Immobilized Photocatalyst Research Articles

Kapasitas Resin Immobilized Photocatalyst Technology (RIPT) untuk Menurunkan Parameter Bod Limbah Cair Industri Tahu

Tofu liquid waste contains organic material, namely BOD which is quite high, if it is directly discharged into water bodies, it will reduce the carrying capacity of the environment. This causes the carrying capacity of the environment to decrease and ecosystem performance to become unbalanced, so that further processing is needed, namely Resin Immobilized Photocatalyst Technology (RIPT). In this study, the BOD reduction process was carried out with resin, photocatalyst, and immobilization. The process of immobilizing the catalyst against the resin aims to expand the surface and maintain photocatalyst activity. The type of catalyst used is ZnO and TiO2. After obtaining the RIP (Resin Immobilized Photocatalyst), then the RIP was added to the wastewater and the BOD concentration in the tofu wastewater was calculated. The resin capacity is calculated with the aim of knowing the ability of the resin to reduce the concentration of BOD. From the research that has been done, it can be concluded that the highest resin capacity when using ZnO catalyst is 0.3159 g/L and 0.2806 g/L using TiO2. The effluent parameter concentration is directly proportional to the resin capacity. As the sampling time increases, the resin's ability decreases.

Photocatalytic Nanocomposite Polymer-TiO2 Membranes for Pollutant Removal from Wastewater

Photocatalytic TiO2-PVDF/PMMA nano-composites flat sheet membranes were fabricated by phase inversion and then employed in a crossflow filtration pilot to remove model pollutants of various sizes and charge from aqueous solution. The dope solution contained a mixture of PVDF and PMMA as polymers, polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) as additives, triethyl phosphate (TEP) as green solvent and TiO2 as immobilized photo catalyst. After undergoing characterization tests such as SEM morphology thickness, porosity, contact angle and water permeability, the membranes were used to eliminate the model pollutants from synthetic aqueous solution. The impact of the operating conditions (i.e., pH, pressure and initial pollutant concentration) and composition of the doping solution on the performance and photocatalytic and antifouling activity of the membranes was investigated. The results showed that Congo Red and Tartrazine despite their small size were rejected at 99% and 81%, respectively, because of their negative charge, while Ciprofloxacin, which is larger than Tartrazine but of neutral charge, crossed the membrane. The permeability did not decrease with a decline in pollutant concentration but diminished when the pressure increased and was reduced by more than half for wastewater.

Visible light photocatalytic activity of metal (Mo/V/W) doped porous TiO2 coating fabricated on Cp-Ti by plasma electrolytic oxidation

Photocatalytic degradation under visible light region acquired a wide interest in the field of wastewater treatment. In this study, the transition metal ion (Mo/V/W) doped TiO2 layer was developed on commercially pure titanium (Cp-Ti), by plasma electrolytic oxidation (PEO), as an immobilized photocatalytic surface for textile wastewater treatment application. The effect of transition metal ion (Mo/V/W) doping on TiO2 coating phase composition, surface morphology, corrosion, wettability, bandgap, charge separation and electron-hole recombination rate are investigated. The phase analysis of coatings showed that the dopants suppressed the formation of the rutile. The doped TiO2 samples exhibited higher surface porosity and active surface area, thereby enhancing the photocatalytic activity. Among the doped titanium oxides, W doped TiO2 exhibited superior charge separation with 95% degradation and 71% mineralisation of methylene blue dye under visible light irradiation for 180 min. This could be attributed to the synergistic effect of lower bandgap, high charge separation, and low electron-hole recombination rate. The present research positively demonstrated an efficient, visible light driven immobilized photo catalyst surface by a simple PEO process as a promising photocatalytic system in the quest for the development of low cost and sustainable process for textile wastewater treatment application.

Multiscale design of ZnO nanostructured photocatalysts.

A systematic investigation of the photocatalytic activity (PCA) of nanostructured ZnO films showed how this is directly affected by the films' morphology at different scales, from the macroscale morphology of films (e.g. thickness and surface area), to the microscale feature arrangement (e.g. aligned vs. randomly oriented structures or interpenetrated ones), to the nanoscale structure (e.g. crystal size and orientation). The interest in immobilizing photocatalysts in water treatment stems from concerns about the potential toxicity of their slurry form, which requires expensive downstream removal. Immobilisation, though, leads to a reduction in PCA, generally attributed to a lower surface area. By reducing the films' feature size to the nanoscale, an immobilized photocatalyst with high surface area can be achieved. At this scale, however, feature structuring and morphology become important as they determine the interaction between light and the photocatalytic material. In this work, nanostructured ZnO films with different morphology, arrangement and structure were produced by electrochemical anodization of zinc and were tested using the degradation of phenol in a batch reactor as a model system. Results show that the PCA for immobilized catalysts can be optimised by controlling microscale arrangement (light absorbance capacity) and nanoscale structure (crystal size and orientation) rather than macroscale morphology (surface area). These results provide a clear direction to maximising the photocatalytic activity of immobilised photocatalysts for the removal of organic pollutants from water.

