Amino-Fe3O4-functionalized multi-layered graphene oxide as an ecofriendly and highly effective nanoscavenger of the reactive drimaren red

Exploring the antioxidant activity and cytotoxicity of the reduced graphene oxide-based nanocomposite

In the current study, the radical scavenging activity and cytotoxicity of reduced graphene oxide (rGO), mediated by titanium dioxide (TiO2) nanocomposite, have been explored. The sol-gel method was utilized to synthesize TiO2 nanoparticles without surfactants, and the improved Hummer's method for the graphene oxide (GO) was followed by the thermal reduction method to obtain rGO. The single-step hydrothermal process was utilized for the synthesis of GO@TiO2 and rGO@TiO2 nanocomposites. Fourier transform infrared spectrum, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectrum of the nanocomposites were investigated. XRD and Raman spectra confirm the anatase phase TiO2 formation on the 2D layer of the rGO nanosheet. FESEM and HR-TEM confirmed the spherical TiO2 with a 6.75 ± 1.42 nm diameter decorated on a 2D rGO nanosheet. The rGO@TiO2 (91.18%) exhibited higher antioxidant properties than the GO@TiO2 (70.00%) nanocomposite at 400 µg/mL concentration, evaluated by the DPPH method. Moreover, the nanocomposite exhibits stronger scavenger activity towards the hole scavenger than the electron scavenger. The rGO@TiO2 nanocomposite showed less cytotoxicity towards L929 cells compared to TiO2 nanoparticles, GO, rGO, and GO@TiO2. The antibacterial properties of the rGO against Staphylococcus aureus bacteria were enhanced by adding TiO2 nanoparticles. Thus, the results support the potential antioxidant properties of rGO-based nanocomposites that can be explored for biomedical and environmental applications.

Surface-modified graphene oxide-based composites for advanced sequestration of basic blue 41 from aqueous solution

Advanced materials for the efficient treatment of textile wastewater need to be developed for the sustainable growth of the textile industry. In this study, graphene oxide (GO) was modified by the incorporation of natural clay (bentonite) and mixed metal oxide (copper-cobalt oxide) to produce GO-based binary and ternary composites. Two binary composites, GO/bentonite and GO/Cu-Co Ox (oxide), and one ternary composite, GO/bentonite/Cu-Co Ox, were characterized by Fourier transform-infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Brunauer-Emmett-Teller (BET) analysis. The adsorption efficiency of these composites was evaluated against a cationic dye, Basic Blue 41 (BB41). The composites had several surface functional groups, and the ternary composite had tubular porous structures formed by the cross-linking of the bentonite and GO planes. The BET surface area of the ternary composite was 50% higher than that of the GO. The BB41 removals were 92, 89, 80, and 69% for GO/bentonite/Cu-Co oxide, GO/bentonite, GO and GO/Cu-Co oxide, respectively. The pseudo-2nd-order and intraparticle diffusion models best describe the kinetics results, indicating chemisorption and slow pore diffusion-controlled adsorption processes. The Langmuir isotherm-derived adsorption capacity of GO/bentonite/Cu-Co oxide was 351.1 mg/g, which was very close to the measured value. After five consecutive cycles, the ternary composite retained 90% BB41 removal efficiency compared to its 1st cycle. Electrostatic interaction and pore diffusion were predicted to be the controlling mechanisms for the adsorption of the BB41. The GO-based ternary composite can be a feasible and scalable adsorbent for BB41 in wastewater treatment.

Adsorptive and photocatalytic activity of Fe3O4-functionalized multilayer graphene oxide in the treatment of industrial textile wastewater

Multilayer graphene oxide (mGO) was synthesized and functionalized via co-precipitation method to produce magnetic Fe₃O₄-functionalized multilayer graphene oxide nanocomposite (MmGO). Photocatalytic properties of MmGO were investigated in the photodegradation of raw textile wastewater samples. Fourier-transformed infrared spectroscopy revealed Fe-O vibrations, characterized by the band shift from 636.27 to 587.25 cm^-1 on MmGO. X-ray diffraction confirmed the successful oxidation of graphite by the (002) peak at 10° and indicated the presence of Fe₃O₄ on MmGO surface by the peaks at 2θ 35.8° (311), 42.71° (400), 54.09° (511), and 62.8° (440). There was no detection of coercivity field and remnant magnetization, evidencing a material with superparamagnetic properties. Then, the textile effluent was treated by heterogeneous photo-Fenton (HPF) reaction. A 2² factorial design was conducted to evaluate the effects of MmGO dosage and H₂O₂ concentration on HPF, with color and turbidity removal as response variables. The kinetic behavior of the adsorption and HPF processes was investigated separately, in which, the equilibrium was reached within 60 and 120 min, for adsorption and HPF, respectively. Pseudo-second-order model exhibited the best fit, with COD uptake capacity at equilibrium of 4094.94 mg g^-1, for chemical oxygen demand. The modeling of kinetics data showed that the Chan and Chu model was the most representative for HPF, with initial removal rate of 95.52 min^-1. The removal of organic matter was 76.36% greater than that reached by conventional treatment at textile mills. The presence of Fe₃O₄ nanoparticles attached to MmGO surface was responsible for the increase of electron mobility and the enhancement of its photocatalytic properties. Finally, MmGO presented low phytotoxic to Cucumis sativus L. with a RGI of 0.53. These results bring satisfactory perspectives regarding further employment, on large scale, of MmGO as nanocatalyst of textile pollutants.

Facile preparation of robust dual MgO-loaded carbon foam as an efficient adsorbent for malachite green removal

This study developed a facile approach for the fabrication of dual MgO-loaded carbon foam (DMCF) via carbonization of a cured MgO/cyanate ester resin mixture, which underwent self-foaming of the resin followed by the carbothermal reduction of MgO. The features of the prepared DMCF prepared were characterized by FESEM, TEM, XRD, FTIR, XPS and so on, and the effects of adsorption conditions, adsorption isotherms, kinetics, and thermodynamics on malachite green (MG) removal using the DMCF as adsorbents were investigated through batch adsorption experiments. Results demonstrate that the DMCF possesses a unique dual loading of MgO particles which are not only loaded onto its foam walls but also filled within the walls with a graphene-wrapped core-shell structure. The experimental maximum adsorption capacity of MG reaches up to 1874.18 mg/g with a partition coefficient of 10.87 mg/g/μM. The adsorption process can be better described with Langmuir, pseudo-second-order, and intraparticle diffusion models. Moreover, the DMCF exhibits a removal percentage of 84.85% after five reuses, indicating that it is an efficient and promising adsorbent for MG adsorption.

Magnetically Functionalized Moss Biomass as Biosorbent for Efficient Co2+ Ions and Thioflavin T Removal

Microwave synthesized iron oxide nanoparticles and microparticles were used to prepare a magnetically responsive biosorbent from Rhytidiadelphus squarrosus moss for the rapid and efficient removal of Co2+ ions and thioflavin T (TT). The biocomposite was extensively characterized using Fourier transformed infrared (FTIR), XRD, SEM, and EDX techniques. The magnetic biocomposite showed very good adsorption properties toward Co2+ ions and TT e.g., rapid kinetics, high adsorption capacity (218 μmol g-1 for Co and 483 μmol g-1 for TT), fast magnetic separation, and good reusability in four successive adsorption-desorption cycles. Besides the electrostatic attraction between the oxygen functional moieties of the biomass surface and both Co2+ and TT ions, synergistic interaction with the -FeOH groups of iron oxides also participates in adsorption. The obtained results indicate that the magnetically responsive biocomposite can be a suitable, easily separable, and recyclable biosorbent for water purification.