overcome the high viscosity and brittleness defects in practical applications, the LEPs were blended with renewable epoxied cardanol glycidyl ether (ECGE) and then cured with methyltetrahydrophthalic anhydride (MeTHPA) to form high-performance epoxy thermosets. The effects of degree of lignin depolymerization, chemical composition of lignin oligomers and dosage of ECGE on thermal and mechanical properties of the cured products were investigated. The LEP/MeTHPA thermosets exhibited good thermal and mechanical properties. Especially, by separating monomer-rich fractions from lignin oligomers, the thermal and mechanical properties of the cured product were improved obviously. Notably, the incorporation of ECGE also possessed a positive effect on reinforcing and toughening the cured products. With 20 wt% ECGE loadings, the tensile, flexural and impact strength of the cured product reached the maximum value of 77 MPa, 115 MPa and 14 kJ/m 2 , respectively, which were equivalent to the commercial bisphenol A epoxy resins thermosets. These findings indicated that the novel bio-based epoxy resins from lignin oligomers and cardanol could be utilized as renewable alternatives for BPA epoxy resins., (Copyright © 2021. Published by Elsevier B.V.)

Well dispersibility of 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO)-oxidized nanochitins under alkaline conditions supports the effective chemical crosslinking between nanochitin and epichlorohydrin. The storage modulus of nanochitin hydrogels can be promoted by approximately 10 times as the nanochitin-to-epichlorohydrin mass ratio changes from 4:1 (120 Pa) to 1:4 (1200 Pa). Besides the enhanced mechanical property of hydrogels, the inter-structure of resulting cryogels is found controllable. With increasing epichlorohydrin dosage, the inter-structure of cryogels transforms from a typical fiber-like to honeycomb-like texture. The balance between chemical crosslinking effect and electrostatic repulsion between nanochitins is believed to result this controllable inter-structure. Further immersing into acetic acid solution can greatly enhance the mechanical strength of nanochitin hydrogels due to the introduction of physical crosslinking domains by shielding the electrostatic repulsion, the storage modulus becomes two times higher after immersing in 50% (w/w) acetic acid solution, while the surface area of nanochitin cryogels decreases due to the denser structure., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nickel (Ni) is one of the most common heavy metals. In this study, nano-sized magnetic ion-imprinted polymers (MIIPs) were synthesized using chitosan as the functional monomer, and used for selective adsorption and recovery of Ni(II) from solutions. The results showed MIIPs possessed high sorption selectivity for Ni(II), and the change in pH (5.0-9.0) exerted insignificant influence on the ion adsorption, allowing almost complete elution and recovery of adsorbed Ni(II) ions by using 0.5% EDTA-Na solution. Moreover, the sorption capacity of the recycled MIIPs decreased by only about 10% after 15 adsorption-desorption cycles. The time required for establishing the adsorption equilibrium was less than 1 h. The sorption process was predominant and endothermic, and could be well described by both Langmuir isotherm model and pseudo-second-order kinetic model. Therefore, the synthesized MIIPs was a suitable adsorbent for highly selective, fast and efficient removal and recovery of low-concentration Ni(II) ions from wastewaters., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Hydrogels, possessing high biocompatibility and adaptability to biological tissue, show great usability in medical applications. In this research, a series of novel cross-linked chitosan quaternary ammonium salt loading with gentamicin sulfate (CTMCSG) hydrogel films with different cross-linking degrees were successfully obtained by the reaction of chitosan quaternary ammonium salt (TMCS) and epichlorohydrin. Fourier transform infrared spectroscopy (FTIR), thermal analysis, and scanning electron microscope (SEM) were used to characterize the chemical structure and surface morphology of CTMCSG hydrogel films. The physicochemical property, gentamicin sulphate release behavior, cytotoxicity, and antibacterial activity of the CTMCSG against Escherichia coli and Staphylococcus aureus were determined. Experimental results demonstrated that CTMCSG hydrogel films exhibited good water stability, thermal stability, drug release capacity, as well as antibacterial property. The inhibition zone of CTMCSG hydrogel films against Escherichia coli and Staphylococcus aureus could be up to about 30 mm. Specifically, the increases in maximum decomposition temperature, mechanical property, water content, swelling degree, and a reduction in water vapor permeability of the hydrogel films were observed as the amount of the cross-linking agent increased. The results indicated that the CTMCSG-4 hydrogel film with an interesting physicochemical property, admirable antibacterial activity, and slight cytotoxicity showed the potential value as excellent antibacterial wound dressing.

Bone defect is usually difficult to recover quickly, and bone scaffold transplantation is considered to be an effective method. Biomaterials have a wide range of application prospects in bone tissue repair, and the two key problems are the selection of materials and cells. The object of this study was to discuss the structural characteristics of bone scaffold materials and their effects on bone repair in vivo. The chitin-hydroxyapatite (HAP)-collagen composite scaffolds (CHCS) was prepared with epichlorohydrin (ECH) as crosslinking agent. The structure was characterized and the compressive strength, porosity, water absorbency and stability were investigated. The biocompatibility and osteogenic differentiation of CHCS in vitro were detected, and the effect of defect repair in vivo was evaluated. The results suggested that HAP not only enhanced the compressive strength of CHCS, but also promoted the formation of calcium nodules due to its bone conductivity. Histological staining showed that collagen promoted collagen deposition and new bone formation. X-ray images also indicated that CHCS transplantation accelerated bone repair. Therefore, CHCs has immense potential in bone regeneration., (Copyright © 2021. Published by Elsevier B.V.)

