Effect of Dye Structure on the Photodegradation Kinetic Using TiO2 Nanoparticles (original) (raw)
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Journal of Photochemistry and Photobiology A: Chemistry, 2003
Anionic (Alizarin S (AS), azo-Methyl Red (MR), Congo Red (CR), Orange G (OG)) and cationic (Methylene Blue (MB)) dyes were degraded, either individually or in mixtures, by using UV-irradiated TiO 2 in suspension or supported on glass and on paper. The influence of the chemical structure of different dyes as well as that of pH and of the presence of inorganic salts on the photocatalytic properties of TiO 2 has been discussed. The role of adsorption is suggested, indicating that the reaction occurs at the TiO 2 surface and not in the solution. S and N hetero-atoms are respectively mineralized into SO 4 2− , NO 3 − and NH 4 + , except azo-groups which mainly formed N 2 which represents an ideal case for a decontamination reaction. The fate of nitrogen strongly depends on its initial oxidation degree. High photocatalytic activities have been found for TiO 2 coated on glass by the sol-gel method. Its efficiency was intermediate between those of PC-500 and P-25 powders. The efficiency of PC-500 TiO 2 sample, fixed on paper by using a binder, is slightly less important than that of the powder. The presence of a silica-binder with an acidic pzc is suggested to be at the origin of the decrease in efficiency.
Photodegradation of organic dyes based on anatase and rutile TiO 2 nanoparticles
RSC Adv., 2016
The present work highlights a simple nanochemistry based clean and efficient process for effective degradation of various organic dyes by use of anatase and rutile TiO 2 nanoparticles. Based on photodegradation studies it was observed that at certain experimental parameters, rutile TiO 2 was as effective as anatase for the degradation of indigo carmine (IC) dye in aq. solution. However, anatase TiO 2 was found to be much more efficient against methylene blue (MB), methyl orange (MO), rhodamine B (RB) and eriochrome black T (EBT) under short UV irradiation. The photodegradation study of these organic dyes was also performed under long UV irradiation employing both anatase and rutile titania and the results showed similar trends. However, only EBT photodegradation indicated equal photocatalytic activity by both phases. The catalytic degradation of the organic dyes was studied by degradation kinetics. The maximum degradation efficiency using anatase and rutile titania photocatalysts was found to be 88% and 77% in the case of MB under short UV irradiation while about 65% was found in the case of EBT under long UV irradiation. The reuse of photocatalyst even after five cycles retained the degradation efficiency of 83% and 71% respectively for anatase and rutile when tested against MB.
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 .
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.
Contemporary Engineering Sciences, 2015
Synthetic dyes are difficult to degrade in nature and contain hazardous material which can generate skin cancer and if not well treat, the synthetic dyes wastewater also can kill the organism live in the environment. One of alternative methods for handling the synthetic dyes wastewater is by using photocatalytic process as one of Advanced Oxidation Processes (AOPs). Semiconductor photocatalyst of TiO2 under solar irradiation was chose in this process. The objective of this work is to study the application of Titanium dioxide (TiO2) nano-particles photocatalyst to degrade the sample of synthetic dye wastewater with solar irradiation assistance. The anatase-powder and anatase-nano powder of TiO2 used in this research was coated on the plastic media to prevent the cost of separation. The synthetic dye wastewater was made from Procion Redas a model of organic pollutant. The concentration of Procion Red was 100 mg/L. The TiO2 concentration of the 1626 Tuty Emilia Agustina et al. coating solution immobilized on the plastic material was varied between5-40% (w/v).The photocatalytic degradation of Procion Red synthetic dye was studied under solar irradiation within 3-12 hours, from 9 am until 3 pm for 2 days. The results show that the highest color degradation of 98% and COD degradation of 56% were achieved when using 40% anatase-nanopowder TiO2concentration of coating solution under sunlight of 12 hrs. The nano-particles have a high interaction surface. As the interaction of particles increase, the catalyst activity will increases and inhibit the recombination reaction. In the nano-particle size, the TiO2photocatalyst can absorb the UV vis from the sunlight to excite the electron and furthermore generate the hydroxyl radical as a strong oxidiser. The hydroxyl radicals oxidize the organic pollutant to be the less harmful compound and finally to carbon dioxide and water. As the generation of hydroxyl radical rise, the degradation of organic pollutant will increase. As the conclusion, it is feasible to apply the TiO2nano-particles photocatalyst to degrade the sample of synthetic dye wastewater with solar irradiation assistance. In this research, the degradation of colour and COD increase as the nano-particles TiO2photocatalyst concentration of coating solution and the exposure time increase. The colour degradation and COD degradation of 98% and 56%, respectively, was obtained under solar irradiation of 12 hours.
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
Effects of Experimental Conditions and Kinetics of Photodegradation of Methylene Blue over TiO 2
The authors investigated the catalytic activity of TiO 2 for methylene blue(MB) degradation under solar light. The reaction parameters such as reaction time, TiO 2 content, temperature, pH, MB concentration and light irradiation were in attention. Then, the experimental data was analyzed to investigate the adsorption order and ad-sorption model. The results indicate that the optimum conditions for the removal of MB are a TiO 2 content of 0.5 g/L, 0.50 mg/L MB solution, a temperature of 30 °C and reaction time of 60 min. It was found that the amount of MB removal was decreased when the pH and temperature increased. This suggests that the removal process is exothermic. However, the solar light irradiation plays a vital role in enhancing the removal amount of MB. In the dark reaction, the ability of TiO 2 to remove MB was increased when the pH increased. The kinetics studies confirm that the adsorp-tion of MB is the Pseudo-second-order. And the adsorption model was fitted with the Freundlich isotherm.
Journal of Photochemistry and Photobiology A: Chemistry, 2004
In this paper, silica gel supported titanium dioxide particles (TiO 2 /SiO 2 ) prepared by acid-catalyzed sol-gel method was as photocatalyst in the degradation of acid orange 7 (AO7) in water under visible light irradiation. The particles were characterized by X-ray diffraction, BET specific surface area determination, and point of zero charge measurement. The supported catalyst had large surface area, high thermal stability and good sedimentation ability. The photodegradation rate of AO7 under visible light irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The photodegradation rate of AO7 using 31% TiO 2 /SiO 2 particles was faster than that using P-25 and TiO 2 (Shanghai) as photocatalyst by 2.3 and 12.3 times, respectively. The effect of the calcination temperature and the TiO 2 loading on the photoactivity of TiO 2 /SiO 2 particles was also discussed.
We investigated the degradation of methylene blue (MB) as an organic dye pollutant upon photocatalytic oxidation of TiO 2 nanoparticles under UV-LED (395 nm) light irradiation. Effect of different parameters, including initial concentration of dye and catalyst dosage on the degradation rate of the dye were evaluated. We found that the photonic efficiency of the photocatalytic degradation rate of the dye was determined by the ratio between the initial concentration of the dye and the number of TiO 2 nanoparticles in the colloidal solution. The optimum photocatalytic degradation rate was achieved when the TiO 2 nanoparticles in the solution are well covered by dye molecules, providing an interpretation that MB–TiO 2 molecular interactions play the key role in the photoinduced oxidation and reduction, leading to the photocatalytic degradation. We also demonstrated that the energy activation of the photocatalytic degradation is related to diffusion-controlled reaction, indicating that the photocatalytic degradation of the dyes is diffusion-controlled reaction of free hydroxyl radicals.