ALL KALE IS WASTE TO ME

Singapore scientists develop a sustainable way to convert kale waste into products for health and personal care

Peer-Reviewed Publication

NANYANG TECHNOLOGICAL UNIVERSITY

 

IMAGE: (L-R) MEMBERS OF THE RESEARCH TEAM INCLUDE CO-AUTHOR DR LIANG YEN NAN, SENIOR RESEARCH FELLOW, ENVIRONMENTAL CHEMISTRY AND MATERIALS CENTRE AT THE NANYANG ENVIRONMENT & WATER RESEARCH INSTITUTE (NEWRI), AND LEAD INVESTIGATOR, PROFESSOR HU XIAO, NTU SCHOOL OF MATERIALS SCIENCE AND ENGINEERING AND PROGRAMME DIRECTOR, SUSTAINABLE CHEMISTRY & MATERIALS, NEWRI. view more 

CREDIT: NTU SINGAPORE

Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a new technique to convert kale waste for use in health and personal care products, reducing food waste and emissions.

Millions of tonnes of food and vegetables are discarded globally every year. In the case of leafy vegetables like kale and lettuce, farmers cut off outer leaves as they are harvested, in order to sell perfectly sized and aesthetically pleasing vegetables with no signs of damage or yellowing. This commercial practice results in a significant amount of perfectly good, edible leaves being thrown away. In Singapore, some 817,000 tonnes of food waste were generated in 2021, almost half of which was fruit and vegetables.

Phytochemicals found in plants are known to prevent damage to cells in the body and are widely used in consumer products. They include health-promoting supplements, like antioxidants and lutein, as well as face scrubs and hair shampoo with kale extracts.

Current processes for extracting phytochemicals from kale are energy-intensive, requiring high pressure and temperatures, which contribute additional CO2 emissions to the environment. Moreover, the industrial extraction processes only target a single type of phytochemical each time.

Seeking a more sustainable and efficient method to turn vegetable waste into ‘treasure’, the NTU researchers looked to naturally derived natural deep eutectic solvents (NADES) - non-toxic liquids made up of plant-based compounds such as amino acid, sugar, and vegetable oil by-product - for answers.

While NADES have long been studied in separation technology for food and pharmaceutical industries, not much is known about their ability to extract different classes of bioactive compounds from vegetable waste.

Focusing on bioactive compounds in kale, the NTU research team explored a range of NADES, mixing them with processed kale waste to observe how molecules reacted to each other.

After repeated testing, the researchers established the best NADES solvent for optimal extraction of bioactive compounds. The NTU team found that when the kale waste and NADES mixture is stirred and set aside, it naturally separated into layers, facilitating the easy extraction of the phytochemicals from kale (polyphenols, carotenoids, and chlorophylls) without the need for heating.

Since there is no need to heat or pre-treat the kale waste, for example by freeze drying, the costs of the simpler extraction process are kept down. The NTU research team is confident their newly developed method would be scalable and attractive cost wise to the industry.

Lead author of the study, Professor Hu Xiao from the NTU School of Materials Science and Engineering (MSE) and Programme Director, Sustainable Chemistry & Materials, Nanyang Environment & Water Research Institute (NEWRI), said, “The use of non-toxic and naturally derived solvents in our method makes it a food-safe technique. At the same time, our method preserves the potency of the extracted active ingredients, making it highly attractive for industry adoption. The extracted nutrients can potentially be used for applications in personal care products, cosmetics, food supplements, and herbal extracts.”

The NTU research team said that their waste-to-resource approach tackles both food waste and reduces emissions, supporting the development of a circular economy with zero waste as outlined in the United Nations Paris Agreement.

The study, which was published in the scientific journal Separation and Purification Technology in July, is aligned with the research pillar of NTU 2025, the University’s five-year strategic plan which aims to leverage innovative research to mitigate human impact on the environment.

 

NTU’s non-toxic and high yield technique

Established industrial methods to extract beneficial compounds from plants involve the use of harmful chemicals like methanol, which can pose significant health and safety risks. In contrast, the NTU research team approach uses naturally derived NADES which are non-toxic.

The newly developed process involves first blending the kale waste into a paste (or freeze-dried and ground into a powder form). The researchers then mixed the kale paste (or powder) with their specially formulated NADES solvent and stirred it mechanically at room temperature, before filtering the mixture to extract the beneficial compounds. The entire low energy process, unlike current industrial methods that require high heat, is also fast and can be completed within 30 minutes.

Since bioactive nutritional compounds are temperature-sensitive and degrade with heating, the NTU method helps to avoid degradation, said the researchers.

In lab experiments, the team found that their approach successfully yielded an extract that was 2.2 times richer in polyphenols, compared to conventional methods using methanol. Moreover, the bioactive phytochemicals remained ‘active’ after storage at four degrees Celsius for 30 days, displaying excellent shelf-life.

First author Dr Lee Sze Ying, a research fellow at the Environmental Chemistry and Materials Centre at NEWRI at the time of the study, said, “Our extraction approach is unique because it allows for the simultaneous recovery and separation of multiple valuable compounds from the vegetable waste in a single process without using heat. Moreover, the polyphenol-rich extract remained stable in the extraction solvent, meaning that manufacturers can simply add the extract directly into the formula of their cosmetic products without further processing, reducing production time.”