While green bioplastic based on carbohydrate polymers have showed considerable promise, the methods typically used to prepare them in a single material have remained a significant challenge. In this study, a simple approach is proposed to fabricate high performance cellulose films composed of chemically and physically dual-crosslinked 2,2,6,6-tetramethylpiperidine-1-oxy-oxidized cellulose nanofibers (DC TEMPO-CNFs). The hydroxyl groups of TEMPO-CNF suspensions were firstly crosslinked chemically with epichlorohydrin (ECH), and subsequently TEMPO-CNF matrices were crosslinked physically via the strong electrostatic interaction between carboxylate and Ca 2+ ions. It was found that the optimized DC TEMPO-CNF films exhibit a good transmittance (90 %) and a high tensile strength (303 MPa). Furthermore, these DC TEMPO-CNF films revealed superior thermal stability and excellent water resistance compared to neat TEMPO-CNF films without crosslinked domains. We believe that these results will pave the way to preparing practical polysaccharide bioplastics with simple, environmentally-friendly manufacturing processes., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Anti-drought is a global challenge. The addition of superabsorbent polymers (SAPs) in soil can lower down the water percolation and evaporation. However, the salt-tolerance and repeating water absorbency (RWA) of prepared SAPs have not satisfied the requirements for implementation. This research investigated the influence of cation valence (Na + , Ca 2+ and Al 3+ ) on the structural variations of a crosslinked carboxymethyl cellulose (CCMC) using carboxymethyl cellulose (CMC) cross linked by epichlorohydrin (ECH). The results showed that higher addition of NaOH resulted in higher water absorbency (WA) due to the existence of more carboxyl group. The prepared CCMC sample with 5% CMC and 3% NaOH (CCMC 53 ) was a qualified SAP with WA of 969.0 g/g in deionized water. The salt resistance and the hydrophilicity of sample CCMC 53 decreased with the increase of cation valence in the solution. The introduction of Na + resulted in the replacement of H + from carboxyl group in sample CCMC 53 -Na. The coordination of carboxyl group and Ca 2+ was bidentate chelating and tridentate bridging for carboxyl group and Al 3+ . The introduction polyvalent cations benefited the stabilization of carboxyl group, however, retarded the swelling ability of sample CCMC 53 and hence resulted in lower WA CS . The RWA of sample CCMC 53 in deionized water and salt solution dropped the most in the first absorption cycle and then reached constant after a few more cycles. It was necessary to control the first swelling degree of SAP in order to keep the RWA at a higher level., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The ortho-phospho-tyrosine (P-Tyr) pseudoaffinity ligand was immobilized via ether linkage onto polyacrylamide-alginate (PAAm-Alg)-epoxy cryogels prepared according to two different approaches in order to explore their performance in the immunoglobulin G (IgG) purification from human serum. In the first approach, the P-Tyr was attached to cryogel prepared by cryocopolymerization of acrylamide and alginate with allyl glycidyl ether (AGE) as functional comonomer, and methylenebisacrylamide and Ca(II) as crosslinkers, obtaining the PAAm-Alg-AGE-P-Tyr. In the second approach, the PAAm-Alg was synthesized under the same conditions, but without AGE, and the P-Tyr was coupled to epichlorohydrin (ECH)-activated cryogel, obtaining the PAAm-Alg-ECH-P-Tyr. Both pseudoaffinity cryogels were characterized by scanning electron microscopy, swelling tests, porosity, ligand density, and flow dynamics. The human IgG differently interacted with the PAAm-Alg-ECH-P-Tyr and PAAm-Alg-AGE-P-Tyr cryogels, depending on the pH and adsorption buffer system used. The selectivity analyzed by electrophoretic profiles was similar for both cryogels, but PAAm-Alg-ECH-P-Tyr achieved higher IgG adsorption capacity (dynamic capacity of 12.62 mg of IgG/mL of cryogel). The IgG purity assayed by ELISA was 95%. The maximum IgG adsorption capacity and dissociation constant of the PAAm-Alg-ECH-P-Tyr, determined by Langmuir isotherm, were found to be 91.75 mg IgG/g of dry cryogel and 4.60 × 10 -6 mol/L at pH 6.0 from aqueous solutions. The PAAm-Alg-AGE-P-Tyr showed potential to purify the Fab fragments from papain-digested human IgG solution at pH 7.0. Fab fragments were separated from Fc fragments (but with uncleaved IgG) in eluted fractions (analyzed by the Western blot technique), with yield of 82% and purity of 95% (determined by radial immunodiffusion)., (Copyright © 2021. Published by Elsevier B.V.)

