Advanced Materials Research Vol. 917

Abstract: Mesoporous material SBA-15 was synthesized using P123 and TEMOS as the templates. Lithium in the form of LiOH was loaded over a previously prepared SBA-15. The basic strength of the prepared samples of SBA-15 was found to increase but the mesoporous structure was severely destroyed. The mesoporous structure of the prepared SBA-15 was retained after coating it with 30 wt. % magnesium prior to LiOH loading. The stability of mesoporous structure was strongly influenced by the extent of magnesium coating. It was also noted that this structure was also affected by LiOH loading and significantly destroyed structure when magnesium coating value exceeded 20 %. These samples were thoroughly characterized for their surface area, pore volume, pore size, basic strength, SAXRD patterns and transmission electron microscopic (TEM) analysis.

Abstract: Ion-exchange of palladium (Pd) precursor for two different types of well-ordered SBA-15 morphologies, necklace-like and rod-like, was studied. Approximately 3.8 wt% Pd was successfully incorporated into SBA-15 at pH 10.3. Formation of SBA-15 and Pd/SBA-15 were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Thermogravimetry with Simultaneous Difference Thermal Spectroscopy coupled with mass spectrometer (TG/SDTA-MS), Thermogravimetry in combination with Simultaneous Difference Thermal Spectroscopy (TG-SDTA), Inductive Coupled Plasma Mass Spectrometer (ICP-MS) and N₂ adsorption-desorption. Reduction of surface area and pore volume of support for Pd/SBA-15 samples may indicate the encapsulation of PdO particles within mesoporous channels of SBA-15.

Abstract: In modern science and engineering nanofluids are playing a vital role in the application of heat transfer devices due to their effective properties. Addition of nanoparticles in the fluid can alter thermophysical properties of the nanofluid. Experimental and theoretical studies are essential to understand the change in fluid dynamics aspects of the fluid by the addition of nanoparticles. This paper presents a brief review on the viscous and thermal transport effects of nanofluids. The main emphasis is on the comparison of previous theoretical and experimental studies for thermophysical properties of nanofluids. These properties include density, viscosity, thermal conductivity and specific heat capacity of nanofluids.

Abstract: Corrosion and scaling are the common problems to all the industries. A remedy of these problems was sought out through chemical treatment: indigenously available raw materials including thiourea, surfactants (cationic, anionic and nonionic containing pre, critical and post micellar concentration). Evaluation of corrosion inhibition properties stainless steel 316 by thiourea based inhibitor and its synergistic effect with cationic cetyl tri-methyl ammonium bromide (CTAB), anionic sodium dodecyl sulphate (SDS) and nonionic triton X-100 have been carried out by weight loss method as a function of concentration of thiourea and surfactants. These materials were applied to the coupons of stainless steel 316 in different acidic concentration. Corrosion rates were calculated using weight loss method. Excellent results were achieved regarding corrosion inhibition in the presence of thiourea and surfactants assuring the better performance of these chemicals. The results showed that corrosion rate was decreased from 90 mpy to 12.1 mpy after 720 hours by the addition of 200ppm thiourea in critical micellar concentration of SDS in 3M HCl acid solution.

