Bubble annular photoeletrocatalytic reactor with TiO<inf>2</inf> nanotubes arrays applied in the textile wastewater

This study proposed a simple and effective annular bubble photoreactor using an array of TiO<inf>2</inf> nanotubes (NTs) prepared in situ by an anodisation process and used as photoanodes. The method is based on photoelectrocatalytic oxidation of the industrial textile wastewater (pH 7.83; conductivity 9.96 mS cm-1; total dissolved solids 4.97 ppt; turbidity 0.04 NTU; colour 1146 mg/Pt; total organic carbon 5680 ppm and inorganic carbon 408.1 ppm) operating as follows: original pH of the effluent corrected to 2; current density of 9 mA cm-2, commercial Hg high press lamp (250 W) irradiating at UV and visible region, and air bubble stirring of 700 mL min-1. Using these optimised conditions, it was possible to obtain 90% colour removal (initial = 1.146 mg Pt), 66% COD reduction (initial = 5680 ppm) and 70% TOC removal after 3 h of treatment, reaching acceptable physicochemical properties for discharge.