Gelatine is a biocompatible and natural polymer with chemical properties similar to the extracellular matrix. However, it has poor mechanical properties and sensitive to enzymatic biodegradation that limits its application in 3D scaffold fabrication. Cellulose nanofibrous (CNF) offers biocompatibility, high surface area and excellent mechanical properties with slow in-vivo degradation. To fine tune their properties, CNF, and gelatine (CNF-GEL) were blended to form biocomposite aerogels. Epichlorohydrin (EPH) was incorporated into CNF-GEL as a chemical crosslinker to investigate its effect on the physiochemical, mechanical, and biological properties of the biocomposite aerogels both in-vitro and in-vivo. Regardless of the composition of the prepared aerogels, they possessed porosity of >90% with the pore size of 7-135 μm, which was confirmed in the morphological analysis. The presence of EPH improved the chemical interaction between CNF and gelatine, hence enhanced the compressive strength compared to uncrosslinked samples. The formulation of crosslinked CNF-GEL 90:10 offered the highest compressive strength of 61.35 kPa. The in-vitro and in-vivo studies showed adequate cytocompatibility, cell viability and cell attachment in the optimal crosslinked formulation with tuned enzymatic degradation. Antimicrobial property was also achieved in the optimal scaffold by incorporating curcumin as an antimicrobial agent., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Herein, the dual-crosslinked chitosan aerogel was prepared using 1-butyl-3-methylimidazolium chloride, an ionic liquid, as a solvent. The hydroxyl groups were covalently crosslinked by epichlorohydrin (ECH), while the amino groups were ionically crosslinked by itaconic acid (IA). The chemical and ionic crosslinkings of the aerogels were analyzed using FT-IR and NMR. Both the types and the degree of crosslinking gave significant influences on the structures of the aerogels. The dual crosslinked aerogel with proper chemical crosslinking dose had the excellent swelling behavior. The prepared aerogel shows potential as a wound healing matrix, with low toxicity and antibacterial function., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The stability and thermodynamic properties of an enzyme are the main factors that governing its applications in industry. With that intention we have immobilized the α-amylase onto synthesized chitosan-magnetite (CSM) composite and its modified forms by gluteraldehyde (CSM-GLA), glyoxal (CSM-GLY) and epichlorohydrin (CSM-ECH). In this study all the immobilized enzymes exhibited improved pH stability about 60-80% of relative activity at pH 9 compared to the free enzyme. The temperature stability at 60 °C is up to 50% of relative activity for covalently immobilized enzymes as enzyme become more rigid by covalent binding and so protected from the conformational changes caused by the environment. The thermal deactivation of the free and immobilized enzymes follows the first order kinetics. The t 1/2 and D-values were prolonged considerably in case of covalently immobilized enzymes, indicating better thermal stability than that of free and adsorbed ones. The Ed values 18.71, 32.00, 27.19 and 20.46 KJmol -1 for CSM-E, CSM-GLY-E, CSM-GLA-E and CSM-ECH-E described the high stability and resistance to heat inactivation. The Km values 0.525 ± 0.04, 0.57 ± 0.06, 0.65 ± 0.04 mg/mL and Vmax values 25 ± 0.06, 19.6 ± 0.02, 16.39 ± 0.01 μmol mg -1 min -1 for CSM-GLY-E, CSM-GLA-E and CSM-ECH-E showing better substrate affinity. The immobilized enzymes have exhibited about 60% of relative activity after 90 days of storage and very good reuse potential., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In current research work, chitosan (Chi) was subjected to subsequent physical and chemical modifications by incorporating kaolin clay (KA) into its polymeric structure, and crosslinking process with a covalent cross-linker namely epichlorohydrin (ECH) respectively. The final product of crosslinked chitosan-epichlorohydrin/kaolin (Chi-ECH/KA) composite was successfully applied for color removal and chemical oxygen demand (COD) reduction of textile dye namely reactive blue 19 dye (RB19) from aqueous environment. The influence of pertinent parameters, i.e. A: Chi-ECH/KA dose (0.02-0.1 g), B: pH (4-10), and C: time (5-30 min) on the RB19 color removal and COD reduction were statistically optimized by using response surface methodology with Box-Behnken design (RSM-BBD). The experimental data of the adsorption kinetic and the adsorption isotherm demonstrated a better fitness to pseudo-second order model and Langmuir isotherm model respectively. Excellent absorption ability of 560.9 mg/g was recorded for Chi-ECH/KA composite. The calculated thermodynamic functions clarified that the RB19 adsorption process was endothermic and spontaneous in nature. The mechanism of RB19 adsorption onto the Chi-ECH/KA may include electrostatic interactions, hydrogen bonding, Yoshida H-bonding, and n-π interactions. This study introduces Chi-ECH/KA composite as an eco-friendly, potential and multi-function composite bio adsorbent for removal of textile dye and COD reduction from aqueous environment., 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 © 2020 Elsevier B.V. All rights reserved.)

Epichlorohydrin crosslinked chitosan/carbon-clay (CSCC) biohybrid adsorbent was prepared for the adsorption of cationic methylene blue (MB) and anionic azo acid blue 29 (AB 29). The 40:60 wt% of chitosan (CS) and carbon-clay (CC) was selected as the best biohybrid adsorbent (CS40CC60) for the adsorption of both dyes. The adsorption of MB and AB 29 on CS40CC60 was carried out in a batch process to investigate the effects of initial dye concentration (25-400 mg/L), initial pH (3-11), contact time and adsorption temperature (30, 40 and 50 °C). The kinetics results of dyes adsorption onto CS40CC60 fit well to the pseudo-second-order model. The isotherms analysis demonstrated that the Freundlich isotherm described the adsorption data, and the q max (mg/g) were 95.31 for MB and 167.35 for AB29 at 50 °C. These findings reveal the potential and effectiveness of the newly prepared biohybrid adsorbent for the adsorption of both dyes., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