Co-author Dr Liang Yen Nan, Senior Research Fellow, Environmental Chemistry and Materials Centre at NEWRI, explained, “Our method essentially manipulates the chemical nature of NADES and other green solvents to maximize the extraction efficiency of the bioactive compounds found in kale. This approach induces simultaneous recovery of multiple phytochemicals from the kale and can easily be adapted for use in other types of vegetable and fruit wastes. Moreover, we have demonstrated that our approach remains viable even if we were to eliminate the energy-intensive freeze-drying of the kale waste, making our technology greener, cheaper, and scalable for industry use.”

 

Investigating approaches for use in other crop waste

The team has filed a patent in Singapore for the innovation. For their next steps, the researchers are investigating the feasibility of applying their newly developed method to extract beneficial compounds from other types of fruits and vegetables, and medicinal plants like dragon fruit, spinach, and lettuce.

Kale waste for the study was provided by Sustenir Agriculture, a Singapore-based high-tech urban farming company. The kale leaves used for the research did not meet commercial quality standards and were intended to be discarded as waste.

***END***

The NTU process first takes kale waste, turning it into a paste or powder form, before mixing it with a specially formulated natural deep eutectic solvent. The mixture is then filtered to extract beneficial compounds from the kale waste.

The NTU method extracts phytochemicals from kale, including chlorophylls and lutein, without the need for heating.

CREDIT

NTU Singapore

Notes to Editor:

Paper titled “Single-step extraction of bioactive compounds from cruciferous vegetable (kale) waste using natural deep eutectic solvents” published in Separation and Purification Technology, 15 July 2023, Volume 317. DOI: 10.1016/j.seppur.2023.123677

 

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JOURNAL

Separation and Purification Technology

DOI

10.1016/j.seppur.2023.123677 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Single-step extraction of bioactive compounds from cruciferous vegetable (kale) waste using natural deep eutectic solvents

 

Clever coating turns lampshades into indoor air purifiers

Reports and Proceedings

AMERICAN CHEMICAL SOCIETY

 

IMAGE: A LAMPSHADE COATED WITH A CATALYST USES HEAT FROM AN INCANDESCENT BULB TO DESTROY INDOOR AIR POLLUTION. view more 

CREDIT: MINHYUNG LEE

SAN FRANCISCO, Aug. 16, 2023 — Indoor air pollution may have met its match. Today, scientists will report that they have designed catalyst-coated lampshades that transform indoor air pollutants into harmless compounds. The lampshades work with halogen and incandescent light bulbs, and the team is extending the technology so it will also be compatible with LEDs.

The researchers will present their results at the fall meeting of the American Chemical Society (ACS). ACS Fall 2023 is a hybrid meeting being held virtually and in-person Aug. 13–17, and features about 12,000 presentations on a wide range of science topics.

The lampshades target volatile organic compounds (VOCs), which account for most indoor airborne pollutants, according to Hyoung-il Kim, Ph.D., the project’s principal investigator. These compounds include acetaldehyde and formaldehyde and are released by paints, cleaners, air fresheners, plastics, furniture, cooking and other sources.

“Although the concentration of VOCs in a home or office is low, people spend more than 90% of their time indoors, so the exposure adds up over time,” Kim says.

“Conventional methods to remove VOCs from indoor air rely on activated carbon or other types of filters, which have to be replaced periodically,” says Minhyung Lee, a graduate student in Kim’s lab at Yonsei University. Lee will present the team’s work at the ACS meeting. Other devices have been developed that break down VOCs with the help of thermocatalysts activated by high temperatures or with photocatalysts, which respond to light. But Kim notes that most of these units need a separate heater or an ultraviolet (UV) light source, which can produce unwanted byproducts. His team wanted to take a simpler approach that would only require a visible light source that also produces heat — such as a halogen or incandescent bulb — and a lampshade coated with a thermocatalyst.

Halogen bulbs convert a mere 10% of the power they use into light, with the other 90% being transformed into heat, according to Lee. Incandescent bulbs are even worse, emitting 5% light and 95% heat. “That heat is typically wasted,” Kim says, “but we decided to use it to activate a thermocatalyst to decompose VOCs.”

In a paper published last fall, the team reported that they had synthesized thermocatalysts made of titanium dioxide and a small amount of platinum. The researchers coated the inside of an aluminum lampshade with the catalyst and placed the shade over a 100-watt halogen bulb in a test chamber containing air and acetaldehyde gas. Turning the lamp on heated the shade to temperatures up to about 250 degrees Fahrenheit — warm enough to activate the catalysts and decompose acetaldehyde. During this oxidation process, the VOC was initially converted into acetic acid, then into formic acid, and finally into carbon dioxide and water. Both of the acids are mild, and the amount of carbon dioxide released is harmless, Kim notes. The researchers also found that formaldehyde can be decomposed under the same conditions and that the technique works with incandescent bulbs.

“This was the first demonstration to utilize waste heat from lamp sources,” Kim says. Most previous research projects, and even a couple of lamps on the market, have instead relied on light-activated photocatalysts to destroy indoor air pollution.

In its latest work, Kim’s group is turning to less expensive substitutes for platinum. The team has already shown that these new iron- or copper-based catalysts can break down VOCs. In addition, copper is a disinfectant, so Kim anticipates that the copper catalyst could kill airborne microorganisms.

The scientists are now looking for ways to extend the pollution-destroying-lampshade concept to LEDs, a fast-growing segment of the lighting market. Unlike halogen and incandescent bulbs, however, LEDs release too little heat to activate thermocatalysts. So Kim’s team is developing photocatalysts that are stimulated by the near-UV light emitted by LEDs, as well as other catalysts that transform part of the LEDs’ visible light output into heat. “Our ultimate goal is to develop a hybrid catalyst that can utilize the full spectrum produced by light sources, including UV and visible light, as well as waste heat,” Kim says.

The researchers acknowledge support and funding from the National Research Foundation of Korea; Ministry of Land, Infrastructure and Transport; Ministry of Environment; and Ministry of Trade, Industry and Energy.

A recorded media briefing on this topic will be posted Wednesday, Aug. 16, by 10 a.m. Eastern time at www.acs.org/acsfall2023briefings. Reporters can request access to media briefings during the embargo period by contacting newsroom@acs.org.

For health and safety information for ACS Fall 2023, please visit the FAQ webpage.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive press releases from the American Chemical Society, contact newsroom@acs.org.

Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society.

Follow us: Twitter | Facebook | LinkedIn | Instagram

Title
Thermocatalytic oxidation of VOC through harnessing indoor waste heat

Abstract
With the onset of modernization, the time spent indoors has increased due to the severity of air pollution (SARS-CoV-2, fine dust, airborne microorganisms, and volatile organic compounds). Hazardous air pollutants mainly occur in various industrial and interior sources. However, due to poor air circulation, more pollutants are exhibited indoors than outdoors. Conventional methods of removing VOC using activated carbon or filters have been used, but these methods require periodic replacement. Technologies such as photocatalysts using ultraviolet light and thermal catalysts using high temperatures (200 ~ 400 °C) have been studied a lot, but these methods have a problem in that they require additional equipment.

In here, we introduce the low-temperature thermocatalysis system that effectively acts on the waste heat from indoor lamps (e.g., halogen-, incandescent-, sodium- and metal halide lamps). Pt-TiO2, which can exhibit high catalytic activity by loading a trace amount of platinum nanoparticles on the TiO2 catalyst surface, was used as the optimal thermocatalyst. The Pt-TiO2 catalyst can adsorb/remove a high concentration of VOC even at room temperature. In addition, VOC is completely oxidized and converted into harmless CO2 under the condition of 120 °C, which is the lowest heating temperature of indoor bulbs. Furthermore, by coating the thermocatalyst on the indoor lampshade, we first implemented a thermocatalyst system using waste heat that can remove VOCs in an eco-friendly way without an additional heat supply device. The proposed thermocatalytic system offers a sustainable and feasible indoor VOC removal method.

 

China’s ongoing efforts in combating air pollution yield remarkable air quality improvements

Peer-Reviewed Publication

SCIENCE CHINA PRESS

 

IMAGE: AVERAGED PERCENTAGE CHANGES IN PM2.5 ANNUAL CONCENTRATIONS IN 31 MAJOR CHINESE CITIES SINCE 2015. view more 

CREDIT: ©SCIENCE CHINA PRESS

Led by Prof. Yinchang Feng from the College of Environmental Science and Engineering at Nankai University, a study has been conducted to understand whether the recent changes in China’s air quality was driven by the meteorological influences or air pollutant emission reduction efforts.

Over the past decade, substantial efforts have been made in China to curb air pollutant emissions. The implementation of two well-known and stricter nationwide Clean Air Actions—the “Air Pollution Prevention and Control Action Plan” (commonly known as the “Ten Measures”) from 2013 to 2017, and the “Three-Year Action Plan to Win the Battle for a Blue Sky” (commonly known as “Blue Sky Battle”) from 2018 to 2020—has played a pivotal role in this improvement. These actions, issued by the State Council of China, aimed to reduce ambient PM2.5 mass concentration in key regions to target levels, and were supported by a series of policy and control measures. Through determined clean air actions, the nation has achieved a remarkable transformation in the state of its air pollution, resulting in cleaner air for its populace. China has witnessed a remarkable improvement in ambient air quality, as evidenced by the consistent decrease in the concentrations of major air pollutants and the number of hazy days. In addition to anthropogenic emissions, weather conditions also regulate the variations of air pollution, especially in short-term timescale. To accurately evaluate the effectiveness of emission reduction efforts, the researchers adjusted the air quality data across 31 major Chinese cities for meteorological influences, using an advanced machine learning based statistical model.

After accounting for meteorological effects, the study confirms that the continuous decline in the annual average concentrations of major air pollutants in the selected 31 major Chinese cities during the 13th Five-Year Plan period (2015-2020) was primarily attributable to the emission reduction programs, particularly the successful control of coal-related combustion emissions. However, along with the ongoing battle against air pollution, the pace of PM2.5 reduction slowed down. And in some cities, emission rates even rebounded, signaling challenges in achieving further air quality improvement and the increasing difficulty in promoting emission reduction in the future. The study also highlighted a concerning trend of worsening ozone pollution in some Chinese cities. Co-corresponding author, Prof. Yinchang Feng says: “Despite notable reductions in nitrogen oxides, one of the precursors of ozone, the emissions of other ozone precursors like volatile organic compounds (VOCs) need to be coordinated to prevent further deterioration in ozone air quality”.

