Removal of Ionic Dyes by Nanofiber Membrane Functionalized with Chitosan and Egg White Proteins: Membrane Preparation and Adsorption Efficiency

Electrospun polyacrylonitrile (PAN) nanofiber membrane was functionalized with chitosan and proteins for use in the treatment of dye-containing wastewater. The PAN nanofiber membrane was subjected to alkaline hydrolysis, before being grafted with chitosan and subsequently the proteins from chicken egg white. The resultant nanofiber membrane (P-COOH-CS-CEW) was comprehensively characterized using thermogravimetric analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The efficiency of P-COOH-CS-CEW in removing cationic dye toluidine blue O (TBO) and anionic dye acid orange 7 (AO7) in aqueous solution was evaluated. Based on the performance of model fitting, Langmuir and pseudo-second-order kinetic model could be used to describe the performance of P-COOH-CS-CEW in the removal of TBO (pH 10) and AO7 (pH 2) from the dye solutions. The adsorbed TBO and AO7 dyes can be completely desorbed by an elution solution made of 50% (v/v) ethanol and 1 M sodium chloride. After five consecutive adsorption-desorption cycles, the efficiency of dye removal by P-COOH-CS-CEW was maintained above 97%.

A phase conversion method to anchor ZIF-8 onto a PAN nanofiber surface for CO2 capture

Poly acryl nitrile (PAN) nanofibers were prepared by electrospinning and coated with zeolitic imidazolate framework-8 (ZIF-8) by a phase conversion growth method and investigated for CO2 capture.

Liquid-Assisted Electrospinning Three-Dimensional Polyacrylonitrile Nanofiber Crosslinked with Chitosan

Electrospinning has become a popular nanotechnology for the fabrication of tissue engineering scaffolds, which can precisely regulate fiber diameter and microstructure. Herein, we have prepared a three-dimensional polyacrylonitrile (PAN) nanofiber by liquid-assisted electrospinning. The spacing between PAN nanofibers can reach to 15-20 μm, as the uniform internally connected pore structure can be formed, through the regulation of parameters. Furthermore, the chitosan attached to the as-prepared nanofibers gives the material antibacterial effect and increases its biocompatibility. Meanwhile, the special structure of chitosan also provides the possibility for further loading drugs in dressings in the future. This newly developed nanocomposite seems to be highly suitable for wound healing due to its unique properties of biodegradability, biocompatibility, and antimicrobial effectiveness.

Kinetic and Thermodynamic Studies of Lysozyme Adsorption on Cibacron Blue F3GA Dye-Ligand Immobilized on Aminated Nanofiber Membrane

The polyacrylonitrile (PAN) nanofiber membrane was prepared by the electrospinning technique. The nitrile group on the PAN nanofiber surface was oxidized to carboxyl group by alkaline hydrolysis. The carboxylic group on the membrane surface was then converted to dye affinity membrane through reaction with ethylenediamine (EDA) and Cibacron Blue F3GA, sequentially. The adsorption characteristics of lysozyme onto the dye ligand affinity nanofiber membrane (namely P-EDA-Dye) were investigated under various conditions (e.g., adsorption pH, EDA coupling concentration, lysozyme concentration, ionic strength, and temperature). Optimum experimental parameters were determined to be pH 7.5, a coupling concentration of EDA 40 μmol/mL, and an immobilization density of dye 267.19 mg/g membrane. To understand the mechanism of adsorption and possible rate controlling steps, a pseudo first-order, a pseudo second-order, and the Elovich models were first used to describe the experimental kinetic data. Equilibrium isotherms for the adsorption of lysozyme onto P-EDA-Dye nanofiber membrane were determined experimentally in this work. Our kinetic analysis on the adsorption of lysozyme onto P-EDA-Dye nanofiber membranes revealed that the pseudo second-order rate equation was favorable. The experimental data were satisfactorily fitted by the Langmuir isotherm model, and the thermodynamic parameters including the free energy change, enthalpy change, and entropy change of adsorption were also determined accordingly. Our results indicated that the free energy change had a negative value, suggesting that the adsorption process occurred spontaneously. Moreover, after five cycles of reuse, P-EDA-Dye nanofiber membranes still showed promising efficiency of lysozyme adsorption.

Fabrication of GO/PAN Nanofiber Membrane Grafted With Chitosan As Efficient Adsorbent For Dye Removal

The adsorption is widely used to remove dyes from wastewater because of its low cost, simple preparation, and environmental friendliness. However, the existing adsorbents suffer from difficult recycling, inconvenient use, and low regeneration rate. In this study, polyacrylonitrile (PAN) and graphene oxide (GO) was mixed for electrospinning GO/PAN nanofiber membrane and then chitosan (CS) was grafted to obtain CS-GO/PAN nanofiber membrane. CS-GO/PAN membrane were characterized with FE-SEM, EDX, FT-IR and, WCA. The effects of membrane types, dosage, solution pH on the removal of dye sunset yellow (SY) were systematically investigated. The results showed that more than 80% of SY were removed within 15 min at pH 2 using 100 mg CS-GO/PAN membrane. Adsorption kinetic data were fitted well with the pseudo-second-order model and adsorption equilibrium achieved within 240 min. The isotherm study followed the Langmuir model with the actual maximum adsorption capacity of 211.54 mg/g. After 5 adsorption-desorption cycles, the adsorption efficiency and the desorption efficiency of CS-GO/PAN were over 90% and 93%, respectively. Moreover, the membrane recovered easily from the water while its integrity was still maintained. The CS-GO/PAN membrane demonstrates the virtue of high adsorption capacity, easy operation, and good reusability, which could be considered as a promising material for adsorbing dyes in wastewater.

Multifunctional CeO2/Co3O4@polyacrylonitrile nanofibers for high-efficiency air-pollutant removal

As many countries in the world are paying increasing attention to air quality, reducing the concentration of pollutants in the air, protecting human health and improving the ecological environment have become problems that need to be solved urgently. This paper describes how ceria and cobalt tetroxide@polyacrylonitrile (CeO2/Co3O4@PAN) nanofiber membranes are produced using electrospinning technology, which have broad applications for the removal of air pollutants. Results show that CeO2/Co3O4@PAN has high electrostatic attraction to particulate matter (PM). CeO2/Co3O4@PAN membranes show better mechanical properties, thermal stability and air-purification performance than pure PAN membranes. Nanofiber membranes with 5 wt% of CeO2/Co3O4 have excellent removal efficiency: 93.4% and 94.5% for PM2.5 and PM10, respectively, and 96.2% and 98% for formaldehyde and total volatile organic compounds, respectively. They also show low pressure drops, high stability and good recyclability. This work shows that they are promising candidates as highly stable, recyclable and efficient agents for the removal of air pollutants.

Efficient Improvement in Fracture Toughness of Laminated Composite by Interleaving Functionalized Nanofibers

Functionalized polyacrylonitrile (PAN) nanofibers were used in the present investigation to enhance the fracture behavior of carbon epoxy composite in order to prevent delamination if any crack propagates in the resin rich area. The main intent of this investigation was to analyze the efficiency of PAN nanofiber as a reinforcing agent for the carbon fiber-based epoxy structural composite. The composites were fabricated with stacked unidirectional carbon fibers and the PAN powder was functionalized with glycidyl methacrylate (GMA) and then used as reinforcement. The fabricated composites’ fracture behavior was analyzed through a double cantilever beam test and the energy release rate of the composites was investigated. The neat PAN and functionalized PAN-reinforced samples had an 18% and a 50% increase in fracture energy, respectively, compared to the control composite. In addition, the samples reinforced with functionalized PAN nanofibers had 27% higher interlaminar strength compared to neat PAN-reinforced composite, implying more efficient stress transformation as well as stress distribution from the matrix phase (resin-rich area) to the reinforcement phase (carbon/phase) of the composites. The enhancement of fracture toughness provides an opportunity to alleviate the prevalent issues in laminated composites for structural operations and facilitate their adoption in industries for critical applications.