The influence of TiO2 powder and film on the photodegradation of methyl orange (original) (raw)
Related papers
Journal of hazardous …, 2005
Electrochemical-assisted photodegradation of methyl orange has been investigated using TiO 2 thin films. The films were prepared by sol-gel dip-coating method. Several operational parameters to achieve optimum efficiency of this electrochemical-assisted photodegradation system have been tested. Photoelectrochemical degradation was studied using different light sources and light intensity. The light sources chosen ranged from ultraviolet to visible light. The effect of agitation of the solution at different speeds has also been studied. Slight improvement of photodegradation rate was observed by applying higher agitation speed. Investigation on the electrode after repeated usages show the electrode can be reused up to 20 times with percentage of deficiency less than 15%. The study on the effect of solution temperature indicated that the activation energy of the methyl orange degradation is 18.63 kJ mol −1 .
Molecules
TiO2 thin films were deposited on quartz substrates by metal–organic chemical vapor deposition (MOCVD) at temperatures of 250, 350, and 450 °C. X-ray diffraction (XRD) data revealed the production of a pure anatase phase, a decrease in crystallite size, and a textural change as deposition temperature increased. Atomic force microscopy (AFM) was used to study the morphological properties and confirm XRD results. UV-Vis.-NIR spectroscopy was used to investigate the optical properties of the samples. The effect of deposition temperature on wettability was investigated using contact angle measurements. Sunlight photocatalytic properties increased with the increase in deposition temperature for methyl orange and methylene blue. Films were post-annealed at 500 °C for 2 h. The effect of annealing on all the above-mentioned properties was explored. The kinetic analysis demonstrated superb agreement with the kinetic pseudo-first-order model. The rate of photocatalytic degradation of MB was ~...
The Role of the Relative Dye/Photocatalyst Concentration in TiO2Assisted Photodegradation Process
Photochemistry and Photobiology, 2013
Despite photocatalytic degradation is studied generally focusing the catalyst, its interaction with the contaminant molecule plays a fundamental role in the efficiency of that process. Then, we proposed a comparative study about the photodegradation of two well-known dyes, with different acidity/basicity-Methylene Blue (MB) and Rhodamine B (RhB), catalyzed by TiO 2 nanoparticles, varying both dye and photocatalyst concentrations. The results showed that the amphoteric character of MB molecules, even in a range of concentration of 5.0-10.0 mg L À1 , did not imply in pH variation in solution. Therefore, it did not affect the colloidal behavior of TiO 2 nanoparticles, independent of the relative dye/catalyst concentration. The acid-base character of RhB influenced the resultant pH of the solution, implicating in different colloidal behavior of the nanoparticles and consequently, in different degradation conditions according to dye concentration. As the isoelectric point of TiO 2 is between the pH range of the RhB solutions used in this study, from 1.0 to 7.5 mg L À1 , the resultant pH was the key factor for degradation conditions, from a well dispersed to an agglomerated suspension. MATERIALS AND METHODS For this study, TiO 2 (Aldrich nanopowder, 99.7% purity) and the salts MB and RhB P.A. (VETEC, >99%) were used without further purification. X-Ray Diffraction (XRD) analysis of the oxide was carried out with a Rigaku Dmax 2500-PC X-ray diffractometer with Cu Ka source (1.5456 A). Crystallographic coherence lengths were calculated according
APLIKASI SINTESIS TiO2 NANOPARTIKEL DALAM DEGRADASI FOTOKATALITIK METIL JINGGA
Sainstek : Jurnal Sains dan Teknologi
The development in textile industry results in the increase of the use of non-organic materials in human life, such as the use of dyes that cannot be decomposed naturally, such as the use of artificial dyes in textile industry and other similar fields. This implies that if those artificial dye are not carefully managed, they will have a definite impact on the environment, such as water pollution where those substances contaminate clean water and therefore will be very dangerous for human daily needs of water for drinking, bathing and other needs. This in turn will cause various diseases in living things and pollute nature as well. The purpose of this study is to figure out the effect of methyl orange degradation by the addition of TiO2 photocatalyst. In this study, 10 ppm orange methyl solution were used, where 5 ml of orange methyl were dissolved in 5 ml of water then added with TiO2 and then irradiated with UV for 180 minutes. By calculating the degradation of methyl orange every 10 minutes, which was measured using a UV-Vis spectrophotometer. The finding shows that the longer the irradiation takes place, the more desirable degradation of methyl orange is desired. The results obtained from 180 minutes are absorbance values that are worth 0.8 down to 0.3.
Effect of Dye Structure on the Photodegradation Kinetic Using TiO<sub>2</sub> Nanoparticles
Journal of Materials Science and Chemical Engineering
In this study the effect of pH, adsorption behavior and the chemical structures of two dyes (Methyl Orange and Bromothymol Blue) on the photodegradation rate constant, was investigated. Adsorption isotherm shows that the adsorption amount of dyes on TiO 2 surface is highly related to the pH of the solution and to the pKa of each dye. In acidic medium the adsorption percentage of Methyl Orange on TiO 2 surface was 76% facing 5% for Bromothymol Blue. The kinetic study shows compatibility between the degradation rate constant and the adsorption percentage on the surface. In basic medium the adsorption percentage of Methyl orange and Bromothymol Blue is similar while the degradation rate of Methyl orange is two times faster than that of Bromothymol Blue which reveals the role of chemical structure in the photodegradation rate.
