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IWRA World Water Congress 2008 Montpellier France
2. Towards the Future: Water Resources and Global Changes
Author(s): José Apolinar Cortes
Maria Teresa Alarcón-Herrera
Maricela Villicaña-Méndez
Jesus Gonzalez-Hernández
Juan F. Pérez-Robles.

Keyword(s): Advanced oxidation, colored water, chromophores groups.

AbstractDEGRADATION OF THE DYE ACID BLUE 9 USING A TiO2/UV ADVANCED OXIDATION PROCESS José Apolinar Cortés *, Maria Teresa Alarcón-Herrera**, M. Villicaña-Méndez, J. Gonzalez- Hernández, J. F. Pérez-Robles. **Centro de Investigación en Materiales Avanzados, Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Chih. , México. Keywords: Advanced oxidation, colored water, chromophores groups. The processes of advanced oxidation constitutes an alternative for the degradation of toxic, recalcitrant and colored organic compounds (Daneshvar et al., 2005; J. M. Chacón et al., 2006; M. A. Behnajaday et al., 2006). However the actual information does not allow designing the process properly because the specific variables and conditions are not fully understood. In order to analyze the reaction kinetics and efficiency of this process, the degradation of acid blue 9 was performed in a completely agitated heterogeneous vertical tubular reactor, using air as an oxidizing agent and disperser of the TiO2 Degussa P-25 catalyst, activated with UV lamps. The oxidation kinetics was evaluated in three series of tests. In the first series, the catalyst concentration was kept constant (150 mg L-1) and the concentration of acid blue 9 was varied (20 - 60 mg L-1). In the second series, the concentration of acid blue 9 was kept constant (40 mg L-1) and the concentrations of the catalyst were varied (150 - 600 mg L-1). In the third series, the concentrations of colorant and catalyst were varied simultaneously while their ratio was kept constant (7.5:1). The degree of oxidation was evaluated spectrophotometrically and by measuring the chemical oxygen demand (DQO). The obtained results show that, for 150 mg L-1 of TiO2, increasing the concentration of acid blue 9 (from 20 mg L-1 to 60 mg L-1) makes the total oxidation time increase exponentially in 5 hours, due to the change in the concentration of the Dye. For a Dye concentration of 40 mg L-1, increasing the catalyst dose from 150 mg L-1 to 600 mg L-1 decreases the oxidation time by 2.5 hours. Increasing the acid blue 9 and catalyst concentration simultaneously increases the reaction time from 2.0 to 3.5 hours. The degradation speed varies in a fashion inversely proportional to the increment in the Dye concentration, and directly proportional to the catalyst concentration (TiO2). When the Dye and catalyst concentrations are simultaneously increased, part of the UV light is absorbed by the Dye. This impedes the photo activation of the catalyst and reduces the reaction speed. The removal of the organic load (DQO) presented zero -order kinetic, showing efficiencies between 65% and 95%. In all tests, a total removal of the chromophorous groups was achieved; this parameter indicates (along with the organic load) the application potentiality of the process for the treatment of colored water. References Chacón J. M., Leal M. T., Sánchez M., Bandala E. R. (2006) Solar photocatlytic degradation of azo-dyes by photoFenton process. Dyes and Pigments 69, 144- 150. Behnajaday M. A. and Modirshshla N. (2006) Kinetic modeling on photooxidative degradation of C.I. Acid Orange 7 in a tubular continuos-flow photoreactor. Chemosphere 62, 1543-1548. Daneshvar N., Aleboyeh A., Khataee A. R. (2005) The evaluation of electrical energy per order (EE0) for photooxidative decolorization of four textile dye solutions by the kinetic model. Chemosphere 59, 761-767
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