Thermodynamic and kinetic analysis of the response surface method for phenol removal from aqueous solution using graphene oxide-polyacrylonitrile nanofiber mats.

Phenolic compound even at low concentrations, are considered to be priority pollutants due to their significant toxicity. Electrospinning was used to create a polyacrylonitril (PAN) nanofiber, which was then impregnated with graphene oxide (GO). After a preliminary investigation into the electrospinning parameters (e.g., using various voltages and polymer concentrations), the electrospun nanofibres were tuned, this study evaluated the effectiveness of these materials in removing phenolic compounds from wastewater through adsorption. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the synthesized nanofiber mats. The scanning electron microscopy (SEM) analysis revealed that the structure of nanofiber mats was altered by the addition of graphene oxide (GO) in different ratios. Specifically, the surface of the fibres exhibited increased roughness, and the diameter of the fibres also experienced an increase. The average diameter of the fibres was measured to be (134.9 ± 21.43 nm) for the PAN/2.5% GO composite and (198 ± 33.94 nm) for the PAN/5% GO composite. FTIR spectra of the PAN/GO nanocomposites nanofiber displayed distinct peaks associated with graphene oxide (GO). These included a wide peak at 3400 cm-1, related to the presence of hydroxyl (O-H) groups, as well as peaks on 1600 as well as 1000 cm-1, which indicated the existence of epoxy groups. In this study response surface methodology (RSM) was implemented. To enhance the efficiency of removing substances, it is necessary to optimise parameters such as pH, contact time, and dosage of the adsorbent. The optimum pH for removing phenol via all nanofiber mats was determined to be 7, while at a dose of 2 mg dose adsorbents maximum removals for pure PAN, PAN/2.5 GO, and PAN/5 GO were 61.3941, 77.2118, and 92.76139%, respectively. All the adsorbents obey Langmuir isotherm model, and the empirical adsorption findings were fitted with the second-order model kinetically, also non-linear Elovich model. The maximal monolayer adsorption capacities for PAN, PAN/2.5 GO, and PAN/5 GO were found to be 57.4, 66.18, and 69.7 mg/g, respectively. Thermodynamic studies discovered that the adsorption of phenol on all adsorbents nanofiber mats was exothermic, the adsorption of phenol on nanofiber mats decreases as the temperature increases. All the adsorbents exhibit negative enthalpy and entropy. The PAN/GO composite's superior phenol removal suggested that it could be used as a latent adsorbent for efficient phenol removal from water and wastewater streams.

Hydrothermally reinforcing hydroxyaptatite and bioactive glass on carbon nanofiber scafold for bone tissue engineering.

As a bone tissue engineering scaffold, the objective of this study was to design hierarchical bioceramics based on an electrospun composite of carbon nanofibers (CNF) reinforced with hydroxyapatite (HA) and bioactive glasses (BGs) nanoparticles. The performance of the nanofiber as a scaffold for bone tissue engineering was enhanced by reinforcing it with hydroxyapatite and bioactive glass nanoparticles through a hydrothermal process. The influence of HA and BGs on the morphology and biological properties of carbon nanofibers was examined. The prepared materials were evaluated for cytotoxicity in vitro using the water-soluble tetrazolium salt assay (WST-assay) on Osteoblast-like (MG-63) cells, and oste-ocalcin (OCN), alkaline phosphatase (ALP) activity, total calcium, total protein, and tar-trate-resistant acid phosphatase (TRAcP) were measured. The WST-1, OCN, TRAcP, total calcium, total protein, and ALP activity tests demonstrated that scaffolds reinforced with HA and BGs had excellent in vitro biocompatibility (cell viability and proliferation) and were suitable for repairing damaged bone by stimulating bioactivity and biomarkers of bone cell formation.

Electrospun non-wovens potential wound dressing material based on polyacrylonitrile/chicken feathers keratin nanofiber.

Electrospinning nanofibers have a tremendous interest in biomedical applications such as tissue engineering, drug administration, and wound healing because of their ability to replicate and restore the function of the natural extracellular matrix found in tissues. The study's highlight is the electrospinning preparation and characterization of polyacrylonitrile with chicken feather keratin as an additive. In this study, keratin was extracted from chicken feather waste using an environmentally friendly method and used to reinforce polymeric nanofiber mats. Scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy were used to examine the morphology and the structure of the prepared nanofiber mats. The effect of keratin on the porosity and the tensile strength of reinforcing nanofibers is investigated. The porosity ratio of the nanofiber mats goes up from 24.52 ± 2.12 for blank polyacrylonitrile (PAN (NF)) to 90.89 ± 1.91% for polyacrylonitrile nanofiber with 0.05 wt% keratin (PAN/0.05% K). Furthermore, keratin reinforcement improves the nanofiber's mechanical properties, which are important for wound dressing application, as well as its antibacterial activity without causing hemolysis (less than 2%). The best antibacterial activities were observed against Pseudomonas aeruginosa (30 ± 0.17 mm inhibition zone) and Staphylococcus aureus (29 ± 0.31 mm inhibition zone) for PAN/0.05% K sample, according to the antibacterial test. This research has a good potential to broaden the use of feather keratin-based nanofibers in wound healing.

