Papers by Keyword: Photocatalyst

Abstract: Accumulation of untreated and unrecycled paper has a negative impact on the environment. Like liquid waste handling, paper waste handling is also still being developed. It is known that activated carbon (AC) is one of the promising adsorbents that can be used to solve the environmental issue. Activated carbon can be made from organic waste, such as waste paper. The objective of this study is to investigate the operation condition of the pyrolysis process to obtain the activated carbon. The furnace temperature was set at 400°C for 1 hour under N₂ stream with a flow rate of 0.5 L/min. To provide a synergistic effect in the adsorption process, ZnO was derived from ZnCl₂ as a chemical activator for making active carbon. While Zn (CH₃COO)₂.2H₂O with different concentrations of 0.01, 0.05, and 0.1 M was grown into the pores of activated carbon. The photocatalytic activity of AC/ZnO was identified in the degradation process of methylene blue as a model of organic pollutants. X-ray diffraction (XRD), scanning electron microscope (SEM), and fourier transform infrared (FTIR) were used to characterize the product. The morphology of ZnO was observed in the form of a flower-like and occupying the surface of activated carbon. The photocatalytic activity showed that the methylene blue was completely degraded.

Abstract: This research investigated the Fe doping effects on the Strontium Titanate (SrTiO₃) structure to improve its photocatalytic activity. The so-called Fe-doped STO photocatalysts with a stoichiometry formula of SrTi_1-xFe_xO₃ (x = 0, 0.01, and 0.05) were successfully fabricated using the coprecipitation method. The XRD characterization confirmed the formation of STO, SrTi_0.99Fe_0.01O₃, and SrTi_0.95Fe_0.05O₃ photocatalysts and the shrinkage crystallite size due to increasing Fe content. The FTIR characterization supported the XRD results, where all samples revealed Sr-Ti-O bonds with no observed Fe-O bonds indicating the successful fabrication and doping. The photocatalytic activity was examined by the degradation of Methylene Blue (MB) dye under UV light for 1, 2, 3, 4, and 5 irradiation times, and the absorbance was determined using a Spectrophotometer instrument. All samples have successfully degraded MB dye where the %degradation linearly increased with longer irradiation times. The results further exhibited that the SrTi_0.95Fe_0.05O₃ sample had the highest %degradation at 75.3% while SrTi_0.99Fe_0.01O₃ samples achieved the highest kinetic rate at 0.2557 min^-1. All Fe-doped samples revealed better photocatalytic activity than the undoped STO, proving that Fe doping could improve the photocatalytic activity of SrTiO₃.

Abstract: In this research, the researchers successfully fabricated photocatalysts hybrid materials using g-C₃N₄ microrods and g-C₃N₄ nanosheets, which were coated on water hyacinth cellulose sponges. The optical properties of the photocatalysts hybrid materials, specifically the g-C₃N₄ microrods and g-C₃N₄ nanosheets, were analyzed using a UV-vis spectrometer. The morphology of the g-C₃N₄ microrods and g-C₃N₄ nanosheets photocatalysts was examined using different procedures, including FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), and TEM (transmission electron microscopy). The results obtained from the study indicate that g-C₃N₄ microrods exhibited a higher level of crystallinity or orderliness in terms of intramolecular orientation compared to g-C₃N₄ nanosheets. This suggests that the microrods possessed a more organized arrangement of atoms within the material structure. Furthermore, the energy bandgap values, as determined from the study, were found to be 2.25 eV for the microrods and 2.75 eV for the nanosheets. As part of this project, the photocatalysts, namely g-C₃N₄ microrods and g-C₃N₄ nanosheets, were utilized as coating materials for water hyacinth-synthesized cellulose sponges. This process led to the formation of hybrid materials known as g-C₃N₄ MCS (Microrods Cellulose Sponge) and g-C₃N₄ NCS (Nanosheets Cellulose Sponge). The efficiency and reaction rate of MB removal were then studied with various models such as First order reaction, Second order reaction, Pseudo first order reaction, Pseudo second order reaction and Elovich model. The results obtained from the research project indicated that the g-C₃N₄ NCS hybrid material exhibited a notably higher rate of organic degradation compared to the g-C₃N₄ MCS hybrid material. In conclusion, this research project successfully achieved the fabrication and characterization of a photocatalysts hybrid material using cellulose sponge from water hyacinth. The material demonstrated excellent performance as an absorbent and degradation agent for organic pollutants in water, highlighting its potential for practical applications in water treatment and environmental remediation.