In this research, an attempt to develop zwitterion composite adsorbent is conducted by modifying chitosan (CHS) with a covalent cross-linker (epichlorohydrin, ECH) and an aluminosilicate mineral (zeolite, ZL). The zwitterion composite adsorbent of chitosan-epichlorohydrin/zeolite (CHS-ECH/ZL) is performed multifunctional tasks by removing two structurally different cationic (methylene blue dye, MB), and anionic (reactive red 120 dye, RR120) dyes from aqueous solutions. The surface property, crystallinity, morphology, functionality, and charge of the CHS-ECH/ZL are analyzed using BET, XRD, SEM, FTIR, and pH pzc , analyses, respectively. The influence of pertinent parameters namely CHS-ECH/ZL dosage (0.02-0.5 g), solution pH (4-10), temperature (303-323K), initial dye concentration (30-400 mg/L), and contact time (0-600 min) on the MB and RR120 removal are tested. The research findings revealed that the adsorption isotherm at equilibrium well explained in according to the Freundlich isotherm model, and the recorded adsorption capacities of CHS-ECH/ZL are 156.1 and 284.2 mg/g for MB and RR120 respectively at 30 °C. The mechanism of MB and RR120 adsorption onto the CHS-ECH/ZL indicates various types of interactions namely, electrostatic interaction, hydrogen bonding, and Yoshida H-bonding in addition to n-π interaction. Overall, this research introduces CHS-ECH/ZL composite as an eco-friendly zwitterion adsorbent with good applicability towards the two structurally different cationic and anionic dyes from aqueous environment., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Inflammation is a key challenge in the treatment of chronic diseases. Spurred by topical advancement in polymer chemistry and drug delivery, hydrogels that release a drug in temporal, spatial and dosage controlled fashion have been trendy. This research focused on the fabrication of hydrogels with controlled drug release properties to control inflammation. Chitosan and polyvinyl pyrrolidone were used as base polymers and crosslinked with epichlorohydrin to form hydrogel films by solution casting technique. Prepared hydrogels were analyzed by swelling analysis in deionized water, buffer and electrolyte solutions and gel fraction. Functional groups confirmation and development of new covalent and hydrogen bonds, thermal stability (28.49%) and crystallinity were evaluated by FTIR, TGA and WAXRD, respectively. Rheological properties including gel strength and yield stress, elasticity (2309 MPa), porosity (75%) and hydrophilicity (73°) of prepared hydrogels were also evaluated. In vitro studies confirmed that prepared hydrogels have good biodegradability, excellent antimicrobial property and admirable cytotoxicity. Drug release profile (87.56% in 130 min) along with the drug encapsulation efficiency (84%) of prepared hydrogels was also studied. These results paved the path towards the development of hydrogels that can release the drugs with desired temporal patterns., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020. Published by Elsevier B.V.)

Although various strategies have been utilized to accelerate bone regeneration in bone tissue engineering (BTE), the treatment and repair of large bone defects remains a clinical challenge worldwide. Inspired by the natural extracellular matrix of bone tissue, organic-inorganic composite scaffolds with three-dimensional (3D) porous structures, sufficient mechanical properties, excellent cytocompatibility, osteoconductivity, and osteogenic potential have received considerable attention within the field of bone engineering. In this work, a novel epichlorohydrin (ECH)-crosslinked hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) porous bi-component scaffold (EHSS) with hydroxyapatite (HAp) functionalization (EHSS/HAp) was constructed for bone defect repair via the combination of lyophilization and in situ biomimetic mineralization. Systematic characterization experiments were performed to assess the morphology, HAp-forming properties, mechanical properties and degradation rate of the scaffold. The results indicated that the prepared scaffolds exhibited an interconnected porous structure, a biomimetic HAp coating on their surfaces, improved mechanical properties in compression and a controllable degradation rate. In particular, semiquantitative analysis showed that the calcium/phosphorus (Ca/P) ratio of EHSS/HAp with 70% SPI content (1.65) was similar to that of natural bone tissue (1.67) according to energy dispersive X-ray spectroscopy analysis. In vitro cell culture experiments indicated that the EHSS/HAp with 70% SPI content showed improved cytocompatibility and was suitable for MC3T3-E1 cell attachment, proliferation and growth. Consistently, in vitro osteogenic differentiation studies showed that EHSS/HAp with 70% SPI content can significantly accelerate the expression of osteogenesis-related genes (Col-1, Runx2, OPN, and OCN) during osteogenic differentiation of MC3T3-E1 cells. Furthermore, when applied to the repair of critical-sized cranial defects in a rat model, EHSS/HAp with 70% SPI was capable of significantly promoting tissue regeneration and integration with native bone tissue. Microscopic computed tomography (micro-CT) results demonstrated that the bone defect site was nearly occupied with newly formed bone at 12 weeks after implantation of EHSS/HAp with 70% SPI content into the defect. Hematoxylin and eosin (H&E) staining and Masson's trichrome staining of histological sections further confirmed that EHSS/HAp with 70% SPI markedly promoted new bone formation and maturation. Collectively, our results demonstrate the potential of EHSS/HAp scaffolds with 70% SPI for successful bone defect repair and regeneration., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, a new biocatalyst was prepared by immobilizing Candida rugosa lipase epichlorohydrin-functionalized onto the surface of the nanoparticles. Magnetite nanoparticles were obtained by chemical co-precipitation method of Fe 2+ and Fe 3+ , and then the prepared uncoated and coated nanoparticles were characterized by XRD, FT-IR and TGA. Lipase was covalently attached to activated nanoparticles. The catalytic properties of free and immobilized lipases were determined. It was found that the optimum temperature for free and immobilized lipases was 30 °C and 35 °C, respectively. The optimum pH values were found to be 7.0 and 8 for free and immobilized lipases, respectively. Immobilized lipase was found to retain significant activity even after the seventh use. In the final section of the study, optically pure compounds were obtained by carrying out the enantioselective hydrolysis studies of racemic esters by using immobilized lipase. Enantiomeric excesses of the products in the enantioselective hydrolysis of racemic ibuprofen and naproxen methyl ester and racemic butyl mandelate were determined to be 94.93, 77.30 and 68.15, respectively.

