This research studied the synthesis of graphene oxide and graphene via a low-cost manufacturing method. The process started with the chemical oxidation of commercial graphite powder into graphite oxide by modified Hummer’s method, followed by the exfoliation of graphite oxide in distilled water using the ultrasound frequency from a laboratory ultrasonic bath. Finally, the oxygen functional groups on exfoliated graphite oxide or graphene oxide were eliminated by stirring in hot distilled water at 95°C, as a replacement for highly toxic and dangerously unstable hydrazine. The results assured that stirring in hot distilled water could give the product of graphene or reduced graphene oxide. The samples were characterized by FTIR, XRD, TGA, Raman spectroscopy, SEM, and TEM methods.

The waste shell was utilized as a bioresource of calcium oxide (CaO) in catalyzing a transesterification to produce biodiesel (methyl ester). The economic and environmen-friendly catalysts were prepared by a calcination method at 700–1,000°C for 4 h. The heterogeneous catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET) method. The effects of reaction variables such as reaction time, reaction temperature, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the CaO catalysts derived from waste shell showed good reusability and had high potential to be used as biodiesel production catalysts in transesterification of palm oil with methanol.

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In this study, poly(vinyl alcohol) (PVA)-graphite oxide and PVA-graphene oxide (XGO) films were prepared by simple and environmentally friendly method. Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscope revealed the strong hydrogen-bonding interactions between XGO and PVA matrix and the layered structure of tensile fracture surfaces of exfoliated PVA-XGO films. These resulted in a remarkable improvement on mechanical and barrier properties of XGO/PVA nanocomposite films. The addition of 0.3 and 2.0 wt.% XGO showed an increase in tensile strength (49%) and failure stain (13-22%), in comparison with the neat PVA films. The dramatic improvement of 144% in elastic modulus was observed in PVA/2.0 wt.% XGO. Both O 2 and water vapour permeability coefficients of PVA film decreased by about 76% and 21% at an XGO loading of 2.0 wt.%, respectively. Preliminary test was performed to determine the use of nanocomposite films to extend the shelf life of bananas. It was found that bananas packaged in nanocomposite films were ripened slower than those unpackaged or packaged in PVA films. These results demonstrate that such films could dramatically promote the application of PVAbased films in the packaging industry.

Abstract:The transesterification of waste frying oil (WFO) with methanol in the presence of potassium hydroxide catalyst supported on Jatropha curcas fruit shell activated carbon (KOH/JS) was studied. The catalyst systems were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the Brunauer-Emmett-Teller (BET) method. The effects of reaction variables such as residence time, reaction temperature, methanol/oil molar ratio and catalyst bed height in packed bed reactor (PBR) on the yield of biodiesel were investigated. SEM images showed that KOH was well distributed on the catalyst support. The optimum conditions for achieving the conversion yield of 86.7% consisted of a residence time of 2 h, reaction temperature of 60 °C, methanol/oil molar ratio of 16 and catalyst bed height of 250 mm. KOH/JS could be used repeatedly five times without any activation treatment, and no significant activity loss was observed. The results confirmed that KOH/JS catalyst had a great potential to be used for industrial application in the transesterification of WFO. The fuel properties of biodiesel were also determined.

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Heterogeneous catalysis of transesterification using potassium hydroxide supported on coconut shell activated carbon (KOH/AC) catalyst was used to produce biodiesel from waste frying oil (WFO) and methanol. The effects of reaction temperature, methanol to oil molar ratio, catalyst bed height, reaction time, and reusability of catalyst on the conversion to fatty acid methyl ester in a packed bed reactor were studied. The results showed that increasing reaction temperature, methanol/oil molar ratio, catalyst bed height, and reaction time can enhance the conversion of WFO. The optimum conditions were a reaction temperature of 60°C, methanol/oil molar ratio 25:1, catalyst bed height 250 mm, and reaction time 2 h which yielded 86.3% of the conversion. KOH/AC could be used repeatedly for 4 times without activity loss and no activation treatment was required. The fuel properties of biodiesel were determined.

Microwave-assisted biodiesel production via transesterification ofJatropha curcasoil with methanol using solid oxide catalyst derived from waste shells of oyster andPyramidellawas studied. The shells were calcined at 900°C for 2 h and calcium oxide (CaO) catalyst characterizations were carried out by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), and the Brunauer-Emmett-Teller (BET) surface area measurements. The effects of reaction variables such as reaction time, microwave power, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the economic and environmentally friendly catalysts derived from oyster andPyramidellashells showed good reusability and had high potential to be used as biodiesel production catalysts under microwave-assisted transesterification ofJatropha curcasoil with methanol.