UV light holds promise for energy-efficient desalination

UCR experiments offer pathway for solar solutions

University of California - Riverside

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Luat Vuong

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Credit: UC Riverside

A team of UC Riverside researchers has uncovered a potential breakthrough in solar desalination that could reduce the need for energy-intensive saltwater treatment.

Led by Luat Vuong, an associate professor of mechanical engineering in UCR’s Marlan and Rosemary Bourns College of Engineering, the team has demonstrated for the first time how the highest frequencies of sunlight—specifically invisible ultraviolet (UV) light—can break the stubborn bonds between salt and water.

“To our knowledge, nobody else has yet articulated this deep UV channel for salt-water separation,” Vuong said. “UV light in the wavelength range of 300-400 nanometers is used for disinfection, but this deep UV channel around 200 nanometers is not well known. We may be the first to really think about how you can leverage it for desalination.”

While much work remains before practical applications are developed, the discovery provides a clear path for further research and innovation.

Published in ACS Applied Materials & Interfaces, the study by Vuong and her colleagues details how the team made a wick from aluminum nitride—a hard, white ceramic—to separate salt from water by harnessing specific light wavelengths that interact with salt water without heating the bulk liquid. Unlike traditional solar desalination methods, which rely on dark materials to absorb heat and boil water, Vuong’s approach could bypass the need for thermal processes altogether.

The experiments involved placing pairs of ceramic wicks in an enclosed chamber, with each allowed to equilibrate or adjust to similar environmental conditions. Under UV light, evaporation rates of salt water increased significantly compared to control samples kept in the dark or exposed to red, yellow, or infrared light.

“Aluminum nitride is well suited for emitting UV light due to its crystalline structure,” Vuong explained.

The material may be triggering a process called “photon upconversion,” in which low-energy photons combine into a single high-energy photon. That upconverted photon delivers a more powerful punch, potentially strong enough to break the salt-water bonds. If this upconversion process occurs without generating excess heat, which is yet to be determined, the approach could offer a non-photothermal alternative to traditional solar desalination systems that boil or heat salt water to produce vapor, which then condenses into fresh water. 

Such solar systems also could reduce the heavy electricity demands of reverse osmosis systems, which use high-pressure pumps to force salt water through membranes. The system could also address the concentrated reverse-osmosis brine waste, which is toxic to marine life when discharged into waterways.

Other potential applications for the wicking approach may be for other waste management processes, harvesting minerals in extreme environments, or replacing “swamp” coolers with salt water evaporation systems.

Still, Vuong emphasized that further research is needed before aluminum nitride-based solar desalination systems can be engineered for widespread use. 

“Other materials may be designed to be just as effective, but aluminum nitride is practical. It is inexpensive, widely available, non-toxic, highly hydrophilic, and durable,” Vuong said.

Click here for more information.
 

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Journal

ACS Applied Materials & Interfaces

DOI

10.1021/acsami.5c12331 

Method of Research

Experimental study

Article Title

Spectrum Selective Interfaces and Materials toward Nonphotothermal Saltwater Evaporation: Demonstration with a White Ceramic Wick

 

Lichens and drones reveal dinosaur bones

University of Reading

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Vibrant orange-coloured lichens are helping scientists discover dinosaur fossils in Canada, according to a new study published today [3 November] in Current Biology.

An international team of palaeontologists and remote sensing scientists have made an exciting discovery at UNESCO World Heritage Site Dinosaur Provincial Park, in Alberta. They have found that certain lichen species preferentially colonise exposed dinosaur bones, creating distinctive spectral signatures that can be detected from 30 metres above ground using drones.

Dr Brian Pickles, from the University of Reading (UK), and lead author of the paper, said: "This research highlights how modern organisms can help us to find ancient  ones.

“It's remarkable to consider that these lichens, essentially miniature ecosystems, are founded upon the remains of dinosaurs that died over 75 million years ago. Using drone technology to detect the spectral signatures of the lichens could potentially revolutionise how palaeontologists search for fossils."

