After preparing composite PSGO films by coating electrospun polystyrene (PS) fibers with graphene oxide (GO), we examined their use as dye adsorbents for water remediation. The GO, which was ...synthesized via a modified Hummers' method, was adsorbed on the surface of the PS fibers. Through X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TGA) analyses, we characterized the structure and morphology of the composite films, confirming that the GO was successfully incorporated onto the PS fibers. SEM images revealed that the PS fibers exhibited a smooth surface and that the GO was uniformly deposited on them. TGA analysis indicated that the PSGO is composed of ∼13 wt% GO and ∼87 wt% PS, and that both components exhibited similar thermogravimetric behavior. We examined the removal of the methylene blue (MB) dye from aqueous solutions as a model system to assess the adsorptive properties of the PSGO films. The composite films had a removal capacity that was approximately 2.3 times greater than that of pure PS membranes. For all MB concentrations investigated, the removal of the dye, which was very fast in the first 30 min, the equilibrium value of the adsorption capacity (qe = 114 mg g−1) was reached after 120 min. The kinetics of the adsorption process was best described by the pseudo-second-order (PSO) model, which predicted an adsorption capacity (qt) of 116.69 mg g−1.
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•Fabrication and use of electrospun polystyrene fiber covered with graphene oxide.•GO-coated polystyrene is a promising adsorbent of the Methylene Blue dye.•Outstanding adsorptive capacity in comparison to other reported adsorbents.
We performed an aqueous in situ polymerization of pyrrole in presence of modified montmorillonite particles to obtain a polypyrrole/organophilic montmorillonite clay (PPy/MMTO) nanocomposite with an ...intercalated structure. The natural clay was previously modified to become organophilic. The PPy/MMTO was mixed to PVA to prepare nanofibers through electrospinning methods. The different nanocomposites were characterized through Fourier transform infrared spectroscopy and UV–Vis spectroscopy, X-ray diffraction, scanning electron microscopy and impedance spectroscopy. We confirmed the clay organophilization by observing the (001) plane displacement from 6,1° to 5,5° and the presence of absorption bands in 2924 cm−1, 2853 cm−1 and 1479 cm−1, by XRD and FTIR analyses, respectively. We observed that the conductivity of the final PVA/PPy-MMTO nanofibers increased upon exposure to ammonia vapors, confirming that this hybrid material exhibits promising properties for use as active elements in gas sensors.
•We synthesized PVA/polypyrrole montmorillonite clay nanofibers by electrospinning.•The successful organophilization of the clay was confirmed by XRD analysis.•FTIR and UV–Vis spectra confirmed the synthesis of the PPY/OMMT nanocomposite.•EIS showed that the nanofibers have a good response to the exposure to ammonia gas.
This work describes the preparation of polyvinyl alcohol/polyaniline-montmorillonite clay (PVA/PANI-OMMT) nanofibers through electrospinning. Initially, for improving the compatibility of the clay ...towards the organic polymer, the montmorillonite (MMT) was submitted to an organophilization process using hexadecyltrimethylammonium bromide (CH3(CH2)15N(Br)(CH3)3). The PANI-OMMT composite, which was obtained after the in situ polymerization of aniline in presence of the organophilic clay (ratio of ≈1:3 in weight), was then placed in a matrix of PVA (weight ratio of 1:7 of composite:PVA) for the production of the PVA/PANI-OMMT composite fibers through electrospinning. We used several characterization techniques (X-ray diffraction (XRD); infrared absorption spectroscopy (FTIR), ultraviolet visible absorption spectroscopy (UV–Vis), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS)) to analyze the different samples produced. The clay organophilization was confirmed after observing the (001) plane displacement from 5,6° to 4,7° and absorption bands in 2924 cm−1, 2853 cm−1 and 1479 cm−1, as analyzed by XRD and FTIR, respectively. The presence of polyaniline in its emeraldine salt was identified by the presence of the characteristic UV–Vis absorption bands in 360 nm, 430 nm and 822 nm, while the formation of the PANI/OMMT nanocomposite was confirmed by observing the characteristic FTIR bands of each individual component. From the SEM images, we could establish that the resulting nanocomposite mats were composed by uniform fibers with an average diameter of 240 nm and presented good surface quality. We have found that EIS is an efficient technique for the evaluation of changes in the electric properties of the nanofibers after their exposure to vapors of methanol. We suggest that this organic-inorganic composite may find useful applications in the preparation of several devices based on polymers, such as heavy metal filtration membranes and gas sensors.
•We synthesized PVA/PANI-montmorillonite nanofibers by electrospinning.•The successful organophilization of the clay was confirmed by XRD analysis.•FTIR and UV–Vis spectra confirmed the synthesis of the PANI/OMMT nanocomposite.•EIS showed that the nanofibers have a good response to the exposure to methanol.
