Photocatalytic Degradation of Nitro and Chlorophenols Using Doped and Undoped Titanium Dioxide Nanoparticles (original) (raw)
Related papers
Photocatalytic degradation of 2-chlorophenol by Co-doped TiO 2 nanoparticles
Applied Catalysis B-environmental, 2005
The photocatalytic degradation of 2-chlorophenol (2-CP) in aqueous solution was studied using Co-doped TiO2 nanoparticles catalyst. The catalyst samples were synthesized by a sol–gel technique from TiCl4 with different concentrations of Co(III) dopant and calcination temperatures. The typical composition of the prepared Co-doped TiO2 was Ti1−xCoxO2, where x values ranged from 0.004 to 0.14. Several analytical tools, such as X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurement, X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDAX), were used to investigate the nanoparticles structure, size distribution, and composition. The catalytic activity of the prepared nanoparticles was measured in a batch photoreactor containing appropriate solutions of 2-CP with UV irradiation of 100 W. High performance liquid chromatography (HPLC) was used for analyzing the concentration of 2-CP in solution at different time intervals during the photodegradation experiment. Parameters affecting the photocatalytic process such as catalyst crystallinity, light absorption efficiency, concentration of the catalyst and the dopant, solution pH, and 2-CP concentration have been investigated.Results obtained revealed that Co-doped TiO2 showed high activity for UV-photocatalytic degradation of 2-CP. The surface area of the catalyst was measured to be 39.7 m2 g−1. The photodegradation process was optimized by using 10 mg/L Co-doped TiO2 with Co doping concentration of 0.036, after 3 h irradiation. The efficiency values of the 2-CP photodegradation were 93.4% and 96.4% at solution pH of 9 and 12, respectively. The photodegradation follows a pseudo-first-order reaction and the observed rate constant values change with the 2-CP concentration. The optical absorption properties of the samples were also measured. The presence of Co ions in the TiO2 structure caused a significant absorption shift towards the visible region. The photodegradation efficiency matched the maximum light absorption efficiency.
Water Science & Technology, 2015
To overcome the drawback of poor solar light utilization brought about by the narrow photoresponse range of TiO2, a silver and sulfur co-doped TiO2 was synthesized. Using the prepared catalyst, solar photocatalytic degradation of 2-nitrophenol (2-NP) by a TiO2-based catalyst was studied for the first time. Effects of the co-doping on the structural, optical and morphological properties of the synthesized nanoparticles were investigated by different characterization methods: X-ray diffraction, N2 adsorption–desorption measurements, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV–visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy. Solar experiments showed that the co-doping with silver and sulfur significantly increased the photocatalytic activity. In various initial concentrations of 2-NP more than 99% of the contaminant was decomposed by Ag-S/TiO2 in less than 150 minutes, while the degradatio...
Removal of 4-Nitrophenol from Water Using Ag-N-P-Tridoped TiO2 by Photocatalytic Oxidation Technique
Analytical Chemistry Insights, 2016
Photocatalytic oxidation using semiconductor nanoparticles is an efficient, eco-friendly, and cost-effective process for the removal of organic pollutants, such as dyes, pesticides, phenols, and their derivatives in water. In the present study, nanosize Ag-N-P-tridoped titanium(IV) oxide (TiO 2) was prepared by using sol-gel-synthesized Ag-doped TiO 2 and soybean (Glycine max) or chickpea (Cicer arietinum) seeds as nonmetallic bioprecursors. Assynthesized photocatalysts were characterized using X-ray diffraction, Fourier transform infrared, and ultra violet (UV)-visible spectroscopic techniques. Average crystallite size of the studied photocatalysts was within 39-46 nm. Whereas doped Ag in TiO 2 minimized the photogenerated electron-hole recombination, doped N and P extended its photoabsorption edge to visible region. Tridoping of Ag, N, and P in TiO 2 exhibited synergetic effect toward enhancing its photocatalytic degradation of 4-nitrophenol (4-NP), separately, under UV and visible irradiations. At three hours, degradations of 4-NP over Ag-N-P-tridoped TiO 2 under UV and visible radiations were 73.8 and 98.1%, respectively.
Removal of 4-Nitrophenol from Water Using Ag-N-P-Tridoped TiO2 by Photocatalytic Oxidation Technique
Analytical chemistry insights, 2016
Photocatalytic oxidation using semiconductor nanoparticles is an efficient, eco-friendly, and cost-effective process for the removal of organic pollutants, such as dyes, pesticides, phenols, and their derivatives in water. In the present study, nanosize Ag-N-P-tridoped titanium(IV) oxide (TiO2) was prepared by using sol-gel-synthesized Ag-doped TiO2 and soybean (Glycine max) or chickpea (Cicer arietinum) seeds as nonmetallic bioprecursors. As-synthesized photocatalysts were characterized using X-ray diffraction, Fourier transform infrared, and ultra violet (UV)-visible spectroscopic techniques. Average crystallite size of the studied photocatalysts was within 39-46 nm. Whereas doped Ag in TiO2 minimized the photogenerated electron-hole recombination, doped N and P extended its photoabsorption edge to visible region. Tridoping of Ag, N, and P in TiO2 exhibited synergetic effect toward enhancing its photocatalytic degradation of 4-nitrophenol (4-NP), separately, under UV and visible i...
DESALINATION AND WATER TREATMENT
In this study, the photocatalytic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) was evaluated under UV radiation by Fe-doped titanium dioxide (Fe-doped TiO 2) nanoparticles (NPs) which were synthesized by a sol-gel method. Diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were applied to identify the synthesized nanoparticles. According to the SEM image, the synthesized nanoparticles had fine and irregular shapes with relatively smooth surfaces, as well as XRD spectrum showed that the crystalline size of Fe-doped TiO 2 NPs was 10.42 nm, furthermore, according to the DRS analysis, the bandgap energy of Fe-doped TiO 2 NPs was determined about 2.9 eV. The effects of operating parameters, including initial 2,4,6-TCP concentration, pH, contact time and Fe-doped TiO 2 NPs dosage on 2,4,6-TCP degradation were studied and optimized based on the response surface methodology with Box-Behnken method. The analysis of 2,4,6-TCP degradation showed that under optimum conditions, the removal efficiency reached 95.9% which is consistent with the model prediction. The optimum degradation conditions were as follows: pH, 3.29; initial 2,4,6-TCP concentration, 50.5 mg L-1 ; Fe-doped TiO 2 NPs dosage, 0.59 g L-1 ; and contact time, 55.7 min. The present results showed that Fe-doped TiO 2 NPs have great potential for removing 2,4,6-TCP from aqueous solutions.
Journal of Cleaner Production, 2019
Nitrophenols are used extensively in the chemical, pharmaceutical, and pesticide industries. Recently, water pollution caused by nitrophenols has gained worldwide attention. Significant efforts have been made over the past years to develop effective treatment options for the removal of nitrophenols in aqueous phase. Photocatalysis using titanium dioxide (TiO 2) is regarded as one of the most effective options to degrade nitrophenols in contaminated water. This review deals with the performance of TiO 2 photocatalysis for the degradation of nitrophenols and related mechanisms. The performance of TiO 2 photocatalysts is assessed by comparing basic performance metrics such as quantum yields and reaction rates before and after modification (e.g., pristine vs. modified forms). Results suggest that TiO 2-based photocatalysis is a promising treatment option for degrading nitrophenol.
