Adsorptive Removal of Formaldehyde from Air Using Mixed-Metal Oxides

Volatile organic air pollutants such as aldehyde compounds have been identified as progressively damaging chemicals impacting human health at small albeit dangerous quantities. This study focuses on evaluating the dynamic adsorption of formaldehyde over binary mixed-metal oxides (MMOs) such as ZrO2/SiO2 and TiO2/SiO2 with different metal ratios. In addition, a metal organic framework (MOP), namely, MIL-101(Cr), was synthesized and used as a base adsorbent to which the performance of MMOs was compared. The formaldehyde dynamic adsorption capacity of the materials was determined through breakthrough experiments. Our results indicated that zirconiabased materials exhibit a comparatively higher affinity toward formaldehyde than their titania-based counterparts at very dilute concentrations. In particular, ZrO2/SiO2 with weight ratio of 25/75 exhibited a dynamic adsorption capacity of 2.9 mmol/g at room temperature using a formaldehyde concentration of 170 ppm, which was comparable to that of MIL-101(Cr). Characterization of the materials before and after formaldehyde exposure indicated that formaldehyde was chemically adsorbed on the MMOs. This study highlights the potential of MMOs for efficient abatement of airborne formaldehyde.