New modified epichlorohydrin chitosan Schiff base (ECS-MC) was successfully synthesized and characterized by various techniques such as FT-IR, TGA, DSC, BET, XRD and SEM. In addition, methyl green ...(MG) removal efficiency from aqueous solution has been studied and the influence of solution pH, sorbent dose, initial MG concentration and contact time were investigated. The results of adsorption study indicated that 99.12% of MG dye were removed
via
adsorption using 0.02 g of ECS-MC at pH of 8 and 120 min solution shaking. Results showed high MG sorption capacity of 194.4 mg/g, when 0.005 g of ECS-MC was used as sorbent. Then, ECS-MC can be more efficient for removal of other cationic dyes.
Graphic Abstract
The mechanism of MG adsorption on the surface of ECS-MC depends on functional groups of both adsorbent and adsorbate. It was clear that the electrostatic interaction such as π–π and H-bonds between the sorbent and methyl green played a main role in MG adsorption.
Crude glycerol (C
H
O
) 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.
Despite the variety of energetic polyoxetane binders, the oxirane-based glycidyl azide polymer (GAP) has largely succeeded in the market due to its advantageous properties. Nevertheless, it suffers ...from various drawbacks such as non-uniform chain termination, possible chlorine content (flame retardant), and toxic epichlorohydrin required for its synthesis. These problems can be bypassed using the structurally related poly(3-azidooxetane). Unfortunately, it is only accessible in moderate yield by polymerization of 3-azidooxetane. Herein, we describe its synthesis by polymer-analogous transformation using the new polymers poly(3-tosyloxyoxetane) and poly(3-mesyloxyoxetane) as precursors. This results in a significantly increased yield and improved safety as handling of the very sensitive 3-azidooxetane is avoided. The aforementioned prepolymers were prepared using boron trifluoride etherate as well as triisobutylaluminum as catalysts. The latter provides polymers of particularly high molecular weight, and the corresponding poly(3-azidooxetane) species was obtained and studied for the first time. In order to shed light on the applicability of poly(3-azidooxetane) as a GAP substitute, it was thoroughly studied with regard to thermal behavior, energetic performance (EXPLO5), plasticizer compatibility, and curing. Moreover, the aquatic toxicity of all involved monomers was analyzed and compared to epichlorohydrin. Here, poly(3-azidooxetane) turned out as a fully adequate, if not more environmentally benign, substitute.
Herein, we discussed the synthesis of quaternized poly epichlorohydrin (QPECH) by the reaction of poly epichlorohydrin (PECH) with N, N-dimethylethanolamine (DMEA). After that, different amounts of ...QPECH were mixed with the polyvinyl alcohol (PVA) and tetraethyl silicate (TEOS) to fabricate a series of anion exchange membranes (AEMs) by sol-gel reaction. The chemical structure of the synthesized QPECH was effectively proved by Fourier transform infrared (FTIR) and 1H NMR. Hereafter, the composite membrane structure was determined by FT-IR, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the physical and chemical properties such as thermogravimetric analysis (TGA), water uptake (WR), ion exchange capacity (IEC), linear expansion rate (LER) and diffusion dialysis (DD) were tested. The performance, such as acid recovery and selectivity of PVA/QPECH composite membranes with different QPECH content, was discussed comprehensively. The results showed that the WR of the composite membrane was 82.35–158.54%, the LER was 19.23–40.74%, and the IEC was from 0.64 to 1.76 mmol/g. In the DD test simulating waste acid recovery, the acid dialysis coefficient (UH+) was in the range of 11.1–30.0*10-3 m/h, and the separation factor (S) was 24.79–42.24. The UH+ and S of the composite membranes were all better than that of commercial membrane DF-120. In conclusion, this study demonstrated that the application of anion exchange membrane based on PVA/QPECH had the potential in acid recovery by DD method.
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•Simple and cost-effective method to fabricate QPECH/PVA based membrane.•The as-prepared membranes possessed excellent dialysis coefficient and separation coefficient.•The as-prepared membranes were used for acid recovery via diffusion dialysis.
Steroid hormone (SH) micropollutants are not efficiently removed with conventional membrane processes. Cyclodextrins are macrocyclic molecules widely applied in water treatment for the removal of ...these micropollutants. In this study, a composite nanofiber membrane (CNM) containing cross-linked β-cyclodextrin-epichlorohydrin (βCDP) was prepared by electrospinning the functionalized nanofibers onto an ultrafiltration membrane support.
The CNM membrane was evaluated for SH removal in both static adsorption and during filtration. A removal of 80 % was reached in static condition with a βCDP loading of 2.5 ng/cm2. During filtration, the hydraulic residence time, SH concentration and nanofiber matrix thickness limited SH removal and uptake. The highest removal of 76 % and uptake of 9.5 ng/cm2 were achieved with a nanofiber matrix thickness of 365 μm. Molecular dynamic simulation revealed that SH type affected the βCDP interaction and inclusion complex formation, the strongest interaction occurred with progesterone and the lowest with testosterone. This was consistent with experimental data.
Overall, the results are promising for the application of this functionalized membrane for SH removal due to the high adsorption capacity and the ability to form a specific inclusion complex interaction with the SH molecules.
