Papers by Keyword: Photocatalytic Activity

Abstract: Fundamental and applied research depends on the removal of organic toxic effluents from textile industries. Photocatalytic dye degradation of CuO-NiO nanocomposite has been studied against methylene blue (MB) dye. CuO-NiO nanocomposite has been prepared by hydrothermal method using radish (Raphanus sativus) leaves as green fuel. Prepared composite nanoparticles (NPs) are characterized by XRD, FTIR, UV-DRS and SEM with EDS for the elemental and structural information. XRD data indicated the formation of monoclinic and hexagonal crystallite structures for CuO and NiO respectively. FTIR confirmed the presence of Cu - O and Ni - O molecular vibrations. Surface morphology and elemental composition of composite was analysed by SEM with EDS. CuO-NiO nanocomposite is capable to degrade 70 % of methylene blue (MB) dye in 180 min under UV light interactions. Recyclability is also good even after 4 cycles of degradation experiment for the CuO-NiO composite.

Abstract: Nowadays, building insulation must be more and more effective to avoid energy loss. This can result in the lack of ventilation which can cause an increase in the concentration of pollutants in the indoor air, such as Volatile Organic Compounds (VOCs) which are harmful to human health. Different approaches have been proposed to reduce this problem such as ventilation, filtration, depolluting plants, etc. The aim of this study consists of developing functionalized textile substrate allowing the VOCs degradation, ideally into H₂O and CO₂, by the photocatalytic effect under visible light. It is necessary to have photocatalytic activity under visible light for indoor applications as the UV light is filtered by window glasses. To achieve this objective, firstly the samples of woven cotton fabrics are functionalized with the dispersion of silver doped/non-doped TiO₂ in Carboxymethyl Cellulose (CMC) and water by padding process. After that, the treatment sustainability of the functionalized fabric is determined.

Abstract: ZnO nanoparticles are semiconductor materials that can act as a photocatalyst to successfully decompose synthetic dye waste. Unfortunately, electron-hole recombination reduces deterioration efficiency. Adding noble metals, such as Ag nanoparticles, to ZnO can boost its photocatalytic activity. The inclusion of SiO₂ prevents ZnO from clumping together, resulting in a wider contact area with synthetic dye waste and a better degrading efficiency value. The effects of SiO₂ content in ZnO/Ag/SiO₂ nanocomposites, ranging from 0 to 5 %wt, on photocatalytic activity have been investigated in this study. The nanocomposites were made in a single step utilizing flame pyrolysis using zinc acetate, AgNO₃ and water glass (Na₂SiO₃) as the precursors. X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV visible spectroscopy were used to characterize the nanocomposites, which were collected using an electrostatic precipitator. The XRD results confirmed the presence of Ag nanoparticle in the produced nanocomposites, with the crystallite size being unaffected by the presence of Ag nanoparticles. EDX mapping and EDX spectroscopy determined the presence of SiO₂ in the composite. The maximum photocatalytic performance was achieved when SiO₂ was added to ZnO at a concentration of 0.5% wt, with an efficiency of MB degradation under UV irradiation reached up to 48.15 %. The photocatalyst is reasonably stable until the fourth recycles, at which point the degrading efficiency decreases by an average of 3-6%.

Abstract: Nickel ferrite NiFe₂O₄ nanoparticles were synthesized through sol-gel auto combustion method using dextrose as a fuel. The prepared nanoparticles were investigated for their structural, optical and magnetic characterization. X-ray diffraction (XRD) revealed the development of single-phase cubic spinel with crystallite size of 14 nm. The optical study showed that the compound has an optical band gap 2.26 eV. The magnetic properties were investigated through M-H hysteresis curve. The photocatalytic activity of nickel ferrite was studied based on the degradation of methylene blue (MB) as a model compound, where the results showed that prepared nanoparticles possess a good photocatalytic activity.

Abstract: Titanium dioxide (TiO₂) has been acknowledged as a promising photocatalyst in environmental remediation including wastewater treatment. In this study, TiO₂ nanoparticles co-doped with iron (Fe) and nitrogen (N) was synthesized via sol-gel method and subsequently followed by calcination process at 300 °C, 500 °C and 700 °C for 3 hours. The prime objective of this study is to investigate an effect of different calcination temperatures in enhancing the photocatalytic activity of synthesized TiO2 which was evaluated through the degradation of methyl orange (MO) dye. The structure and properties of the prepared samples were studied by X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDX), Field Emission-Scanning Electron Microscope (FE-SEM) and Ultraviolet-Visible Spectrophotometer (UV-Vis). The results obtained from XRD showed the presence of anatase phase in all samples at 300 °C and 500 °C. Further increase of calcination temperature up to 700 °C, mixed-phase of anatase and rutile formed. XRD results also suggest that the addition of impurities has a great effect on the crystallinity and particle size of TiO₂. The obvious agglomeration phenomena existed in the annealed samples with nanometer size, as observed in FESEM images. The photocatalytic performance under UV light shows that co-doped Fe, N-TiO2 at 500 °C indicated highest MO degraded of 96.5 % within 3 hours of irradiation time. From the current finding, Fe,N-TiO₂ possessed the potential to be commercialized as a photocatalyst in wastewater remediation especially in treating dye pollution.