The team found that the two lichen species – Rusavskia elegans and Xanthomendoza trachyphylla – colonised as much as 50% of exposed fossil bones but less than 1% of surrounding rock fragments. This likely occurs because dinosaur bones provide the alkaline, calcareous, and porous substrates these lichens favour.

Dr Caleb Brown, from the Royal Tyrrell Museum of Palaeontology (Canada), said: “This pattern of lichen growing preferentially on fossil bone has been noted for decades, but never quantified until now. When first encountering high concentrations of exposed fossil bone like bonebeds, it is often the ‘meadow’ of orange lichen that is noticed first, not the bones themselves.” 

Using Remotely Piloted Aircraft Systems (drones) with specialised sensors, the team successfully identified lichen-colonised fossils from aerial images with 2.5cm pixel resolution. The lichens exhibit distinct spectral properties, showing lower reflectance in blue wavelengths and higher reflectance in infrared regions.

The method can offer significant advantages for palaeontological prospecting, particularly in remote terrain where traditional ground surveys are challenging. The approach could accelerate fossil discovery while reducing field costs and environmental impact.

The research builds on decades of anecdotal observations by palaeontologists. In 1980, palaeontologist Darren H. Tanke speculated that the orange pigmentation of the lichen on Centrosaurus bones might be detectable by satellites – a prediction that seems closer than ever now that they can be found using airborne drone technology.

Dr Derek Peddle, part of the remote sensing team from the University of Lethbridge (Canada), said:  "This drone study lays the groundwork for mapping much larger areas using aircraft and satellites. The new lichen indicators we've developed will help us find fossils across vast landscapes. It's exciting to combine our imaging technology with this international team's expertise to advance dinosaur discovery through remote sensing of lichen."

The team emphasises that the method works well in semi-arid environments like the Canadian Badlands, where the specific lichen species thrive and bones remain exposed long enough for colonisation. They intend to explore the broader extent of this association in their future work.

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Journal

Current Biology

DOI

10.1016/j.cub.2025.09.036 

Article Title

Remote sensing of lichens with drones for detecting dinosaur bones

Article Publication Date

3-Nov-2025

 

Antarctic glacier retreated faster than any other in modern history

University of Colorado at Boulder

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Hektoria Glacier on Antarctica’s Eastern Peninsula experienced the fastest retreat recorded in modern history—in just two months, nearly 50 percent of the glacier disintegrated. This video illustrates how and why Hektoria Glacier retreated so rapidly in late 2022 and early 2023. New CU Boulder-ledresearch shows the main driver was underlying flat bedrock that enabled the glacier to go afloat after it substantially thinned, causing a rare rapid calving process.

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Credit: Lauren Lipuma/CIRES

A glacier on Antarctica’s Eastern Peninsula experienced the fastest retreat recorded in modern history—in just two months, nearly 50 percent of the glacier disintegrated. 

A new CU Boulder-led study, published today in Nature Geoscience, details how and why Antarctica’s Hektoria Glacier retreated at an unprecedented rate in 2023, losing a total of eight kilometers of ice in two months. The main driver was the glacier's underlying flat bedrock that enabled the glacier to go afloat after it substantially thinned, causing a rare calving process. 

The new findings may help researchers identify other glaciers to monitor for rapid retreat in the future. Hektoria Glacier is small by Antarctic standards—only about 115 square miles, or roughly the size of Philadelphia—but a similar rapid retreat on larger Antarctic glaciers could have catastrophic implications for global sea level rise. 

“When we flew over Hektoria in early 2024, I couldn’t believe the vastness of the area that had collapsed,” said Naomi Ochwat, lead author and CIRES postdoctoral researcher. “I had seen the fjord and notable mountain features in the satellite images, but being there in person filled me with astonishment at what had happened.”  

