After absorbing water vapor from the atmosphere, a loofah-based material yields liquid water just by squeezing—much like wringing out a loofah after a bath. This mechanical method for extracting water uses an estimated 1/1,000 of the energy used by traditional methods, which tend to drive water out with heat after a sorbent absorbs the water from the air (ACS Sustainable Chem. Eng. 2026, DOI: 10.1021/acssuschemeng.6c01261).
Harvesting water from air promises safe, clean water in areas where potable water is scarce. Many sorbents—including metal-organic frameworks and hydrogels—are good at sucking up atmospheric moisture, but the ones that capture water best also suck at releasing it. That trade-off means a lot of energy is needed to extract the absorbed water, which is typically achieved by heating the sorbents.
Releasing water by physically compressing a sorbent is a “promising direction,” says materials scientist Guihua Yu of the University of Texas at Austin, who wasn’t involved in this research. Loofah is a “particularly suitable scaffold” for testing this idea, he says. “Its interconnected fibrous structure can store water while also surviving repeated compression.”
Two teams led by Yi Guo and Ming Li at Wuhan Textile University prepared the loofah-based composite material by soaking pieces of loofah in a solution containing the precursors to a superhydrophilic dendrimer—a branched polyamidoamine containing many nitrogen functional groups—and chitosan, which bridges the loofah and the polyamidoamine.
By adjusting the loofah’s soak time, the researchers optimized the balance between the density of channels within the loofah composite, its pore space for holding water, and its structural strength.
At an ideal condition of 95% relative humidity, the best-performing loofah composite could absorb 1.7 g of water per gram of its own weight in 10 h. Importantly, while water enters the loofah composite as vapor, it naturally condenses into liquid water as the loofah composite’s pores become saturated with moisture. That condensation allows liquid water—clean enough to meet World Health Organization drinking-water standards—to be squeezed out by hand. In the Wuhan teams’ experiments, the loofah composite remained structurally intact through fifty water-harvesting cycles at 95% relative humidity while averaging almost 1.5 g of water per gram of its own weight per cycle.
David Warsinger at Purdue University sees the main advantage of this material as its ability to release water when squeezed. He expects the loofah composite to outperform other atmospheric-water harvesters that use heat to release water in terms of the energy required for overall water production.
But the loofah composite’s water-absorbing capabilities drop sharply with lower atmospheric humidity. At 65% humidity, the composite absorbs just 0.68 g per gram of material, and at 35% humidity, just 0.34 g.
This poor performance at lower humidities is partly because the researchers used hydrophilic functional groups for water absorption in the material rather than hygroscopic salts, Austin’s Yu says. For now, salts are incompatible with the squeeze-to-release strategy because they tend to leak and contaminate the water.
While good performance at low humidity is a key metric, Warsinger points out that plenty of places in Latin America or South and Southeast Asia have abundant, but unsafe, water, whether due to pollution or lack of disinfection infrastructure, and their high humidities would allow the material to perform well.
But ultimately, for becoming useful in arid regions, Yu thinks that scientists could try to merge the best of both worlds by pursuing materials systems that contain salts but won’t leak those salts when squeezed.