Nanocellulose membranes exhibit good stability and high strength. However, the conventional synthetic routes rely on solvent volatilization of a nanocellulose suspension or solution. The complete hydrogen bonding that occurs in this process leads to a dense structure and poor strength in water. Hereby, lignosulfonate and polycation were mixed to form a complex and then attached to cellulose. The freeze-dried nanocellulose foam was hot-pressed to membrane, resulting in simultaneous co-crosslinking and membrane formation. The membrane had a porous structure with a high mechanical performance, excellent stability and a fast shape recovery. This also represents a method for processing functional nanocellulose membranes, as further demonstrated by the hybrid membrane with exceptional solar-driven seawater desalination and water-flow electricity generation properties. This work established facile methods for tackling the structural weakness of the conventional nanocellulose membrane, and opens the door to the application of nanocellulose membrane with a combination of mechanical stability and functionality., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Bulk homogeneous polyelectrolyte complex hydrogels (PCH) are difficult to prepare due to the flocculation effect between polyelectrolytes with opposite charges. Herein, novel chitosan/sodium polyacrylate (PAAS) polyelectrolyte complex hydrogels (CPG) were fabricated successfully by cross-linking chitosan and PAAS with epichlorohydrin (ECH) through inhibiting protonation effect of chitosan in alkali/urea aqueous solution. The swelling behaviors of CPG were studied systematically in different solutions. The equilibrium swelling ratio of chitosan hydrogel in water increased dramatically from 46.3 to 404.8 g/g by the introduction of PAAS. CPG exhibited different swelling ratios towards different pH solutions, physiological solutions and salt solutions with different concentrations, showing obvious smart responsive properties. Moreover, CPG hydrogels exhibited relatively high compressive strength, good biocompatibility and in vitro biodegradability. Therefore, this work provided a novel PCH and shed light on the fabrication of other PCH, showing potential applications in the fields of agriculture, foods, tissue engineering and drug delivery., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Crude glycerol (C 3 H 8 O 3 ) is a major by-product of biodiesel production from vegetable oils and animal fats. The increased biodiesel production in the last two decades has forced glycerol production up and prices down. However, crude glycerol from biodiesel production is not of adequate purity for industrial uses, including food, cosmetics and pharmaceuticals. The purification process of crude glycerol to reach the quality standards required by industry is expensive and dificult. Novel uses for crude glycerol can reduce the price of biodiesel and make it an economical alternative to diesel. Moreover, novel uses may improve environmental impact, since crude glycerol disposal is expensive and dificult. Glycerol is a versatile molecule with many potential applications in fermentation processes and synthetic chemistry. It serves as a glucose substitute in microbial growth media and as a precursor in the synthesis of a number of commercial intermediates or fine chemicals. Chlorinated derivatives of glycerol are an important class of such chemicals. The main focus of this review is the conversion of glycerol to chlorinated derivatives, such as epichlorohydrin and chlorohydrins, and their further use in the synthesis of additional downstream products. Downstream products include non-cyclic compounds with allyl, nitrile, azide and other functional groups, as well as oxazolidinones and triazoles, which are cyclic compounds derived from ephichlorohydrin and chlorohydrins. The polymers and ionic liquids, which use glycerol as an initial building block, are highlighted, as well.

Owing to its chemical structure, wide availability and renewable nature, lignin is a promising candidate for the partial replacement of fossil-based raw material in the synthesis of epoxy resins. Its poor compatibility has been reported to be one of the main drawbacks in this domain. On the other hand, a well-established modification method for lignin epoxidation has been used for many years for the improvement of lignin compatibility. However, the extent of the effect of lignin epoxidation on the improvement of bio-based epoxy mechanical properties, applied as adhesives, is still an open question in the literature. In this context, a pristine and industrial grade kraft lignin (AKL) was reacted with epichlorohydrin to yield epoxidized lignin (E-AKL) in this work. Afterwards, AKL or E-AKL were separately blended with petroleum-based epoxy resin at 15 and 30 wt% and cured with a commercial amine. The adhesive curing kinetic was evaluated using a novel technique for thermal transition characterization, Temperature Modulated Optical Refractometry (TMOR); the results showed that the incorporation of AKL reduces the crosslinking rate, and that this effect is overcome by lignin modification. Mechanical tests revealed an improvement of impact and practical adhesion strength for samples containing 15 wt% of E-AKL. These results elucidate the effect of lignin epoxidation on the application of lignin-based epoxy adhesives, and might support the further development and application of these bio-based materials., Competing Interests: The authors declare no conflict of interest.

