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    A new sensor detects harmful “forever chemicals” in drinking water

    MIT chemists have designed a sensor that detects tiny quantities of perfluoroalkyl and polyfluoroalkyl substances (PFAS) — chemicals found in food packaging, nonstick cookware, and many other consumer products.

    These compounds, also known as “forever chemicals” because they do not break down naturally, have been linked to a variety of harmful health effects, including cancer, reproductive problems, and disruption of the immune and endocrine systems.

    Using the new sensor technology, the researchers showed that they could detect PFAS levels as low as 200 parts per trillion in a water sample. The device they designed could offer a way for consumers to test their drinking water, and it could also be useful in industries that rely heavily on PFAS chemicals, including the manufacture of semiconductors and firefighting equipment.

    “There’s a real need for these sensing technologies. We’re stuck with these chemicals for a long time, so we need to be able to detect them and get rid of them,” says Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT and the senior author of the study, which appears this week in the Proceedings of the National Academy of Sciences.

    Other authors of the paper are former MIT postdoc and lead author Sohyun Park and MIT graduate student Collette Gordon.

    Detecting PFAS

    Coatings containing PFAS chemicals are used in thousands of consumer products. In addition to nonstick coatings for cookware, they are also commonly used in water-repellent clothing, stain-resistant fabrics, grease-resistant pizza boxes, cosmetics, and firefighting foams.

    These fluorinated chemicals, which have been in widespread use since the 1950s, can be released into water, air, and soil, from factories, sewage treatment plants, and landfills. They have been found in drinking water sources in all 50 states.

    In 2023, the Environmental Protection Agency created an “advisory health limit” for two of the most hazardous PFAS chemicals, known as perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonate (PFOS). These advisories call for a limit of 0.004 parts per trillion for PFOA and 0.02 parts per trillion for PFOS in drinking water.

    Currently, the only way that a consumer could determine if their drinking water contains PFAS is to send a water sample to a laboratory that performs mass spectrometry testing. However, this process takes several weeks and costs hundreds of dollars.

    To create a cheaper and faster way to test for PFAS, the MIT team designed a sensor based on lateral flow technology — the same approach used for rapid Covid-19 tests and pregnancy tests. Instead of a test strip coated with antibodies, the new sensor is embedded with a special polymer known as polyaniline, which can switch between semiconducting and conducting states when protons are added to the material.

    The researchers deposited these polymers onto a strip of nitrocellulose paper and coated them with a surfactant that can pull fluorocarbons such as PFAS out of a drop of water placed on the strip. When this happens, protons from the PFAS are drawn into the polyaniline and turn it into a conductor, reducing the electrical resistance of the material. This change in resistance, which can be measured precisely using electrodes and sent to an external device such as a smartphone, gives a quantitative measurement of how much PFAS is present.

    This approach works only with PFAS that are acidic, which includes two of the most harmful PFAS — PFOA and perfluorobutanoic acid (PFBA).

    A user-friendly system

    The current version of the sensor can detect concentrations as low as 200 parts per trillion for PFBA, and 400 parts per trillion for PFOA. This is not quite low enough to meet the current EPA guidelines, but the sensor uses only a fraction of a milliliter of water. The researchers are now working on a larger-scale device that would be able to filter about a liter of water through a membrane made of polyaniline, and they believe this approach should increase the sensitivity by more than a hundredfold, with the goal of meeting the very low EPA advisory levels.

    “We do envision a user-friendly, household system,” Swager says. “You can imagine putting in a liter of water, letting it go through the membrane, and you have a device that measures the change in resistance of the membrane.”

    Such a device could offer a less expensive, rapid alternative to current PFAS detection methods. If PFAS are detected in drinking water, there are commercially available filters that can be used on household drinking water to reduce those levels. The new testing approach could also be useful for factories that manufacture products with PFAS chemicals, so they could test whether the water used in their manufacturing process is safe to release into the environment.

    The research was funded by an MIT School of Science Fellowship to Gordon, a Bose Research Grant, and a Fulbright Fellowship to Park. More

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    Illustrating India’s complex environmental crises

    Abhijit Banerjee, the Ford Foundation International Professor of Economics at MIT, and Sarnath Banerjee (no relation), an MIT Center for Art, Science, and Technology (CAST) visiting artist share a similar background, but have very different ways of thinking. Both were raised for a time in Kolkata before leaving India to pursue divergent careers, Abhijit as an economist who went on to win the 2019 Nobel Memorial Prize in Economic Sciences (an award he shares with MIT Professor Esther Duflo and Harvard University Professor Michael Kremer), and Sarnath as a visual artist and graphic novelist. 

