Photocatalytic characteristic and photodegradation kinetics of toluene using N-doped TiO₂ modified by radio frequency plasma

Abstract

This study investigates the feasibility of applications of the plasma surface modification of photocatalysts and the removal of toluene from indoor environments. N-doped TiO₂ is prepared by precipitation methods and calcined using a muffle furnace (MF) and modified by radio frequency plasma (RF) at different temperatures with light sources from a visible light lamp (VLL), a white light-emitting diode (WLED) and an ultraviolet light-emitting diode (UVLED). The operation parameters and influential factors are addressed and prepared for characteristic analysis and photo-decomposition examination. Furthermore, related kinetic models are established and used to simulate the experimental data. The characteristic analysis results show that the RF plasma-calcination method enhanced the Brunauer Emmett Teller surface area of the modified photocatalysts effectively. For the elemental analysis, the mass percentages of N for the RF-modified photocatalyst are larger than those of MF by six times. The aerodynamic diameters of the RF-modified photocatalyst are all smaller than those of MF. Photocatalytic decompositions of toluene are elucidated according to the Langmuir–Hinshelwood model. Decomposition efficiencies (η) of toluene for RF-calcined methods are all higher than those of commercial TiO₂ (P25). Reaction kinetics of photo-decomposition reactions using RF-calcined methods with WLED are proposed. A comparison of the simulation results with experimental data is also made and indicates good agreement. All the results provide useful information and design specifications. Thus, this study shows the feasibility and potential use of plasma modification via LED in photocatalysis.

Keywords:

• N-doped TiO₂
• radio frequency plasma
• kinetics
• photocatalysis
• LED

Acknowledgements

We express our sincere thanks to the National Science Council of Taiwan for its financial support, under contract number 100-2221-E-197-005-MY3.