Adsorption and Photocatalytic Degradation of Reactive Brilliant Red K-2BP by TiO2 AC in
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* Corresponding author. Phone: +86-532-84022757. Fax: +86-53284022757. E-mail: jngengqijin@.
fluorination on the surface adsorption of dyes and on the energy band structure of TiO2. Aarthi and Madras8 used Rhodamine B, 6G, Blue, and 6G perchlorate as substrates and investigated the effect of organic solvents (ethanol and acetonitrile) and metal ions (Cu2+, Fe3+, Zn2+, and Al3+) on the photodegradation under UV irradiation. These results indicated that the presence of solvents and metal ions significantly reduced the degradation rate. Zhuang9 et al. investigated the photodegradation of RhB over the prepared TiO2 films and proposed that the defect sites at the surface or the interface of TiO2 films promote the separation of photogenerated electron-holes, leading to a higher photocatalytic activity of defective TiO2 films. Smith10 et al. studied the physicochemical parameters influencing photocatalytic degradation of methyl orange (MO) over TiO2 nanotubes. The overall initial dye degradation rate demonstrates three types of dependence on dye concentration over a range from 2.5 to 100 µM. In conclusion, the photocatalysis was obviously influenced by the catalyst characteristics, dye attributes, and additives.
An activated carbon-supported titanium dioxide photocatalyst (TiO2/AC) was prepared by a spinning coating method and applied in a designed bubbling fluidized bed photocatalytic reactor (BFBPR). Adsorption and
photocatalytic degradation of reactive brilliant red K-2BP in BFBPR were investigated considering the pH
value, Na2SO4 added, and initial dye concentration. The experimental results indicated that the adsorption and photocatalytic degradation efficiencies of K-2BP were influenced by the pH value, Na2SO4 added, and initial dye concentration. The adsorption and photocatalytic degradation of K-2BP was approximated to the
degradation efficiency above 80%. The Langmuir-Hinshelwood kinetic model was applied to explore the
adsorption and degradation. Finally, the special reaction paths were inferred with variation of experimental
Qijin Geng* and Wenwen Cui Department of Chemistry and Chemical Engineering, Weifang UniVersity, Shandong ProVince, 261061, People’s Republic of China
environments.
Байду номын сангаас
1. Introduction
Textile and leather industries are large consumers of dyes, using them in conjunction with a wide range of auxiliary chemicals for various dyeing and finishing processes. If these dyes are discharged into the environment without any treatment, there are highly harmful to the local environment and people. Recently, new and tighter regulations coupled with increased enforcement concerning wastewater discharges have been established in many countries, especially in China. However, it is difficult to find a unique treatment that insures complete elimination of dye wastewater, including biological processes, physical methods of discoloration, and adsorption by some natural inexpensive materials.1-6 The main drawback of these physical methods is only to operate by transfer or concentration of these pollutants to another phase rather than to decompose them. The present research is focused on the reactive dyes because they represent an increasing market share, and a large fraction of the applied reactive dye is wasted due to dye hydrolysis in alkaline solution.
Recent developments in advanced oxidation processes (AOPs) via heterogeneous photocatalysis in the presence of TiO2 have shown a promising prospective to completely mineralize such contaminates. Several studies have demonstrated complete destruction of the dye with reasonably high efficiencies.7-10 The initial dye concentration, light intensity, mass transportation rates/limitations, initial pH, catalyst size/loading, oxygen saturation, and temperature influencing photocatalysis must be considered. Wang7 et al. investigated the photocatalytic degradation of four dyes with positively charged nitrogen-alkyl groups using F-TiO2 and pure TiO2, and the relationship between surface fluorination and the degradation rate/pathway of dyes under visible irradiation was explored based on the effect of
maximum value at pH value 5.7. The complex influence of Na2SO4 added on photocatalytic degradation of K-2BP at alkaline suspension was observed and explained according to the adsorption models proposed and degradation mechanism of a new free radical (SO4•-) produced. In addition, the presence of Na2SO4 plays dual functions, i.e., salt bridge-role in adsorption for Na+ and competition adsorption between anion dye molecules and SO42-, conformed by adsorption models proposed and FT-IR spectra for dye adsorption on TiO2/AC. The mass-transfer limited and screening effect that resulted from variation of the initial dye concentration may be approximated to the minimum effect at concentration of 3.75 mg L-1, with the maximum
Ind. Eng. Chem. Res. 2010, 49, 11321–11330
11321
Adsorption and Photocatalytic Degradation of Reactive Brilliant Red K-2BP by TiO2/AC in Bubbling Fluidized Bed Photocatalytic Reactor
fluorination on the surface adsorption of dyes and on the energy band structure of TiO2. Aarthi and Madras8 used Rhodamine B, 6G, Blue, and 6G perchlorate as substrates and investigated the effect of organic solvents (ethanol and acetonitrile) and metal ions (Cu2+, Fe3+, Zn2+, and Al3+) on the photodegradation under UV irradiation. These results indicated that the presence of solvents and metal ions significantly reduced the degradation rate. Zhuang9 et al. investigated the photodegradation of RhB over the prepared TiO2 films and proposed that the defect sites at the surface or the interface of TiO2 films promote the separation of photogenerated electron-holes, leading to a higher photocatalytic activity of defective TiO2 films. Smith10 et al. studied the physicochemical parameters influencing photocatalytic degradation of methyl orange (MO) over TiO2 nanotubes. The overall initial dye degradation rate demonstrates three types of dependence on dye concentration over a range from 2.5 to 100 µM. In conclusion, the photocatalysis was obviously influenced by the catalyst characteristics, dye attributes, and additives.