The research team, which included CIRES Senior Research Scientist Ted Scambos, surveyed the area surrounding Hektoria Glacier using satellites and remote sensing for a separate research study. They wanted to understand why sea ice broke away from a glacier a decade after an ice shelf collapse in 2002. While analyzing results for the first study, Ochwat noticed data that indicated Hektoria had all but disappeared over a two-month period.  

So, she set out to understand: why did this glacier retreat so fast?

Many glaciers in Antarctica are tidewater glaciers—glaciers that rest on the seabed and end with their ice front in the ocean and calve icebergs. The topography beneath these glaciers is often varied; they may sit upon deep canyons, underground mountains, or big flat plains. In Hektoria's case, the glacier rested on top of an ice plain, a flat area of bedrock below sea level. Researchers previously found that 15,000-19,000 years ago, Antarctic glaciers with ice plains retreated hundreds of meters per day, and this helped the team better understand Hektoria’s rapid retreat. 

When tidewater glaciers meet the ocean, they can go afloat, where they float on the ocean's surface rather than resting on solid ground. The point at which a glacier goes afloat is called the grounding line. Using several types of satellite data, the researchers discovered Hektoria had multiple grounding lines, which can indicate a glacier with ice plain topography underneath. 

Hektoria’s ice plain caused a large part of the glacier to go afloat suddenly, causing it to calve quickly. Going afloat exposed it to ocean forces that opened up crevasses from the bottom of the glacier, eventually meeting crevasses exposed from the top, causing the entire glacier to calve and break away. 

The team used satellite data to study the glacier at different time intervals and created a robust picture of the glacier, its topography, and its retreat. 

“If we only had one image every three months, we might not be able to tell you that the glacier lost two and a half kilometers in two days,” Ochwat said. “Combining these different satellites, we can fill in time gaps and confirm how quickly the glacier lost ice.” 

The researchers also used seismic instruments to identify a series of glacier earthquakes at Hektoria that occurred simultaneously with the rapid retreat period. The earthquakes confirmed the glacier was grounded on bedrock rather than floating, proving both the presence of an ice plain topography and that the ice loss contributed directly to global sea level rise.

Ice plain topographies have been detected across numerous glaciers in Antarctica, and the research on Hektoria will help scientists anticipate and forecast potential rapid retreat across the continent. 

“Hektoria’s retreat is a bit of a shock—this kind of lighting-fast retreat really changes what’s possible for other, larger glaciers on the continent,” Scambos said. “If the same conditions set up in some of the other areas, it could greatly speed up sea level rise from the continent.”    

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Journal

Nature Geoscience

DOI

10.1038/s41561-025-01802-4 

 

Research Center for Eco-Environmental Sciences (CAS) scientists envision environmental catalytic cities for air pollution control

These new urban engines with self-purification function are expected to remove air pollution without additional energy consumption

Editorial Office of Journal of Environmental Sciences

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Researchers envision a new engine for air pollution control in the near future.

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Credit: barnyz from Flickr Image Source Link: https://openverse.org/image/4521bb08-870b-4b51-a7c7-18c1ec1cb22e

Over the last century, anthropogenic activities have profoundly impacted the Earth’s environment, ushering in the era of climate change and global warming that threatens the sustainability of humankind. Human activities generate and emit particulate matters, volatile organic compounds, as well as inorganic pollutants such as nitrogen oxides, sulfur dioxide, and ammonia, into the troposphere. Notably, precursor volatile organic compounds and nitrogen oxides react in sunlight to form another major pollutant in the form of ozone. These pollutants deteriorate air quality, significantly harm human health, ecosystems, and crop yields, and expedite climate change.

To tackle these challenges head on, governments worldwide have put in place stringent air quality standards and air pollutant emission standards. However, air pollution control still faces several bottlenecks, especially in developing countries, which suffer from severe ozone pollution, require full particulate matter control, and must collaboratively control particulate matter and ozone. While simultaneous precursor control is a promising strategy to reverse ozone rebound, it is quite difficult to substantially bring down the emission of volatile organic compounds in a short period.

