Long-lasting removal of indoor formaldehyde in continuous airflow by B–TiO2@AC composites

Abstract

Formaldehyde can cause unacceptable indoor air quality. Traditional adsorption-based materials for indoor formaldehyde removal have the problem of short lifespan and potential secondary pollution. The black TiO2 was synthesized to engineer a material for long-lasting removal in this study, which has a disordered surface layer and defects, resulting in higher light absorption and a narrower band gap under UV and visible light. The novel TiO2 catalyst was composited with different mass fraction of activated carbon to increase active adsorption sites and improve electron transport efficiency. Besides, the formaldehyde decomposition mechanism and kinetics were investigated by material characterization. The performance of the developed material in removing formaldehyde was evaluated using a high-precision, variable-condition continuous flow system designed to simulate actual application environment. B–TiO2@15AC exhibited 1.5 times higher cumulative removal capacity than traditional KMnO4@Al2O3 material after 16h, while maintaining constant efficiency over 40h. Formaldehyde concentration, activated carbon ratio, relative humidity, irradiation wavelength and air flow were chosen as variables and their effect on the removal efficiency was analyzed using Response Surface Methodology. This study presents a promising new material which is low-cost, easy-to-prepare and applicable in indoor formaldehyde removal.