Materials Science Forum Vol. 889

Abstract: La₁₀Si_6-2xBi_2xO_27-x (x = 0.22, 0.46 and 0.72) ceramics have been synthesized by the solid-state reaction method. The calcination temperature of La₁₀Si_6-2xBi_2xO_27-x was 900°C for 4 hours and the sintering temperature was 1500°C for 5 hours with the heating and cooling rates of 10°C per minute. Crystal structures of La₁₀Si_6-2xBi_2xO_27-x have been characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Room temperature XRD patterns of La₁₀Si_6-2xBi_2xO_27-x ceramics doped with Bi³⁺ show hexagonal apatite structure with space group P6₃/m as the primary compound with minor appearance of La₂SiO₅ impurity as the secondary compound. As the bismuth oxide content increased the La₂SiO₅ impurity also increased. La₁₀Si_5.56Bi_0.44O_26.78 has the highest bulk density of 5.2 gcm^-3 and good microstructure compared to La₁₀Si_5.08Bi_0.92O_26.54 and La₁₀Si_4.56Bi_1.44O_26.28.

Abstract: Nowadays, the anthocyanin natural dye has been used as a good photosensitizer for TiO₂ solar cells due to its availability as well as its performance. However, the dye still has a problem regarding its narrow absorbance at 550 nm. The aim of study will extend the dye’s absorbance up to NIR spectrum, so that it will increase the TiO₂ solar cell performance. The cyanidin-3-glucoside-7- diphenilamine-2'-acrylic acid (CGDA) will be introduced as the new modification of D-π-A functional material in anthocyanin dye. The investigation of the material has been carried out by the density functional theory of TD-DFT/UB3LYP/6-31+G(d,p) level. The findings show that first; the dye absorbance has broadened up to 885 nm due to the reduction of gap energy and the increase of electronic transition probabilities from 84.7% to 96.0%. Second, the molecular orbital analysis shows that both diphenylamine and acrylic acid perform as promising donor and acceptor groups for anthocyanin. Third, CGDA has the light harvesting efficiency of 46.7% surrounding NIR spectrum area. Finally, the NIR anthocyanin dye possessing HOMO of -5.536 eV and LUMO of -2.886 eV fulfills the criteria of both the effective charge transfer from LUMO dye into conduction band TiO₂ and the good dye regeneration by the electrolyte redox.

Abstract: This study is conducted to determine the potential of palm oil mill effluent (POME) as medium for growing sulfate-reducing bacterium (SRB) in anaerobic condition for microbial fuel cell application. In this study, effect of different percentage (20-70%) of POME was investigated on the growing cell of SRB. The bacterium was propagated in 400 ml Schott bottle at 35°C, pH 7.8 purged with nitrogen gas. The optical density during the growth of SRB was measured using UV-Vis Spectrophotometer at 600nm wavelength and the weight of dry cell was calculated to determine the specific growth rate. The highest specific growth rate (0.0636/hr) of SRB was achieved using 20% of POME compared to the media without POME (0.0464/hr). The increment is around 37%. The output voltage with 20% of POME is 0.23V which is 55.5% improvement compared to the medium without POME, thus proved that POME has the potential as growth medium for SRB in anaerobic condition for microbial fuel cell application. Booster circuit is possible to be used to boost the output voltage of the MFC until 3V which is more useful for electronic applications.

Abstract: Graphene has recently gained much interest in applications such as energy storage, catalysis and gas sensing. In terms of energy storage, micro supercapacitor has attracted a lot of interest in fields such as bioMEMS, biomedical implants such as cardiac pacemaker and the promising field of powering small electronic devices. In this paper, the structure of the micro supercapacitor PECVD graphene on electrodes consists of SiO₂ substrate, graphene on Nickel (Ni) electrodes, with Polypyrrole (Ppy), graphene and Polyvinyl Alcohol (PVA) layers. To improve performance, graphene is one of the more promising material being investigated for micro supercapacitor electrodes due to several advantages such as high specific surface area and high electron mobility. Graphene was then grown on the Ni electrodes using the Plasma- Enhanced Chemical Vapor Deposition (PECVD) process. The graphene growth structure on the interdigital electrodes of micro supercapacitor was characterized by Raman Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray (EDX) and Atomic Force Microscopy (AFM). A Raman spectrum of graphene growth on interdigital electrode has identified three peaks which are the D band, G band and 2D band. The broad peaks at 1340 cm^-1 and 1580 cm^-1 correspond to the D and G bands, respectively.

Abstract: New layered perovskite oxides with samarium (Sm⁺³) rare earth doped layered perovskite materials were synthesized and characterised by using X-ray diffraction, scanning electron microscopy (SEM), particle size measurements and thermogravimetric analysis (TGA). Sm_0.5Ba_0.5MnO_3-δ and SmBMn₂O_5+δ, were synthesized by conventional solid state reaction method. Rietveld analysis of XRD data shows that all materials crystallize in the orthorhombic symmetry in the Pmmm space group. SEM images show porous structures which should be suitable as electrode materials for solid oxide fuel cells (SOFCs). TGA results indicate the mass loss of 0.022% for SmBMn₂O_5+δ. Density calculation shows the materials have about 85% relative density.