Abstract: TiO₂ aggregates-based dye solar cells (DSCs) have gained an increasing attention due to their enhanced harvesting of light radiance. The capability of this photoelectrode material is attributed to the submicron spherical aggregates that introduce light scattering effect which can generate more electrons whilst high internal surface area for dye chemisorption is provided by nanocrystallites which made up the aggregates. Here, TiO₂ aggregates (0.45-0.20 μm) composing of nanocrystallites (10-28 nm) with desired physicochemical properties for enhanced overall light conversion efficiency of DSC were synthesized by varying the water content in the hydrolysis of titanium alkoxide in ethanol and calcination temperature. TiO₂ aggregates obtained were characterized using FESEM, XRD and UV-Vis spectroscopy. The assembled DSCs were then evaluated using solar simulator under AM 1.5 (100 mW/cm²) simulated sunlight. With higher water content in the hydrolysis process, the aggregates reduce in size and lose their spherical shapes resulting in lower absorption intensity indicating the occurrence of low light scattering in the TiO₂ film. Nanocrystallites were found to have an increasing size of 12 nm to 28 nm with increasing calcination temperature of 400°C to 700°C. Sample of aggregates calcined at 450°C recorded the highest efficiency (~4%). Highest conversion efficiency was observed for DSC that used well-defined spherical TiO₂ aggregates composing of nanocrystallites which were synthesized at optimum synthesis parameter which is by using ethanol with low water content (0.9 vol%) followed by calcination at 450°C. Thus, optimized TiO₂ nanocrystallites which form spherical aggregate is critical in order to improve light harvesting efficiency of DSCs.

Abstract: This article reports on the estimation of solubility parameters using refractive index for a series of imidazolium-based ionic liquids (ILs) and their dependencies on the carbon number of alkyl side-chain of cation and anion. Gathering about 35 ILs of refractive indices data from the literature, the solubility parameters estimation fit well with the suggested correlation. The precision of the estimated solubility parameters obtained indicates that the refractive index-solubility parameters correlation can be an alternative tool to estimate solubility parameter value for ILs.

Abstract: This Silica sols were synthesized by alkali hydrolysis of tetraethyl orthosilicate (TEOS). These sols were modified with different percentage of aluminum sol to convert silica from hydrophilic to hydrophobic. The compositions of unmodified and modified silica nanoparticles were studied by X-ray fluorescence (XRF) and confirmed that the aluminum was anchor to the surface of silica nanoparticles. Further analysis by FESEM and Thermo gravimetric analysis (TGA) showed that the amount of modifier added to the silica sols had distinct effect on morphology and thermal stability of silica nanoparticles respectively. X-ray diffraction analysis illustrated that modified silica nanoparticles are amorphous.

Abstract: Bio-oil production from pyrolysis of 0.15-0.5 mm and 1-2 mm palm kernel shell (PKS) has been investigated in a fluidized bed reactor under the nitrogen gas flow rate of 25 L(NTP)/min, with reactor temperature of 450^°C. The pyrolysis unit has six successive condensers. Thus, six fractions of bio-oil samples were acquired from the six condensers. The calorific value, water content, ash content, and element content of each bio-oil samples were determined. The bio-oil yield from palm kernel shell with the size of 0.15-0.5 mm and 1-2 mm were 20 % and 26 %, respectively. The highest calorific value among the six bio-oil samples was 25.1 MJ/kg which was drawn from the forth condenser from pyrolysis of 0.15-0.5 mm of palm kernel shell. The incondensable gas was a mixture of hydrogen, methane, carbon dioxide and ethane.

Abstract: Biodiesel is an alternative fuel to replace petro diesel with some advantages. One of the methods to produce biodiesel is in-situ transesterification. In this study, in-situ methanolysis of Jatropha curcas seeds in Soxhlet extractor was investigated. Normal hexane was added to enhance the solubility and extractability of methanol in the presence of NaOH as catalyst to Jatropha curcas oil. Response surface methodology based on Box Behnken design was used to determine the optimum reaction conditions. The ratio of mixture volume to seed weight (7.5; 12.5), catalyst concentration (1.75; 2.25 wt.%) and volume ratio of methanol to mixture (0.3; 0.7) were selected as experimental parameters. The biodiesel yield of (91.37 ± 0.57) %, which was insignificantly different with the predicted value, was obtained with the optimum conditions as follows: the ratio of the mixture volume to seed weight of 12.48 (ml/g), 1.75 wt.% of sodium hydroxide concentration, 0.31of the ratio of methanol volume to the mixture volume at 60 °C for 60 min reaction time. The maximum yield of (98.63 ± 2.9) % was achieved at optimum conditions during 3 hours reaction time at 60 °C.