Mechanistic study of the degradation of multiple indoor air pollutants through Vacuum UV photocatalysis

by Prof. Yiu Cheong Leung, Mechanical Engineering
Jan 16, 2016

Summary of the NSFC/RGC project (Prof. Dennis Y.C. Leung)

Project Reference: N_HKU718/15
Project Title: Mechanistic study of the degradation of multiple indoor air pollutants through Vacuum UV photocatalysis
HK Principal Investigator: Professor Yiu Cheong Leung (The University of Hong Kong)
Mainland Principal Investigator: Dr. Haibao Huang (Sun Yat Sen University)


Indoor air quality is very important to us as we spend most of our times in the indoor environment. However, our indoor environments may contain various types of air pollutants, mold and pathogens, some of them (such as formaldehyde) are even carcinogenic. Therefore, good indoor air quality can safeguard our health and increase our productivity. There are different types of air cleaning devices in the market but they are either ineffective in removing multi-pollutants or may even produce secondary pollutants. 

In this NSFC/RGC project, the research team of Professor Dennis Y.C. Leung from HKU Mechanical Engineering Department and Dr. H.B. Huang from Sun Yat Sen University will focus on a novel technology of air cleaning using Vacuum ultraviolet (VUV) technology. Preliminary study indicated that VUV light produces a great enhancement on the photocatalytic degradation of indoor air pollutants and pathogenic bacterial contaminants over traditional photocatalytic oxidation (PCO) process. VUV-PCO technology presents an efficient and highly promising technology for the purification of indoor air pollutants due to the coexistence and synergetic effect of VUV photolysis, PCO and catalytic ozonation during the process. However, the whole process is mainly contributed by the high energy VUV photolysis while the contribution from photocatalytic oxidation process is so small that their capability has not been fully utilized yet. Furthermore, ozone, a strong oxidant, will be generated that can be used to enhance the degradation of pollutants. The residual ozone needs to be purified before discharging. Unfortunately, traditional catalysts have poor capacity for ozone decomposition. The abovementioned problems are the bottleneck and constraints for further development and application of this technology, of which Prof. Leung’s research team would tackle in this study. 

Based on the traditional photocatalysis process and the preliminary results obtained on the VUV photocatalysis, this project will adopt the VUV photocatalysis process, making use of the synergetic effect of the photolysis, photocatalysis and ozonation reactions, for the degradation of multiple indoor air pollutants. Multi-functional mesoporous TiO2 photocatalysts will be prepared and modified with transition metals to improve its capabilities for the elimination and utilization of residual ozone as well as to enhance its photocatalytic oxidation capability. The purification performance and structural characteristics of the catalysts developed will be studied thoroughly. In particular, the mechanism of the complex air pollutant transformation route and its synergetic effects with other processes (such as ozonation and photolysis) will be focused. The main objective of this research is to investigate the key scientific questions related to the degradation of indoor air pollutants and bacteria by the VUV photocatalysis technology. This will enhance the future development of the air cleaning technology, which will have a long term impact on the indoor air quality and our health.


Figure 1. Diagram showing the VUV photocatalytic degradation of complex indoor air pollutants.