Cr(VI) and Cd(II) are typical heavy metal ions and their co-removal is significant. Nitrogen-doped, bi-functional, and biomass-based composites (CP-BA) were successfully applied for efficient and synergistic removal of Cr(VI) and Cd(II). The mutual promotion ratios of adsorption capacity by Cr(VI) and Cd(II) were 161.32 % and 14.13 %, respectively. In addition, all coexisting inorganic anions could extremely promote the removal of Cd(II) with the best promotion ratio upon phosphate ions as high as 80.00 %. The following co-removal mechanisms were deeply revealed: (1) Cr(VI) combined with protonated imine groups could weaken the electrostatic repulsion between CP-BA and Cd(II) by electrostatic shielding, and further promoted the coordination of Cd(II) with hydroxyl, carboxyl and neutral imine groups. (2) Cd(II) which were coordinated to neutral imine groups could form cation bridges, and thus promoted the interaction with Cr(VI) because of the electrostatic attraction. Moreover, the removal capacity for Cr(VI) and Cd(II) did not display obvious reduction even after four cycles. Therefore, CP-BA showed a great potential in the co-removal of inorganic anion-cation complexes from wastewater., 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 © 2019 Elsevier B.V. All rights reserved.)

Ensete ventricosum (Welw.) cheeseman which belongs to the family of Musaceae is one of the main sources of starch in Ethiopia. This study aimed at evaluating epichlorohydrin cross-linked enset starch as a drug release sustaining excipient in microsphere formulations of theophylline. Extracted enset starch was cross-linked using epichlorohydrin as a cross-linking agent. The effect of cross-linker concentration, cross-linking duration, and cross-linking temperature on the degree of cross-linking and release rate of microspheres prepared by emulsion solvent evaporation method was investigated using the two-level full factorial design. Accordingly, the concentration of epichlorohydrin and duration of cross-linking were the most significant factors affecting both the degree of cross-linking and drug release rate. Thus, the effects of these two factors were further studied and optimized using the central composite design. As per the numerical method of central composite design, the optimal points were obtained at epichlorohydrin concentration of 13.70% and cross-linking time of 3.82 h. Under these optimal conditions, the model predicts the degree of cross-linking of 74.70% and drug release rate of 28.00 h 1/2 . The validity of these optimal points was confirmed experimentally. The microspheres of the optimum formulation also exhibited minimum burst release with sustained release for 12 h. Besides, the optimized formulation followed the Higuchi square root kinetic model with non-Fickian diffusion release mechanism. The finding of this study suggested that cross-linked enset starch can be used as an alternative drug-release-sustaining pharmaceutical excipient in microsphere formulation., Competing Interests: There is no any conflict of interest with regard to this research work., (Copyright © 2020 Desta Tesfay et al.)

Dissolved oil palm empty fruit bunch cellulose (EFBC) and sodium carboxymethylcellulose (NaCMC) were chemically crosslinked with epichlorohydrin (ECH) to generate designated hydrogel. After swelling process in distilled water, the swollen hydrogel was frozen and freeze-dried to form cryogel. The swelling phenomenon of hydrogel during the absorption process gave substantial effects on thinning of crosslinked network wall, pore size and volume, steadiness of cryogel skeletal structure, and re-swelling of cryogel. The swelling effects on hydrogel were confirmed via microscopic study using variable pressure scanning electron microscope (VPSEM). From the retrieved VPSEM images, nano-thin crosslinked network wall of 24.31 ± 1.97 nm and interconnected pores were observed. As a result, the amount of water, the swelling degree, and the freeze-drying process indirectly affected the VPSEM images that indicated pore size and volume, formation of interconnected pores, and re-swelling of cryogel. This study determined the intertwined factors that affected both hydrogel and cryogel properties by investigating the swelling phenomenon and its ensuing effects., Competing Interests: Declaration of competing interest There is no conflict of interest., (Copyright © 2019. Published by Elsevier B.V.)