Photocatalytic Degradation of Methyl Orange: Influence of H2O2 in the TiO2-Based System
Journal of Nanoscience and Nanotechnology, 2008
The purpose of this study was to investigate the photocatalytic oxidation of a reactive azo dye. The photocatalytic activity of the TiO2 was studied using a reactor equipped with UV-A sources, with maximum emission at 365 nm. The photocatalytic activity of the TiO2 powder (99.9% anatase) and thin films has been measured through the decomposition of methyl orange solutions. The thin film was prepared by doctor blade and spray pyrolysis deposition (SPD). The TiO2 suspensions were prepared at 1 g/L concentration, and the initial methyl orange concentration was fixed at 7.8125 mg/L. The influence of the TiO2 (powder or thin films) and/or O2 and H2O2 on the photobleaching rate, was tested under different experiments, at pH = 5. Thin films (doctor blade) of TiO2 formed of mezo-sized aggregates formed of nanosized anatase crystallites show better photobleaching efficiency than thin film (SPD) due to their large internal surface. The rate is even higher in H2O2 compared to oxygen environment.
Layer by layer TiO2 thin films and photodegradation of Congo red
Journal of Photochemistry and Photobiology A: Chemistry, 2011
Layer by layer (LbL) self-assembled technique was used to fabricate TiO 2 films onto glass and quartz slides. The LbL sequence was PAH/PSS/TiO 2 (PSS/TiO 2 ) 5 (PSS = poly(sodium-4-styrene sulfonate), PAH = poly(allylamine hydrocloride)). These LbL thin films were characterized by Raman spectroscopy. The Raman spectrum confirmed the formation of TiO 2 nanoparticles in the anatase phase which average size of the particles around 30 nm and thickness of the film estimated around 40 nm as determined by atomic force microscopy (AFM). The photodegradation of Congo red (CR) dye immobilized over the LbL film was studied. Reference resonance Raman scattering (RRS) and Raman scattering (RS) spectra of Congo red were recorded with the 514.5 nm and 785 nm excitation laser lines. The photodegradation experiments were carried out by exposing the LbL TiO 2 film/CR to UV radiation in a container with distilled water. After UV exposure, degradation products were monitored by Raman spectroscopy.
Titanium dioxide thin films: the effect of the preparation method in their photocatalytic properties
Journal of Molecular Catalysis A-chemical, 2005
Titanium dioxide thin films were deposited by DC reactive magnetron sputtering and spray pyrolysis methods on glass and glass coated with fluorine tin oxide (FTO). The films were characterized by X-ray diffraction, scanning and transmission electron microscopy, atomic force microscopy and UV–vis spectroscopy. The influence of a reactive atmosphere: a 50/50 Ar–O2 mixture on TiO2 thin films deposited by sputtering has been studied following the evolution of surface and structural properties and has been correlated, when possible, with photocatalytic properties under UV illumination. Also transparent TiO2 thin films have been prepared by spray pyrolysis using a low concentration of titanium precursor and different substrates temperatures. At higher substrate temperatures the films were polycrystalline in anatase phase; at lower substrate temperatures the films presented amorphous configuration. The best photocatalytic activity was found for films deposited by spray pyrolysis at Ts = 450 °C and for those deposited by magnetron sputtering those deposited at 16 mTorr gave the higher photodegradation rates.The behavior of photodegradation of methylene blue on TiO2 thin films when illuminated with UV radiation can be observed in the graphic. For films deposited by magnetron sputtering the variation is followed for pressure increasing in the sputtering chamber. For films deposited by spray pyrolysis the influence of substrate temperature on the photocatalytic activity of TiO2 thin films can be followed from the graphic. The best results are obtained in films deposited at 16 mTorr and with Ts = 400 °C, respectively.
Photoelectrochemical Degradation of Methyl Orange Using TiO
Acta Chim. …, 2007
TiO 2 thin films have been prepared using the sol-gel method. The chemically modified sol-gel precursor solution was obtained by the addition of polyethylene glycol and diethanolamine to the titanium alkoxide precursor. Hydrolysis and polycondensation reactions of the precursors in the presence of water were controlled. Electrochemical assisted photocatalytic degradation system has been investigated on a model pollutant, methyl orange dye. Properties of the films were determined as a function of calcination temperatures by surface morphology, X-ray diffraction and photoelectrochemical studies. The photoelectrochemical degradation rate is almost linearly increased with an increased in applied bias potential. The improved in percentage of degradation for about 30% for every increases of 0.5 V was observed for potential range between 0 V and 1.0 V. However, direct electrochemical oxidation of dye begins to occur at potential of 1.5 V and above due to dark current as indicated from current-potential curve behaviour. Introduction of more concentrated dye leads to a decrease in the photodegradation percentage but the rate of photoelectrochemical degradation was almost the same. Larger photocatalyst coated area gives higher degradation rate but showed less charge density.