See the article:

https://doi.org/10.1360/SSTe-2022-0271

Dai Q, Dai T, Hou L, Li L, Bi X, Zhang Y, Feng Y. 2023. Quantifying the impacts of emissions and meteorology on the interannual variations of air pollutants in major Chinese cities from 2015 to 2021. Science China Earth Sciences, 66(8): 1725–1737, https://doi.org/10.1007/s11430-022-1128-1

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JOURNAL

Science China Earth Sciences

DOI

10.1007/s11430-022-1128-1 

 

Using glowing fish to detect harmful pesticides

by Douglas Fox, UC Davis

Sean Burgess (right) and Bruce Draper, professors in the UC Davis College of Biological Sciences, are using zebrafish to detect chemicals that may cause reproductive harm. The GloNad fish glow red or green to indicate the presence of chemicals that affect the male or female reproductive organs. Credit: Sasha Bakhter/UC Davis College of Biological Sciences

Birth defects related to chromosomal abnormalities often stem from exposure to chemicals early in the mother's life. But determining which chemicals are at fault poses a serious challenge—akin to solving a hit-and-run case, decades after the fact. Two researchers in the UC Davis College of Biological Sciences are developing a method that could identify harmful chemicals far more quickly, with the help of red- and green-glowing zebrafish.

Their work could benefit millions of people in California's Central Valley, who are at elevated risk for exposure to pesticides because they live or work near agricultural production sites. Pesticide exposure can cause both acute and long-term health problems in humans, including harm to the reproductive system. This harm often occurs because chemicals interfere with sensitive stages of fetal development, during which the cells that will one day produce sperm or oocytes are forming.

Finding generational effects

"You won't see the effect until those children grow up and try to have children of their own," said Sean Burgess, a professor in the Department of Molecular and Cellular Biology. At that point, women may experience infertility or repeated miscarriage; the children they bear may be at increased risk for Down syndrome or other serious conditions that are caused by having extra copies of chromosomes.

Burgess is working with Bruce Draper, a professor in the same department, to develop a technique that could greatly accelerate the screening of chemicals and more rapidly identify those with long-term reproductive effects. The gap between the chemical "hit-and-run" and reproductive consequences is often decades, said Burgess: "We're shrinking that time down to basically weeks."

Standard testing is slow and expensive, because it relies on mice, which must be individually dissected and examined by technicians to see the effects of chemicals on reproductive tissues. Burgess and Draper plan to circumvent this cumbersome process by using a newly developed strain of zebrafish (Danio rerio). This freshwater fish species, native to South Asia, is popular in home aquariums. It is also frequently used as a model organism to study the early stages of human development.

"Seventy percent of the genes in zebrafish have human counterparts, called orthologs," said Draper. And if you look at the genes involved in oogenesis—the production of female oocytes, or egg cells—the percentage is even higher.

Zebrafish are well-suited for studying the reproductive effects of chemicals because unlike mammals, their sex is not determined by special X or Y chromosomes. Instead, it is determined in part by environmental cues. In captivity, roughly half of the fish develop into females. But if fish larvae are exposed to chemicals that disrupt oogenesis, then a higher percentage of them will develop as males. This means that scientists can screen a chemical for reproductive toxicity by exposing a few dozen zebrafish larvae to it—then waiting several weeks to see if their sex ratio is skewed toward males. Draper and Burgess are developing a strategy to do this—using genetically modified zebrafish that display their sex prominently, through color coding.

These fish, developed by members of Draper's lab, carry three genetic changes. First, their Sertoli cells, found only in the male gonad, produce green fluorescent protein. Second, their oocytes (or immature eggs), found only in the female gonad, produce red fluorescent protein. And finally, the fish manufacture less of their natural pigment—making their bodies more transparent, so the red or green colors of their gonads show more clearly.

Zebrafish are easier and less expensive to care for than rodents. Burgess and Draper expect to raise 80 fish larvae in each tank, exposing the animals in each one to a selected chemical between 10 and 20 days post-fertilization. One would ordinarily have to wait until 90 days post-fertilization to distinguish male and female zebrafish visually. But the fishes' color-coded gonads should allow them to do this at 40 days.

"We should be able to determine the sex of a cohort of 80 animals, almost simultaneously, just by taking a picture," Draper said. Seeing an unusually high percentage of males or females, or seeing intersex animals with gonads shining both red and green, would indicate that the chemical is toxic to the reproductive system.

GloNad assay

Earlier this year, Burgess and Draper began to develop their "GloNad" assay for toxicity screening. The two of them hope that later this year they can begin using it in a pilot experiment to screen nine of the most commonly used pesticides in California for reproductive effects.

That initial test could eventually pave the way for broader use of the GloNad assay. Ninety pesticides are currently known to the state of California to cause birth defects or reproductive harm. But these toxicities could potentially be linked to a broader range of pesticides and other chemicals, such as bisphenols, which are used in manufacturing some plastics.

The real power of the GloNad assay is that it could be scaled up to test many more chemicals beyond those that are currently possible. And each of those chemicals could be tested in large numbers of fish—allowing detection of even rare reproductive effects.

"It's way more efficient than anything else out there right now," said Draper. "We have high expectations that this is going to work."

Provided by UC Davis Female zebrafish shown to be able to choose which sperm to use to fertilize their eggs

 

Cleaning water with ‘smart rust’ and magnets (video)

Reports and Proceedings

AMERICAN CHEMICAL SOCIETY

 

IMAGE: IN THIS ILLUSTRATION, A “SMART RUST” NANOPARTICLE ATTRACTS AND TRAPS ESTROGEN MOLECULES, WHICH ARE REPRESENTED BY THE FLOATING OBJECTS. view more 

CREDIT: DR. DUSTIN VIVOD AND PROF. DR. DIRK ZAHN, COMPUTER CHEMISTRY CENTER (CCC), FRIEDRICH-ALEXANDER-UNIVERSITÄT ERLANGEN-NÜRNBERG

SAN FRANCISCO, Aug. 16, 2023 — Pouring flecks of rust into water usually makes it dirtier. But researchers have developed special iron oxide nanoparticles they call “smart rust” that actually makes it cleaner. Smart rust can attract many substances, including oil, nano- and microplastics, as well as the herbicide glyphosate, depending on the particles’ coating. And because the nanoparticles are magnetic, they can easily be removed from water with a magnet along with the pollutants. Now, the team is reporting that they’ve tweaked the particles to trap estrogen hormones that are potentially harmful to aquatic life.

