Evaluation of degradation kinetic and photostability of immobilized TiO2/activated carbon bilayer photocatalyst for phenol removal

Abstract

Fabrication of immobilizable titanium (IV) oxide (TiO2) and activated carbon (AC) were done using epoxidized natural rubber-polyvinyl chloride as adhesive. The two materials were combined in an immobilized layer by layer manner to remove phenol from aqueous media. This immobilized bilayer TiO2/AC photocatalyst operated via simultaneous synergy processes of phenol adsorption into AC layer and photocatalytic degradation by TiO2 top layer. The pseudo second order rate equation as derived from Langmuir Hinshelwood model was used to determine the optimal conditions for phenol degradation. It was found that the optimized loading of immobilized AC and TiO2 were 2.54 and 0.32 mg cm−2, respectively. The kinetics of phenol degradation was investigated over operational parameters namely pH of the solution (pH 2-10), initial concentration (10-100 mg L−1), light intensity (0.03-22 Wm−2) and dissolved O2 supply (0-500 mL min−1) and they were optimized at pH 6.5, 10 mg L−1, 6.0 Wm−2 of UV leakage and 100 mL min−1 of aeration rate, respectively. The optimized TiO2/AC bilayer photocatalyst could remove 94% of phenol while single TiO2 only removed 47% from the solution after 90 min in the presence of UV-vis light. The reusability and stability of TiO2/AC photocatalyst exhibited positive outcome as observed after 10 cycles of application showing the favorability of the bilayer photocatalyst for various applications.