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Atmospheric water vapor is an abundant and renewable resource that can alleviate growing water scarcity. Hybrid hydrogel desiccants composed of hygroscopic salts hold significant promise for atmospheric water harvesting (AWH) due to their increased capacity for water uptake. Thus far, many efforts in fabricating these desiccants require multistep processes, where the salt impregnation is achieved post-hydrogel fabrication. Here, we develop a scalable wet spinning methodology using aramid nanofibers (ANFs) to template and coagulate hydroxypropyl cellulose (HPC) into filaments in a coagulation bath consisting of water and lithium chloride (LiCl). HPC serves as the matrix to retain the captured water vapor, and later releases it upon heating. ANFs serve as the physical cross-linker between HPC, allowing for wet spinning at a speed up to 61 m h–1. The composite filaments achieve up to 0.55 g g–1 water uptake at 30% relative humidity (RH) and 21 °C, reaching 80% saturation in 40 min. With a lower critical solution temperature of 39 °C, the desiccant filaments can release up to 72% of the captured water at 60 °C after 30 min. In an AWH chamber, the filaments can achieve daily water production of 5.21 L kg–1 day–1 at 30% RH and 21 °C.
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This content will become publicly available on May 1, 2027
Biomass Polymer‐Stabilized Hygroscopic Salts in Cellulose Foams for Durable Atmospheric Water Harvesting
ABSTRACT Atmospheric water harvesting (AWH) is a promising strategy to alleviate freshwater scarcity, with hygroscopic salts (e.g., LiCl) widely employed as active sorbents due to their high water affinity. However, practical deployment is hindered by the deliquescence of salts, which can lead to leakage, migration, and potential corrosion. Herein, we report a robust LiCl+CMC@cellulose composite foam fabricated via a scalable room‐temperature impregnation–drying strategy. By introducing carboxymethyl cellulose (CMC) as a polymeric stabilizer, we effectively immobilize LiCl within the cellulose scaffold through ionic coordination, suppressing salt aggregation and leakage. Benefiting from the hierarchical porous architecture of cellulose and this salt immobilization strategy, the optimized composite (treated by 15 wt% LiCl, 0.5 wt% CMC solution) achieves a high water uptake of 3.57 ± 0.15 g at 25°C and 90% relative humidity (RH) within 24 h, corresponding to 16.04± 0.82 g g−1when normalized to pristine cellulose foam, representing a 15.4% enhancement over non‐stabilized counterparts. Crucially, the composite exhibits excellent durability, retaining 82.4% of its capacity after ten water uptake–release cycles. Furthermore, a spray‐coated carbon black (CB) surface layer enables rapid photothermal heating (up to 50.6°C under one sun irradiation), facilitating efficient solar‐driven water release. This integrated, environmentally benign design offers a low‐cost, durable platform for scalable, high‐performance AWH.
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- PAR ID:
- 10689881
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Small Methods
- Volume:
- 10
- Issue:
- 9
- ISSN:
- 2366-9608
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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