Physical properties of reduced graphite oxide prepared via chemical reduction by using ammonia solution as a reducing agent

This research studied the synthesis of graphite oxide and reduced graphite oxide via a low- cost manufacturing method. The process started with the chemical oxidation of commercial graphite powder into graphite oxide by Staudenmaier's method, followed by the chemical reduction of graphite oxide in ammonium hydroxide vapor. Subsequently, graphite oxide and reduced graphite oxide were assembled into a thin film, and microscale liquid droplets were placed into the film surface for measurement of wettability and contact angle. It is found that a graphite oxide sheet is hydrophilic while a reduced graphite oxide is hydrophobic with a contact angle equal to 120°C and 53°C respectively

Preparation and evaluation of reduced graphite oxide for oil spill removal

The production of reduced graphite oxide, graphite oxide and their associates has sparked the interests of the nanomaterials scientists and engineers for the past decade. With their superior properties, these materials can be functionalized or modified to fit specific applications from nanocomposites to smart and functionalized materials. The typical and most efficient reduction agent used is Hydrazine Hydrate (N2H4), a highly toxic chemical. The objectives of this work were to synthesize and characterize the hierarchical and porous structure of reduced graphite oxide using reduction integrated chemical treatment methods. In addition, this study aimed to evaluate the potential of reduced graphite oxide as an absorbent for oil spill removal. Graphite Oxide was synthesized using the modified Staudenmaier‘s method and chemically reduced using 30% heated Ammonia solution (NH3) at 90˚C. Different chemical treatments were done namely leavening method (10 hours) and spaced method (5, 10 and 17 hours using either soxhlet or rotary evaporator). A two-step reduction (calcination of reduced graphite oxide (4 hours) under a nitrogen atmosphere at 500oC) was also done. For the oil removal test, crude oil was recovered from a simulated sample and the absorbent was regenerated by washing it in hexane. The GO and rGO products were characterized using different characteristic tools. In general, it was found that different methods produced reduced graphite oxide with different properties even though the same reducing agent was used throughout the experiment. The results showed that rGO paper lost most of O-H functional groups, less defects and more thermally stable compared to GO. The percentage of impurities was significantly reduced from 15.37 for graphite oxide to 0.23 for calcined reduced graphite oxide. All the reduced graphite oxide papers produced in this study had a density that was lighter than water. They are also hydrophobic and super oleophilic with a contact angle 120o. The produced materials were able to absorb oil up to 41.3 g g-1, while completely repelling water. The reusability test for the reduced graphite oxide paper was conducted for five cycles. It was found that the reduction in the absorption efficiency was from 3.5% to 4% after each cycle. This indicates that the paper could be used more than five times in the oil removal process. In addition, the efficiency of the COD removal was 95%. This work had demonstrated effective methods to prepare the reduced graphite oxide paper. It offers a new alternative methods using either direct contact with ammonia vapor only or with both ammonia liquid and vapor, at a much lower temperature 90˚C and can be produced at ambient pressure. The material also showed a strong potential as an absorbent for oil spill remova

Preparation of chemically reduced graphene oxide reinforced Epoxy Resins polymer as a composite for electromagnetic interference shielding and microwave absorbing applicationns

The preparation of chemically reduced graphene oxide (rGO) and the optimization of epoxy resins’ properties using micro or nanofillers are now common practices. rGO nanoparticles (60 nm) based on an epoxy resin polymer were prepared at the concentrations of 0, 1, 2, 3, 4, and 5% weight percentage with fixed 6-mm thicknesses. The dielectric properties of the composites were measured by the reflection/transmission technique in connection with a vector network analyser (VNA) at a frequency range of 8–12 GHz. The microwave absorption and shielding effectiveness properties were calculated by using the reflection S₁₁ and transmission S21 results. The microstructure and morphology of the polymer and the rGO/cured epoxy composites were studied by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FT-IR) spectroscopy, and the X-ray Diffraction (X-RD) technique for characterizing crystalline materials. The dielectric and other properties of the rGO/cured epoxy composites were investigated based on the filler load and frequency. It was found that the applied frequency and the filler concentrations affected the dielectric properties of the rGO/cured epoxy composites. The results showed that the introduction of rGO particles to the composites increased their dielectric properties smoothly. The study of the dependence on frequency of both the dielectric constant ε′ and the dielectric loss ε″ showed a decrease in both quantities with increasing frequency, indicating a normal behaviour of the dielectrics. Cole–Cole plots were drawn with ε′ and ε″. A theoretical simulation in terms of the Cole–Cole dispersion law indicates that the Debye relaxation processes in the rGO/cured epoxy composites are improved due to the presence of the rGO filler. Moreover, with the addition of rGO as a filler into the Epoxy matrix, it now exhibits promise as a lightweight material for microwave absorption as well as an effective electromagnetic interference (EMI) shielding material