The application of dielectric barrier discharge non-thermal plasma in VOCs abatement: A review

Rapid industrialization and urbanization in developing countries has led to an increase in air pollution, along a similar trajectory to that previously experienced by the developed nations. In China, particulate pollution is a serious environmental problem that is influencing air quality, regional and global climates, and human health. In response to the extremely severe and persistent haze pollution experienced by about 800 million people during the first quarter of 2013 (refs 4, 5), the Chinese State Council announced its aim to reduce concentrations of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 micrometres) by up to 25 per cent relative to 2012 levels by 2017 (ref. 6). Such efforts however require elucidation of the factors governing the abundance and composition of PM2.5, which remain poorly constrained in China. Here we combine a comprehensive set of novel and state-of-the-art offline analytical approaches and statistical techniques to investigate the chemical nature and sources of particulate matter at urban locations in Beijing, Shanghai, Guangzhou and Xi'an during January 2013. We find that the severe haze pollution event was driven to a large extent by secondary aerosol formation, which contributed 30-77 per cent and 44-71 per cent (average for all four cities) of PM2.5 and of organic aerosol, respectively. On average, the contribution of secondary organic aerosol (SOA) and secondary inorganic aerosol (SIA) are found to be of similar importance (SOA/SIA ratios range from 0.6 to 1.4). Our results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from, for example, fossil fuel combustion and biomass burning is likely to be important for controlling China's PM2.5 levels and for reducing the environmental, economic and health impacts resulting from particulate pollution.

Volatile organic compounds (VOCs) severely threaten human health and the ecological environment because most of them are toxic, mutagenic, and carcinogenic. The persistent increase of VOCs together with the stringent regulations make the reduction of VOC emissions more imperative. Up to now, numerous VOC treatment technologies have emerged, such as incineration, condensation, biological degradation, absorption, adsorption, and catalysis oxidation et al. Among them, the adsorption technology has been recognized as an efficient and economical control strategy because it has the potential to recover and reuse both adsorbent and adsorbate. Due to their large specific surface area, rich porous structure, and high adsorption capacity, carbonaceous adsorbents are widely used in gas purification, especially with respect to VOC treatment and recovery. This review discusses recent research developments of VOC adsorption onto a variety of engineered carbonaceous adsorbents, including activated carbon, biochar, activated carbon fiber, carbon nanotube, graphene and its derivatives, carbon-silica composites, ordered mesoporous carbon, etc. The key factors influence the VOC adsorption are analyzed with focuses on the physiochemical characters of adsorbents, properties of adsorbates as well as the adsorption conditions. In addition, the sources, health effect, and abatement methods of VOCs are also described.