Abstract: SrTiO_3, or STO, is an intriguing candidate and has been extensively studied for photocatalytic degradation because of its outstanding features. This study purposed to compare and determine the effects of low Mn doping (x= 1% and 3%) on the phase, structural property, and photocatalytic activity of Mn-doped STO (SrTi_1-xMn_xO₃) as a photocatalyst for degrading MB dye. The synthesis performed the co-precipitation method with a sintering temperature of 1000°C for 4 h holding time. The phase and structural properties of the powder samples were characterized using X-Ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR) instruments. The XRD and FTIR data validated that all Mn-doped STO samples had been successfully fabricated. The photocatalytic activity of STO:Mn 1% and STO:Mn 3% was confirmed by Methylene Blue (MB) dye degradation under UV light. It revealed that the STO:Mn 1% showed better photocatalytic activity than STO:Mn 3%, with the highest degradation percentage of 58.01% at 6 h irradiation.

Abstract: Photocatalyst activity relates to the active surface area between pollutants and catalyst compounds. The insertion of Al atoms as a substantial defect in ZnO structures can reduce the particle size thus the active surface area increases. Another way to raise the photocatalytic activity of ZnO is by combination with other oxide materials such as TiO₂ (Titanium dioxide). In this study, the ZnO-Al:TiO₂ powder was successfully prepared via the sol-gel method using zinc acetate dihydrate as a precursor, 0.5wt% of aluminum nitrate nonahydrate as a dopant precursor, and TiO₂ anatase. In order to understand the role of the combination of these two metal oxides, the concentration ratio of ZnO-Al and TiO₂ was varied by 1:1 (ZAT) and 4:1 (ZA4T) under low (150°C) and high (450°C) temperature calcination. Photocatalytic testing was carried out using a 3.2 ppm methylene blue (MB) solution under UV-A lamp irradiation for 120 minutes. The high calcination temperature facilitates the growth of ZnO-Al. Besides that, the different ratio concentrations and calcination temperatures produce different defect states in each sample. The most optimum results in the photocatalytic activity performed by ZnO-Al:TiO₂ 150°C (ZAT 15) with degradation rate constant (k) of 0.033/min and efficiency of 97% for MB removal. The unexpected zinc vacancies defect is estimated produce at the samples in high-temperature calcination. This defect type can accelerate electron-hole pair recombination. In Addition, samples with high-temperature calcination were considered to have lower hydroxyl/oxygen bonds on the surface thus affecting the photocatalytic performance.

Abstract: Synthesis of magnetic photocatalyst, Fe₃O₄/TiO₂-Ag, with characterization and photoactivity examination have been investigated. The synthesis was initiated by preparation of Fe₃O₄ particles using coprecipitation method. The Fe₃O₄ particles were then coated with TiO₂-Ag, weight ratios of concentrations Silver dopant were varied from 1 to 3, 5 and 7 wt%. The Fe₃O₄/TiO₂-Ag was characterized by FTIR, XRD, TEM, SEM-EDX, DR UV-visible and VSM methods. The degradation of metanil yellow solution was performed under exposure to UV, visible light and dark condition at optimum condition. The Fe₃O₄ and anatase diffraction peaks were presence on the X-ray diffractogram. The Fe₃O₄/TiO₂-Ag was responsive to visible light, according to DR UV-Vis spectra. The Fe₃O₄/TiO₂-Ag band gap energy was 2.49, 2.30, 2.00, and 2.46 eV, respectively, with dopant concentrations of 1; 3; 5; and 7%. Metanil yellow solution can be photodegraded for 180 minutes at a pH of 2.3. The Fe₃O₄/TiO₂-Ag has the highest ability to metanil yellow photodegradation with dopant concentration of 5% gave degradation yield of 82.18% and 72.53% under UV and visible irradiation, respectively. With K values of 0.52 g mg^-1 min^-1 under visible light and 0.5255 g mg^-1 min^-1 under UV light, the degradation kinetics of methanyl yellow dye followed Ho and McKay's kinetic model. The Fe₃O₄/TiO₂-Ag material exhibited magnetic characteristics that could be applied under visible light and reused.