The researchers will present their results today at the fall meeting of the American Chemical Society (ACS). ACS Fall 2023 is a hybrid meeting being held virtually and in-person Aug. 13–17, and features about 12,000 presentations on a wide range of science topics.

A video on the research is available at www.acs.org/SmartRust.

“Our ‘smart rust’ is cheap, nontoxic and recyclable,” says Marcus Halik, Ph.D., the project’s principal investigator. “And we have demonstrated its use for all kinds of contaminants, showing the potential for this technique to improve water treatment dramatically.”

For many years, Halik’s research team has been investigating environmentally friendly ways to remove pollutants from water. The base materials they use are iron oxide nanoparticles in a superparamagnetic form, which means they are drawn to magnets, but not to each other, so the particles don’t clump.

To make them “smart,” the team developed a technique to attach phosphonic acid molecules onto the nanometer-sized spheres. “After we add a layer of the molecules to the iron oxide cores, they look like hairs sticking out of these particles’ surfaces,” says Halik, who is at Friedrich-Alexander-Universität Erlangen-Nürnberg. Then, by changing what is bound to the other side of the phosphonic acids, the researchers can tune the properties of the nanoparticles’ surfaces to strongly adsorb different types of pollutants.

Early versions of smart rust trapped crude oil from water collected from the Mediterranean Sea and glyphosate from pond water collected near the researchers’ university. Additionally, the team demonstrated that smart rust could remove nano- and microplastics added to lab and river water samples.

So far, the team has targeted pollutants present in mostly large amounts. Lukas Müller, a graduate student who’s presenting new work at the meeting, wanted to know if he could modify the rust nanoparticles to attract trace contaminants, such as hormones. When some of our body’s hormones are excreted, they are flushed into wastewater and eventually enter waterways. Natural and synthetic estrogens are one such group of hormones, and the main sources of these contaminants include waste from humans and livestock. The amounts of estrogens are very low in the environment, says Müller, so they are difficult to remove. Yet even these levels have been shown to affect the metabolism and reproduction of some plants and animals, although the effects of low levels of these compounds on humans over long periods aren’t fully known.

“I started with the most common estrogen, estradiol, and then four other derivatives that share similar molecular structures,” says Müller. Estrogen molecules have a bulky steroid body and parts with slight negative charges. To exploit both characteristics, he coated iron oxide nanoparticles with two sets of compounds: one that’s long and another that’s positively charged. The two molecules organized themselves on the nanoparticles’ surface, and the researchers hypothesize that together, they build many billions of “pockets” that draw in the estradiol and trap it in place.

Because these pockets are invisible to the naked eye, Müller has been using high-tech instruments to verify that these estrogen-trapping pockets exist. Preliminary results show efficient extraction of the hormones from lab samples, but the researchers need to look at additional experiments from solid-state nuclear magnetic resonance spectroscopy and small-angle neutron scattering to verify the pocket hypothesis. “We are trying to use different puzzle pieces to understand how the molecules actually assemble on the nanoparticles’ surface,” explains Müller.

In the future, the team will test these particles on real-world water samples and determine the number of times that they can be reused. Because each nanoparticle has a high surface area with lots of pockets, the researchers say that they should be able to remove estrogens from multiple water samples, thereby reducing the cost per cleaning. “By repeatedly recycling these particles, the material impact from this water treatment method could become very small,” concludes Halik.

The researchers acknowledge support and funding from the German Research Foundation, the German Federal Environmental Foundation and Friedrich-Alexander-Universität Erlangen-Nürnberg.

A recorded media briefing on this topic will be posted Wednesday, Aug. 16, by 10 a.m. Eastern time at www.acs.org/acsfall2023briefings. Reporters can request access to media briefings during the embargo period by contacting newsroom@acs.org.

For health and safety information for ACS Fall 2023, please visit the FAQ webpage.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive press releases from the American Chemical Society, contact newsroom@acs.org.

Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society.

Follow us: Twitter | Facebook | LinkedIn | Instagram

Title
Smart rust to clean water from hormones

Abstract
Access to clean water is recognized as a human right by the United Nations. However, anthropogenic molecular pollutants, like hormones are present in our ground water and find their way into drinking water due to careless disposal and insufficient remediation. Already at the trace concentration level such compounds have been shown to have severe effects on aquatic flora and fauna, but also to us humans, especially children. Still consequences of long term exposure are often unknown. Therefore, it exists a big demand in affordable and efficient removal of such organic contaminants from water. Having this in mind, we are en route to develop a promising concept to solve this problem. Superparamagnetic iron oxide nanoparticles (SPIONs) are surface-functionalized with self-assembled monolayers (SAMs) composed of permanently binding phosphonic acid derivates to address certain interaction motifs of selected hormones (“smart rust”). Such particles attract the pollutants and can be easily remediated from water by an external magnetic field due to the magnetic moment of its cores. Basing on previous successful remediation of the herbicide glyphosate, micro- and nanoplastics as well as crude oil via single major interaction motifs (covalent binding – electrostatic interactions – hydrophobic interaction respectively), we pursue the next logical step. We establish the interaction of rationally designed mixed SAMs on SPIONs with dedicated trace organic pollutants, i. e. various estrogen derivates. Therefore, we envision sorbent systems that are not only thermodynamically attractive for the pollutants of choice by combination of multiple interaction motifs, but also present suitably-sized cavities in the mixed SAM. This approach benefits from synergy of experimental materials science and analytical chemistry to tailor hybrid nanoparticles.

