photocatalytic degradation of chlorophenol in water (original) (raw)
This work aims to study the photocatalytic degradation of chlorophenols. They belong to a notable group of pollutants because of their high toxicity, and hardly biodegradable, and are difficult to remove from the environment. Photocatalytic degradation of chlorophenols using UV light was investigated over mesoporous catalysts. Ti-MCM-41(20), Ti-MCM-41(10), TiO2/MCM-41, Fe-Ti-MCM-41, TiO2/Fe-MCM-41 and TiO2/SBA-15 catalysts were prepared from the corresponding metal salts by the sol-gel technique. The catalyst were investigated using X-ray diffraction (XRD), FT-IR spectroscopes, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and BET surface areas of the samples were determined using the nitrogen adsorption and desorption isotherms. 100 ppm was used as model pollutants. High purity 2,4,6-trichlorophenol and 4-chlorophenol solutions individually and 0.1 g/L of each catalyst was tested at different irradiation times. At each interval time 10 ml of irradiated solution was taken and analyzed by High Performance Liquid Chromatography (HPLC), Ion Chromatography (IC). Aromatic intermediates, organic acid and chloride ions were detected. The reaction mechanism has been proposed.
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Given the known adverse effect of chlorophenols for the aquatic environments which they can reach, the development of efficient methods both technically and economically to remove them has gained increasing attention over time. The combination of photocatalytic oxidation with biological treatment can lead to high removal efficiencies of chlorophenols, while reducing the costs associated with the need to treat large volumes of aqueous solutions. Therefore, the present paper had as its main objective the identification of the minimum photocatalytic oxidation period during which the aqueous solutions of 4-chlorophenol and 2,4-dichlorophenol can be considered as readily biodegradable. Thus, the results of photocatalytic oxidation and biodegradability tests showed that, regardless of the concentration of chlorophenol and its type, the working solutions become readily biodegradable after up to 120 min of irradiation in ultraviolet light. At this irradiation time, the maximum organic conte...
Mesoporous Ti-MCM-41 materials as photodegradation catalysts of 2,4,6-trichlorophenol in water
Titanium-modified MCM-41 type mesoporous silica materials were prepared by hydrothermal [Ti-MCM- 41(HT)], sol–gel [Ti-MCM-41(SG)] and post-synthesis impregnation [TiO2/MCM-41] methods. The materials were characterized and tested as photocatalysts in the oxidative degradation reaction of 2,4,6-trichlorophenol (2,4,6-TCP) in water. The catalysts showed high initial activity. The produced acetate and chloride ions were found to inhibit the degradation reaction. The Ti-MCM- 41(HT) sample showed higher overall activity than the Ti-MCM-41(SG) catalyst. One of the probable reasons for this is the difference in the distribution of the active sites that determines the rates of electron (e-)–hole (h?) recombination within the photoactive species. The HT preparation was found to contain silica-bound titania in higher dispersion, while the SG preparation contained also polymerized species with Ti–O–Ti bonds
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 photodeg...
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