Researchers discover new method to collect water from humidity using organic crystals

Thanks to two high-resolution microscopes, curiosity, and some luck, researchers have unveiled a completely new method to autonomously harvest water from aerial humidity.
Sade Agard
Could crystals hold the key to tackling Earth's water shortages?
Could crystals hold the key to tackling Earth's water shortages?

Houssem Chaaouri/iStock 

  • A scarcity or shortage of freshwater currently affects millions of people worldwide— with the numbers affected set to almost triple by 2050.
  • New water-harvesting technologies hold the potential to alleviate the foreseeable socioeconomic impacts of severe water scarcity.
  • Researchers at NYU Abu Dhabi discuss their novel method for harvesting water whereby naturally-organic crystals capture water from aerial humidity. 

Fresh water is one of the most precious resources on our planet, and it's a fundamental need for all living things. However, the reality is that fresh water is becoming increasingly scarce in many parts of the world. 

According to the UN, more than 2 billion people live without safely managed drinking water services, and by 2050, it's estimated that up to two-thirds of the world's population could be living in areas where water is scarce for at least one month of the year. With the growing global population and the increasing impact of climate change, the demand for freshwater is expected to continue rising while the supply remains limited. 

Subsequently, also in demand are innovative technologies offering a sustainable means to address the water crisis. Recently, Interesting Engineering (IE) reported on one such initiative whereby organic crystals collect water from humidity in the air, including mist and fog. 

In the study, Research Scientist Patrick Commins and Postdoctoral Associate Marieh B. Al-Handawi at NYU Abu Dhabi (NYUAD) observed for the first time the process of water spontaneously condensing from its vapor to liquid form and moving across the surface of a slowly subliming organic crystal.

Sublimation is the process of a substance changing directly from a solid phase to a gas phase, without first becoming a liquid.

To gain a deeper insight into what their findings could mean for future water-harvesting technologiesIE interviewed the duo, along with the nominated corresponding author on the paper, Panče Naumov — a leader of the Smart Materials Lab and Director of the Center for Smart Engineering Materials at NYUAD.

The following Q&A session has been edited slightly for flow. 

IE: In your own words, could you outline how this process works?

Commins: In this work, we discovered a new mechanism by which humidity from air can be collected on the surface of an organic crystal, and the resulting water can move across that surface due to a combination of physical processes. 

We studied the principles of this water transport, which are general and would — in principle — apply to other surfaces that are dynamic in nature; the concept. Therefore, it is not specific to the material used in this work. 

The mechanism requires the surface to have very thin channels and change their width over time. In our case, this is due to a slow sublimation process where the crystal's surface slowly transitions from the solid to the gas phase. 

Researchers discover new method to collect water from humidity using organic crystals
The particles on the crystalline surface are picked up by water and carried down the channel as the channel sublimes and widens.

This changes the width of the channels, and as a result, we found that the water can move along the channels. This motion causes the water to carry dust and other solid particles along its way.

IE: Please could you tell us about the technology that aided your discovery?

Commins: We were initially using a combination of techniques to study the mechanical properties of this material, which is known to be bendable. We performed careful observation of the surface of the material to be able to understand the mechanism of that deformation. 

In the experiments, we used a combination of two high-resolution microscopes, a curiosity with which we approach all our experiments, and some luck. 

While we were observing the surface of the crystals overnight, we noticed an unusual phenomenon — bits of dust were running along the surface following a clear, linear trajectory, which is not expected for solid particles, as they are usually static. 

The optical microscope enabled us to see the large macroscopic changes, such as particles moving. At the same time, we used an atomic force microscope to investigate the minute changes of the surface during the process, such as the change in the shape of the surface channels.

IE: Please describe how the crystals capture water (i.e. the technical method) from, for example, resources found in the desert? 

Naumov: We must mention here that, at this stage, our research is the fundamental observation of a physical process that could become the basis for new technology in the future.

While we could imagine this process being implemented in various engineering applications, our results are at the stage where more research is necessary to translate this principle into tangible, operational devices for water collection. 

This is a lengthy process that involves both scientists and engineers working together to build real-world devices that would then be optimized, tested and scaled up. 

At this first stage of the research, we look forward to potential sponsorship and partnership with relevant stakeholders interested in translating this discovery into practical applications. We are happy to work with the interested parties toward the implementation of the new technology.

IE: What are some real-world applications where your method could be useful? i.e. who do you suppose would benefit from the crystals/ method?

Al-Handawi: At the current stage of development, this new mechanism is most interesting from a fundamental science perspective as we discovered a new way to autonomously move water across surfaces. 

The principles of the mechanism of having a slowly changing surface to move water are general. We believe it should be possible to be replicated with purposefully fabricated materials other than the prototypical material we studied in our work. 

Since this is such a universal phenomenon, we could envisage an array of applications that involve contact of water with solid surfaces. In one instance, we could think of conceptually new self-cleaning surfaces, where the dust and other particles would autonomously get wiped away as the water condenses on the surface. 

For example, we could imagine coating solar panels with materials that would facilitate the removal of dust and sand that normally deposits onto them.

IE: What are the limitations of your research, including challenges for going to scale? Could you briefly outline the next steps for your approach?

Naumov: As with the translation of any new technology, the limitations are usually related to the process of assessment of performance, optimization of the material, design of the related devices, and perhaps most importantly, scaling up to real-world applications. 

Each of these steps brings some inherent challenges that need to be overcome by proposing suitable technical solutions. One possible limitation of this research is scaling up to real-world conditions. 

In laboratory settings, we could only test the material on microscopic sizes of crystals. At the next stage, this would be scaled by using an ensemble of crystals aligned in some way. 

We are now considering approaches to this challenge. We hope to be able to expand this research by involving external sponsors who are interested in this new technology, which would enable us to include engineers who would work on the practical aspects of the new self-cleaning surfaces.

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