    The two collaborated on a pair of short films, “The Land of Good Intentions” and “The Eternal Swamp,” that blend their expertise in a unique and captivating form. Each film addresses a particular environmental crisis facing present-day India by tracing its origins back through the centuries. The films are presented in a kind of lecture style, with Abhijit appearing as the narrator, unraveling historical details, as graphics by Sarnath visualize the story with an often wry and easy wit. The results apply logic and narrative coherence to problems with complex roots in the forces of nature, economics, and local culture. 

    “The Land of Good Intentions” explores the conditions and policies that led to mass protests by farmers, in Punjab and elsewhere, following the passage of farming legislation in September 2020. The film begins by providing historical context from multiple angles, including the significance of rice to regional culture, its growing conditions (which require a lot of water), the region’s climate (which produces very little), and previous government subsidies that led to its overproduction. The 2020 Farm Bills were intended to address rice overproduction and its consequences, including the depletion of Punjab’s groundwater supply, pollution from the burning of rice stalks, and a surplus going to waste. But farmers considered that they were being asked to shoulder the costs of a problem the government created. 

    “The arguments in the film don’t necessarily align with popular liberal arguments, but it gives subtler shape and layers to them,” Sarnath says. “That dialectical way of thinking is important to the liberal movement, which is driven by passion and a sense of justice. Abhijit is driven by factual analysis, which sometimes makes the argument more complex.”

    Their second film, “The Eternal Swamp,” addresses the crisis of flooding in Kolkata and its causes in the geographical and economic development of the city from the start. Because Kolkata was built on very wet land, and real estate has long been one of the only viable industries in the city, it has been developed without regard to proper drainage in a climate that produces more rainfall than it can handle. There is a pervading sense that Kolkata will eventually be entirely below water.

    “It was a good collaboration from the beginning,” Sarnath says of working with Abhijit on the CAST Visiting Artist project, a process which began just before Abhijit was awarded the Nobel Prize in 2019 and continued through the pandemic. “Both of us work on instinct, but the way he shapes an argument is very different from me,” Sarnath says. “My work does not follow a linear approach to telling a story; it’s fragmentary, driven by mood and emotion more than narrative, like composing a piece of music.”

    Since they first met at a literary conference years ago, Abhijit and Sarnath have been close friends and intellectual sparring partners. Though Sarnath is based in Berlin and Abhijit in Boston, the two often cross paths in different locales and have long, ambling discussions that traverse a wide array of topics. “We spend a lot of time walking together wherever we find ourselves, whether it’s down the Longfellow Bridge in Boston or through Delhi or Kolkata,” Sarnath says. The idea for this project was born out of such conversations, in response to pressing events in their home country. 

    Abhijit wrote a proposal to MIT CAST, and the questions they received through the process helped them further shape the project. “It’s important, when you have the luxury, just to spend time together. Thanks to MIT, we managed to do that across continents,” Sarnath says of their creative process. “It’s more than just telling a story; Abhijit unpacked what was in his head, and I drew and wrote a bit as well,” Sarnath says. And they worked with the editor and animator Niusha Ramzani, whom Sarnath says lent an Iranian aesthetic to the film’s animations. 

    As for the format of the films, they wanted to capture the sense of a serene Bengali afternoon, with Abhijit seated in his home in Kolkata speaking in a relaxed tone. “We wanted it to be a bit like a Royal Society lecture,” Sarnath says, somewhat like a TED Talk but more personable and intimate. The aim was to make their complicated subjects more easily comprehensible, through the language of Abhijit’s narration and with the help of visual metaphors. Still, they did not want to sacrifice complexity.

    “Economists are fabulists,” says Abhijit Banerjee. “We tell stories, simple stories, but that tends to get obscured in the telling, often because we like to be very careful about not overstating our case. Irony and the kind of playful humor that Sarnath brings to narration seemed to offer a different way to avoid being too emphatic, while allowing the story to be told in a way that it reaches a much larger audience. What is brilliant about Sarnath’s work is the play between reliable and the unreliable — the readers are happy to be misdirected because they know that it will ultimately lead them where they want to be. I was hoping we could bring a little of that into economics.” 

    “You have to emancipate yourself from any one definitive answer,” Sarnath Banerjee says, describing Abhijit’s expansive way of thinking, through which he follows multiple thought processes to their logical conclusions. The result allows for ambiguity and contradiction, though the pathways of thinking are clear. The films illustrate the situations facing farmers in Punjab and the waterlogged streets of Kolkata by tracing their roots and examining the history of cause and effect. The results provide clarity, but no simple answers.

    The process was an enriching one for both of them, the kind of advancement in understanding that can only come in dialogue. “With each collaboration, you learn, and learning to me is an artistic form,” Sarnath says. “We are always learning.” More

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    MADMEC winner creates “temporary tattoos” for T-shirts

    Have you ever gotten a free T-shirt at an event that you never wear? What about a music or sports-themed shirt you wear to one event and then lose interest in entirely? Such one-off T-shirts — and the waste and pollution associated with them — are an unfortunately common part of our society.

    But what if you could change the designs on shirts after each use? The winners of this year’s MADMEC competition developed biodegradable “temporary tattoos” for T-shirts to make one-wear clothing more sustainable.

    Members of the winning team, called Me-Shirts, got their inspiration from the MADMEC event itself, which ordinarily makes a different T-shirt each year.

    “If you think about all the textile waste that’s produced for all these shirts, it’s insane,” team member and PhD candidate Isabella Caruso said in the winning presentation. “The main markets we are trying to address are for one-time T-shirts and custom T-shirts.”

    The problem is a big one. According to the team, the custom T-shirt market is a $4.3 billion industry. That doesn’t include trends like fast fashion that contribute to the 17 million tons of textile waste produced each year.

    “Our proposed solution is a temporary shirt tattoo made from biodegradable, nontoxic materials,” Caruso explained. “We wanted designs that are fully removable through washing, so that you can wear your T-shirt for your one-time event and then get a nice white T-shirt back afterward.”

    The team’s scalable design process mixes three simple ingredients: potato starch, glycerin, and water. The design can be imprinted on the shirt temporarily through ironing.

    The Me-Shirt team, which earned $10,000 with the win, plans to continue exploring material combinations to make the design more flexible and easier for people to apply at home. Future iterations could allow users to decide if they want the design to stay on the shirt during washes based on the settings of the washing machine.

    Hosted by MIT’s Department of Materials Science and Engineering (DMSE), the competition was the culmination of team projects that began in the fall and included a series of design challenges throughout the semester. Each team received guidance, access to equipment and labs, and up to $1,000 in funding to build and test their prototypes.

    “The main goal is that they gained some confidence in their ability to design and build devices and platforms that are different from their normal experiences,” Mike Tarkanian, a senior lecturer in DMSE and coordinator of MADMEC, said at the event. “If it’s a departure from their normal research and coursework activities that’s a win, I think, to make them better engineers.”

    The second-place, $6,000 prize went to Alkalyne, which is creating a carbon-neutral polymer for petrochemical production. The company is developing approaches for using electricity and inorganic carbon to generate a high-energy hydrocarbon precursor. If developed using renewable energy, the approach could be used to achieve carbon negative petrochemical production.

    “A lot of our research, and a lot of the research around MIT in general, has to do with sustainability, so we wanted to try an angle that we think looks promising but doesn’t seem to be investigated enough,” PhD candidate Christopher Mallia explained.

    The third-place prize went to Microbeco, which is exploring the use of microbial fuel cells for continuous water quality monitoring. Microbes have been proposed as a way to detect and measure contaminants in water for decades, but the team believes the varying responses of microbes to different contaminants has limited the effectiveness of the approach.

    To overcome that problem, the team is working to isolate microbial strains that respond more regularly to specific contaminants.

    Overall, Tarkanian believes this year’s program was a success not only because of the final results presented at the competition, but because of the experience the students got along the way using equipment like laser cutters, 3D printers, and soldering irons. Many participants said they had never used that type of equipment before. They also said by working to build physical prototypes, the program helped make their coursework come to life.

