Development Of Integrally Skinned Polysulfone Ultrafiltration Membrane: Effect Of Casting Parameters

Tesis ini memfokuskan pada pembangunan membran penurasan ultra polisulfona berselaput integrasi This thesis focuses on the development of integrally skinned polysulfone ultrafiltration membrane

Development Of Integrally Skinned Polysulfone Ultrafiltration Membrane: Effect Of Casting Parameters. [TP159.M4 M214 2005 f rb Kejuruteraan] [Microfiche 7714].

Tesis ini memfokuskan pada pembangunan membran penurasan ultra polisulfona berselaput integrasi dan juga kesan parameter penebaran terhadap prestasi membran untuk menghasilkan membran yang konsisten dan reproduksi. This thesis focuses on the development of integrally skinned polysulfone ultrafiltration membranes and the effect of casting parameters on the membrane performance to produce a consistent and reproducible membrane

Preparation of RF/Brij 58 mesoporous carbon film as supercapacitor electrode

Mesoporous carbon (MC) film was prepared using carbon precursor of resorcinol and formaldehyde via self-assembly soft templating method for supercapacitor application with high electrochemical performance. A neutral surfactant of Brij 58 was used as structure directing agent for the pore structure geometry tuning while preparing the MCs. It was then carbonized to obtain the ordered mesoporous carbon (OMC) films or namely as RF/Brij58 film. The mesostructure was characterized by X-ray diffraction patterns (XRD) and electrochemical analysis. The carbonized RF/Brij58 film show excellent electrochemical property for supercapacitor application and the specific capacitance up to 10.57 mFcm-1 at 5 mV s−1 scan rate was obtained

Controlled concentration of Mn salt for the synthesis of manganese oxide/mesoporous carbon film as potential

Manganese oxide (Mn2O3) mesoporous carbon (MPC) was synthesized by the incipient wetness of impregnation at room temperature and followed by calcination of 300 °C. The structure and morphology of Mn2O3/MPC were characterized by Fourier transform infrared (FTIR) spectrum, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The electrochemical performance of synthesized composites was evaluated by cyclic voltammetry (CV), galvanostatic measurement of charge-discharge (GCD) as well as power and energy density characteristics. The specific capacitance of the composite electrode when 10 wt.% Mn salt was coated on the surface of MPC film could reach 53.59 mF cm-2 as compared to MPC film at only 15.23 mF cm-2. These are in good agreement with the electrochemical performance improvement results of the energy and power density recorded for Mn2O3/MPC, which lead to higher specific capacitance as supported by the CV and GCD results in 1 M potassium chloride (KCl) of electrolyte. This enhanced capacitance was attributed to the outstanding electric properties of MPC film as well as the faradaic redox reactions of manganese oxide as proven by FESEM and EDX analysis. The results indicate the promising application of the fabricated Mn2O3/MPC composite as electrodes for supercapacitors

Development of mesoporous carbon nanocomposites film from synthetic precursor and natural cellulose incorporated with Mn₂O₃ for supercapacitor application