Biodegradable cellulose nanocrystals hydrogels for removal of acid red 8 dye from aqueous solutions.

Biodegradable cellulose nanocrystals hydrogels (CNCsH) were synthesized from cellulose nanocrystals (CNCs) which were prepared from office wastepaper (OWP) by a chemical crosslinking method using epicholorohydrin (ECH) as a cross-linker. CNCsH were tested for their swelling behavior and biodegradability and the point of zero charge had been determined. The ability of CNCsH for removing the Acid Red 8 (AR8) anionic dye from its aqueous solution was evaluated. The different parameters affecting removal of the dye, such as pH, initial concentration of dye, content of CNCs, temperature and adsorbent dosage were investigated. The optimum conditions for 68% removal efficiency were pH = 1, initial concentration of dye = 10 ppm, contact time = 105 min, CNCs content = 5% and CNCsH dosage = 0.5 g at 30 °C. The adsorption isotherms, kinetics, and thermodynamic parameters have been studied. The results showed an appropriate fit for Langmuir adsorption isotherm and pseudo-second order kinetics model with an adsorption capacity of 17.12 mg/g. According to the obtained values of thermodynamic parameters, the removal of Acid red 8 by CNCs hydrogels was exothermic spontaneous process.

Viscoelasticity, Mechanical Properties, and In Vitro Bioactivity of Gelatin/Borosilicate Bioactive Glass Nanocomposite Hydrogels as Potential Scaffolds for Bone Regeneration.

Chemical cross-linking was used to create nanocomposite hydrogels made up of gelatin (G) and borosilicate bioactive glass (BBG) with different content (0, 3, and 5 wt.%). The G/BBG nanocomposite hydrogels were studied for their morphology, mechanical properties, and viscoelasticity. SEM images revealed a macroporous interconnected structure with particles scattered across the pore walls. Studies of water absorption and degradation confirmed that the nanocomposite scaffolds were hydrophilic and biodegradable. The addition of 5% BBG to the scaffold formulations increased the compressive modulus by 413% and the compressive intensity by 20%, respectively. At all frequency ranges tested, the storage modulus (G') was greater than the loss modulus (G″), revealing a self-standing elastic nanocomposite hydrogel. The nanocomposite scaffolds facilitated apatite formation while immersed in simulated body fluid (SBF). According to the findings, G/BBG nanocomposite scaffolds could be a promising biomaterial for bone regeneration.

In-Vitro Cytotoxicity Study: Cell Viability and Cell Morphology of Carbon Nanofibrous Scaffold/Hydroxyapatite Nanocomposites.

Electrospun carbon nanofibers (CNFs), which were modified with hydroxyapatite, were fabricated to be used as a substrate for bone cell proliferation. The CNFs were derived from electrospun polyacrylonitrile (PAN) nanofibers after two steps of heat treatment: stabilization and carbonization. Carbon nanofibrous (CNF)/hydroxyapatite (HA) nanocomposites were prepared by two different methods; one of them being modification during electrospinning (CNF-8HA) and the second method being hydrothermal modification after carbonization (CNF-8HA; hydrothermally) to be used as a platform for bone tissue engineering. The biological investigations were performed using in-vitro cell counting, WST cell viability and cell morphology after three and seven days. L929 mouse fibroblasts were found to be more viable on the hydrothermally-modified CNF scaffolds than on the unmodified CNF scaffolds. The biological characterizations of the synthesized CNF/HA nanofibrous composites indicated higher capability of bone regeneration.

Preparation and characterization of carbon nanofibrous/hydroxyapatite sheets for bone tissue engineering.

Critical size bone defects are orthopedic defects that will not heal without intervention or that will not completely heal over the natural life time of the animal. Although bone generally has the ability to regenerate completely however, critical defects require some sort of scaffold to do so. In the current study we proposed a method to obtain a carbon nanofibrous/Hydroxyapatite (HA) bioactive scaffold. The carbon nanofibrous (CNF) nonwoven fabrics were obtained by the use of the electrospinning process of the polymeric solution of poly acrylonitrile "PAN" and subsequent stabilization and carbonization processes. The CNFs sheets were functionalized by both hydroxyapatite (HA) and bovine serum albumin (BSA). The HA was added to the electrospun solution, but in case of (BSA), it was adsorbed after the carbonization process. The changes in the properties taking place in the precursor sheets were investigated using the characterization methods (SEM, FT-IR, TGA and EDX). The prepared materials were tested for biocompatibility via subcutaneous implantation in New Zealand white rabbits. We successfully prepared biocompatible functionalized sheets, which have been modified with HA or HA and BSA. The sheets that were functionalized by both HA and BSA are more biocompatible with fewer inflammatory cells of (neutrophils and lymphocytes) than ones with only HA over the period of 3weeks.