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  • In situ photoelectrochemical/photocatalytic study of a dye discoloration in a microreactor system using TiO2 thin films.

In situ photoelectrochemical/photocatalytic study of a dye discoloration in a microreactor system using TiO2 thin films.

Environmental science and pollution research international (2012-10-12)
C Montero-Ocampo, A Gago, G Abadias, B Gombert, N Alonso-Vante
ABSTRACT

In this work, we report in situ studies of UV photoelectrocatalytic discoloration of a dye (indigo carmine) by a TiO(2) thin film in a microreactor to demonstrate the driving force of the applied electrode potential and the dye flow rate toward dye discoloration kinetics. TiO(2) 65-nm-thick thin films were deposited by PVD magnetron sputtering technique on a conducting glass substrate of fluorinated tin oxide. A microreactor to measure the discoloration rate, the electrode potential, and the photocurrent in situ, was developed. The dye solutions, before and after measurements in the microreactor, were analyzed by Raman spectroscopy. The annealed TiO(2) thin films had anatase structure with preferential orientation (101). The discoloration rate of the dye increased with the applied potential to TiO(2) electrode. Further, acceleration of the photocatalytic reaction was achieved by utilizing dye flow recirculation to the microreactor. In both cases the photoelectrochemical/photocatalytic discoloration kinetics of the dye follows the Langmuir-Hinshelwood model, with first-order kinetics. The feasibility of dye discoloration on TiO(2) thin film electrodes, prepared by magnetron sputtering using a flow microreactor system, has been clearly demonstrated. The discoloration rate is enhanced by applying a positive potential (E (AP)) and/or increasing the flow rate. The fastest discoloration and shortest irradiation time (50 min) produced 80% discoloration with an external anodic potential of 0.931 V and a flow rate of 12.2 mL min(-1).

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Indigo carmine, for microscopy (Bact., Hist.), indicator (pH 11.5-14.0)
Sigma-Aldrich
Indigo carmine, certified by the Biological Stain Commission, Dye content 85 %
Supelco
Indigo carmine, analytical standard
Sigma-Aldrich
Indigo carmine, JIS special grade, ≥97.5%
Sigma-Aldrich
Indigo carmine, SAJ first grade, ≥90.0%