IWRA World Water Congress 2008 Montpellier France
2. Towards the Future: Water Resources and Global Changes
José Apolinar Cortes
Maria Teresa Alarcón-Herrera
Juan F. Pérez-Robles.
Advanced oxidation, colored water,
AbstractDEGRADATION OF THE DYE ACID BLUE 9 USING A TiO2/UV ADVANCED OXIDATION
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.
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-
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