Abstract: Ionic conductivity for polymethyl acrylate (PMA) and polyvinyl acetate (PVAc) blend at composition 90:10 in the presence of tetrapropyl ammoinum iodide (TPAI) showed linear increment with temperature. At selected frequencies, the values for both dielectric constant, ε_r and dielectric loss, ε_i are found to increase with temperature. It is also found that the variation of ε_r is in agreement with conductivity variation of PMA/PVAc-TPAI samples. The imaginary part of electric modulus,M_i showed the occurance of dispersion peak. Relaxation time of ionic charge carrier are extracted from the M_i maximum peak at various temperatures. It is found that relaxation time decreased with increasing temperature from ~10^-4 s at 343 K to ~10^-5 s at 373 K.

Abstract: Activated carbon from biomass namely coconut shell (CS-AC), rubber seed pericarp(RSP-AC) and their mixed blend (50:50 w/w) coconut shell-rubber seed pericarp activated carbon(CSRSP-AC) were successfully produced by using ZnCl2 as chemical activating agent viamicrowave irradiation heating system. Activation process was performed in commercial microwaveoven at power of 600W for 20 min by using 30%, 40% and 50% of ZnCl2 concentrations. Theactivated carbon was characterized according to BET surface morphology, iodine number andpercentage of MB removal. The results showed that the mixed CSRSP-AC produced the highestsurface area of 584.68 mg2/g with comparison to single CS-AC and RSP-AC at 445.9 mg2/g and462.5 mg2/g respectively. Although CSRSP-AC has the highest surface area and pore volumedevelopment, RSP-AC was found to have the highest iodine number, with the opposite trend beingobserved with MB removal indicating that RSP-AC has the highest adsorptive capacity among thethree activated carbons. The iodine number value and percentages of MB removal increased as theZnCl2 concentration increase from 30% to 50%. These findings revealed that activated carbonproduced from mixed blend of coconut shell and rubber seed pericarp has almost similarcharacteristics to their respective activated carbon derived from single individual biomass.

Abstract: Single and mixed coconut shell (CS) and palm kernel shell (PKS) were successfully converted to activated carbon by using potassium hydroxide (KOH) as activating agent. Mixed activated carbon was produced from coconut shell: palm kernel shell at different KOH concentrations of 30%, 40% and 50%. Activation process was performed in a conventional microwave oven at fixed power and time of 600W and 20 minutes respectively. The results showed that activated carbon produced from single and mixed biomass at 40% concentration of KOH exhibited higher adsorption capacity for iodine number and percentage removal of MB with comparison to 30% and 50% of KOH concentrations. The highest BET surface area of 441.19 m²/g was obtained by CSAc-40. Further both CSAc-40 and PKSAc-40 produced an average pore size diameter of less than 2.0 nm which is in the range of micropore region. On contrary, the mixed CSPKSAc-40 produced an average pore size diameter of 6.0 nm which is in the region of mesopore. All the CSAc-40, PKSAc-40 and mixed CSPKSAc-40 showed similar adsorption trend for iodine number and percentage removal of MB. Interestingly, this finding showed that in the mixed activated carbon some chemical reactions might have occurred during the activation process producing mesoporous instead of microporous as obtained by the single biomass activated carbon.

Abstract: Cocoa pod husk, an agricultural waste was chemically modified using Zinc Chloride (ZnCl₂) and used as an adsorbent for removal of acid dyes; (i) Acid Violet 17 (AV17) and (ii) Acid Yellow 36 (AY36) from aqueous solution. The raw (CPHC) and chemically modified cocoa pod husk carbon (ZCPHC) were characterized by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (EDX). The adsorption was performed on removing AV17 and AY36 from aqueous solution in batch adsorption system. The experimental data was simulated using Langmuir and Freundlich isotherm models. The isotherm study revealed that the AV17 adsorption on ZCPHC matched well with the Langmuir model, whereas AY36 adsorption on ZCPHC fitted well with Freundlich model. The maximum adsorption capacity determined from the Langmuir isotherm was 11.02 mg/g and 11.37 mg/g for AV17 and AY36 respectively at room temperature.

Abstract: In this research, the effect of different hydrothermal treatment temperature (100, 150, and 200 °C) on the products obtained by hydrothermal method was studied. Various characterization techniques was carried out such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive of x-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FTIR). XRD analysis shows that titanate phase was formed at 150 and 200 °C hydrothermal treatment. On the other hand, at 100 °C anatase TiO₂ phase structured was gained which is similar with the TiO₂ precursor. Morphological study using FESEM revealed that nanofibers and nanorods samples obtained at 150 °C and 200 °C, respectively. At 100°C, irregular shaped particle was attained similar with TiO₂ precursors. FTIR spectra for the all studied sample displayed three main broad peaks at the range of 3700-2800, and 1800-1400 assigned to –OH stretching and deformation mode due to H₂O molecules and M-O stretching mode at 900-400 cm^-1 assigned to Ti-O bond.