Purification of indoor air

Purification of indoor air (dust and water-soluble gases such as CO2 and ammonia). 

Ti02 photocatalysis is very successful for the purification of indoor air in which the air pollutants are relatively low in concentration. Experimental results have indicated that the quantum efficiency of photocatalytic reactions is high at low light intensities (Fig. 8) [25]. Thus, the... 

Pichat P, Disdier J, Hoang-Van C, Mas D, Goutailler G, Gaysse C. Purification/deodorization of indoor air and gaseous effluents by Ti02 photocatalysis. Catal Today 2000 63 363-369. 

The indoor air quality control appliance consists of air handling, filtration, purification and dehumidification systems. Mr. Peter Chan of Chiaphua Industries Ltd. was closely consulted in completing the engineering specifications for the product. 

As has been shown there are a number of pollutants that have undergone gaseous photocatalytic oxidation and the research within this field is continually progressing. Unlike water photocatalytic oxidation which has found application on both a scientific and industrial basis gaseous PCO development has currently been limited to terrestrial indoor air purification (Table 2). The vast majority of industrial development and application is confined to Japan and the USA. 

The conditioning and control of indoor environments is an ever increasing problem. Lately this does not only include the traditional control of temperature and moisture but also the elimination of contaminants and odors from the atmosphere. Particulates, including organic matter, such as mold, germs, and viruses, can be captured and retained by sometimes electrically assisted ultrafiltration. Cartridges are either discarded or cleaned/reactivated. For the elimination of chemicals and odors, absorption, adsorption, and chemical reactions with air purification media are required. 

Organophosphate esters have been analyzed mainly in the indoor air samples. SAE has been relatively popular in the extraction of organophosphates from air samples, which have been collected either on filters or adsorbents. Both static and dynamic extraction can be used. An example of dynamic SAE (DSAE) is the extraction of OPEs from quartz filters by hexane MTBE (7 3). The flow rate was 0.2 ml/min, and the total extraction time was only 3 min, at a temperature of 70°C. The recoveries were compared with static SAE (2 X 20 min) and PEE and the recoveries obtained with DSAE (>95%) were at the same level or better than those obtained with other methods. No further purification or concentration was needed before GC-NPD analysis of organophosphates. The GC column was a 30 m X 0.32 mm i.d. DB% column with a phase thickness of 0.1 /rm. Splitless injection was applied in the sample introduction. The LODs were better than 0.4 ng/m. The system was developed further, and the DSAE was connected online with GC using PTV and large volume injection during the transfer. The most abundant compound found in the air was tri(w-butyl) phosphate. ... 

The oxidation of carbon monoxide at around room temperature is the most famous reaction known for gold catalysts. Haruta s group discovered in 1987 [1, 2] that gold is a unique catalyst for this reaction when gold metal particles are smaller than 5 nm and supported on oxides. Since then, extensive and intensive fundamental works have been published, and expanding new applications, from air purification (gas masks, gas sensors, indoor air quality control) to hydrogen purification for fuel cells (PROX, preferential selective oxidation of CO in the presence of Hj) have been developed. 

Acetone is another model compound utilized for VOCs indoor air purification. Using photocatalysis, the degradation of this compound was achieved, using both titania-based oxides [68] and different families of perovsldtes [69]. 

What is a chemical product One possibility is a new specialty chemical. A new drug is a chemical product. A new catalyst or solvent for use in the commodity chemical industry is a chemical product. Post-it Notes are a chemical product. A fuel cell is a chemical product. A device for indoor air purification is a chemical product. Technologies enploying chemical engineering principles could be considered to be chemical products. Even the ChemE Cars that many students build as part of the AIChE competition could be considered chemical products. 

Ao C, Lee S, Mak C, Chan L (2003) Photodegradation of volatile organic compounds (VOCs) and NO for indoor air purification using Ti02 promotion versus inhibition effect of NO. Appl Catal Environ 42 119-129... 

Mo J, Zhang Y, Xu Q, Lamson JJ, Zhao R (2009) Photocatalytic purification of volatile organic compounds in indoor air a literature review. Atmos Environ 43(14) 2229-2246... 

Air purification is a very important issue. Air cleaning devices are needed for respiratory protection (gas masks) and for removing CO, CO2, water vapour and trace amounts of VOCs and ozone from ambient air indoor office space (due to smoking, etc.) and in submarines or space crafts on long missions [2,6,7,18,31,64,71,110,125,126,132,251,260-264,598]. 

Fig. 9 Schematic diagram of the components of an indoor room air-purification unit (Courtesy of Dai kin Industries).

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