3D printed photocatalytic reactor for air purification

Abstract

A 3D printed plastic sinusoidal reactor with a 3D printed photocatalytic lining is prepared and used to purify air, containing the test pollutants, NO2, NO, acetaldehyde and ozone. This 3D printed, air-purifying photocatalytic reactor, 3D APPR, is first UVA pre-conditioned (168 h, 1.5 mW cm−2), to render its P25 TiO2 containing photocatalytic lining active, through the destruction of the thin layer of polymer that covers the photocatalytic particles at, or near, to the surface. When testing for pollution removal, unless stated otherwise, the typical reaction conditions are, [pollutant] = ca. 1000 ppb, flow rate = 0.26 L min−1, relative humidity = 50%, UVA irradiance (352 nm) 1 mW cm−2 and irradiation time, t, = 5 h. Under these conditions the 3D APPR removes 27% of the NO2, 25.3% of the NO, but simultaneously generates 17.3% NO2 so %NOx removed is only ca. 8%. With acetaldehyde, [pollutant] = ca. 5000 ppb; 3 h irradiation, 34.2% is removed. Finally, with ozone, [pollutant] = ca. 420 ppb; 1 h irradiation; 2.8 mW cm−2 368 nm, 99% is removed. Indeed, the latter process is so effective that the small amount (47 μW cm−2) of UV in cool white fluorescent tubes is able to effect the removal of 70 % of the ozone. In all cases, the 3D APPR is more effective at removing the test pollutant than Activ™ self-cleaning glass, even though the latter has nearly 3 times the irradiated surface area and over 12 times the residence time. Long term (5 day) irradiations of the same systems produces very similar, if not enhanced, % removal values for all the pollutants tested. The potential of this type of disposable, plastic film photocatalytic reactor, made using a biodegradable plastic, polylactic acid, PLA, is discussed briefly.