• Energy Research

Polyimide/SiO2 composite films were prepared from tetraethoxysilane (TEOS) and poly(amic acid) (PAA) based on aromatic diamine (4-aminophenyl sulfone) (4-APS) and aromatic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride) (BTDA) via a sol-gel process in N-methyl-2-pyrrolidinone (NMP). The prepared polyimide/SiO2 composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The FTIR results confirmed the synthesis of polyimide (4-APS/BTDA) and the formation of SiO2 particles in the polyimide matrix. Meanwhile, the SEM images showed that the SiO2 particles were well dispersed in the polyimide matrix. Thermal stability and kinetic parameters of the degradation processes for the prepared polyimide/SiO2 composite films were investigated using TGA in N2 atmosphere. The activation energy of the solid-state process was calculated using Flynn–Wall–Ozawa’s method without the knowledge of the reaction mechanism. The results indicated that thermal stability and the values of the calculated activation energies increased with the increase of the TEOS loading and the activation energy also varied with the percentage of weight loss for all compositions.

Polyimide/SiO2 composite films were prepared from tetraethoxysilane (TEOS) and poly(amic acid) (PAA) based on aromatic diamine (4-aminophenyl sulfone) (4-APS) and aromatic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride) (BTDA) via a sol-gel process in N-methyl-2-pyrrolidinone (NMP). The prepared polyimide/SiO2 composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The FTIR results confirmed the synthesis of polyimide (4-APS/BTDA) and the formation of SiO2 particles in the polyimide matrix. Meanwhile, the SEM images showed that the SiO2 particles were well dispersed in the polyimide matrix. Thermal stability and kinetic parameters of the degradation processes for the prepared polyimide/SiO2 composite films were investigated using TGA in N2 atmosphere. The activation energy of the solid-state process was calculated using Flynn–Wall–Ozawa’s method without the knowledge of the reaction mechanism. The results indicated that thermal stability and the values of the calculated activation energies increased with the increase of the TEOS loading and the activation energy also varied with the percentage of weight loss for all compositions.

In this study, activated carbons (ACs) were produced from oil palm leaves (OPL) and palm kernel shells (PKS) using different concentrations (0%, 11%, and 33%) of H3PO4 as the activating agent. The Brunauer–Emmett–Teller (BET) results indicated that surface area decreases with the decreasing of the concentration of the H3PO4 in the following order: AC from oil palm leaves was (OPLAC-0% H3PO4) < (OPLAC-11% H3PO4) < (OPLAC-33% H3PO4), with the BET surface area values of 37, 760, and 780 m2/g, respectively. Similarly, the PKS-derived AC followed the same trend of (PKSAC-0% H3PO4) < (PKSAC-11% H3PO4) < (PKSAC-33% H3PO4), with the BET surface area values of 3, 52, and 1324 m2/g, respectively. Based on this finding, it was observed that H3PO4 had exhibited an influential role on enhancing the surface properties of the AC. On the contrary, it slightly decreased the graphitic trait of the AC by considering their IG/ID trends, which were generated from the Raman spectral analysis. The energy storage capacity of the AC was further tested using cyclic voltammetry. Three of the samples were found to have high capacitance values of 434 F g−1, 162 F g−1, and 147 F g−1 at 5 mVs−1. The first (434 F g−1) is much higher than the specific capacitance value (343 F g−1) of the only oil palm leaf-derived porous carbon nanoparticles ever reported in the literature.

In this study, activated carbons (ACs) were produced from oil palm leaves (OPL) and palm kernel shells (PKS) using different concentrations (0%, 11%, and 33%) of H3PO4 as the activating agent. The Brunauer–Emmett–Teller (BET) results indicated that surface area decreases with the decreasing of the concentration of the H3PO4 in the following order: AC from oil palm leaves was (OPLAC-0% H3PO4) < (OPLAC-11% H3PO4) < (OPLAC-33% H3PO4), with the BET surface area values of 37, 760, and 780 m2/g, respectively. Similarly, the PKS-derived AC followed the same trend of (PKSAC-0% H3PO4) < (PKSAC-11% H3PO4) < (PKSAC-33% H3PO4), with the BET surface area values of 3, 52, and 1324 m2/g, respectively. Based on this finding, it was observed that H3PO4 had exhibited an influential role on enhancing the surface properties of the AC. On the contrary, it slightly decreased the graphitic trait of the AC by considering their IG/ID trends, which were generated from the Raman spectral analysis. The energy storage capacity of the AC was further tested using cyclic voltammetry. Three of the samples were found to have high capacitance values of 434 F g−1, 162 F g−1, and 147 F g−1 at 5 mVs−1. The first (434 F g−1) is much higher than the specific capacitance value (343 F g−1) of the only oil palm leaf-derived porous carbon nanoparticles ever reported in the literature.

Biodiesel is viewed as the most promising alternative fuel to replace petroleum-based diesel since it is derived from renewable sources such as animal fats, vegetable oil and grease. Out of various vegetable oil resources for biodiesel production, Jatropha curcas oil (JCO) is a viable choice for biodiesel because it is non-edible and can be grown easily in a harsh environment. In this study, Nd2O3-La2O3 catalyst was prepared for transesterification of JCO with methanol, in order to evaluate its potential as a heterogeneous catalyst for biodiesel production. Under suitable transesterification condition at 210 °C with catalyst amount of 3 wt.%, methanol/oil molar ratio of 45 and reaction time for 4 h, the conversion of JCO to fatty acid methyl ester (FAME) achieved was more than 93% over Nd2O3-La2O3 catalyst.

Biodiesel is viewed as the most promising alternative fuel to replace petroleum-based diesel since it is derived from renewable sources such as animal fats, vegetable oil and grease. Out of various vegetable oil resources for biodiesel production, Jatropha curcas oil (JCO) is a viable choice for biodiesel because it is non-edible and can be grown easily in a harsh environment. In this study, Nd2O3-La2O3 catalyst was prepared for transesterification of JCO with methanol, in order to evaluate its potential as a heterogeneous catalyst for biodiesel production. Under suitable transesterification condition at 210 °C with catalyst amount of 3 wt.%, methanol/oil molar ratio of 45 and reaction time for 4 h, the conversion of JCO to fatty acid methyl ester (FAME) achieved was more than 93% over Nd2O3-La2O3 catalyst.

Abstract Tin selenide semiconductor films have been potentiostatically deposited onto a tin substrate from an aqueous solution containing SnCl 2 and Na 2 SeO 3 . Deposition at various concentrations was attempted in order to investigate the effect of the electrolytes concentration on the film properties and to determine the optimum bath composition. The structure, morphology and photoactivity of the films were studied using X-ray diffraction, scanning electron microscopy and linear sweep photovoltammetry techniques. The semiconducting property of the deposit is strongly affected by the electrolytes concentration. The optimum bath composition was found to be 0.010 M for SnCl 2 and 0.015 M for Na 2 SeO 3 .

Abstract Tin selenide semiconductor films have been potentiostatically deposited onto a tin substrate from an aqueous solution containing SnCl 2 and Na 2 SeO 3 . Deposition at various concentrations was attempted in order to investigate the effect of the electrolytes concentration on the film properties and to determine the optimum bath composition. The structure, morphology and photoactivity of the films were studied using X-ray diffraction, scanning electron microscopy and linear sweep photovoltammetry techniques. The semiconducting property of the deposit is strongly affected by the electrolytes concentration. The optimum bath composition was found to be 0.010 M for SnCl 2 and 0.015 M for Na 2 SeO 3 .