Optimization of photocatalytic oxidation conditions for the removal of indoor air pollutants

HUGO DESTAILLATS; MARIA LAURA VERA; MARTA I. LITTER

Aberdeen

Conferencia; Second International Conference on Semiconductor Photochemistry; 2007

The Robert Gordon University

Photocatalytic oxidation of volatile organic compounds (VOCs) is a promising technology to improve indoor air quality in a cost-efficient manner. However, incomplete photocatalytic oxidation may result in the generation of unwanted toxic and irritant species such as formaldehyde and acetaldehyde. Another drawback is related with the loss of catalytic efficiency (i.e., inactivation) over extended operation periods. In this study we explore the mechanism of photocatalytic oxidation of common indoor VOCs (alcohols, aromatic compounds, terpenes) using a bench-scale photoreactor. The experimental setup consists on a single-pass quartz flow reactor filled with glass Raschig rings coated with TiO2, prepared as follows: Pyrex glass rings (frosted surface) were immersed in KOH at pH 13.5 for 48 h, impregnated with a TiO2 suspension 5 % w/v at pH 2.5, applied by dip coating (four times), and calcined at 450 °C for 2 h. The reactor can be illuminated with UV-A and UV-C lamps. Samples are collected during steady-state introduction of the reacting VOC upstream and downstream the reactor, to identify and quantify yields of volatile byproducts. Conversion efficiencies are evaluated for a variety of experimental conditions that include reactor residence time, relative humidity, and light intensity and emission spectrum, in order to identify operation conditions that produce optimal conversion conditions and minimal generation of toxic byproducts.