Improving Indoor Air Quality with Plants that Capture Formaldehyde

Objective

Contribute to the development of a greenwall system—one that can be flexibly scaled and architecturally integrated into multiple building types and sizes—by designing and experimentally testing the ability of plants growing in engineered soil to capture the common toxin formaldehyde.

Background

Certain types of construction materials and building elements—e.g., paints, coatings, and materials infused into furniture—can give off toxins that significantly degrade indoor air quality (IAQ) over time. These ambient toxins have negative impacts on human health, and require expensive outlays of energy to maintain IAQ at satisfactory levels within buildings. Accordingly, there is a need for air purifying devices that can effectively and affordably clean and circulate the air inside buildings.

One proposed solution involves biological systems that rely upon the ability of plants to remove toxins from indoor spaces. The plants can be integrated into hydroponic systems that include growth media—engineered soil—that incorporates chemical elements capable of capturing selected toxins. The toxins are adsorbed by the growth media, and the plants then metabolize them into fertilizer—in effect creating a self-regenerating filtration system.

This project will focus on formaldehyde, a toxin commonly found in paint and furniture, and which not only degrades IAQ but can be carcinogenic as well. And it will focus on ionic liquids (ionic salts with a relatively low melting point) as growth media binders that can be tuned to selectively capture ambient formaldehyde.

Suggested Approaches

(i)  Conduct background research into:  various existing and proposed greenwall systems (active, passive, and building-integrated); the basics of formaldehyde capture and carbon dioxide capture; varieties of ionic liquids and their applications in biological media; etc.

(ii)  Focusing on ionic liquids, investigate which ionic liquid(s) are optimal in terms of efficient capture of formaldehyde, effective integration with growth media, and reasonable cost.

(iii)  Design a small-scale media filtration cassette (essentially a single “test cell” consisting of a single plant in growth media). Use this test cell to experimentally test the performance of ionic liquids as growth media binders that capture ambient formaldehyde.