123 research outputs found
Preparation and characterization of graphene membrane electrode assembly
No full textFuel cell has been of great demand as power sources for electronic devices. However this has been delayed by the deficiency of catalyst material properties. The aim of this research is to design and synthesis graphene membrane electrode assembly (MEA) as catalyst support in direct methanol fuel cell (DMFC). Graphene was produced from pure graphite powder using chemical reduction method of graphene oxide aqueous solution with a reducing agent. The modified membrane electrode assembly of graphene sulfonated poly (ether ether ketone) (SPEEK) was fabricated for DMFC testing. After the reduction process, the FTIR spectrum showed the disappearance of the carbonyl group of graphene oxide. XRD spectrum showed a sharp peak at 2? = 26.4o whichcan be assigned as 002 indexed peak with hexagonal crystal structure. The morphology of graphene observed is a uniform multi layer with crumple flakes and the product has conductivity of as high as 1.36 x 104 S/m. The characteristic of the synthesized graphene membrane electrode assembly suggest potential application in direct methanol fuel cell
Corrosion inhibition of q235a steel in acid medium using isatin derivatives: a qsar study
No full textQuantitative Structure-Activity Relationship (QSAR) study was performed on 10 isatin derivatives which were reportedly used as corrosion inhibitors. Dragon software was used to calculate the molecular descriptors. Partial least square (PLS) method was used to run the regression analysis between the descriptors and the corrosion inhibition efficiencies (IE) of the inhibitors. A predictive QSAR model was developed with a correlation coefficient (r2cal) of 0.9676. The model validity was assessed through internal and external validation. The results show that cross-validation regression coefficient (r2cv) and prediction regression coefficient (r2pred) are 0.8163 and 0.9189, respectively. The model was used to predict the IE for ten isatin derivatives. The results confirm a good stability and predictive ability of the model. Dragon-based descriptors provide a very good description of the corrosion inhibition properties of the inhibitors. The results of the QSAR study were found to be consistent with the experimental data
Preparation and characterization of PVdF/ENR-50 polymer blend electrolyte
No full textThe present study is focused on the characterization of polymer electrolyte based on poly(vinylidene fluoride) (PVdF) and epoxidised natural rubber (ENR). Polymer electrolyte film from the blending of PVdF and ENR-50 doped with lithium triflate (LiCF3SO3) and N-lithiotrifluoromethane-sulfonimide (LiN(CF3SO3)2 are produced through solution casting technique. The best ionic conductivity recorded from the polymer electrolyte which is doped with certain ratio of LiCF3SO3 is 1.38?10-5 S/cm at room temperature. For the polymer blend doped with LiN(CF3SO3)2 the ionic conductivity is 2.69?10-5 S/cm at 20oC. Characterizations of these polymer electrolytes were carried out using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). SEM managed to illustrate the different morphologies between the polymer electrolyte films studied. Meanwhile, DSC is employed to determine the glass transition temperature indicating the presence of homogenous and heterogeneous phases in the polymer electrolyte prepared
Preparation and luminescence properties of rare earth doped nanostructured zinc oxide thin films by sol gel technique
No full textZinc oxide is a semiconductor cosidered promising for optoelectronic and solar cell applications. The wide bandgap nature of the zinc oxide has been a limitation in producing devices. Doping has been considered as one of the ways to reduce the band gap. In the present studies rare earth ions in the form of terbium and erbium nitatres have been introduced in the zinc oxide structure by the sol gel technique. Homogeneous thin film of nanostructured oxide and the doped homologue of the size range 30 to 80 nm were produced as characterized by scanning electron microscopy. The luminescence properties were investigated and the doped samples showed enhanced results. The enhancement were characterized as the extra energy levels produced by the dopants allowing more transitions to the lower states to take place. The dominant transitions were attributed to the 5D4 to 7FJ (J = 6 - 3) for the terbium doped systems and (4F7/2) to the ground state (4I15/2) for the erbium systems
Kesuperkonduksian
No full textBuku ini mengandungi beberapa bab iaitu kandungan, prakata, unit-unit, simbol-simbol, bab 1 keadaan superkonduktif, pensuperkonduksi, litar-litar superkonduksi, bab 2 sifat-sifat magnetik keadaan superkonduktif, spesimen-spesimen pukal-kesan meissner, medan di luar satu spesimen pukal, bab 3 pensuperkonduksi jenis 1, dua jenis pensuperkonduksi, peralihan superkonduktif dalam satu medan magnet, bab 4 pensuperkonduksi-pensuperkonduksi jenis 2, keadaan bercampur, garis-garis vorteks, bab 5 sifat semulajadi keadaan superkonduktif,, ciri-ciri elektromagnetik statik, tenaga sempadan, indeks perkara