 

Collecting clean water from fog

Peer-Reviewed Publication

ETH ZURICH

In countries such as Peru, Bolivia and Chile, it’s not uncommon for people who live in foggy areas to hang up nets to catch droplets of water. The same is true of Morocco and Oman. These droplets then trickle down the mesh and are collected to provide water for drinking, cooking and washing. As much as several hundred litres of water can be harvested daily using a fog net only a few square metres in area. For regions with little rain or spring water, but where fog is a common occurrence, this can be a blessing.

One crucial drawback with this method, however, is atmospheric pollution, since the hazardous substances also end up in the droplets of water. In many of the world’s major cities, the air is so polluted that any water harvested from fog isn’t clean enough to be used untreated either for drinking or for cooking.

Researchers at ETH Zurich have now developed a method that collects water from fog and simultaneously purifies it. This uses a close-mesh lattice of metal wire coated with a mixture of specially selected polymers and titanium dioxide. The polymers ensure that droplets of water collect efficiently on the mesh and then trickle down as quickly as possible into a container before they can be blown off by the wind. The titanium dioxide acts as a chemical catalyst, breaking down the molecules of many of the organic pollutants contained in the droplets to render them harmless.

“Our system not only harvests fog but also treats the harvested water, meaning it can be used in areas with atmospheric pollution, such as densely populated urban centres,” Ritwick Ghosh explains. A scientist at the Max Planck Institute for Polymer Research in Mainz, Ghosh conducted this project while on an extended guest stay at ETH Zurich. During this time, he was a member of the group led by Thomas Schutzius, who has since taken up a post as professor at the University of California, Berkeley.

Photocatalytic memory

Once installed, the technology needs little or no maintenance. Moreover, no energy is required apart from a small but regular dose of UV to regenerate the catalyst. Half an hour of sunlight is enough to reactivate the titanium oxide for a further 24 hours – thanks to a property known as photocatalytic memory. Following reactivation with UV, the catalyst also remains active for a lengthy period in the dark. With periods of sunlight often rare in areas prone to fog, this is a very useful quality.

The new fog collector was tested in the lab and in a small pilot plant in Zurich. Researchers were able to collect 8 percent of the water in artificially created fog and break down 94 percent of the organic compounds that had been added to it. Among the added pollutants were extremely fine diesel droplets and the chemical bisphenol A, a hormonally active agent.

Potential use in cooling towers

In addition to harvesting drinking water from fog, this technology could also be used to recover water used in the cooling towers. “In the cooling towers, steam escapes up into the atmosphere. In the United States, where I live, we use a great deal of fresh water to cool power plants,” says Schutzius. “It would make sense to capture some of this water before it escapes and ensure that it is pure in case you want to return it back to the environment.”

Past research by Ghosh focused on water recovery from cooling towers. He would now like to advance this technology and explore marketable applications. His hope is to make greater use of fog and steam as a hitherto underutilised source of water and thereby play a role in alleviating the scarcity of this vital resource.

###

Reference

Ghosh R, Baut A, Belleri G, Kappl M, Butt HJ, Schutzius TM: Reactive Nanoengineered Meshes for Simultaneous Fog Harvesting and Water Treatment. Nature Sustainability, 16 August 2023, doi: 10.1038/s41893-023-01159-9

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JOURNAL

Nature Sustainability

DOI

10.1038/s41893-023-01159-9 

ARTICLE TITLE

Reactive Nanoengineered Meshes for Simultaneous Fog Harvesting and Water Treatment

ARTICLE PUBLICATION DATE

16-Aug-2023

 

Tubing and swimming change the chemistry and microbiome of streams

Reports and Proceedings

AMERICAN CHEMICAL SOCIETY

SAN FRANCISCO, Aug. 16, 2023 — With Labor Day approaching, many people are preparing to go tubing and swimming at local streams and rivers. These delightful summertime activities seem innocuous, but do they have an impact on these waterways? Today, scientists report preliminary results from the first holistic study of this question, which shows that recreation can alter the chemical and microbial fingerprint of streams, but the environmental and health ramifications are not yet known.

The researchers will present their results at the fall meeting of the American Chemical Society (ACS). ACS Fall 2023 is a hybrid meeting being held virtually and in-person Aug. 13–17, and features about 12,000 presentations on a wide range of science topics.

The project stemmed from a conversation between Carsten Prasse, Ph.D., and James Ranville, Ph.D., about the impact of human activities on surface waters. “There's a lot of talk about things like wastewater getting into surface waters,” Prasse says, “but one aspect that hasn't really been thought about is people swimming in surface water — especially in relation to climate change and hotter summers, as water levels drop.”

So, the researchers teamed up to explore the effect of summer fun on freshwater streams. Ranville, who is at Colorado School of Mines, proposed nearby Clear Creek for the study. His group would examine inorganic contaminants, including metals and nanoparticles. Prasse’s team at Johns Hopkins University would evaluate organic contaminants, such as pharmaceuticals. Ranville also enlisted the help of John Spear, Ph.D., at Colorado School of Mines to investigate the microbiome of the stream.

