A Hybrid Hydrogel
with High Water Vapor Harvesting Capacity
for Deployable Solar-Driven Atmospheric Water Generator
Abstract:
The Earth’s atmosphere
holds approximately 12,900 billion tons of fresh water and it distributes all
over the world with fast replenishment. The atmospheric water harvesting is
emerging as a promising strategy for clean water production in arid regions,
land-locked, and remote communities. The water vapor sorbent is the key
component for atmospheric water harvesting devices based on absorbing-releasing
process. In this work, a flexible hybrid photothermal water sorbent composed of
deliquescent salt and hydrogel was rationally fabricated. It possesses superior
water sorption capacity even in low humidity air thanks to the deliquescent
salt and it maintains a solid form after it sorbs a large amount of water owing
to the hydrogel platform. The harvested
water could be easily released under regular sunlight via the photothermal
effect, and it can be directly reused without noticeable capacity fading. An “easy-to-assemble-at-household”
prototype device with 35 g of the dry hydrogel was tested outdoors in field
conditions and delivered 20 g of fresh water within 2.5 h under natural
sunlight. It is estimated that the material cost of making such a device to
supply minimum daily water consumption for an adult (i.e., 3 kg) is only $3.2
(USD). This type of atmospheric water generator (AWG) is cheap and affordable, perfectly
works with a broad range of humidity, does not need any electricity, and thus
is suitable especially for clean water production in remote areas.
Keywords:
atmospheric water harvesting, hydrogel, deliquescent salt, sunlight, potable
water