Optical properties of sensitized tin dioxide thin film prepared by using sol-gel spin coating method
No full textUndoped tin dioxide (SnO2)thin films were prepared by sol-gel spin coating process using an alcoholic solution of tin chloride dihydrate (SnCl2.2H2O) as the precursor. The tin dioxide doped terbium (Tb3+) and erbium (Er3+) ion thin films were also prepared using sol gel method in order to form SnO2:Tb3+ and SnO2:Er3+ thin films. The concentration of Tb3+ and Er3+ is 5% in relation with the tin content in the sol. The doped and undoped SnO2 films were sensitized with eosin Y. The diameter of particles in the SnO2 film ranges from 20 to 46 nm with spherical morphology. The particle size of SnO2 doped Tb3+ and SnO2 doped Er3+ thin films are bigger than undoped SnO2 thin films. SnO2 thin films have tetragonal structure with prominent peaks corresponding to (110), (101) and (211) crystal lattice planes. The band gap energy is decreased with the addition of dopant (Tb3+ and Er3+ ion) in sensitized SnO2 thin films. The PL emission peaks of SnO2:Tb3+ sensitized with eosin Y corresponding to the characteristic D?Ftransitions between the energy levels of Tb3+ ion. The addition of erbium (Er3+) to the SnO2 sol results in PL emission peaks that are associated with G?Iand H? I transitions in Er3+ ion
Adsorption and Thermodynamic Characteristics of Phenylpropanoids of <i>Alpinia galanga</i> as Corrosion Inhibitors on Mild Steel
No full textSolubilization of Oleic Acid by Myrj 59 Surfactant
No full textPalm oil mill effluent (POME) is one of the sources of contamination in effluent that leads to problems such asclogging in drainpipes and sewer lines. POME discharge consists of high content of free fatty acids (FFAs) aswell as high concentration of biochemical oxygen demand (BOD), chemical oxygen demand and suspendedsolids. FFAs in effluent are not favorable due to low water solubility and resistant to biodegradation whenprecipitated from effluent and binds to soil limiting their bioavailability to microorganisms for biodegradation.Nonionic surfactants are favorable as hydrocarbon or oil solubilizer because they can perform at lowtemperatures, has low-foaming characteristics and relatively stable at high temperatures and under harshchemical conditions. Therefore, there is a need for the usage of surfactant that is biodegradable and at the sametime effective at solubilizing FFAs in POME before being released to streams. Thus, FFAs will be keptmobilized and readily available for biodegradation by microorganisms. Oleic acid is a long chain free fatty acidpresents as the major fatty acid component (40-52 %w/w) in palm oil. Oleic acid was selected for solubilizationby biodegradable nonionic surfactant polyoxyethylene (100) stearate with the commercial name Myrj 59. Thesolubilizations were conducted with various concentrations of Myrj 59; below, at and above the critical micelleconcentration (CMC). The amount solubilized was determined by gas chromatography (GC) using flameionization detector (FID) technique. The solubilization process was confirmed by characterizing the solubilizedoil using Fourier Transform infrared (FTIR) to observe changes in chemical bonds. Highest solubilization wasachieved with Myrj 59 solution at above its CMC, solubilizing 516.31 ppm oleic acid. The FTIR spectra showedstrong peak at 2927 cm-1 with high intensity suggesting intermolecular hydrogen bonding between oleic acid andethylene oxide (EO) groups of surfactant
Assessing the Effect of PVP of Various Molecular Weight (MW) in PES-Ag Membranes: Antimicrobial Study Using E.Coli
No full textNew polymeric silver (Ag) composites were prepared using polyethersulfone (PES) as polymer material, N-Methyl-2-pyrrolidone (NMP) as solvent and polyvinylpyrollidone (PVP) of various molecular weight (MW) as organic fillers. Silver nitrate (AgNO3) was added by various loading in order to impart an antibacterial property to the composites. The miscibility of PES/Ag/fillers composites were characterized using TGA and any changes in chemical bonding were characterized using ATR-FTIR techniques. The XPS results showed high intensity in Eb(Ag3d) range of 378.1-378.5 and 372.2-372.5 for the highest Ag loading with PVP with the highest MW. This phenomenon had altered the hydrophilicity property of composites. In this study, composites have undergone a bacteria rejection test from E.coli suspension and a domestic waste sample. Composites with highest loading of silver and highest MW of PVP (PES-Ag2P360) was observed for significantly high bacteria rejection, log reduction value (LRV~3). Therefore, PES-silver nanocomposites is a potential membrane for bacteria removal, disinfection and maybe effective for overcoming biofouling problems
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