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•Cross-linked cyclodextrin can be cross-linked into nanofiber membrane.•Nanofiber matrix thickness and residence time controls hormone removal.•Removal occurs by inclusion complex formation evidenced by molecular dynamics.•Hormone type affects inclusion complex stability with time.
Nanocellulose films possess numerous merits ascribing to their inherent biocompatibility, non-toxic and biodegradability properties. The potential for practical applications would be improved if ...their mechanical strength and toughness requirements could be met simultaneously. Herein, dual cross-linked nanocellulose (DC) film was fabricated by the treatments of chemical and physical cross-linking, which was mechanically superior to pure nanocellulose (CNF) films. To further increase the toughness of DC films, spherical cellulose (Sph) was incorporated into DC film (DC-Sph film), and analyzed under different humidity conditions (RH) (from 10 % to 90 %). The changes of functional groups of CNF, DC and DC-Sph films were detected by FTIR and XPS spectrum. The epichlorohydrin and Sph content were optimized, followed by the investigation of RH on the toughness of films. The highest tensile strength (146.6 ± 4.6 MPa) was obtained in DC film at 50 % RH, while the DC-Sph film showed the largest toughness (40.3 ± 3.7 kJ/m2) at 70 % RH. Furthermore, the possible toughening mechanism of DC-Sph film was also discussed.
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To meet the requirement of personalization, there is an urgent need to develop a simple, efficient and versatile manufacturing method for customized contact lens manufabrication. Here, we report a ...novel electrofabrication methodology (i.e., electrodeposition) for the fabrication of hydrogel contact lenses, which can induce covalent cross-linking between chitosan and epichlorohydrin simultaneously. The transmittance and toughness of hydrogels are improved by electrochemical cross-linking without affecting their oxygen permeability. Furthermore, the geometry of the chitosan based hydrogel contact lenses can be customized simply by the electrode template, and its characteristics can be regulated by electrical signals and electrochemical cross-linking. The electrodeposited hydrogel contact lenses have good optical properties, mechanical properties and biocompatibility, and their anti-adhesion properties to Staphylococcus aureus are close to commercial contact lenses. This work reveals the mechanism of electrochemical cross-linking between chitosan and epichlorohydrin and provides an alternative method for contact lens fabrication.
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•Branched anionic and cationic β-cyclodextrins were obtained from parent β-CDs.•Water solubility of ionic branched β-cyclodextrins (bβCD) was higher than neutral ones.•No cytotoxic effects were ...observed for ionic bβCDs.•Ionic bβCDs form complexes with triclosan but show a complexation limit.•Complexes of triclosan with anionic bβCDs showed higher stability constant than with cationic bβCDs.
This study aims to synthesize, characterize and investigate the water solubility and cytotoxicity of branched anionic/cationic β-cyclodextrins (bβCDs) obtained by reaction with epichlorohydrin and chloroacetic acid or choline chloride, respectively, by a single step polycondensation reaction. Obtained ionic bβCDs were investigated as an attempt to comparatively study anionic and cationic bβCDs. Water solubility of both ionic derivatives was similar (400mg/mL) at neutral and basic pHs and remarkably higher than that of their neutral homologues. Additionally, a pH-dependent solubility of anionic bβCDs was observed. Cytotoxicity of ionic bβCDs was evaluated on Human colon carcinoma Caco-2 cells and high cell viability (>99%) was observed in the range of 0–100mg/mL for anionic and cationic samples, in the same range of that of neutral and parent β-CDs. Additionally, complexes formation capacity with triclosan, a poor water soluble antimicrobial agent, was confirmed by several techniques observing a complexation limit around 4mg/mL for both systems and higher stability constant for anionic bβCDs than cationic derivatives.
The results of development of frost-resistant rubber based on epichlorohydrin rubber (ECHR) of Hydrin T6000 brand of Zeon Chemicals L.P. (USA) are described in the present work. The properties of ...ECHRs are determined by the nature of the structural units that constitute the macromolecules. The absence of olefinic functionality in the main chain gives ECHR the resistance to heat, oxygen, ozone and other factors. The presence of chlorine causes the high resistance of Hydrin T6000 rubber to the effect of hydrocarbon media (oils, fuels, fats, waxes, solvents), and the presence of oxygen atoms helps to maintain the flexibility and elasticity of materials at low temperatures. Hydrin T6000 rubber has the lowest glass transition temperature (Tgt = -60 ° C) from all the epichlorohydrin rubber brands, high oil resistance, increased heat and ozone resistance, and, therefore, attracts researchers' interest as a promising rubber for the development of frost-resistant rubber with sealing capability. The paper presents the formulation of rubbers based on Hydrin T6000 and the results of studies of their physical and mechanical properties. Analysis of the data revealed that the obtained rubber has excellent frost resistance, increased oil resistance at a satisfactory level of residual deformation after compression and strength characteristics. Thus, Hydrin T6000 has established itself as a promising rubber for manufacturing frost-resistant rubber with sealing function and will provide increased reliability and durability of equipment operation in extreme conditions of cold climate in Russia.
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