Papers by Keyword: Photocatalyst

Abstract: The process of final disposal of industrial wastewater is an important issue to avoid contamination. Photocatalyst technology can be a solution to waste control by degrading organic pollutants. The synthesis process of TiO₂ catalyst immobilized with supporting materials has been proven more efficient in photocatalyst activation. This gives a high UV adsorption power and does not require further handling of the final purification process because it does not produce a catalyst suspension. Immobilization methods are simplest but still produce high efficiency, namely, the thermal milling method and the sol-gel method. Both methods can produce 97% efficiency. Immobilization using thermal milling can take quickly and only through one step but requires a long time in the degradation process. Besides, immobilization using the sol-gel method requires several steps, but the process of degradation is fast. The method used must be by the type of support material, the pollutants to be degraded, and the operating system like coating time. This paper focuses on the immobilization method suitable to support materials to maximize the degradation process.

Abstract: Nanocomposites carbon nanotube (CNT)/TiO₂ nanofibers have been prepared by electrospinning. A mixed solution of titanium(IV) tetraisopropoxide (TTIP), polyvinyl pyrrolidone (PVP), and CNT were electrospun at 15 kV with 1 mL/h of flow rate and 10 cm for the distance between needle-tip and collector. The resulted fibers were calcined at 450 °C for 2 h to remove all the PVP. TiO₂ and CNT/TiO₂ nanofibers were characterized using X-ray Diffraction and SEM. The XRD analysis showed diffraction patterns for anatase TiO₂ with a diameter of ~81 nm. As combined with CNT, the fiber diameter increased to be 200-400 nm. The composite fiber of CNT/TiO₂ demonstrated enhanced photocatalytic performance for methylene blue photodegradation (~70%) under UV-light irradiation for 2 h compared to pristine TiO₂ nanofiber (~50%).

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: Zinc oxide (ZnO) is a metal oxide material that is interested in research due to its possibility of bandgap tailoring, doping with various types of materials as well as being able to form many structures from zero-dimensional to three-dimensional structures. All these properties allow ZnO to be used in broad applications. Several research studies have been reported on the synthesis of ZnO nanostructures by the physical vapour deposition (PVD) technique. One of the potential PVD technique is thermal evaporation process. Generally, the technique is used to grow thin-film but researchers have found a potential to be used in the growth of nanostructures due to the ability to provide high crystallinity with homogeneous and uniform nanostructures. This analysis will therefore explore more about the thermal evaporation synthesized ZnO nanostructures and the application as photocatalyst material in wastewater treatment.

Abstract: Graphene, functionalized with the heteroatoms like nitrogen, oxygen and sulphur atoms has been well explored for a wide range of applications but only few reports are available on its adsorption and photocatalytic application in the degradation of chlorophenols and organic dyes. A simple and energy-efficient process to prepare graphene oxide and sulphur doped graphene oxide was developed. The micro structure and surface morphology were confirmed by the analytical techniques of Powder X-ray diffractogram (PXRD), Fourier Transformed Raman Spectroscopy (FT-Raman), Scanning Electron Microscopy. The results were suggestive of the structures suitable for screening their catalytic activity in the degradation of the highly toxic polychlorophenols and organic dyes. The adsorption and photo catalytic properties of the asprepared samples were screened for the degradation process and it was found that sulphur doped graphene oxide showed more positive results for the degradation of chlorophenols than graphene oxide. Under the given experimental conditions the decoloration of dyes were not satisfactory. Ultimately, the study provided an economical and efficient, method for tuning graphene structures for the removal of pollutants in wastewater.

Abstract: In this research, visible-light responsive g-C₃N₄, photocatalyst was achieved through the simple calcination of urea at 600 °C by using the muffle furnace. The effects of calcination soaking time on preparation of high performance g-C₃N₄ were studied at 1, 2, 3, and 4 h. The g-C₃N₄ prepared at various soaking times were characterized by the X-ray diffraction (XRD) for crystallographic information and the Fourier-transform infrared spectroscopy (FTIR) for chemical composition analysis. Further, in the case of morphology and surface area of prepared photocatalysts, the Transmission Electron Microscope (TEM) and Brunauer, Emmett and Teller (BET) were applied. The results demonstrated that g-C₃N₄ with tri-s-triazine based units could be synthesized by calcination of urea at 600 °C and soaking for 1-4 h, as evidently confirmed by XRD and FTIR. For photocatalytic performance in rhodamine B dye degradation under visible light irradiation of achieved g-C₃N₄ tended to increase as soaking time increased. Moreover, the dye adsorption ability of prepared photocatalysts was obviously developed upon increase of soaking times. Herein, the highest photocatalytic performance was obtained from sample which was soaked at 4 h.

