Cyanoethyl Chitosan Research Articles

Biosorptive removal of cobalt(II) from aqueous solutions using magnetic cyanoethyl chitosan beads

Biosorption is a cleaner technology for the treatment of heavy metal-containing wastewater. In this study, a cleaner method was proposed for preparing a novel biosorbent, magnetic cyanoethyl chitosan beads, which was characterized by FT-IR, SEM-EDS, XRD, TGA, BET, and vibrating sample magnetometer, and applied for removing Co2+ from aqueous solutions. The influencing factors, such as contact time (0−120 min), pH (5–8), and initial concentration of cobalt ions (10−600 mg L−1), were examined. The first-order, second-order, intraparticle diffusion, and Elovich models were used to simulate the kinetics of the cobalt adsorption process. The experimental data of isotherms were analyzed by the Langmuir, Freundlich, and Temkin models. Among them, the second-order model and Langmuir model were the best fitting. The adsorption capacity was calculated to be 17.92 mg g−1 according to the Langmuir model. From the analysis of the FT-IR spectra, it can be inferred that CN and NH2 were mainly responsible for the adsorption of Co2+ from aqueous solutions. The grafting of cyanoethyl groups on chitosan enhanced the sorption capacity towards Co2+, the magnetic cyanoethyl chitosan bead is economical and effective biosorbent for the treatment heavy metal-containing wastewater.

Synthesis of novel 1H-tetrazole derivatives of chitosan via metal-catalyzed 1,3-dipolar cycloaddition. Catalytic and antibacterial properties of [3-(1H-tetrazole-5-yl)ethyl]chitosan and its nanoparticles.

New tetrazole derivatives of chitosan with low, moderate, and high degrees of substitution were obtained using a novel approach, i.e. metal-catalyzed 1,3-dipolar cycloaddition of azide ion to cyanoethyl chitosan in water - the most straightforward, selective and preparatively convenient route to tetrazole chitosan derivatives. Ionic gelation of these tetrazole derivatives with sodium tripolyphosphate resulted in nanoparticles with an apparent hydrodynamic diameter of 100-800 nm and ζ-potential of 22-57 mV. The tetrazole derivatives of chitosan and their nanoparticles were tested as catalysts of the aldol reaction between p-chlorobenzaldehyde and acetone. The tetrazole derivatives have been found to possess better catalytic properties than the corresponding nanoparticles. The obtained data indicate that the tetrazole-chitosan polymers exhibit high catalytic activity in aldol reaction, and these catalysts are among the best studied so far. Tetrazole derivatives and their nanoparticles were also tested as antibacterial agents. The in vitro antibacterial activity against S. aureus and E. coli of the tetrazole-chitosan-based nanoparticles is much more than the activity of the corresponding tetrazole-chitosan polymers, and their activity is comparable with that of antibiotics ampicillin and gentamicin.

Study on Performances of Cyanethyl Chitosan Fiber Prepared from [Asp]Cl Ionic Liquid

Aspartic acid hydrochloride ionic liquid ([Asp]Cl) was successfully synthesized from aspartic acid powder and 36% hydrochloric acid. The derivative of chitosan cyanoethyl chitosan was prepared by acrylonitrile and alkali chitosan at room temperature. Structures of ionic liquid and cyanoethyl chitosan were characterized by FT-IR. Crystalline properties of cyanoethyl chitosan were characterized by XRD. Cyanoethyl chitosan was dissolved in [Asp]Cl ionic liquid aqueous solution and subjected to wet spinning. The mechanical properties of cyanoethyl chitosan fibers were tested by type LLY-06 electronic single fiber strength tester, and the surface morphology of fibers were observed by microscope. The results show that the maximum breaking strength of fiber was 2.212CN/dtex when the concentration of cyanoethyl chitosan was 6.5% relativing to 3% ionic liquid and the coagulating bath temperature was 30°C.

Synthesis of cyanoethyl chitosan derivatives

Cyanoethyl chitosan derivatives with various substitution degrees have been synthesized by the nucleophilic addition of acrylonitrile to the functional groups of chitosan. The process proceeds under homogeneous conditions without any catalyst at various pH values and reagent concentrations in the temperature range of 273–333 K. The formation of cyanoethyl chitosans is established by a gain in the weight of chitosan, a change in its content of nitrogen, and the appearance of an absorption band at 2250 cm−1 in the IR spectrum which corresponds to the stretching vibrations of a-C≡N group. It has been shown that the most efficient addition of acrylonitrile occurs at 273 K and pH 5.5. Cyanoethyl chitosan samples show better mechanical parameters and are characterized by a lower ordering than the parent chitosan.