As a promising candidate of Cr(VI) decontamination, cellulose is limited in the Cr(VI) uptake due to its poor accessibility. Herein, We describe the synthesis of a novel cellulose-based adsorbent (PQC, where P and QC designate the polyethylenimine and quaternized cellulose, respectively) with functional groups of quaternary ammonium and amino for enhanced capture of Cr(VI) from water. For preparing PQC, cellulose is first quaternized homogeneously, followed by grafting and/or cross-linking with polyethylenimine in the presence of epichlorohydrin. The PQC follows the Langmuir isotherm and presents a maximum Cr(VI) uptake capacity of 490.3 mg/g at 30 °C and initial pH about 2.0, much higher than many other reported cellulose-based adsorbents. The adsorption of PQC is spontaneous and endothermic, which follows the pseudo-second-order kinetic model and achieves the equilibrium after contacting about 50 min. Furthermore, the PQC, with favorable reusability, can work well in a high coexisting anion concentration. These excellent absorption performances are attributed to its physicochemical properties such as the robust porous structure and high density of functional groups including quaternary ammonium, amino and hydroxyl, which improve the availability to capture or reduce Cr(VI). This work demonstrates the significant potential of cellulose-based adsorbent for remediating aqueous Cr(VI)., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The present work elucidates achieving superior Cu(II) adsorption capacity using a facile protocol and a biodegradable material. Copper is one of the most prevalent metals used in industries, which creates severe health effects to the human and aquatic lives when present in excess. Cellulose sponge (CS) used as kitchen wipe was chosen and amine functionalities were introduced on it using ethylenediamine. Potentiality of the amine functionalized cellulose sponge (AF-CS) in Cu(II) removal is investigated for the first time. The batch adsorption parameters were optimized and various nonlinear kinetic and isotherm models were elaborately studied. The adsorption using CS and AF-CS behaved under a pseudo-second-order model and followed chemisorption. The maximum adsorption capacity values using AF-CS and CS from the Langmuir isotherm model were calculated to be 596.96 mg/g and 230.63 mg/g, respectively. Thence, AF-CS possesses proportionately higher adsorption capacity in comparison with CS due to the insertion of -NH 2 groups. Further, the mechanism involved in the adsorption process was explored in detail through FESEM, FT-IR, FT-Raman and TGA analysis. The AF-CS sponge was stable on repeated use and retained 90% efficiency at the end of the 10th cycle. A highly effective, easily recyclable, biodegradable and cost-effective adsorbent has been synthesized possessing an extraordinarily high adsorption capacity towards Cu(II) ions., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Cellulose based hydrogels with a relatively high stretchability were fabricated in the NaOH/urea system via sequential chemical crosslinking and dual network fabrication. The first step involved crosslinking of cellulose using epichlorohydrin as a crosslinker. Cryo-electron microscopy analysis revealed the utilization of diluted acid to treat hydrogels significantly affected the morphology of the first network and improved the mechanical properties. After diffusion of precursors into the first network, the dual network hydrogels were generated after the UV light-initiated polymerization. Raman spectroscopy demonstrated a spatial distribution of second networks within the first network. The compression strength of hydrogels synthesized under the optimized conditions was effectively enhanced from 0.04 MPa to 10.9 MPa. In addition, the tensile properties of hydrogels were easily adjusted via copolymerization of acrylic acid with acrylamide. The highest strain could reach 219.5% with a tensile strength of 1.4 MPa. This work provides a promising and simple strategy to develop a cellulose based hydrogel with enhanced and tunable mechanical properties for wide applications., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The aim of this study was to modify a discontinued, toxic antiseptic agent 2,4,5-trichlorophenol (TCP) by reacting it with epichlorohydrin (ECH) to obtain a nontoxic novel compound with similar antimicrobial effectiveness. A novel compound named {[1,3-bis(2,4,5-trichlorophenoxy) propan-2-yl] oxy}-3-(2,4,5-trichlorophenoxy) hexan-2-ol (TPTH) was synthesized from this reaction. Chemical and physical structures of the product were characterized by FTIR, MS, Uv-vis, NMR, SEM and TEM. The thermal stability of TPTH was evaluated by conducting thermogravimetric analysis. Biological interactions of the compound were investigated by performing antimicrobial activity and cytotoxicity assays. The compound displayed a good antimicrobial activity where minimum inhibitor concentrations were found to be 0.02, 0.08, and 0.15 µg mL -1 against Staphylococcus aureus (S. aureus), Methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli ( E. coli ) respectively. Additionally, well diffusion assay demonstrated that, the zone of inhibitions for S. aureus, MRSA and E. coli were 24 mm, 22 mm and 18 mm, respectively. Cytotoxicity assay results revealed that TPTH is nontoxic against cells at effective anti-microbial concentrations. TPTH shows thermal stability up to 220 °C. Results here demonstrate the successful conversion of toxic TCP to a nontoxic form; TPTH with a good anti-microbial activity and thermal stability.

Fast-swelling, porous cellulose hydrogels (PCHs) were generated via simple acid treatment of cellulose hydrogel prepared in NaOH/urea medium. Structural characteristics of the PCHs were investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behavior was assessed by measuring the swelling kinetics in deionized water. Mechanical properties were also examined. The results showed that acid treated PCHs had many more micropores, mesopores and macropores, and PCH-6% displayed a high specific surface area of 33.98 m 2 /g. However, cellulose hydrogel without acid treatment had a low specific surface area (2.499 m 2 /g). Mechanical property of hydrogel was found to be slightly deteriorated with the improvement of porous structure. The equilibrium swelling rate of PCHs had drastically improvement after acid treatment. This porous cellulose hydrogel skeleton presents a wide range of possibilities for the further development of fast swelling cellulose-based functional hydrogel., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Novel adsorbent, diethylenetriamine-grafted Spirodela polyrhiza (DSP), was synthesized via modifying natural S. polyrhiza (SP) with diethylenetriamine by cross-linking with epichlorohydrin and applied to adsorb Ni 2+ and Pb 2+ from water. The effecting parameters on adsorption of Ni 2+ and Pb 2+ such as adsorbent dosage, pH, contact time, temperature, and initial concentration were studied through equilibrium experiments. The adsorption of Ni 2+ and Pb 2+ followed the pseudo-second-order model and the Langmuir isotherm adsorption model. The study discusses thermodynamic parameters, including changes in Gibbs free energy, entropy, and enthalpy, for the adsorption of Ni 2+ and Pb 2+ on DSP, and revealed that the adsorption process was spontaneous and exothermic under natural conditions. The maximum Ni 2+ and Pb 2+ adsorption capacities of DSP were 33.02 and 36.50 mg/g, respectively. The newly prepared materials were characterized through scanning electron microscopy (SEM), mapping analysis, and zeta potential analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that functional groups (-OH and N-H) were involved in Ni 2+ and Pb 2+ adsorption. Notably, DSP can be easily regenerated and reused for multiple cycles. Therefore, DSP is a promising adsorbent for effective Ni 2+ and Pb 2+ removal.