An activated carbon-supported titanium dioxide photocatalyst (TiO2/AC) was prepared by a spinning coating method and applied in a designed bubbling fluidized bed photocatalytic reactor (BFBPR). Adsorption and
photocatalytic degradation of reactive brilliant red K-2BP in BFBPR were investigated considering the pH
value, Na2SO4 added, and initial dye concentration. The experimental results indicated that the adsorption and photocatalytic degradation efficiencies of K-2BP were influenced by the pH value, Na2SO4 added, and initial dye concentration. The adsorption and photocatalytic degradation of K-2BP was approximated to the
degradation efficiency above 80%. The Langmuir-Hinshelwood kinetic model was applied to explore the
adsorption and degradation. Finally, the special reaction paths were inferred with variation of experimental
Qijin Geng* and Wenwen Cui Department of Chemistry and Chemical Engineering, Weifang UniVersity, Shandong ProVince, 261061, People’s Republic of China
environments.
Байду номын сангаас
1. Introduction
Textile and leather industries are large consumers of dyes, using them in conjunction with a wide range of auxiliary chemicals for various dyeing and finishing processes. If these dyes are discharged into the environment without any treatment, there are highly harmful to the local environment and people. Recently, new and tighter regulations coupled with increased enforcement concerning wastewater discharges have been established in many countries, especially in China. However, it is difficult to find a unique treatment that insures complete elimination of dye wastewater, including biological processes, physical methods of discoloration, and adsorption by some natural inexpensive materials.1-6 The main drawback of these physical methods is only to operate by transfer or concentration of these pollutants to another phase rather than to decompose them. The present research is focused on the reactive dyes because they represent an increasing market share, and a large fraction of the applied reactive dye is wasted due to dye hydrolysis in alkaline solution.
Recent developments in advanced oxidation processes (AOPs) via heterogeneous photocatalysis in the presence of TiO2 have shown a promising prospective to completely mineralize such contaminates. Several studies have demonstrated complete destruction of the dye with reasonably high efficiencies.7-10 The initial dye concentration, light intensity, mass transportation rates/limitations, initial pH, catalyst size/loading, oxygen saturation, and temperature influencing photocatalysis must be considered. Wang7 et al. investigated the photocatalytic degradation of four dyes with positively charged nitrogen-alkyl groups using F-TiO2 and pure TiO2, and the relationship between surface fluorination and the degradation rate/pathway of dyes under visible irradiation was explored based on the effect of
maximum value at pH value 5.7. The complex influence of Na2SO4 added on photocatalytic degradation of K-2BP at alkaline suspension was observed and explained according to the adsorption models proposed and degradation mechanism of a new free radical (SO4•-) produced. In addition, the presence of Na2SO4 plays dual functions, i.e., salt bridge-role in adsorption for Na+ and competition adsorption between anion dye molecules and SO42-, conformed by adsorption models proposed and FT-IR spectra for dye adsorption on TiO2/AC. The mass-transfer limited and screening effect that resulted from variation of the initial dye concentration may be approximated to the minimum effect at concentration of 3.75 mg L-1, with the maximum
Ind. Eng. Chem. Res. 2010, 49, 11321–11330
11321
Adsorption and Photocatalytic Degradation of Reactive Brilliant Red K-2BP by TiO2/AC in Bubbling Fluidized Bed Photocatalytic Reactor