Simultaneous removal of formaldehyde and benzene in indoor air with a combination of sorption- and decomposition-type air filters

• Published in: Environmental technology 2011-12, Vol.32 (16), p.1983-1989
• Main Authors: Sekine, Yoshika, Fukuda, Mitsuru, Takao, Yosuke, Ozano, Takahiro, Sakuramoto, Hikaru, Wang, Kuan Wei
• Format: Article
• Language: English
• Subjects: activated carbon; Adsorption; air; air filter; air filters; air flow; Air Pollutants - chemistry; Air Pollutants - isolation & purification; air pollution; Air Pollution, Indoor; air quality; ambient temperature; Applied sciences; Atmospheric pollution; benzene; Benzene - chemistry; Benzene - isolation & purification; buildings; Catalysis; Catalytic reactions; Charcoal - chemistry; Chemical engineering; Chemistry; cleaners; environmental technology; Exact sciences and technology; Filtration - methods; formaldehyde; Formaldehyde - chemistry; Formaldehyde - isolation & purification; General and physical chemistry; indoor air quality; Indoor pollution and occupational exposure; irradiation; Manganese Compounds - chemistry; manganese dioxide; odors; Oxides - chemistry; photocatalysts; Photochemical Processes; Pollution; pollution control; Reactors; sorption; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; urban areas; volatile organic compounds
• ISSN: 1479-487X; 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2011.562924

Urgent measures for indoor air pollution caused by volatile organic compounds are required in urban areas of China. Considering indoor air concentration levels and hazardous properties, formaldehyde and benzene should be given priority for pollution control in China. The authors proposed the use of air-cleaning devices, including stand-alone room air cleaners and in-duct devices. This study aimed to find the best combination of sorption and decomposition filters for the simultaneous removal of formaldehyde and benzene, employing four types of air filter units: an activated charcoal filter (ACF), an ACF impregnated with a trapping agent for acidic gases (ACID), a MnO₂ filter (MDF) for oxidative decomposition of formaldehyde at room temperature and a photocatalyst filter (PHOTO) coupled with a parallel beam ultraviolet (UV) irradiation device. The performance of the combined systems under air flow rates of 35–165 m³ h⁻¹ was evaluated in a test chamber (2 m³) with a constant gas generation system. The experimental results and data analysis using a kinetic approach showed the combined system of ACF, PHOTO and MDF significantly reduced both concentrations of formaldehyde and benzene in air without any unpleasant odours caused by the UV-induced photocatalytic reaction. The system was then evaluated in a full-size laboratory (22 m³). This test proved the practical performance of the system even at full scale, and also suggested that the filters should be arranged in the order of PHOTO/ACF/MDF from upstream to downstream. The proposed system has the potential of being used for improving indoor air quality of houses and buildings in China.