Mechanical and electrical properties of paper sheets treated with chitosan and its derivatives

This work focused on studying the dependence of paper sheet strength properties on the composition of additives, namely chitosan, cyanoethyl and carboxymethyl chitosan. Chitosan and its derivatives enhanced the strength properties of unagged and aged paper sheets. Also, cyanoethyl chitosan improved the dielectric properties of the treated paper sheets. The dielectric study was carried out over a frequency range from 100 Hz to 100 kHz at temperature range from 20 to 140 °C. The variations of permittivity ε′ versus the cyanoethyl chitosan content at three different temperatures show the highest dielectric properties at cyanoethyl chitosan of 0.3%. The variation of ε″ versus the applied frequency was fitted by a superposition of Fröhlich and Havriliak–Negami functions in addition to the conductivity term. These functions could be ascribed by the Maxwell–Wagner effect and the orientation of the large aggregates formed by the addition of chitosan to the paper sheet.

Carbonization of Polyacrylonitrile Composites with Nitrogen-containing Cellulose Derivatives

Thermal carbonization of nitrogen-containing cellulose derivatives (chitin, chitosan, cyanoethyl chitosan, cyanoethyl cellulose, copolymers of allyl carboxymethyl cellulose with polyacrylonitrile) as models of probable products of thermal reaction of cellulose with polyacrylonitrile was studied. The quantitative characteristics of carbonization of the model compounds are influenced by the nitrile group.

Studies on the effect of substitution degree on the liquid crystalline behavior of cyanoethyl chitosan

Studies on the effect of substitution degree on the liquid crystalline behavior of cyanoethyl chitosan

Textures and disclinations in the cholesteric liquid-crystalline phase of a cyanoethyl chitosan solution

Disclinations in the fingerprint-like cholesteric texture of a natural polymer derivative, cyanoethyl chitosan, were observed and studied by both polarizing optical microscopy and scanning electron microscopy. In the latter technique, permanganic etching was developed for this cholesteric texture to increase the contrast. A special mechanism for cholesteric phase etching is suggested and discussed. Some χ, λ, and τ disclinations and domain walls were observed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 980–986, 2000

Crystalline Morphology Developing from Cholesteric Mesophase in Cyanoethyl Chitosan Solutions

Two completely different crystals can grow from cyanoethyl chitosan/formic acid solutions in which the anisotropic liquid crystalline (LC) and isotropic phases coexisted. One was normal spherulites developing from isotropic region, and the other was cholesteric-like crystallites developing from mesophase region. The latter had similar optical characters as fingerprint texture. This implies that the crystal structure in solution cast film from cholesteric LC phase remained the main structure characters of cholesteric LC texture. A model is presented to explain the crystallization process from these liquid crystalline polymer solutions.

Fine structure in cholesteric fingerprint texture observed by scanning electron microscopy

The fine structure in some cholesteric fingerprint textures of cyanoethyl chitosan (CNCS)/acrylic acid solution and photo-solidified CNCS/polyacrylic acid composite film was studied using scanning electron microscopy (SEM), small angle light scattering (SALS) and polarizing optical microscopy (POM). Permanganic etching was developed to reveal the cholesteric liquid crystalline textures in the composite films. A schematic model was presented to explain this kind of fine structure. The directors within each cholesteric molecular layer did not orient in nematic-like order, but varied their orientation by an ill-defined period.

Pervaporation separation of water‐ethanol through modified chitosan membranes, II. Carboxymethyl, carboxyethyl, cyanoethyl, and amidoxime chitosan membranes

The present study investigates the pervaporation performance of four kinds of modified chitosan membranes to separate water from aqueous ethanol solution. Chitosan was prepared from chitin abstracted from the crab shell and subsequently deacetylated with aqueous NaOH solution. Modified chitosan membranes examined in this study include carboxymethyl chitosan, carboxyethyl chitosan, cyanoethyl chitosan, and amidoxime chitosan. The incorporation of hydrophilic functional groups into the 6-O position of chitosan enhances the selectivity of modified chitosan membrane compared to the previously reported chitosan-acetic acid complex membrane. Among the modified chitosan membranes, membranes containing carboxy groups show the best pervaporation performance. Carboxymethyl chitosan membranes show the maximum swelling and ethanol flux at approx. 15 wt.-% feed ethanol concentration due to the coupling and plasticizing effect.