In 2022, the Colorado researchers collected water samples during the busy Labor Day weekend and on a quieter weekday afterward. On many weekends, as many as 500 people per hour use the stream for tubing and swimming at that part of Clear Creek. An undisturbed location upstream was sampled for comparison. The samples were then tested with state-of-the-art analytical approaches, including inductively coupled plasma-mass spectrometry and liquid chromatography-high resolution mass spectrometry. The main goal was to look for changes in chemicals that could be detected in the water.

“We used software and high-level instrumental analysis to piece together a story of what people were doing to the stream,” says Noor Hamdan, a graduate student in Prasse’s lab who will present the work at the meeting. “We found a lot of human metabolites, a lot of pharmaceuticals, some illicit drugs and some sunscreens — really a whole slew of compounds that humans are associated with,” says Hamdan. Those compounds presumably washed off people’s skin or were released in sweat or urine, among other possible sources.

Preliminary results from Prasse’s lab suggested the presence of cocaine, lidocaine (a topical anesthetic), fexofenadine (an antihistamine), lamotrigine (a treatment for seizures and bipolar disorder) and gabapentin (a medication for seizures and nerve pain), as well as polyethylene glycol (used in medications and numerous other applications) and phthalates (plasticizers). Organic sunscreens and UV filters were also detected.

Carmen Villarruel, a grad student in Ranville’s lab, found that human recreation stirred up sediments in the creek, thereby raising the water’s concentration of metals, such as copper, lead, zinc, aluminum and iron. “Much of the metal was in particulate form, which has implications for wildlife,” Villarruel says. For example, these sediments could clog the gills of fish, making it harder for them to absorb oxygen from the water. In addition to the metal particulates, the team found some dissolved metals in the water, which could affect reproduction, species diversity and the health of aquatic species, Ranville notes.

Tubing and swimming also altered the creek’s microbial profile, increasing the abundance of microorganisms commonly associated with human waste. Spear says that could impact species that live in the river, such as fish, as well as microorganisms that occur naturally in the water and are key components of the ecosystem.

The team used Environmental Protection Agency software to run a risk assessment on the compounds in the river. They found that most of the compounds aren’t particularly prone to bioaccumulate, Hamdan says. But the researchers also emphasize that there are no data available on long-term toxicity or persistence in the environment, and there are insufficient data to evaluate exposure risks for a lot of the compounds.

“So that's an important finding from this project,” Hamdan says. “We now know that these compounds are in the river. But we don’t know their concentrations or how they impact the fish or other species in the environment.” In future research on this project, the team plans to collect more samples to track trends over time.

In the meantime, Prasse has some useful advice for people who want to have fun in the water. “Don’t pee in rivers,” he says half-jokingly. “When you urinate into a toilet, the water goes to a wastewater treatment plant before it is discharged into a river. But if you urinate into a river, all those chemicals go directly into the water. We know that things like pharmaceuticals can impact aquatic species, such as fish, even at very low concentrations.” He also recommends using mineral sunscreens, such as zinc oxide, instead of sunscreens that contain UV filters, which can be toxic to aquatic organisms.

The researchers acknowledge support and funding from Johns Hopkins University and the National Science Foundation.

A recorded media briefing on this topic will be posted Wednesday, Aug. 16, by 10 a.m. Eastern time at www.acs.org/acsfall2023briefings. Reporters can request access to media briefings during the embargo period by contacting newsroom@acs.org.

For health and safety information for ACS Fall 2023, please visit the FAQ webpage.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

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Title
Assessing the impact of recreational activities on a natural stream: a Colorado River case study

Abstract
Water-based recreational activities introduce a substantial amount of human activity to freshwater streams and rivers, specifically during warmer weather. Despite the clear potential for perturbation of freshwater stream conditions, anthropogenic alteration of the chemical fingerprint of natural streams has seen little study. We examined Clear Creek in Golden, Colorado as a test case utilizing state-of-the-art analytical approaches including single-particle ICP-MS and LC-HRMS to determine the chemical changes of inorganic and organic water constituents resulting from recreational activities, primarily float tubing. Changes due to high use were observed through spatial and temporal sampling for three days over Labor Day weekend, where Clear Creek saw a large influx of tubing activity. For the analysis of organic compounds, the samples were extracted using solid-phase extraction and analyzed for organic contaminants using a nontarget approach. The results showcase significant changes in the organic fingerprint of the stream when comparing days and locations that coincided with high or low/no recreational use. High confidence level hits of specific compounds, such as avobenzone, cocaine, lamotrigine, and specific xenobiotic metabolites were also observed. Analysis of inorganic constituents using ICP-MS shows an increase in total suspended solids correlated with suspended particulate metals (Al, Cu, Pb, Ti, Pb, and Zn) in the water column. Element ratios implicated recreation-induced resuspension of streambed sediments as the metal source rather than other direct anthropogenic inputs (i.e., Ti/Zn-containing sunscreens). This study is the first to holistically approach the impact of human activity on a natural stream by simultaneously considering the changes in the organic and inorganic fingerprints. In using this approach, the influences on the stream’s ecosystem could be assessed through the identification of compounds that drive the ecotoxicity and by quantifying any potential hazards resulting from the resuspension of metal-containing sediments.

 

Pollutants are important to biodiversity’s role in spread of wildlife diseases

Researchers found that environmental pollutants like road salt influence whether increased biodiversity helps or hinders disease outbreaks in wildlife, which can complicate how we value protecting diverse animal communities.

