Air purifying material

Specific surface area is crucial for air purifying materials, because unlike usual catalytic reactions the reaction products (nitric acid or nitrate) remain on the surface to cover active sites. This has been demonstrated by the fact that photocatalytic performance is very much improved by using finer Ti02 particles, increasing Ti02 content and making porous structures. 

Table 8.6 Typical performance of the air-purifying materials for NOx removal3 ...

Table 8.7 Possible application of passive air-purifying materials ...

Figure 8.23 shows the effect of UV light intensity on NO removal. The removal percentage did not depend very much on the UV intensity under our experimental conditions. It is thus concluded that 0.1 mW cm-2 is enough for removing ppm levels of NO. This level of UV intensity is observed even on cloudy days in winter from the sun. Consequently, fhe air purifying materials could work in the outdoor environment during the daytime. 

Fig. 8.22 Dependence of 24 h average NO removal on NO feed concentration. Air-purifying material, 200 Cm2 flow-rate, 1.5 1 min-1 UV intensity, 0.5 mW cm-2.

We conducted a field test for examining the performance characteristics of the air purifying materials for NO removal from ambient air. As the test site, a roadside of a 6-lane, east and west bound highway in Tokyo was selected. The average traffic was 113,000 vehicles a day. 

Two types of plastic panels [effective size, 0.6 x 1.0 m made from poly(vinyl chloride) resin] were used for testing the sheets in polluted areas. One is the open type (the sheets are exposed to air) and the other a windowed type. The open type can simulate realistic conditions. The windowed type has a Pyrex glass window that allows the UV light to reach the sheets. The roadside air was continuously pumped to the windowed panels at 15-60 1 min-1. This type was used for estimating the amount of air coming into contacted with the materials. The air purifying materials were attached to the panels using adhesive tape. 

The volume of fhe ventiiatior gas by washing for a 6-lane tunnel 1 km in length is approximately 1.5 million m h-, which is almost equivalent to that from middle-size power station plants, while the concentration of NO and other pollutants is much lower. To treat the ventilation air, about 4,000 units of the apparatus in Fig. 8.25 may be necessary. This is considered to be a very large system, but it is estimated that this system is smaller in scale and more cost-effective than those systems using concentrations of NO and NH3, the selective catalytic reduction method. Furthermore, the scale can be smaller if more active air-purifying materials are developed. 

Devices consisting of a body and a canister that contains air-purifying materials. 

The pesticide mixture sample from the air of the GC lab in which raw materials and pesticide products are analyzed was collected for three consecutive months. The sample to be analyzed was made using the extraction of the filter taken from the air purifier. 

Metal carbonyls decompose in light to produce carbon monoxide. They are incompatible with strong oxidizers and readily form explosive mixtures with air. Some decompose at ordinary temperatures in contact with porous materials [e.g., activated carbon used in air purifying respirator (APR) filters] and produce carbon monoxide. 

Personal protective equipment is clothing and/or respiratory equipment worn to protect the body against various forms of contamination. Some of the most common forms of personal protective equipment include dust masks, air purifying respirators, protective suits made from particulates or chemically resistant materials such as Tyvek (E.I. Du Pont de Nemours Company, Inc., Wilmington, DE) and/or other fabrics, and lightweight protective rubber gloves or chemical-resistant gloves. 

The crude acid is purified by dissolving in 360-400 ml. of cold 5% sodium bicarbonate solution, filtering, and acidifying the filtrate with sufficient excess of mineral acid to turn Congo red paper blue. The product is separated by suction filtration, washed with water to remove mineral acid, and air-dried. Material thus obtained weighs 17.9-18.7 g. (67-70% yield). It melts generally (Note 6) between 202° and 205°, and is sufficiently pure (Note 7) for most practical purposes. 

Now that we have determined what processes the facility will be used for, we can finalize utility requirements. The following utilities are required for our solid-dose facility heating, ventilation, and air conditioning (HVAC), hot and cold water, steam, electrical service, compressed air, vacuum systems, dust collection, chillers, effluent stream, and purified water. For the more specialized processes or special material handling, we may need specialized gases and breathing air. Purified water is one of the more difficult utilities to maintain the quality of. From a source of potable water, a series of treatments must be performed to control microbiological quality. Typical treatment options include carbon filters, reverse osmosis, and UV radiation. 

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