Photodegradation of taste and odor compounds in water in the presence of immobilized TiO2-SiO2 photocatalysts

Disinfection by ultraviolet (UV) radiation is a growing trend in public water treatment systems because of its effectiveness with respect to inactivation of protozoa and other pathogenic microorganisms. However, removal of different classes of organic compounds, including taste and odor compounds in water is not effective with UV irradiation. In this study, a novel TiO2-based immobilized photocatalyst is developed to enhance the UV photodegradation of two of the major taste and odor compounds, 2-methylisoborneol (MIB) and Geosmin (GSM) in water. Evonik (formerly Degussa) P-25 powder-modified TiO2 was immobilized on glass slides using TiO2-SiO2 sol-gel mixture as the binder and calcined at 500 °C. Several catalyst films with different Si amounts were synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL) and scanning electron microscopy (SEM). Photocatalytic degradation of MIB and GSM was investigated by irradiating aqueous solutions under UV-A light (350 nm). Generation of hydroxyl radicals (OH) was also assessed to evaluate the activity of the photocatalyst films. Catalyst films with surface ratios of Ti:Si ≈6 showed similar degradations rates but better robustness compared to immobilized P25 films.

Flexible woven metal wires supported nanosheets and nanoparticles double-layered nitrogen-doped zinc stannate toward enhanced solar energy utilization

For enhanced solar energy application, double-layered nitrogen-doped Zn2SnO4 film consisting of bottom nanosheets and top nanoparticles is designed and synthesized on flexible woven metal wires. The effects of doping concentration of nitrogen element (N) and the amount of coating nanoparticles on electronic, optical properties and stability are investigated in detail by various testing techniques. The results show that in the double-layered structure, the nanosheets array can provide direct transport pathways for photoinduced electrons, while the nanoparticles can provide high surface area. On the other hand, doped N element is conducive not only to the absorption of visible light due to narrowed band gap, but also to suppression of charge recombination. With the optimized double-layered N-doped Zn2SnO4 as photoanodes of flexible dye-sensitized solar cells, the corresponding photoelectric conversion efficiency is 2.302% compared to 1.332% and 1.826% in case of pure Zn2SnO4 nanosheets and N-doped Zn2SnO4 nanosheets; The double-layered N-doped Zn2SnO4 is also determined to be high-performance immobilized photocatalyst with a better recyclability for the photodegradation of organic pollutant under sunlight irradiation; More importantly, the preparation methods is also applicable to fabricate other composite oxides on wire-shaped substrate for more practical applications in flexible devices.

ZnO/spiral-shaped glass for solar photocatalytic oxidation of Reactive Red 120

ZnO/glass spiral (GS) was prepared by immobilization of ZnO on GS with facile method, and was characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and the crystallite size of ZnO on GS surface was calculated. SEM showed rod-like shape of ZnO particles on GS surface. Photocatalytic activity of prepared immobilized photocatalyst was investigated for decolourization and degradation of C.I. Reactive Red 120 (RR-120) dye under sunlight. The kinetics of decolourization and degradation removal has been investigated. The effect of pH on decolourization and degradation of dye was studied. The decolourization and degradation of dye were followed by pseudo-first order reaction. The decolourization and degradation of RR-120 dye were enhanced by H2O2 addition to definite dosage beyond that the effect is diminished. Also, the reusability of immobilized ZnO on GS was tested for photocatalytic degradation of dye and it was worth noting that it has high efficiency with slight decrease (5%) after five successive runs.

