Performance of photocatalytic reactors using immobilized TiO 2 film for the degradation of phenol and methylene blue dye present in water stream

Abstract

TiO 2 thin film photocatalyst was successfully synthesized and immobilized on glass reactor tube using sol–gel method. The synthesized TiO 2 coating was transparent, which enabled the penetration of ultra-violet (UV) light to the catalyst surface. Two photocatalytic reactors with different operating modes were tested: (a) tubular photocatalytic reactor with re-circulation mode and (b) batch photocatalytic reactor. A new proposed TiO 2 synthesized film formulation of 1 titanium isopropoxide: 8 isopropanol: 3 acetyl acetone: 1.1 H 2O: 0.05 acetic acid (in molar ratio) gave excellent photocatalytic activity for degradation of phenol and methylene blue dye present in the water. The half-life time, t 1/2 of photocatalytic degradation of phenol was 56 min at the initial phenol concentration of 1000 μM in the batch reactor. In the tubular photocatalytic reactor, 5 re-circulation passes with residence time of 2.2 min (single pass) degraded 50% of 40-μM methylene blue dye. Initial phenol concentration, presence of hydrogen peroxide, presence of air bubbling and stirring speed as the process variables were studied in the batch reactor. Initial methylene blue concentration, pH value, light intensity and reaction temperature were studied as the process variables in the tubular reactor. The synthesized TiO 2 thin film was characterized using SEM, XRD and EDX analysis. A comparative performance between the synthesized TiO 2 thin film and commercial TiO 2 particles (99% anatase) was evaluated under the same experimental conditions. The TiO 2 film was equally active as the TiO 2 powder catalyst.