    “It was a chance to try something new by applying my skills to a different environment,” PhD candidate Zachary Adams said. “I can see a lot of the concepts I learn in my classes through this work.” More

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    K. Lisa Yang Global Engineering and Research Center will prioritize innovations for resource-constrained communities

    Billions of people worldwide face threats to their livelihood, health, and well-being due to poverty. These problems persist because solutions offered in developed countries often do not meet the requirements — related to factors like price, performance, usability, robustness, and culture — of poor or developing countries. Academic labs frequently try to tackle these challenges, but often to no avail because they lack real-world, on-the-ground knowledge from key stakeholders, and because they do not have an efficient, reliable means of converting breakthroughs to real-world impact.

    The new K. Lisa Yang Global Engineering and Research (GEAR) Center at MIT, founded with a $28 million gift from philanthropist and investor Lisa Yang, aims to rethink how products and technologies for resource-constrained communities are conceived, designed, and commercialized. A collaboration between MIT’s School of Engineering and School of Science, the Yang GEAR Center will bring together a multidisciplinary team of MIT researchers to assess today’s most pressing global challenges in three critical areas: global health, climate change mitigation and adaptation, and the water-energy-food nexus.

    “As she has shown over and over through her philanthropy, Lisa Yang shares MIT’s passion for connecting fundamental research and real-world data to create positive impact,” says MIT president Sally Kornbluth. “I’m grateful for her powerful vision and incredible generosity in founding the K. Lisa Yang GEAR Center. I can’t imagine a better use of MIT’s talents than working to improve the lives and health of people around the world.”

    Yang’s gift expands her exceptional philanthropic support of human health and basic science research at MIT over the past six years. Yang GEAR Center will join MIT’s Yang Tan Collective, an assemblage of six major research centers focused on accelerating collaboration in basic science, research, and engineering to realize translational strategies that improve human health and well-being at a global scale.

    “Billions of people face daily life-or-death challenges that could be improved with elegant technologies,” says Yang. “And yet I’ve learned how many products and tools created by top engineers don’t make it out of the lab. They may look like clever ideas during the prototype phase, but they are entirely ill-suited to the communities they were designed for. I am very excited about the potential of a deliberate and thoughtful engineering effort that will prioritize the design of technologies for use in impoverished communities.”

    Cost, material availability, cultural suitability, and other market mismatches hinder many major innovations in global health, food, and water from being translated to use in resource-constrained communities. Yang GEAR Center will support a major research and design program with its mission to strategically identify compelling challenges and associated scientific knowledge gaps in resource-constrained communities then address them through academic innovation to create and translate transformative technologies.

    The center will be led by Amos Winter, associate professor of mechanical engineering, whose lab focuses on creating technologies that marry innovative, low-cost design with an in-depth understanding of the unique socioeconomic constraints of emerging markets.

    “Academia has a key role to play in solving the historically unsolvable challenges in resource-constrained communities,” says Winter. “However, academic research is often disconnected from the real-world requirements that must be satisfied to make meaningful change. Yang GEAR Center will be a catalyst for innovation to impact by helping colleagues identify compelling problems and focus their talents on realizing real-world solutions, and by providing mechanisms for commercial dissemination. I am extremely grateful to find in Lisa a partner who shares a vision for how academic research can play a more efficient and targeted role in addressing the needs of the world’s most disadvantaged populations.”

    The backbone of the Yang GEAR Center will be a team of seasoned research scientists and engineers. These individuals will scout real-world problems and distill the relevant research questions then help assemble collaborative teams. As projects develop, center staff will mentor students, build and conduct field pilots, and foster relationships with stakeholders around the world. They will be strategically positioned to translate technology at the end of projects through licensing and startups. Center staff and collaborators will focus on creating products and services for climate-driven migrants, such as solar-powered energy and water networks; technologies for reducing atmospheric carbon and promoting the hydrogen economy; brackish water desalination and irrigation solutions; and high-performance, global health diagnostics and devices.

    For instance, a Yang GEAR Center team focused on creating water-saving and solar-powered irrigation solutions for farmers in the Middle East and North Africa will continue its work in the region. They will conduct exploratory research; build a team of stakeholders, including farmers, agricultural outreach organizations, irrigation hardware manufacturers, retailers, water and agriculture scientists, and local government officials; design, rigorously test, and iterate prototypes both in the lab and in the field; and conduct large-scale field trials to garner user feedback and pave the way to product commercialization.