Abstract: Using a facile hydrothermal method, ZnO nanomaterials with various morphological structures (nanowires, nanodiscs, and nanostars) were produced. An investigation was conducted into the relationships between the exposed polar facets and the photocatalytic activities. Based on XPS, Pl, and structural analysis, it was discovered that the exposed facets’ chemsorption ability of the different ZnO nanomaterials with different morphologies plays a vital role in their photocatalytic properties. Zinc-terminated surfaces had the highest chemsorption ability and consequently the ZnO nanodiscs with the highest fraction of exposed Zinc-terminated facets were the ideal photocatalysts from the tested morphologies. This work emphasises the important influence of rational control over the nanomaterial morphology on its physical and chemical properties and therefore on its performance in various practical applications.

Abstract: The synthesis of sulfur-doped titania magnetite composite and its activity as a photocatalyst in the degradation of metanil yellow have been investigated. The variations of sulfur dopan concentration studied were 1%, 3%, 5%, and 7%. The synthesized Fe₃O₄/TiO₂-S composite was characterized using FTIR, XRD, TEM, SEM-EDX, DR-UV, and VSM. The results showed that the Fe₃O₄/TiO₂-S photocatalyst is visible light responsive with magnetic properties. Sulfur dopan concentrations of 1, 3, 5, and 7 (%) had band gap energies of 2.83, 2.81, 2.76, and 2.84 (eV), respectively. The photodegradation results showed that Fe₃O₄/TiO₂-S 5% composite material could degrade metanil yellow in acidic pH at 180 min under visible light irradiation (73.44). The structural stability was observed after three times of photocatalyst reuse. The degradation kinetics of metanil yellow dye followed the pseudo-second order of Ho and McKay's kinetic model, with K values of 0.52 g mg^-1min^-1 under visible light. This composite has good photodegradation activity for metanil yellow can be applied under visible light and can be reused after use.

Abstract: Tungsten (W) and Cerium (Ce) doped nanoTitanium oxide (TiO₂) nanophotocatalyst were prepared by the sol-gel method and their photodegradation effect against atrazine herbicide were investigated. The doping of the nanocatalyst took place at 50 °C within a time interval of 120 minutes. The prepared gel was dried and calcined in the oven at 350 °C for 75 minutes. The XRD result revealed that the synthesized nanocatalyst was 16.7 nm in size with a mostly monoclinic structure. With FTIR spectra, characteristic peaks of TiO₂ were found at 516 cm^-1, Ti-O-Ce at 1104 cm^-1, and W-O with a single bond at 1609 cm^-1. Scanning electron microscope analysis revealed the surface morphology of synthesized nanophotocatalyst. The photocatalytic activity of synthesized nanocatalyst was tested on the degradation of atrazine herbicide (ATZ) under visible and UV light in a batch reactor. The efficiency of nanocatalyst was compared for effective utilization. About 46.5 % of photocatalytic activity was observed without UV light irradiation within 120 minutes. The photocatalytic activity of W-Ce co-doped TiO₂ to degrade atrazine further increased up to 99.1 % when the solution was irradiated under UV light. Factors like pH, time, and concentration of nanocatalyst were optimized to check the photocatalytic activity of nanocatalyst on ATZ. It was concluded that nanocatalyst showed an efficient photocatalytic degradation at pH 6 within 120 mins time interval after exposure to UV light.

Abstract: CoO nanocrystal is well-known photocatalyst for overall water splitting. However it suffers from a very short lifetime of only 1 h. The poor stability is derived from carrier recombination-induced thermal oxidation. This research will provide information about synthesis of CoO/ZnO nanocrystalline that can potentially enhance photocatalysts. CoO has been synthesized first under hydrothermal method, followed by calcination process. Thereafter, CoO has been used to produce CoO/ZnO under precipitation method. The samples were characterized using XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), and UV-VIS (UV–Visible Spectroscopy) to analyze their composition, chemical functional group, optical absorption, and band gap. The XRD spectrum showed that CoO/ZnO had cubic spinel and hexagonal phase structure with crystallite size of 69.0, 46.4, 32.8, and 32,4 nm. The bands in obtained FTIR spectrum at 586.36, 671.23, and 410-429 cm⁻¹ were correlated with vibrations of the Co³⁺ in octahedral hole, the Co²⁺ in tetrahedral hole, and Zn-O, respectively. The band gap energy of CoO, CoO/ZnO with variation of 1:1 and 1:3 were 4.39, 4.14, and 3.65 eV, respectively. The photocatalytic activities of CoO/ZnO were confirmed by methylene blue dyes photodegradation of 663 nm under UV light irradiation in aqueous solution. The 22.4% methylene blue can be removed within 3 h. Overall, these findings reveal the potential of CoO/ZnO for practical application.