The Journal of Physical Chemistry B, 2002
A set of polycrystalline TiO 2 photocatalysts loaded with various ions of transition metals (Co, Cr, Cu, Fe, Mo, V, and W) were prepared by using the wet impregnation method. The samples were characterized by using some bulk and surface techniques, namely X-ray diffraction, BET specific surface area determination, scanning electron microscopy, point of zero charge determination, and femtosecond pump-probe diffuse reflectance spectroscopy (PP-DRS). The samples were employed as catalysts for 4-nitrophenol photodegradation in aqueous suspension, used as a probe reaction. The characterization results have confirmed the difficulty to find a straightforward correlation between photoactivity and single specific properties of the powders. Diffuse reflectance measurements showed a slight shift in the band gap transition to longer wavelengths and an extension of the absorption in the visible region for almost all the doped samples. SEM observation and EDX measurements indicated a similar morphology for all the particles, and a not homogeneous distribution of the metal species onto the surface of catalyst particles. The impregnated samples revealed recombination rates always higher than that of bare TiO 2 . The photoactivity of TiO 2 was reduced by the presence of transition metal ions with the exception of W, which instead played a beneficial role. The results of femtosecond pumpprobe diffuse reflectance spectroscopy appear quite in accord with the observed photocatalytic activity only for the lowest values of electron-hole recombination rate of the samples.
Advanced Materials Letters, 2015
Nanosized bare and carbon (C)-doped TiO 2 were prepared using reverse micro-emulsion method. Synthesized powders were characterized with the help of X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscope (EDX) and UV-visible spectrophotometer. EDX study reveals that as calcination temperature increases amount of C on TiO 2 decreases. SEM and TEM images show that TiO 2 particles are spherical in shape and after increasing the calcination temperature size of particle increases. Particle size of TiO 2 obtained from TEM data varies between 10 to 17nm. Visible light photocatalytic degradation of 2,4,6-trichlorophenol (TCP) aqueous solution was carried out using nanosized bare as well as C-doped TiO 2. UV-visible spectrophotometer and high pressure liquid chromatography (HPLC) techniques were used to analyze the concentration of TCP during the degradation process. In presence of visible light C-doped TiO 2 obtained after calcination of precursor at 300°C shows better photocatalytic activity. Parameters affecting the photocatalytic process such as calcination temperature, amount of catalyst and TCP concentration are investigated. TCP photocatalytic degradation process was optimized. It is observed that to get better photocatalytic activity optimum amount of photocatalyst and concentration of TCP solution required are 1.0 gL-1 and 20 mg L-1 respectively. Reusability study indicates that C doped TiO 2 prepared in the present work is highly stable and reusable photo catalyst.
2012
The anatase structure of titanium dioxide (TiO2) nanoparticles was prepared via sol–gel technique and investigated by X-ray diffraction (XRD). The activity of TiO2 was evaluated by photocatalytic degradation of chlorophenolic compounds namely 2-chlorophenol (CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) under solar radiation. A computational technique based on semiempirical and density functional theory (DFT) was used to study the effects of chlorophenolic compounds adsorption on the anatase TiO2 (100) surface. Then, EHOMO, ELUMO and ∆E were evaluated by three methods, each of which uses density functional theory (DFT) with semiempirical methods. A molecular dynamics (MD) simulation was employed to obtained a great understanding of the adsorption behavior of chlorophenolic compounds on the anatase TiO2 (100) surface. The results of the CP and DCP molecules revealed a perpendicular adsorption via chloride with the surface lattice titanium ion, while this behavior was ...
This paper reports the synthesis of various molar concentrations of iron (Fe)-doped TiO 2 nanoparticles and their efficient use as potential photocatalysts for photocatalytic degradation of toxic and harmful chemical, paranitrophenol. The nanoparticles were synthesized by a novel and facile ultrasonic assisted hydrothermal method and characterized in detail by various analytical techniques in terms of their morphological, structural, compositional, thermal, optical, pore size distribution, etc properties. The photocatalytic activities of the as-prepared Fe-doped TiO 2 nanoparticles were examined under visible light illumination using para-nitrophenol as target pollutant. By detailed experimental findings revealed that the Fe dopant content crucially determines the catalytic activity of TiO 2 nanoparticles. The maximum degradation rate of para-nitrophenol observed was 92% in 5 h when the Fe 3+ molar concentration was 0.05 mol%, without addition of any oxidizing reagents. The prepared nanoparticles demonstrated excellent photocatalytic response because of their small size, excellent crystalline structure, increase in threshold wavelength response and maximum separation of photogenerated charge carriers. Further, the determination of reaction intermediates has also been carried out and plausible mechanism of photocatalytic degradation of para-nitrophenol has been proposed.