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In this study, the synthesis of reduced graphene oxide-silver nanoparticles (rGO-AgNPs) was carried out simultaneously by reducing graphene oxide and silver salts. The synthesized nanocomposites were successfully characterized by using UV-vis spectroscopy, X-ray diffraction, and scanning electron microscope (SEM). Methyl Orange dye was used to study the adsorption efficiency of rGO-AgNPs nanocomposites. Parameters affecting the adsorption rate such as the effect of time and pH were investigated. The results showed that the rGO-AgNPs composite was effective in absorbing dyes of methyl orange for 3 hours with a degradation percentage of 15%. [ABSTRACT FROM AUTHOR]

The effect and mechanism of green corrosion inhibitor of Morinda Citrifolia (Noni) toward low carbon steel material has been researched. The general background is to develop the cheap and eco-friendly corrosion inhibitor based on components taken from tropical plants that grow +in Indonesia. This research aims to determine the effectiveness of the use of the extracts of noni as green corrosion inhibitor of carbon steel material in aggressive environment. The medium applied for this experiment is 3.5% natrium chloride solution. The variation of the concentration and immersion time duration has been applied as the experimental parameters. All the work was done at room temperature. The corrosion rate was measured by electrochemical polarization method with CMS 600-Gamry instruments and weight loss. The adsorption of inhibitor into the metal surface, which induced bonding formation after immersion was observed by using FTIR method. Inhibition mechanism was observed by polarization curves and fitted by the Langmuir adsorption models. The experimental results show that the higher concentration of inhibitor increasing the inhibition effect. The optimum inhibition is obtained at 3 ppm noni fruit extract, after immersion for about 288 hours. The corrosion rates obtained was 1.385 mpy, with the inhibitor efficiency of 76.92%. The monolayer film is formed coating the surface material as a result of mixed type corrosion inhibitor behavior of Noni. It can be concluded that this green inhibitor is effective to be used for low carbon steel material. [ABSTRACT FROM AUTHOR]

Graphene has many applications and is a promising material. Graphene synthesis methods include mechanical exfoliation, GO reduction, and chemical vapor deposition. In this work, the graphite synthesis to produce graphite oxide powder as a raw material for graphene oxide with a variation in oxidation time using the Hummers method was performed. Characterization of the result was analyzed using x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The XRD investigations resulted in a peak of graphite oxide material with the highest intensity is obtained at the oxidation time of 20 hours. Based on SEM images, sample thickness morphology is uneven and overlaps. The surface morphology of the thinner graphite oxide is slightly transparent under oxidation-time conditions of 20 hours. [ABSTRACT FROM AUTHOR]