A good matching between the electrode material, pore size suitable for diffusion of electrolyte ions and the dimensions of ionic species is necessary for an optimal performance of electrode materials. By developing a cost-effective mesoporous carbon (MPC) electrode material with highly developed surface area and high electric conductivity may address the issues to enhance the capacitive performance of the material as well as power density, energy density and its cycle life. Thus, this study aims at developing MPC film from Resorcinol(R) /Formaldehyde(F)/F127 and modifying the carbon precursor using natural cellulose of carboxymethyl cellulose (CMC) before incorporated with manganese oxide (Mn2O3). That is purposedly to enhance the capacitance attributed from electric double layer (EDLC) properties in MPC film as well as the pseudocapacitive properties from faradaic redox reactions of Mn2O3. All samples were synthesised by using a spin coating self-assembly soft templating method and incipient wetness impregnation followed by calcination. The experimental conditions such as carbonisation temperature, molar ratio, stirring time, concentrations and calcination temperature and time were manipulated to enhance the capacitive performance of the electrode materials. X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM) analysis was conducted to confirmed the structure and surface morphology of the samples. The electrochemical measurements e.g. cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurement was performed in 1 M potassium chloride (KCl) electrolyte solution in a three-electrode system assembly. From the results, it was revealed that the specific capacitance of Mn2O3/MPC composites film calcined at 300 °C showed 3.5 times higher with 53.59 mF cm-2 than optimised MPC film only 15.23 mF cm-2. These are in good agreement with the impressive results of a low internal resistance value recorded for Mn2O3/MPC, which could lead to the interpretation of higher specific capacitance compared to MPC as supported by the CV and GCD results. Mn2O3/MPC composite film displayed the highest energy and power density and shows fairly stable capacitance with sample could retain about 71% of its initial capacitance until reaching 1000 cycles. Then the research geared onwards by applying green raw material which is CMCs as a carbon source for the electrode materials. In this study, two types of CMC; bamboo CMC and agro-based CMC commercial were used before Mn2O3 incorporation. The enhancement in specific capacitance with 31.98 mF cm-2 for Mn2O3/CMCPCbam was observed to be 3.3 times higher compared to pure carbon samples. Mn2O3/CMCPCbam and Mn2O3/CMCPCcom show a relatively stable capacitance of around 65.6% and 68.5% of the initial capacitance after 1000 charge-discharge cycles and showing highest energy and power density. The incorporation of pseudocapacitance metal oxides with EDLC carbon films is therefore an effective way to increase electrochemical performance in terms of specific capacitance, power density and energy density characteristics of carbon materials. The presence of Mn2O3 was strongly proved by the XRD, XPS and FTIR analysis while FESEM-EDX and HRTEM confirmed their existence in the structure. This strategy highlights well-organised mesoporous carbon films from synthetic and natural cellulose precursor with superior electrochemical performance as the promising materials for advanced supercapacitor applications

Mesoporous carbon film via spin coating soft templating method for supercapacitor electrode

Mesoporous carbon films were prepared by using spin coating self-assembly soft templating method onto titanium foils as substrates. A surfactant of triblock copolymer Pluoronic F127 (F127) which act as structure directing agent for the pore structure geometry tuning while preparing the mesoporous carbon film and carbon precursor of resorcinol (R) and formaldehyde (F) was used in the study. It was then carbonized to obtain the final product of F127/RF carbon film. The samples were characterized by electrochemical analysis. The carbonized F127/RF film show excellent electrochemical property for supercapacitor application and the specific capacitance 15.23 mFcm-1 at 5 mV s−1 scan rate was obtained using electrolyte of 1.0 M potassium chloride (KCl) neutral aqueous solution. These results suggest that the mesoporous F127/RF carbon film coated titanium foil is a promising candidate for high performance electrodes for electric double layer capacitors (EDLC)

Chemical characterization of pyrolysis liquids from Dyera costulata and evaluation of their bio-efficiency against subterranean termites, Coptotermes curvignathus

Wood degradation caused by fungi and insects is a major problem for the rubberwood industry. This study evaluated the potential of using pyrolysis liquids (wood vinegar) from Dyera costulata as a natural biocide against termites. The infestation rates of Coptotermes curvignathus on filter paper samples treated with 0.5%, 1.0%, 5.0% and 10.0% of Dyera costulata wood vinegar were observed in laboratory conditions. The effects of D. costulata wood vinegar treatment depended on the concentration. Filter paper samples treated with 10% D. costulata wood vinegar had the highest resistance against C. curvignathus attack, with the lowest relative mass loss, followed in rank order by the 5% and 1% treatments. Results from tests on Hevea brasiliensis wood treated with wood vinegar also showed a similar trend. The results suggest that D. costulata wood vinegar acts as a wood preservative against termites, provided proper concentration is used

