Biodegradable porous adsorbent for efficient formaldehyde removal from indoor air

Prolonged formaldehyde exposure in indoor environments poses significant health risks. This study presents a biodegradable, cost-effective porous adsorbent engineered for efficient formaldehyde removal from indoor air. Comprising alginate, carboxymethyl cellulose, and attapulgite, the composite adsorbent leverages alginate and carboxymethyl cellulose to establish a stable porous framework, while attapulgite optimizes pore architecture. Polyethyleneimine was incorporated to introduce amino functional groups, thereby enhancing adsorption performance. At a polyethyleneimine concentration of 7 wt%, the adsorbent achieved a formaldehyde adsorption capacity of 2.31 mg/g, with a distribution coefficient quadrupling that of activated carbon at only 30 % of its cost. Adsorption kinetics conformed to a pseudo-second-order model, and isotherm analysis aligned with the Sips model, suggesting chemisorption as the predominant mechanism, complemented by physisorption. Moreover, the adsorbent demonstrated outstanding reusability and biodegradability, retaining 94.29 % of its initial capacity after four regeneration cycles and exhibiting a decomposition rate of 49 % after 30 days. This study provides a sustainable, high-performance solution for indoor formaldehyde removal with strong potential for practical applications.