Organic Sorbents for Air Purification: A New Application for Recyclable Hyper-Cross-Linked Polystyrene

Sorption-based air purification is typically performed using inorganic sorbents such as activated carbon. Organic polymeric sorbents with a microporous or nanoporous structure could be a promising alternative. We investigated the effectiveness of four hyper-cross-linked polystyrenic sorbents against formaldehyde and compared it to the effectiveness of three activated-carbon-based preparations. One of the polystyrenic sorbents (MN270) was nanostructured, and it reduced formaldehyde concentration by over 95% (from 0.463 ± 0.037 mg/m3 to 0.020 ± 0.002 mg/m3) in short-duration tests. In the long-duration tests (500 min), MN270's performance was comparable to that of the pure coconut shell activated carbon. MN270 was found to be nanostructured (10–200 nm pores), which was associated with its superior sorptive properties and the comparatively high Brunauer–Emmett–Teller (BET) result of 1370.49 ± 19.19 m2/g, which was higher than the best-performing activated carbon sorbent (941.76 ± 18.10 m2/g). The novel application of the hyper-cross-linked polystyrenic sorbents for air purification provides a feasible and potentially more sustainable alternative to inorganic sorbents, thanks to their recyclability and manufacturability from biomass.