Abstract: ZIF-67@Ta₂O₅ graded hetero-structure material was designed and prepared using F-Ta₂O₅ as a raw material and Zeolite imidazole ester(ZIF-67) as framework structure material. The hetero-structure Ta₂O₅ and ZIF-67@Ta₂O₅ were annealing 6 hours at 900°C in nitrogen ambience. The photolysis properties of the Ta₂O₅ and ZIF-67@Ta₂O₅ materials as catalysts for photocatalytic decomposition of water to hydrogen were characterized. The results show that the heterogeneous composite structure formed by cobalt-tantalum oxide and tantalum pentoxide can significantly improve the hydrogen production performance of tantalum pentoxide samples, and the properties of samples obtained under nitrogen atmosphere are better. Among them, the N-50 sample (F-Ta₂O₅ is 50mg, Cobalt nitrate dosage is 6ml, annealing 6 hours at 900°C in nitrogen ambience) has the best hydrogen production performance, and the hydrogen production rate is 116μmol/g/h.

Abstract: A simple route has been developed for the synthesis of Ag₂O/ZnO heterostructures and the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and photoluminescence (PL) spectroscopy analysis. Considering the porous structure of Ag₂O/ZnO, the photocatalytic degradation for the organic dyes, such as eosin red (ER), methyl orange (MO), methylene blue (MB) and rhodamine B (RhB), under visible light irradiation was investigated in detail. Noticeably, Ag₂O/ZnO just took 40 min to degrade 96 % MB. The rate of degradation using the Ag₂O/ZnO heterostructures was 2.3 times faster than that of the bare porous ZnO nanospheres under visible light irradiation due to that the recombination of the photogenerated charge was inhibited greatly in the p-type Ag₂O and n-type ZnO semiconductor. So the Ag₂O/ZnO heterostuctures showed the potential application on environmental remediation.

Abstract: One of the basic needs for human is clean water. Many lowlands and marshy areas in larger islands in Indonesia such as Sumatra and Kalimantan are the source of peat water. This type of water is harmful for people living in such areas and it cannot be used directly for drinking and living. According to the standard quality of good water, peat water does not meet the requirements as a source of water for daily life. Peat water is acidic, red-brownish coloured, and it contains higher organic matters especially humic acid and its derivatives. Photocatalysis process is one of the promising way to treat solution that contains humic acid. This research aims to pre-eliminary study activity of PVDF-TiO₂/ZnO nanofiber for degradation of humic acid solution. Photocatalytic activities were studied inside photoreactor system with artificial UV radiation with 254 nm wavelength. The percentage of degradation after contacting humic acid solution to photocatalyst was determined by measuring humic acid solution before and after degradation by using UV-Vis spectrophotometer with maximum lambda in 219 nm. The rate constants were calculated and the results were 0,03909 min^-1 and 0.02832 min^-1 respectively for PVDF-4%TiO₂/ZnO and PVDF-8%TiO₂/ZnOnanofibers and it is in pseudo first order kinetic model.

Abstract: The paper presents the results of experimental studies of a photoactive catalyst in the form of barium titanate fibers with deposited particles of nickel, platinum and gold. Barium titanate fibers were synthesized by the molten salt method. The obtained barium titanate fibers were studied by SEM, TEM, XRD, and Raman spectroscopy. Photocatalytic studies showed that barium titanate fibers with platinum nanoparticles are the most active of the three prepared Metal/BaTiO3 samples.

Abstract: Thin film is a thin material that is resulting from the condensation of species through the deposition of atoms on the substrate. Thin films are usually used in the production of electronic devices, optical coatings, solar cells, and for decorative items. The bilayer of TiO₂/ZnO and ZnO TiO₂ thin films have some advantages such as can enhance the surface state and surface atomic mobility, which are useful for improving the photocatalytic activity. The motivation to a used double layer of ZnO and TiO₂ is to enhance the properties and photocatalytic activity using the different deposition temperature between the layers. The structural of ZnO/TiO₂ thin films were studied using X-Ray diffraction (XRD). Field Emission Scanning Electron Microscope (FESEM) was used to determine the surface morphology of ZnO/TiO₂ thin films. The photocatalytic activity of ZnO/TiO₂ thin films was analysed using the photodegradation of methylene blue (MB) solution. The XRD analysis revealed that highest anatase crystalline phase for TiO₂ growth with orientation (1 0 1), while the ZnO crystal phase, zincite occurred at the highest intensity with (1 0 1) orientation.. The bilayer TiO₂/ZnO thin film had the highest reaction rate, K, which is 0.0972 h-1 for photocatalytic activity. The characteristics of bilayer TiO₂/ZnO and ZnO/TiO₂ thin-film is strongly influenced by the calcination temperature and the presence and combination between the two types of materials.