Optimization of the heterogeneous Fenton-oxidation of the model pollutant 2,4-xylidine using the optimal experimental design methodology (original) (raw)
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Photo-Fenton degradation of wastewater containing organic compounds in solar reactors
Separation and Purification Technology, 2004
In this work, the photo-Fenton oxidation of phenol in aqueous solutions has been investigated using Fe 2+ , H 2 O 2 and UV-visible light (sunlight). Laboratory-scale experiments were carried out using solar reactors of two different configurations: (1) a concentrating parabolic trough reactor (PTR) and (2) a non-concentrating thin-film reactor. Global solar irradiance was measured during the experiments. Additional laboratory experiments were carried out in an annular photochemical reactor using an artificial light source, at the same experimental conditions. The results indicate that the photo-Fenton process using solar irradiation is an effective treatment for industrial wastewater containing phenol. At low contaminant concentration (TOC 0 = 100 ppm), more than 90% of the total organic carbon content of the initial phenol solution could be converted to inorganic carbon within about 3 h of irradiation, using artificial light or sunlight (even on cloudy days), in reactors of different geometry. At moderate or higher phenol concentrations (TOC 0 = 550 or 1000 ppm), the results indicate satisfactory TOC removal (45-55%) at reasonable degradation rates. Experiments under different insolation conditions suggest a direct linear dependence of the organic carbon removal on the accumulated sunlight energy reaching the system. Solar light can be used either as a complementary or alternative source of photons to the process.
Water Science & Technology
This paper deals with catalytic and photocatalytic oxidation of organic substances using H202 over heterogeneous Fenton-type catalysts. In the study a series of Fe-containing catalysts was experienced. A zeolite named as FeZSM-5 was selected as the most active heterogeneous Fenton-type catalyst. The FeZSM-5 reported was prepared by hydrothermal crystallization in the presence of iron salt. In contrast to the homogeneous Fenton system the catalyst prepared had minimal, if any, leaching of iron ions, was stable during 30 catalytic runs and didn't lose its activity in the presence of complexing agents, e.g. P2O7(4-). The catalyst was active in oxidation of organic substances at pH from 1.5 to 8, maximum activity was observed at pH = 3. The FeZSM-5 effectively oxidized a simulant of the warfare agent, diethylnitrophenil phosphate, which is hardly detoxified by other methods. It appeared that the rate of oxidation of formic acid, ethanol and benzene over FeZSM-5 increased under the a...
Modelling and experimental verification of a solar reactor for photo-Fenton treatment
Water Science and Technology, 2010
In the present work, a novel design of a solar reactor is presented. This pilot plant scale reactor uses the UV-Visible and Near-Infrared solar radiation to promote the photo-Fenton treatment. A theoretical study and experimental verification were performed using formic acid as a model pollutant. The radiative transfer, thermal energy and mass balances equations were solved to compute the formic acid (F) and hydrogen peroxide (P) concentrations as a function of time. The spectral and broadband solar radiation incident on the reactor window was calculated from a computational code: the SMARTS2 program. Statistical estimators have been used to measure the departure of theoretical model from experimental data. A good agreement for formic acid and hydrogen peroxide concentrations, temperature and total and UV broadband solar radiation was obtained. The normalized root mean square errors (NRMSE) of the model for predicted variables were lower than 11%.
Recent Overview of Solar Photocatalysis and Solar Photo-Fenton Processes for Wastewater Treatment
International Journal of Photoenergy, 2017
This literature research, although not exhaustive, gives perspective to solar-driven photocatalysis, such as solar photo-Fenton and TiO2 solar photocatalysis, reported in the literature for the degradation of aqueous organic pollutants. Parameters that influence the degradation and mineralization of organics like catalyst preparation, type and load of catalyst, catalyst phase, pH, applied potential, and type of organic pollutant are addressed. Such parameters may also affect the photoactivity of the catalysts used in the studied solar processes. Solar irradiation is a renewable, abundant, and pollution-free energy source for low-cost commercial applications. Therefore, these solar processes represent an environmentally friendly alternative mainly because the use of electricity can be decreased/avoided.