Addressing this concern, a team of researchers from China, led by Hong He from the Laboratory of Atmospheric Environment and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, China, has comprehensively reviewed the next-generation technologies that can directly purify pollutants in the atmospheric environment: photocatalysis and ambient temperature catalysis. Their study, which included researchers from the Institute of Chemistry and the Institute of Urban Environment at Chinese Academy of Sciences, Tsinghua University, and the University of Chinese Academy of Sciences, was made available on 25 February 2025 and has been published in Volume 156 of the Journal of Environmental Sciences on 1 October 2025.

Hong says: “Ozone air pollution is a major challenge to the improvement of urban environmental quality. Ozone is a typical secondary air pollutant, and its formation chemistry from its precursors is highly nonlinear. As a result, the emission reduction of its precursors is not always effective and therefore new assisted approaches to control ozone pollution are needed. Photocatalysis and ambient catalysis technologies are expected to be applied in open atmosphere as a new booster to the direct purification of air pollutants in emission sources.”

Photocatalysis involves the light-induced generation of electron−hole carrier pairs that migrate to surface and initiate redox reactions of adsorbents with various reactive species that degrade pollutants. This green and sustainable technology has been implemented practically in Japan and Europe. However, further progress is necessary in terms of catalyst stability, cost considerations, and engineering applications.

Besides photocatalysis, ambient temperature non-photocatalytic purification is another promising method for air pollutant removal. It involves their decomposition into harmless products such as water, carbon dioxide, and oxygen. This technology is especially useful for the removal of formaldehyde and ozone using TiO2-supported noble metal and NiFe-layered double hydroxide catalysts, respectively.

Based on these technologies, the research team proposes the novel concept of an ‘Environmental Catalytic City.’ It refers to the spontaneous purification of low-concentration urban air pollutants in the atmosphere directly using a coating of stable, efficient, and green catalytic materials on artificial surfaces, such as walls of buildings, roads, and radiator surfaces of motor vehicles, in the city. Through this futuristic technology, an urban city with technologically enhanced self-purification function can successfully mitigate air pollution without any additional energy consumption.
“In the future, scientists must strive to develop low-cost catalysts that can efficiently remove ozone and other pollutants, so as to improve the practicability and feasibility of ‘Environmental Catalytic City,’ and thus provide an additional new engine to better solve the problem of urban air pollution,” concludes Hong optimistically.

 

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Reference
DOI: 10.1016/j.jes.2025.02.019

 

About the Research Center for Eco-Environmental Sciences, CAS
Research Center for Eco-Environmental Sciences (RCEES), Chinese Academy of Sciences, established in 1975, is a research institution involved in research on eco-environmental science and technology in China. It currently hosts 473 staff members, including academicians, research, associate, and assistant professors, and junior researchers or administrators working in various areas in its 11 research departments or laboratories. RCEES carries out frontier researches on environmental chemistry, environmental science, and systems ecology and has made made historical contribution to the development in the eco-environmental sciences and technology in China.
Website: http://english.rcees.cas.cn/

 

About Hong He from Research Center for Eco-Environmental Sciences, CAS
Hong He leads the Laboratory of Atmospheric Environment and Pollution Control and is a Deputy Director at the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, China. His research interests include environmental catalysis, heterogeneous atmospheric chemistry, and air pollution control technology. He is the author of more than 400 peer-reviewed scientific publications, with over 13,700 citations, and the first inventor on 45 authorized patents. He received his doctorate at the University of Tokyo in 1994.

 

Funding information
The authors appreciate the support of the National Natural Science Foundation of China (NSFC) (Nos. 52425003, 22188102, and 52400144), the Project funded by China Postdoctoral Science Foundation (Nos. BX20220325 and 2023M743707), and the Youth Innovation Promotion Association, CAS (Nos. Y2021020 and Y2022023).

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Journal

Journal of Environmental Sciences

DOI

10.1016/j.jes.2025.02.019 

Method of Research

Systematic review

Subject of Research

Not applicable

Article Title

Environmental catalytic city: New engine for air pollution control