Sensitive and Precise Detection of Volatile Organic Compounds and Carbon Dioxide for Evaluating Photo-Degradation Processes of Indoor Air Pollutants

Abstract

Typical concentrations of volatile organic compounds (VOCs) in indoor environments range from hundreds of ppb to several ppm. Even at these low concentrations, prolonged indoor exposure to VOCs has been linked to sick building syndrome, a condition associated with adverse effects on human health. Therefore, an increasing amount of research has been focused on removing VOCs from indoor air. To research VOC degradation reactions at low concentrations, highly sensitive detection methods should be designed and employed. In this work, we report on the development of a photo-reaction setup, including VOC and CO2 detection at ppm–ppb level. We designed a temperature-controlled photocatalytic reactor that enables batch-mode photocatalytic reactions. The developed setup enables reliable testing of photocatalytic materials for VOC degradation at ppm–ppb levels, while allowing for precise yet flexible control of reaction conditions, including relative humidity (RH) control of the gas phase and adaptable light source selection. A gas chromatograph with a VOC and CO2 detection limit of 200–250 ppb analyzes the gas phase. The setup was benchmarked with acetone as model VOC and P25-TiO2 as widely used photocatalyst using simulated solar light and initial VOC concentrations between 5 and 1000 ppm. After photocatalytic degradation, acetone was detected down to 1 ppm.