Preparation, photocatalytic performance and electronic structures of visible-light-driven Fe–N-codoped TiO 2 nanoparticles

Fe–N-codoped TiO 2 powder prepared by sol–gel method is loaded on low-density polyethylene film to obtain immobilized photocatalyst. The obvious agglomeration phenomena exist in the annealed samples with nanometer size, as observed in SEM images. XRD results suggest that the adding amount of impurities has a great effect on the crystallinity and particle size of TiO 2. Compared with undoped and Fe/N-doped TiO 2, Fe–N-codoped TiO 2 shows an obviously higher catalytic activity under visible irradiation. The DFT calculations indicate that the doping of nitrogen and Fe induced the formation of new states between the valence band and conduction band. The codoping of TiO 2 with nitrogen and Fe leads to the much narrowing of the band gap and greatly improves the photocatalytic activity under visible irradiation. Moreover, the Fe–N-codoping can promote the separation of the photogenerated electrons and holes to accelerate the transmission of photocurrent carrier.

Removal of mixed pesticides from drinking water system by photodegradation using suspended and immobilized TiO2

Lindane (1α, 2α, 3β, 4α, 5α, 6β-hexachloro cyclohexane), methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and dichlorvos (2,2-dichlorovinyl-O-O-dimethyl phosphate) are removed from water individually and as a mixture by photo degradation using suspended and immobilized forms of TiO2 (Degussa P-25). Studies were conducted to optimize the coating thickness of immobilized photo catalyst. The rate of degradation of pesticides was compared in both suspended and immobilized TiO2 systems. Degradation studies of mixed pesticides were carried out with low concentrations (1.0 and 2.5 mg/L) of pesticides. Only three intermediate byproducts such as methyl paraoxon, O,O,O-trimethyl phosphonic thionate and p-nitrophenol were observed during the methyl parathion degradation in suspended, immobilized TiO2 systems and mixed pesticides degradation studies. At the end of the reaction methyl parathion and its by-products were completely degraded. During lindane degradation hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene, 1-hydroxy 2,3,4,5,6-chlorocyclohexane, 1-hydroxy 2,3,4,5,6-chlorobenzene, pentachloro cyclopentadiene, 1,2,3,4,5-hydroxy cyclopentene and 1,2,3-hydroxy cyclobutane were identified in suspended and immobilized TiO2 systems, whereas only hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene and pentachloro cyclopentadiene were observed during mixed pesticides degradation. No intermediate by-product was observed during the photo degradation of dichlorvos. Langmuir-Hinshelwood pseudo first order kinetic equation showed that there was not much change in the rates of degradation in both suspended and immobilized TiO2 systems irrespective of the pesticide. During mixed pesticides degradation, the degradation pattern was not similar to that of single pesticide.

Photocatalytic decolorization of rhodamine B by immobilized TiO2 onto silicone sealant

The photocatalytic performance of immobilized TiO2 supported on silicone sealant was evaluated using the photocatalytic oxidation of rhodamine B (RhB) under weak illumination conditions. Three 8 W germicidal lamps were used as the light source and the reactor volume was 1.7 l. The optimum dosage of immobilized photocatalyst was 210.7 g/l (TiO2 weight percentage: 15%). The initial decolorization rate constants of RhB in an aqueous solution were determined in the presence or absence of immobilized TiO2 and UV irradiation in order to study each decolorization effect due to adsorption onto the immobilized TiO2, direct photolysis by UV irradiation and photocatalytic decolorization. The order of initial decolorization rate constant was photocatalytic oxidation > adsorption > photolysis. The initial decolorization rate constant of the RhB by the immobilized TiO2 was higher than that of the powder TiO2. The used immobilized photocatalyst retained a constant photocatalytic activity.

Photocatalytic degradation of gaseous trichloroethene using immobilized ZnO/SnO2 coupled oxide in a flow‐through photocatalytic reactor

AbstractThe photocatalytic degradation of gaseous trichloroethene (TCE) was investigated on immobilized ZnO/SnO2 coupled oxide in a flow‐through photocatalytic reactor. It was found that gaseous photocatalysis is an efficient method for volatile organic compounds' abatement and air purification. Degradation of ∼100% was found for TCE at the concentrations examined, up to 400 ppmv, in a flow‐through dry synthetic gas stream. In our tested conditions, the flow rate had little influence on the photocatalytic degradation efficiencies of TCE, while the relative humidity had a significant influence on the photocatalytic degradation of TCE. The photocatalytic degradation efficiencies of TCE increased slowly below 20% relative humidity and then decreased as the relative humidity increased further. The deactivation of used immobilized photocatalyst was not observed within the 200 h testing period in the present experiment, although the surface of the photocatalyst changed greatly during the use of the photocatalyst. Copyright © 2004 Society of Chemical Industry