Solar photo-Fenton treatment of winery effluents in a pilot photocatalytic reactor
Catalysis Today, 2015
A pilot-scale solar Fenton process has been applied for the treatment of winery wastewater collected during the vinification period. The importance of the experimental variables was investigated at lab-scale experiments through the application of experimental design methodology. The pilot-scale study was conducted on a pilot CPC photocatalytic reactor under natural solar irradiation. The results show that at low catalyst dose (i.e. [Fe 2+ ] = 5 mg L −1 ) mineralization (i.e. ca. 50%) is dependent on the oxidant consumption (i.e. 500 mg L −1 ), irrespective of the excess oxidant present; however, shorter reaction times are required under excess H 2 O 2 , indicating higher reaction rates due to higher availability of oxidant molecules in the bulk liquid. Increasing the catalyst dose enhances the reaction rate due to higher H 2 O 2 decomposition and HO • production. This is corroborated with the lower H 2 O 2 consumption (i.e. 1270 mg L −1 ) occurring at low catalyst, signifying, however, a more effective use of the oxidant (i.e. less oxidant is required to achieve similar mineralization).
Evaluation of heterogeneous photo-Fenton oxidation of Orange II using response surface methodology
2010
A mesoporous SBA-15 doped iron oxide (Fe 2 O 3 /SBA-15) was synthesized by co-codensation, characterized and used as heterogeneous catalysts for the photo-Fenton decolorization of azo dye Orange II under UV irradiation. Response surface methodology (RSM) was used to investigate operating condition effects, such as hydrogen peroxide concentration, initial pH and catalyst loadings, on the decolorization rate. UV irradiation is found to enhance the activity of the catalyst in the process. RSM analysis evidenced the influence of the initial pH value and H 2 O 2 concentration on the dye degradation rate. The coupled UV/Fe 2 O 3 /SBA-15/H 2 O 2 process at room temperature is revealed as a promising friendly process for wastewater treatment. Indeed, the use of a heterogeneous catalyst allows an easy active phase recycling without multi-step recovering while the heterogeneous catalyst used here exhibits high catalytic activity for the reaction considered.
Recent Overview of Solar Photocatalysis and Solar Photo-Fenton.pdf
This literature research, although not exhaustive, gives perspective to solar-driven photocatalysis, such as solar photo-Fenton and TiO 2 solar photocatalysis, reported in the literature for the degradation of aqueous organic pollutants. Parameters that influence the degradation and mineralization of organics like catalyst preparation, type and load of catalyst, catalyst phase, pH, applied potential, and type of organic pollutant are addressed. Such parameters may also affect the photoactivity of the catalysts used in the studied solar processes. Solar irradiation is a renewable, abundant, and pollution-free energy source for low-cost commercial applications. Therefore, these solar processes represent an environmentally friendly alternative mainly because the use of electricity can be decreased/avoided.
Journal of environmental management, 2015
This study reports the application of the photo-Fenton process for the degradation of the herbicide 2,4-dichlorophenoxyacetic (2,4-D). The objective of this research was the evaluation of the procedure at natural pH (pH = 5) using the ferrioxalate complex as iron source at two incident irradiation levels. For this purpose, different combinations of attenuation filters from a solar simulator were tested. Since the process depends on several parameters, the influence of the temperature (T) and peroxide to 2,4-D initial concentration ratio (R) were investigated and optimized by the application of a three-level factorial experimental design combined with the Response Surface Methodology (RSM). The significance of models and their coefficients were assessed with the analysis of variance (ANOVA). The found optimal conditions were: T = 50 °C and R = 46.3 and T = 41.53 °C and R = 41.46, achieving experimental conversions of 91.4 and 95.9% for the low and high radiation levels, respectively....
Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis
Water Science and Technology, 2004
The effect of combining the photocatalytic processes using TiO2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 is used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H2O2 and TiO2 in the degradation of DCA.