Peer-Reviewed Publication

UNIVERSITY OF WISCONSIN-MADISON

 

IMAGE: WOOD FROG TADPOLES LIKE THIS ONE ARE MORE SUSCEPTIBLE TO A PARASITIC FLUKE WHEN THEY LIVE IN WATER TAINTED BY ROAD SALT. BUT WHEN THEIR POLLUTED ECOSYSTEM INCLUDES OTHER SPECIES, LIKE THE AMERICAN TOAD, WHICH ARE NOT MORE LIKELY TO BE INFECTED IN SALTIER WATER, BIODIVERSITY WORKS IN ALL THE TADPOLES’ FAVOR. view more 

CREDIT: JESSICA HUA

Conventional wisdom among ecologists holds that the more species there are inhabiting an ecosystem, the less vulnerable any one species will be to a threat like a parasite. A new study of tadpoles at the University of Wisconsin–Madison illustrates how overlapping biological and environmental factors can complicate how we value protecting diverse animal communities. The researchers found that environmental pollutants like road salt influence whether increased biodiversity helps or hinders disease outbreaks in wildlife, which can complicate how we value protecting diverse animal communities.

“There's an idea in the field of disease ecology that communities with more species living together, communities with higher biodiversity, are less vulnerable to diseases than less biodiverse communities,” says Jessica Hua, a W–Madison professor of forest and wildlife ecology.

Ecologists believe that in a biodiverse ecosystem, vulnerability to disease is shared across many species. One species could act as a decoy, drawing the attention and energy of parasites away from more susceptible neighbors and protecting the vulnerable by reducing the growth, reproduction and spread of parasites.

“The idea that biodiversity can dampen disease outbreaks is an exciting idea because it provides a clear benefit and great reason for protecting biodiversity,” says Hua. “Our research suggests that whether biodiversity protects communities from disease depends on environmental conditions. We cannot understand the role of biodiversity on disease without considering how environmental factors like pollutants change host susceptibility.”

Studies of biodiversity’s sway on disease have produced mixed results. Sometimes, communities with higher biodiversity do have lower levels of disease, called a dilution effect. Other times, communities with higher biodiversity have higher levels of disease, called an amplification effect. And sometimes, there’s no effect at all. In the field of disease ecology, the varying outcomes have generated intense debates over biodiversity’s relationship with disease.

Hua studies the way pollutants — be they pesticides, other chemical contaminants or even light and noise — can upset natural ecosystems. She thought that pollution may be one important contributor shaping when biodiversity dilutes or amplifies wildlife susceptibility to disease.

“We know that a lot of environments have pollutants, and one thing polluted environments do is change patterns of disease susceptibility,” says Hua, whose work is supported by the National Science Foundation. “We think one reason for why this relationship between biodiversity and disease is so equivocal is because of pollutants in the water.”

Hua and Nicholas Buss, a former graduate student in Hua’s lab during her time at Binghamton University, published a study on Aug. 16 in the Journal of Animal Ecology showing how road salt pollution reduced overall parasite susceptibility in an amphibian community — but only because the salt made two of three amphibian species more likely to be infected.

Hua and Buss studied three amphibians that share overlapping ranges, including ponds in Pennsylvania and New York where the researchers collected eggs. They raised newly hatched wood frogs (Rana sylvatica), spring peepers (Pseudacris crucifer) and American toads (Anaxyrus americanus) separately, splitting the tadpoles of each species into groups that lived either in unpolluted water or in water with salt added. Then they moved the tadpoles into water with trematodes, tiny parasites often called flukes, which infect each tadpole species in the wild and disrupt their growth and development.

“In the absence of salt, the susceptibility of each species of these tadpoles to parasites was essentially the same,” Buss says. “In the presence of salt, the wood frogs and the peepers became more susceptible to trematodes, while toads were unaffected. This suggests that toads may act as a decoy species — but only in environments with salt.”

The researchers then generated artificial communities in the lab that differed in biodiversity with respect to amphibians. Some communities had only one species, some had two species and some had all three species. They reared the amphibians in either pollutant-free or salt-polluted water and then added trematodes.

The researchers found that when peepers and wood frogs were placed in communities with higher biodiversity, the negative effects of salt on individual species were dampened.

“In the water without salt, communities with higher biodiversity were similarly susceptible to trematodes compared to communities with lower biodiversity,” says Buss. “However, when raised in water with salt — even though salt makes peepers and wood frogs living alone more susceptible to trematodes — total infections were cut almost in half for the wood frogs and peepers living in communities with higher biodiversity.”

The toad tadpoles served as a decoy species, drawing the parasites away from the more susceptible peepers and wood frogs sharing their home water. Hua plans to study the interactions with new species and pollutants, as they should weigh on future research on biodiversity and ecosystem management.

“This work highlights the need to understand all the interacting facets of an ecosystem — environment, biodiversity, disease, etc. — when making decisions about how to manage that system,” says Andrea Porras-Alfaro, a program director for biodiversity and ecology research at NSF. “Research like this can be applied to conservation and land management policies, helping to protect valuable resources and environments.”

This research was funded by a grant from the U.S. National Science Foundation (Award 2314625).

JOURNAL

Journal of Animal Ecology

DOI

10.1111/1365-2656.13988 

ARTICLE TITLE

Integrating ecology, evolution, and toxicology to understand the effects of pesticides in aquatic systems