Eliminación de contaminantes por fotocatálisis heterogénea, M.A. Blesa y B. Sánchez (Editores), Editorial CIEMAT, Madrid , ISBN: Get this from a library! Eliminación de contaminantes por fotocatálisis heterogénea. [Miguel A Blesa; CYTED (Organización);]. Get this from a library! Eliminación de contaminantes por fotocatálisis heterogénea. [Miguel Blesa;].
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This behavior agrees with what has been reported by other authors who claim that the degradation of azo dyes increases with decreasing pH 13 This article revises the most important investigations related to the subject and mentions some of the advantages photocatalysis has if compared to other systems.
For the two test controls with TiO 2 and without UV light, and with UV light but TiO 2 freethere were no changes, as the dye oxidation is mainly mediated by the action of the TiO 2 semiconductor in the presence of UV light, which activates the catalyst. Results obtained for six assays: Thereby, six additional trials independent to the experimental design were proposed, being stricter concerning to TiO 2 concentration see tests 16—21, in Table 2.
According to the experimental design Table fotoctalisis, Figure 1mL beakers were used, with mL of the dye solution and TiO 2.
Table 6 shows the results obtained for the samples and the positive control doxorubicin. This hetwrogenea of TiO 2 would allow treating several loads of RB5 using the same catalyst, and therefore a system of continuous degradation could be implemented.
Additionally, it provides the possibility of using solar radiation as a primary source of energy. It is important to note that LC50 was the same for all of the samples, i. However, other possible treatments such as advanced oxidation processes have been explored.
Heterogeneous photocatalytic methodologies are based on the band model. Doxorubicin was used as positive cytotoxicity control, as it is a cytotoxic agent intercalating the DNA; untreated cells were used as negative cytotoxicity control Using a numerical method implemented in Statgraphics, a maximum expected AUC of Advanced oxidation of acid and reactive dyes: The total area was obtained by summing the area of the trapezoids under the curve, which is formed between pairs of decolorization percentage readings over time Furthermore, it was observed that the degradation of 50 mg L -1 of RB5 using 0.
It was determined that the decolorization process could be improved using 0. The growth of the cells submitted to the different treatments was similar heterogfnea that of the untreated control cells, i.
Revista Colombiana de Química
Decolorization and degradation of reactive azo dyes via heterogeneous photocatalytic processes. RB5 decolorization percentage in aqueous heteroegnea vs. However, to reduce costs and to facilitate the catalyst separation, low concentrations of TiO 2 0. Also, there are several studies related to synthetic dyes with cases of toxicity, carcinogenesis, mutagenesis, and teratogenesis in humans 5. RB5 decolorization in aqueous solution The RB5 decolorization was followed spectrophotometrically Shimadzu UV spectrophotometer at nm.
Fotocatálisis heterogénea para el abatimiento de tensoactivos aniónicos en aguas residuales
The objective of our research was not to identify the byproducts of the reaction, but the evaluation of its cytotoxicity; this parameter indicates the degree of toxicity of the by-products.
Preserving and protecting natural resources, such as water, is one of the nowadays main environmental concerns. Additionally, other authors have reported that the degradation of azoic dyes and other substances by heterogeneous photocatalysis, using TiO 2 and UV, light can be followed by a first-order kinetics process 19 The evaluated samples did not show toxicity in the HepG2 cell line.
Control cells without treatment. Adsorption of methylene blue on low-cost adsorbents: The RB5 decolorization percentage was measured as the response variable. The biological evaluation is presented in Figure 7. Although reaction rate depends mainly on the light intensity, this parameter does not affect the reaction mechanism. Another possible cause for such results is the UV-screening effect of the dye itself.
However, longer treatment times than those used in this work have also been reported in the literature, for instance, Threrujirapapong et al. Additionally, after 10 h of reaction, a decolorization percentage of Evaluation of Titanium dioxide photocatalytic technology for the treatment of reactive Black 5 dye in synthetic and real greywater effluents. From the above, it is possible to conclude that the catalyst load used in the optimization tests is not a determining factor in the improvement of the process productivity Figures 5 and 6.
Cytotoxicity tests on the HepG2 cell line indicated that photocatalytic degradation of RB5 did not generate cytotoxic byproducts. First-order kinetics for RB5 decolorization, under the conditions of test 15 0.
However, high substrate concentrations decrease the photonic efficiency and saturate the TiO 2 surface, which leads to catalyst deactivation and a decrease of the degradation efficiency 15 The MTT reduction method was employed to establish the cytotoxicity of the reaction mixtures corresponding to the tests with the highest percentage of RB5 decolorization, utilizing the HepG2 cell line Due to the fact that pH can affect the adsorption of dye on the catalyst surface, the point of zero charge pzc of the TiO 2 must be taken into account; the pzc corresponds to a pH value of 6.
Dual effect of photocatalysis and adsorption in degradation of azorubine dye using Nanosized TiO2 and activated carbon immobilized with different techniques. TiO 2 concentration 0. Conversely, Chong et al. Thus, photocatalytic degradation of RB5 is faster in low initial dye concentration, reaching a maximum in acidic conditions at 10 h.
Simultaneous decolorization and detoxification of black reactive 5 using TiO2 deposited over borosilicate glass.
Conventional water treatments with surfactants are made by a biological action during the primary sedimentation. Kinetic and mechanistic investigations: This implies an increase the generation of oxidizing species with capacity to degrade the dye.
Photocatalytic Degradation of Textile Azo Dyes. Decontamination and disinfection of water by solar photocatalysis: