Measuring the effect of photocatalytic purifiers on indoor air hydrocarbons and carbonyl pollutants.
Laboratory tests of photocatalytic air purifiers are usually performed with a single pollutant, in the parts per million by volume domain and at airflow rates < or =0.1 m3/hr. Clearly, it is necessary to probe photocatalytic materials and apparatuses under real conditions or conditions closely mimicking reality. Photocatalytic prototypes were placed in an ordinary room. To collect hydrocarbons over a shorter period (15 min) than with adsorbent-containing cartridges, solid-phase microextraction (SPME) was used. Typically, concentrations in substituted benzene hydrocarbons and tetrachloroethene were decreased to 20-35% of initial values; toluene and m- + p-xylene concentrations dropped to 2-6 parts per billion by volume, and o-xylene and benzene concentrations were still lower. In the absence of appropriate, commercialized SPME fibers, carbonyl compounds (both formed and destroyed by photocatalysis) were extracted using cartridges containing 2,4- dinitrophenylhydrazine-coated silica. The concentration ranges (in parts per billion by volume) were shifted to higher values in treated air: from 9-15.5 to 12.5-18 for methanal, from 1.5-3 to 8-11.5 for ethanal, and from 4.5-19 to 8-26.5 for propanone with the prototype used; these unprecedented results do not exclude using photocatalysis to treat air, but they illustrate that improvement is needed. Because these tests are time-consuming, preliminary tests are useful; results obtained with a 225-L closed-loop, airtight, photocatalytic reactor with an external turbine enabling the ambient air inside the reactor to be circulated through the purifier device at 15-450 m3/hr flow rates are reported.
Disdier
Jean
J
Laboratoire Photocatalyse, Catalyse et Environnement, CNRS UMR IFoS, Ecole Centrale de Lyon, Ecully, France.
Pichat
Pierre
P
Mas
Denis
D
D000393:Air Pollutants / Q000302:isolation & purification*; D016902:Air Pollution, Indoor / Q000517:prevention & control*; D002244:Carbon / Q000302:isolation & purification; D002384:Catalysis; D004867:Equipment Design; D006838:Hydrocarbons / Q000302:isolation & purification*; D010777:Photochemistry
D000393:Air Pollutants; D006838:Hydrocarbons; D002244:Carbon