Evaluation of TiO₂, ZnO, CuO and Ga₂O₃ on the Photocatalytic Degradation of Phenol Using an Annular-Flow Photocatalytic Reactor

Flavia Cristina Sertori Paschoalino, Matheus Paes Paschoalino, Elizabete Jordão, Wilson de Figueiredo Jardim

Department of Analytical Chemistry Institute, UNICAMP-University of Campinas, Campinas, Brazil.
Department of Chemical Systems Engineering, Laboratory of Catalytic Processes Development (LDPC), Faculty of Chemical Engeneering, UNICAMP-University of Campinas, Campinas, Brazil.

DOI: 10.4236/ojpc.2012.23018                

Abstract

Even with rigorous environmental regulations, phenol still is a major contaminant. One possible solution is the use of heterogeneous photocatalysis due to low chemical addition, feasibility and reliability to be implanted on cost-effective industrial process. TiO₂ is the most employed photocatalyst because of its favorable (photo) chemical properties and ZnO is considered one of the best alternative for that. Other oxides were tested in lesser proportions, like CuO and Ga₂O₃. When the photocatalyst is dispersed as slurry, higher degradation rates are achieved due to high solid to liquid contact area when compared with supported form. The aim of this work was to develop a batch recirculating photocatalytic reactor and evaluate its efficiency when assisted by the photocatalysts TiO₂ P25, ZnO, CuO and β-Ga₂O₃. TiO2 achieved 95% mineralization after 200 min reaction in an average degradation rate of 0.68 mg·L^﹣1·min^﹣1 and ZnO was less efficient (0.41 mg·L^﹣1·min^﹣1). Ga₂O₃ and CuO presented poor performance, mainly due to low surface area for the CuO syntesized and the absorption of the UV radiation by the reactor walls, decreasing Ga₂O₃ activity. Degradation intermediates were detected in diverse concentrations and at different operational times for each oxide tested, which indicate different degradation mechanisms.

Keywords

Phenol; TiO₂; ZnO; CuO; Ga₂O₃; Heterogeneous Photocatalysis

Conflicts of Interest

The authors declare no conflicts of interest.

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