Search

In this study, graphene oxide (GO) was prepared from graphite by improved Hummers method. Graphene aerogels (GAs) were synthesized from GO by chemical reduction in which ethylenediamine (EDA) was used as a reducing agent. Influences of conditions on GA synthesis including content of EDA, reduction temperature and time were investigated. The structure and morphology of GAs were studied by density, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) specific surface area. It was found that the suitable conditions of GA synthesis were 30 μL of EDA, reduction temperature of 90 °C, and time of 6 h. The density and BET specific surface area of suitable GA were determined to be 4.57 mg/cm3 and 845 m2/g, respectively. FTIR, XRD, and Raman results showed the oxygen-containing groups on the GO surface were partially reduced and self-assembly of reduced GO formed three-dimensional framework. SEM images presented the interconnected porous structure of GA with the pore size of 50 μm. The suitable GA was used as an adsorbent for removal of cadmium ions (Cd2+) from water. Effects of factors including pH, contact time, and initial Cd2+ concentration on the adsorption capacity of GA were studied. The adsorption data fitted well to a pseudo-second-order kinetic and Langmuir isotherm models with the maximum adsorption capacity of 149.25 mg/g. Accordingly, GA could be used as a potential adsorbent for removal of Cd2+ ions from water.

In this work, a one-pot hydrothermal route was synergistically applied for TiO2 immobilized reduced graphene oxide (TiO2/rGO) facilitation. The material was characterized by modern analysis methods and studied the photocatalytic performance with methylene blue (MB) in the water. The characteristic results expressed that TiO2 in truncated octahedral bipyramidal structure with 4–25 nm was disseminated onto the rGO base. Simultaneous effects of the reaction temperature, pH, adsorption time, photocatalytic time, MB concentration, and catalyst dosage on the MB photodegradation of TiO2/rGO were also conducted by full factorial experimental design according to Placket–Burman and Box–Behnken designs. At room temperature, after 2h–adsorption and photodegradation with MB concentration of 23 mg/L in pH of 10 solution and 20 mg catalyst, nearly 100% of MB was productively decomposed out of the medium with a relatively high reaction rate constant. The photocatalytic performance showed an excellent impact toward other types of organic contaminants with the above condition, indeed affirming an extensive use in wastewater treatment with organic pollutants.

Herein, MgFe2O4-doped TiO2/reduced graphene oxide (MFO-TiO2/rGO) was synthesized via the ultrasound-assisted hydrothermal method and directly used for photodegradation p-nitrophenol from water. The characteristics of the catalyst material were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Scanning electron microscope, Transmission electron microscopy, Energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller specific surface area, thermal gravimetric analysis, and UV–vis spectroscopy. The photodegradation studies via the catalytic recovering property were also investigated with comparing to TiO2/rGO, TiO2, and MFO. The results showed that the MFO and TiO2 nanoparticles were homogeneously distributed on the GO sheet with an average diameter of 5–14 nm. The empirical data indicated a good photocatalytic property under visible light of MFO-TiO2/rGO compared to others with the photodegradation yield 99.53% in 50 min via 40 mg amount of catalysts, 1 mL H2O2 substitution, and a pH of 9. The kinetic studies exhibited that the reaction followed the pseudo-first order with a rate constant of 0.1011 min−1. Besides, it can be easily separated and reused with an insignificant change in photodegradation yield. According to the results, MFO-TiO2/rGO is highly promising for organic contaminant elimination in the effluent for the future wastewater treatment plant.

In this study, silver/graphene oxide (Ag/GO) nanocomposites were synthesized using the in situ method. Glucose was selected as an eco-friendly reducing agent for the reduction of Ag+ into silver nanoparticles (AgNPs). The characterization of GO and Ag/GO with Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopye, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Results showed that Ag/GO was successfully synthesized. Silver nanoparticles (AgNPs) with an average size of 17.68 ± 4.48 nm were uniformly distributed onto GO sheets. The antibacterial activity of GO, AgNPs, and Ag/GO were tested against Staphylococcus aureus ATCC 25,923 (S. aureus) and Salmonella enterica ATCC 35,664 (S. enterica) bacteria by optical density and plate colony–counting methods. Test results showed that Ag/GO had higher antibacterial activity than its precursors (bare AgNPs and GO) with a bactericidal rate of more than 99.90 %. Thus, Ag/GO was selected for further experimentation. Simultaneous effects of the interaction time, Ag/GO concentration, pH, annealing temperature, and S. aureus density on the antibacterial activity of Ag/GO were also investigated with full factorial experimental design according to Placket–Burman and Box–Behnken designs. After 10 min of interaction time at 37 °C, the optimal values of these factors were determined to be: Ag/GO concentration of 48 μg/mL, pH 5, and S. aureus density 5.3 × 106 CFU/mL, corresponding to an antibacterial capacity of 99.95 % towards S. aureus. The presented experiment confirmed Ag/GO to be able of eliminating about 99.99 % of S. aureus. All results of the present study affirmed the potential applications of Ag/GO as an antibacterial agent in the medical field.

In this study, magnetic iron oxide nanoparticles decorated graphene aerogel (Fe3O4/GA) with different Fe3O4:GO mass ratios of 0.5:1, 1:1, and 2:1, which were synthesized in the presence of ethylenediamine as a reducing agent. The suitable mass ratio of Fe3O4:GO was determined to be 1:1 for the preparation of Fe3O4/GA (FGA2). The FGA2 was characterized by vibrating sample magnetometer, contact angle and Fourier transform infrared spectroscopy, X–ray diffraction, transmission electron microscopy, scanning electron microscope, Raman spectroscopy and Brunauer–Emmett–Teller specific surface area. The adsorption process of FGA2 for bisphenol A (BPA) was studied by single factor experiments including contact time, pH and initial BPA concentration. The adsorption data were followed the intraparticle diffusion and pseudo-second-order kinetic models. The maximum adsorption capability of FGA2 for BPA from Langmuir isotherm model was calculated to be 253.80 mg/g. The adsorption mechanism of FGA2 for BPA was mainly described by π−π interactions. Based on these results, the FGA2 could be concerned as an efficient adsorbent for the removal of BPA from water.