Synthesis of Cuo and Zno nanoparticles and Cuo doped Zno nanophotocatalysts

Nanocrystalline copper oxide (CuO) particles were precipitated by using different sources of copper salts and oxalic acids. The transformation to monoclinic CuO is achieved by heating the copper precipitate at 300°C for 4 h. Dice-like and flower-like structures were obtained from the effects of by-product’s acidity to the morphology of copper oxalate (Cu (C2O4)). The particle sizes of all samples, determined by transmission electron microscopy (TEM), were in the range of 10-30 nm. 0.5% CuO doped ZnO (CuO-ZnO) nanophotocatalysts were successfully prepared by mixing synthesized CuO nanoparticles with synthesized ZnO in absolute methanol. No significant changes in morphology were observed between the undoped and doped ZnO except for a higher surface area obtained for CuO doped ZnO. The doping of CuO on ZnO also resulted in enhanced photocatalytic performance of ZnO in the photodegradation of methyl orange dye

Aggregation of Partially Hydrophilic Silica Nanoparticles in Porous Media: Quantitative and Qualitative Analysis

In this experimental work, the adsorption of partially hydrophilic silica nanoparticles, SiO2 has been investigated to determine the degree of silica nanoparticle aggregation in the porous media. An integrated quantitative and qualitative method was used by flowing silica nanoparticles into Buff Berea cores and glass micromodel. Water wet Buff Berea cores were flooded with 5 pore volumes of 0.05% silica nanoparticles solution followed by 10 pore volumes of brine post flush subjected to 30 and 60°C. The pressure drops increased rapidly at the initial stage of silica nanoparticles injection indicated the adsorption had taken place. Pressure drops reached the maximum value of ~3.1 psi and between 26.6–82.6 psi at 30 and 60°C respectively. Pressure drops gradually declined and stabilized in between ~0.4 and ~0.7 psi after couple of pore volumes of brine post flush, suggesting complete reversible and irreversible adsorption. Micromodel test provide qualitative information where the straining or log-jamming observed in the form of gelled-like suspension when silica nanoparticles in contact with brine. The adsorption is considered reversible when the suspension decreased after post flooded with brine. Silica nanoparticles used in this experimental work shows minimal aggregation that can be beneficial as improved oil recovery agent

Synthesis and characterisation of copper oxide doped zinc oxide nanophotocatalyst and its photocatalytic ability in methyl orange dye degradation

CuO-doped ZnO (CuO-ZnO) nanophotocatalyst was synthesized by stirring CuO and ZnO in absolute methanol solution overnight, at ambient pressure and temperature. CuO was initially produced from four different precursors namely copper acetate, copper sulphate, copper chloride, and copper nitrate while the precursor of ZnO was produced from zinc acetate. Effects of different precursors to the properties of CuO (CA, CS, CCl, CN) were investigated. Next, the produced CuOs were doped onto ZnO (CZA, CZS, CZCl, CZN) and the properties were studied. Thermogravimetry analysis (TGA), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Fluorescence (XRF), Atomic Absorption Spectroscopy (AAS), surface area and pore distribution (BET and BJH), and Zeta potential were used to characterize the synthesized ZnO, CuO and CuO-ZnO nanophotocatalysts. In photocatalysis, the ability of ZnO, CuO and CuO-ZnO nanophotocatalysts in decolorizing methyl orange (MO) dye were evaluated using UV-Vis spectroscopy while the degradation process was determined through Total Organic Carbon (TOC) analysis. Interaction between intermediates and by-products during the synthesis process of CuO affected the crystallinity, morphology and particle size of synthesized CuOs. Although no significant changes in most of the physical properties of ZnO was observed, the introduction of CuO had improved the photoactivity of ZnO. This attributed to the enhancement in surface area of the CuO-ZnO photocatalyst and the ability of CuO to act as electron acceptor that prolongs charge separation which resulted in a better photodegradation process. Among the prepared CuO-ZnO nanophotocatalysts, CZN (CuO produced from copper nitrate) exhibited the highest rate of methyl orange photodegradation. In order to determine the optimum % of CuO to be doped on ZnO, 0.5 – 2.0 % CuO-ZnO photocatalyst were synthesized using CZN. No significant changes in the properties of ZnO as the % of CuO doped were varied. In photodegrading MO, 1.0% of CuO-ZnO nanophotocatalyst showed the highest degradation rate. The optimum condition in degradation of MO was obtained at dye concentration of 30 ppm and pH of 7 by using 1.5g of 1.0% of CuO-ZnO photocatalyst. The photoactivity of CuO-ZnO was maintained until fifth cycle in the study of reusability. 1.0% of CuO had significantly improved the photoactivity of bare ZnO under visible-light irradiation. The potential of 1.0% CuO-ZnO nanophotocatalyst in degrading real dye-containing industrial wastewater from one of textile factories at Melaka was evaluated. From the TOC analysis, 22% of total organic carbon in the real wastewater was degraded within 60 min