Impact of Wastewater Strength and Photocatalyst Loading on Decolourization of Acid Orange 7 by Co-Doped TiO2 (original) (raw)
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Chemical Industry and Chemical Engineering Quarterly, 2007
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The photocatalytic removal of colour of a synthetic textile effluent, using TiO 2 suspensions under solar radiation, has been studied at pilot plant scale. A synthetic dye solution was prepared by a mix of six commercial textile dyes. A photochemical reactor of parallel CPC reflectors with UV-transparent tubular receivers was used. The study of photodegradation was carried out using the TaguchiÕs parameter design method. Following this methodology, the reaction was conducted under different flow conditions, pH and H 2 O 2 concentrations. The results show that all dyes used in the experiences can be degraded successfully by photo-oxidation. The process shows a significant enhancement when it is carried out at high flows, alkaline media and high H 2 O 2 concentration. Colour removal from the effluent was reached at 55 min operating time.
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The textile industry consumes large quantity of water and produces large volume of wastewater from printing and dyeing units which is rich in color, containing residues of reactive dyes and chemicals, and requires proper treatment before being released into the environment. Released colored organic compounds in effluent contaminate the water and are source of non- aesthetic pollution and eutrophication. In the present paper a laboratory experiment have been performed to investigate photocatalytic decolouration by using TiO2 photocatalyst for treating textile effluent. Various operational parameters such as catalyst concentration, pH and optimum time were investigated in order to study their effect on photoreduction process using TiO2. Results indicate that the photocatalytic decolouration process can efficiently treat textile effluent and reduce the levels of BOD , COD, turbidity, TDS and alkalinity. Experimental runs can be used to identify the operational parameters to perform was...
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Journal of Environmental Sciences, 2017
A nitrogen-doped titanium dioxide composite photocatalyst (N-TiO 2) with heterojunction structures is synthesized by three different approaches: a novel UV-assisted thermal synthesis, annealing, and microwave technique. Photocatalytic activities of synthesized photocatalysts are evaluated by the degradation of Methyl Orange under ultraviolet light types A (UV-A), B (UV-B), and C (UV-C), visible light, and direct sunlight irradiation. Results show that by using N-TiO 2 photocatalyst prepared by the UV-assisted thermal synthesis and annealing, the degradation increases by 16.5% and 20.4%, respectively, compared to that by bare TiO 2. The best results are obtained at a nitrogen to TiO 2 mass ratio of 0.15 (N: TiO 2). The enhancement of the photocatalytic activity observed in the visible range is mainly attributed to the increasing separation rate of photogenerated charge carriers. The novel UV-assisted thermal synthesis has produced encouraging results as a preparation method for the nitrogen-doped TiO 2 photocatalyst; thus, further studies are recommended for process optimization, immobilization, and scale-up to evaluate its applicability in wastewater treatment.
Photocatalytic Degradation of Textile Dyeing Wastewater Using Titanium Dioxide and Zinc Oxide
Photodegradation of a real textile dyeing wastewater taken from Hilla textile factory in Babylon Governorate, Iraq have been investigated. Photocatalytic degradation was carried out over suspensions of titanium dioxide or zinc oxide under ultraviolet irradiation. Photodegradation percentage was followed spectrophometrically by the measurements of absorbance at λmax equal to 380 nm. The rate of photodegradation increased linearly with time of irradiation when titanium dioxide or zinc oxide was used. A maximum color removal of 96% was achieved after irradiation time of 2.5 hours when titanium dioxide used at 303K and 82% color reduction was observed when zinc oxide used for the same period and at the same temperature. The effect of temperature on the efficiency of photodegradation of dyestuff was also studied. The activation energy of photodegradation was calculated and found to be equal to 21 ± 1 kJ mol -1 on titanium dioxide and 24 ± 1 kJ mol -1 on zinc oxide.