Abstract: In this study, the synthesis of CoFe₂O₄ by using the fine sediment of the Bengawan Solo River, Trucuk District, Bodjonegoro Regency as raw materials with the coprecipitation method has been successfully carried out. The fine sediment is used as a source of Fe cation in the synthesis of CoFe₂O₄. The XRD confirmation results showed that CoFe₂O₄ is formed at an annealing temperature of 800° C with crystallite sizes ranging from 34.88 to 38.05 nm. Thus, the VSM characterization showed that the magnetic properties of the CoFe₂O₄ nanoparticles depend on the heat treatment of the fine sediments as ore materials. Finally, the obtained CoFe₂O₄ samples can be used as photocatalysts with a maximum reduction rate ratio of 83%.

Abstract: Lousy odor is severe pollution in natural rubber processing industries and the air pollution treatment by using photocatalytic decomposition method has not much known. This study aims to explore the photocatalyst preparation and characterization of Fe doped ZnO immobilized on fiberglass cloth. Fe doped ZnO was prepared both with and without co-precipitation agent of NaOH. Both methods confirmed the metal existence and gave crystallite catalyst particles with mean diameters of 50 nm according to XRD characterization methods. SEM-EDS analysis showed Fe-ZnO particles prepared without co-precipitation were less aggregated particles than those made with the other method. EDS data identified the elemental composition of Zn, Fe, and O, and the fiberglass cloth composition, including Si and Mg. In the co-preparation method, sodium was always existed along with Fe and ZnO. DR-UV analysis showed the bandgap of Fe-ZnO was 3.20 and 3.22 eV without and with co-precipitation methods, respectively. TEM analysis of the catalyst slurry shows all particles were agglomerated in both preparations. Spherical-like particles existed non-precipitation method, and a spherical- and rod particle shapes were detected in co-precipitation preparation. The non-co-precipitation process was a preparable step in immobilization of the Fe-ZnO particles onto fiberglass cloth

Abstract: Cerium (Ce) doped ZnO is a promising material for advanced photocatalysis. It is useful for inducing the treatment of many organic pollutants in water. However, the stability of its performance under varying temperature and saline condition has never been not fully assessed. In this study, powder form photocatalyst comprising 99.0 mol% ZnO and 1 mol% CeO₂ has been synthesized via modified citrate gelation technique and solid-state sintering at 1200 °C for 5 hours. The conversion of Ce doped ZnO from its precursors has been confirmed using XRD, SEM, and EDX techniques. The photocatalytic efficiency of the synthesized Ce doped ZnO under UV-C light (λ=265 nm) was determined. In the experiment, the operating temperature was varied between 25 to 40 °C, and the salinity of the treated solution was increased from 0 to 40 g/L NaCl. The findings revealed that the photocatalytic efficiency of Ce doped ZnO under UV light improved from 78.2% to 88.6% as the temperature increased from 25 to 40 °C. The performance of Ce doped ZnO decreased from 86.7% to 36.7% when the salinity increased from 0 g/L to 40 g/L. The elevation of temperature encouraged the photogeneration of electron-hole pairs on catalyst surface while the presence of chloride ions in treated medium caused scavenging of hydroxyl radicals or hole.

Abstract: Herein, Ag-anatase photocatalysts were synthesized though chemical reduction method under room temperature by using PVP and NaBH₄ as stabilizer and strong reducing agent, respectively. The prepared photocatalysts were characterized by the following technique: XRD, SEM, HR-TEM, EDX, and UV-Vis-NIR. The photocatalytic performance of 0.05 g of photocatalysts were performed under UV irradiation within 1 h by using 10 mg/L of rhodamine B as the representative of organic pollutant. The results demonstrated that the optimum Ag loading contents were 2 %wt (2-ST) which can degrade rhodamine B up to 98.54%. Therefore, the photocatalytic performance of bare anatase could be enhanced by deposited Ag nanoparticles. Further, this prepared Ag-anatase could be suitable for environmental application.