Effect of temperature and growth time on vertically aligned ZnO nanorods by simplified hydrothermal technique for photoelectrochemical cells

Despite its large band gap, ZnO has wide applicability in many fields ranging from gas sensors to solar cells. ZnO was chosen over other materials because of its large exciton binding energy (60 meV) and its stability to high-energy radiation. In this study, ZnO nanorods were deposited on ITO glass via a simple dip coating followed by a hydrothermal growth. The morphological, structural and compositional characteristics of the prepared films were analyzed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). Photoelectrochemical conversion efficiencies were evaluated via photocurrent measurements under calibrated halogen lamp illumination. Thin film prepared at 120 °C for 4 h of hydrothermal treatment possessed a hexagonal wurtzite structure with the crystallite size of 19.2 nm. The average diameter of the ZnO nanorods was 37.7 nm and the thickness was found to be 2680.2 nm. According to FESEM images, as the hydrothermal growth temperature increases, the nanorod diameter become smaller. Moreover, the thickness of the nanorods increase with the growth time. Therefore, the sample prepared at 120 °C for 4 h displayed an impressive photoresponse by achieving high current density of 0.1944 mA/cm2

Electrochemically reduced Titania nanotube synthesized from glycerol-based electrolyte as supercapacitor electrode

In this paper the synthesis of self-organized Titania nanotubes (TNTs) by a facile potentiostatic anodization in a glycerol-based electrolyte is reported. The optimized TNTs were subsequently reduced through a cathodic reduction process to enhance its capacitive performance. FESEM and XRD were used to characterize the morphology and crystal structure of the synthesized samples. XPS analysis confirmed the reduction of Ti4+ to Ti3+ ions in the reduced Titania nanotubes (R-TNTs). The tube diameter and separation between the tubes were greatly influenced by the applied voltage. TNTs synthesized at voltage of 30 V for 60 min exhibited 86 nm and 1.1 µm of tube diameter and length, respectively and showed high specific capacitance of 0.33 mF cm−2 at current density of 0.02 mA cm−2. After reduction at 5 V for 30 s, the specific capacitance increased by about seven times (2.28 mF cm−2) at 0.5 mA cm−2 and recorded about 86% capacitance retention after 1000 continuous cycling at 0.2 mA cm−2, as compared to TNTs, retained about 61% at 0.01 mA cm−2. The charge transfer resistance drastically reduced from 6.2 Ω for TNTs to 0.55 Ω for R-TNTs, indicating an improvement in the transfer of electrons and ions across the electrode–electrolyte interface

Effect of annealing temperature on the performance of ZnO seed layer for photoanode in photoelectrochemical cells

Zinc oxide (ZnO) thin films were coated onto Indium Tin Oxide (ITO) glass substrate using spin coating technique as a function of annealing temperature. The thin film preparation was undertaken by utilising zinc acetate dihydrate, ethanol and diethanolamine as the precursors. The films were coated at room temperature prior to being annealed at temperatures ranging from 300 °C to 450 °C. The resulting crystalline structure and surface morphology of the thin films were then examined using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). UV-visible spectrophotometer was also used to record the optical absorbance in wavelengths ranging from 200 to 800 nm. The findings revealed that the ZnO thin films showed a single phase of wurtzite with n-type semiconductor, with the lowest value of band gap energy of 3.28 eV for ZnO thin films annealed at 350 °C. FESEM results showed that the ZnO nanoparticles were very compact on the surface, whereby the average particle size was equivalent to 108.5, 115.3, 108.2 and 107.8 nm at the temperatures 300 °C, 350 °C, 400 °C, and 450 °C, respectively. Additionally, the highest photoconversion efficiency (0.11%) recorded for the sample was annealed at 350◦C. Thus, annealing temperature was found to significantly affect the optical and electrical properties of ZnO nanoparticle seed layer, as well as its band gap energy and surface morphology