The traditional polyvinyl alcohol composite hydrogel exhibited poor swelling and mechanical properties, which limited its application. To solve these issues, we use biomass lignin as raw material, PVA as matrix template and epichlorohydrin as cross-linker to prepare the Lignin-PVA super-absorbent hydrogels with the swelling ratio of up to 456 g/g under mild condition. When the lignin concentration was increased from vacancy to 5%, the swelling ratio of the Lignin-PVA hydrogels was increased from 92 g/g to 456 g/g. The lignin-based hydrogel synthesized by the higher molecular weight PVA showed better swelling performance. Softwood lignin, hardwood lignin and corncob lignin could also be used to fabricate the Lignin-PVA super-absorbent hydrogels with the swelling ratio of higher than 500 g/g. However, the optimum amount varied from different lignin types, which was related to the molecular weight and phenolic hydroxyl content of lignin. The structural mechanism of the Lignin-PVA hydrogel was proposed to clearly certify the enhancing role of lignin. The adsorption capacity of the Lignin-PVA hydrogel with respect to rhodamine 6G, crystal violet and methylene blue dyes was up to 196, 169 and 179 mg/g, respectively. The Lignin-PVA hydrogel presents great potential applications in the fields of soil water retention and seed cultivation in agriculture, and dye pollutant removal., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Wood plastic composites (WPCs) made from plant fibres and plastics have gained more and more attention. Studies have been focused on preparation and mechanical performance of WPCs. While mechanism of chemical modification of cereal straw has rarely been reported. In the present work, rice straw was etherified with epichlorohydrin (EPI) and the mechanism of etherification was investigated. Natural rice straw (NRS) was pretreated with NaOH to move most of hemicellulose and lignin. The alkali treated rice straw (ARS), whose dominant component being cellulose, was etherified with EPI at 120 °C for 1-8 h in toluene with NaOH as catalyst. NRS, ARS and etherified rice straw (ERS) were characterized and analyzed by FT-IR, solid CP/MAS 13 C-NMR, elemental analysis and neutral sugar analysis. The etherification reaction was finished within 5 h, and C 3 H 6 O units were introduced into the structure of cellulose, leading to the increase of contents of C and H in ERS. The etherification process of ARS in alkaline medium was divided into three stages, during which two hydroxyl groups were replaced by two ether bonds successively, and a new hydroxyl group was formed in the last step. The number of hydroxyl groups in ERS was reduced, and reduction of hydrophilicity of ERS could be expected.

Substantial adsorption of water vapor triggered by hydrogen-bonding interactions between water molecules and cellulose chains (or nanoplates) is hard to avoid in nanocomposite films, although the addition of nanoplates can improve the oxygen (or carbon dioxide) barrier property. In the present work, an effective strategy is raised to decline adsorption by weakening hydrogen-bonding interactions via chemical cross-linking by epichlorohydrin (ECH) without sacrificing the homogeneous dispersion of nanoplates. The generated microdomain structure of the chemical cross-linking reaction via ECH is explicitly revealed by micro-Raman imaging. Unambiguously, Raman maps of scanning elucidate the distribution and morphology of physical and chemical cross-linking domains quantitatively. The chemical cross-linking domains are nearly uniformly located in the matrix at a low degree of cross-linking, while the interconnected and assembled networks are formed at a high degree of cross-linking. ECH boosts the formation of chemical cross-linking microdomains, bringing out the terrific water vapor barrier property and alleviating the interfacial interactions in penetration, consequently magnifying the water contact angle and holding back the water vapor permeability. Our methodology confers an effective and convenient strategy to obtain remarkable water vapor-resistant cellulose-based films that meet the practical application in the packaging fields.

By a simple and convenient method of using epichlorohydrin as linkages, a novel Alternanthera philoxeroides (AP) derivative modified with diethylenetriamine (DAP) was synthesized, which can remove copper(II) ions (Cu(II)) in the water environment efficiently. The adsorption capacity of DAP for Cu(II) under various factors was measured using ultraviolet spectrophotometer. The adsorption capacity and removal ratio were 19.33 mg/g and 95.57% at pH 5.5 and 298 K. The kinetic and equilibrium study shows that pseudo-second-order kinetic (R 2 = 0.9964) and Langmuir isotherm models (R 2 > 0.982) could properly describe DAP adsorption behaviors, and thermodynamic parameters indicate a spontaneous endothermic process (ΔG = - 3.6636 kJ/mol). The combined results of SEM, XRD, FTIR, and XPS analyses reveal that the dominant contribution for enhancement in Cu(II) adsorption is made by the formation of an amino group. And the adsorption mechanism is mainly the complexation reaction. The adsorption efficiency of DAP remained above 72.06% after 6 cycles of adsorption-desorption, which indicated that DAP has good regenerability and stability. All the results suggest that DAP could serve as promising adsorbents for Cu(II) pollution minimization.