Conventional wastewater treatment technologies have difficulties in feasibly removing persistent organics. The photocatalytic oxidation of these contaminants offers an economical and environmentally friendly solution. In this study, TiO2 membranes and Ag/TiO2 membranes were prepared and used for the decomposition of dissolved formic acid in wastewater. The photochemical deposition of silver on a TiO2 membrane improved the decomposition rate. The rate doubled by depositing ca. 2.5 mg of Ag per 1 g of TiO2. The influence of salinity on formic acid decomposition was studied. The presence of inorganic salts reduced the treatment performance of the TiO2 membranes to half. Ag/TiO2 membranes had a larger reduction of ca. 40%. The performance was recovered by washing the membranes with water. The anion adsorption on the membrane surface likely caused the performance reduction.
Two types of alumina ceramic membrane in hollow fibre shape was used in this study. Both alumina hollow fibres (AHF) were sintered at different temperatures; (a) 1350oC and (b) 1450oC. In order to improve the catalytic activity of the alumina membrane for oxygen separation purposes, surface modification of the membranes was carried out using La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite catalyst. LSCF was synthesised using simple Pechini sol-gel method. The evaporation time and temperature of the LSCF-sol were varied to obtain various viscosity of catalytic sol. From XRD analysis, pure LSCF perovskite structure formed at temperature at 850oC. The morphological of unmodified and surface-modified alumina hollow fibre membranes (AHF) were studied using FESEM. The effect of LSCF catalytic sol viscosity was studied and it was found that as the viscosity of the sol increases, the amount of catalyst deposited on the alumina hollow fibre were increased. Besides, the amount of catalyst deposited on 1350 AHF was found to be higher than 1450 AHF. This result is supported by the result of pore distribution data whereby 1350 AHF was observed to be more porous than 1450 AHF, with porosity percentage of 40.38% and 28.80%, respectively. Although higher viscosity of catalytic sol could lead to a high amount of catalyst deposited on the AHF substrate, there is a tendency for micro-cracks to develop. Thus, the viscosity of the catalytic sol is important to control in order to have higher oxygen permeation flux.
In the current paper, fundamental aspects of heavy oil and wax deposition problems are defined. Wax or in another term is cloud point occur when the oil starts to precipitate. When it’s started to precipitate, it can cause major problem to industry of oil and gas. In this study, ZnO nanoparticles were chosen to study the effect of varying molar ratio from 1:1, 1:2, 1:3 to the morphology and size of the nanoparticle. The structures and properties were recognized with energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) methods. EDX and FE-SEM is to study the morphology of ZnO structure while XRD is to determine the purity and size of the nanoparticle. From the study, 1:1 ratio has the smallest size of nanoparticle with 10.37 nm while 1:2 and 1:3 give the size of 12.3 nm and 16.37 nm respectively. As the molar ratio is increases, the size of nanoparticle become bigger. The influenced of ZnO nanoparticles on rheological behaviour of model oils and the wax content is reported. From the study, the addition of ZnO nanoparticle reduced the rheology behaviour of crude oil by varying nanoparticle sizes, temperature and shear rate. ZnO nanoparticle can reduce the deposition of wax up to 50% with influenced of smaller nanoparticle size. Effect of size of nanoparticle highly impact the viscosity and wax content. This prove that, by introducing nanoparticle into crude oil, wax content can be reduced thus decrease the chance for crude to precipitate.
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