    “Grounded in foundational scientific research and blended with excellence in the humanities, MIT provides a framework that integrates people, economics, research, and innovation. By incorporating multiple perspectives — and being attentive to the needs and cultures of the people who will ultimately rely on research outcomes — MIT can have the greatest impact in areas of health, climate science, and resource security,” says Nergis Mavalvala, dean of the School of Science and the Curtis and Kathleen Marble Professor of Astrophysics.

    An overarching aim for the center will be to educate graduates who are global engineers, designers, and researchers positioned for a career of addressing compelling, high-impact challenges. The center includes four endowed Hock E. Tan GEAR Center Fellowships that will support graduate students and/or postdoctoral fellows eager to enter the field of global engineering. The fellowships are named for MIT alumnus and Broadcom CEO Hock E. Tan ’75 SM ’75.

    “I am thrilled that the Yang GEAR Center is taking a leading role in training problem-solvers who will rethink how products and inventions can help communities facing the most pressing challenges of our time,” adds Anantha Chandrakasan, dean of the School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science. “These talented young students,  postdocs, and staff have the potential to reach across disciplines — and across the globe — to truly transform the impact engineering can have in the future.” More

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    A new way to swiftly eliminate micropollutants from water

    “Zwitterionic” might not be a word you come across every day, but for Professor Patrick Doyle of the MIT Department of Chemical Engineering, it’s a word that’s central to the technology his group is developing to remove micropollutants from water. Derived from the German word “zwitter,” meaning “hybrid,” “zwitterionic” molecules are those with an equal number of positive and negative charges.

    Devashish Gokhale, a PhD student in Doyle’s lab, uses the example of a magnet to describe zwitterionic materials. “On a magnet, you have a north pole and a south pole that stick to each other, and on a zwitterionic molecule, you have a positive charge and a negative charge which stick to each other in a similar way.” Because many inorganic micropollutants and some organic micropollutants are themselves charged, Doyle and his team have been investigating how to deploy zwitterionic molecules to capture micropollutants in water. 

    In a new paper in Nature Water, Doyle, Gokhale, and undergraduate student Andre Hamelberg explain how they use zwitterionic hydrogels to sustainably capture both organic and inorganic micropollutants from water with minimal operational complexity. In the past, zwitterionic molecules have been used as coatings on membranes for water treatment because of their non-fouling properties. But in the Doyle group’s system, zwitterionic molecules are used to form the scaffold material, or backbone within the hydrogel — a porous three-dimensional network of polymer chains that contains a significant amount of water. “Zwitterionic molecules have very strong attraction to water compared to other materials which are used to make hydrogels or polymers,” says Gokhale. What’s more, the positive and negative charges on zwitterionic molecules cause the hydrogels to have lower compressibility than what has been commonly observed in hydrogels. This makes for significantly more swollen, robust, and porous hydrogels, which is important for the scale up of the hydrogel-based system for water treatment.

    The early stages of this research were supported by a seed grant from MIT’s Abdul Latif Jameel Water and Food Systems Lab (J-WAFS). Doyle’s group is now pursuing commercialization of the platform for both at-home use and industrial scale applications, with support from a J-WAFS Solutions grant.

    Seeking a sustainable solution

    Micropollutants are chemically diverse materials that can be harmful to human health and the environment, even though they are typically found at low concentrations (micrograms to milligrams per liter) relative to conventional contaminants. Micropollutants can be organic or inorganic and can be naturally-occurring or synthetic. Organic micropollutants are mostly carbon-based molecules and include pesticides and per- and polyfluoroalkyl substances (PFAS), known as “forever chemicals.” Inorganic micropollutants, such as heavy metals like lead and arsenic, tend to be smaller than organic micropollutants. Unfortunately, both organic and inorganic micropollutants are pervasive in the environment.

    Many micropollutants come from industrial processes, but the effects of human-induced climate change are also contributing to the environmental spread of micropollutants. Gokhale explains that, in California, for example, fires burn plastic electrical cables and leech micropollutants into natural ecosystems. Doyle adds that “outside of climate change, things like pandemics can spike the number of organic micropollutants in the environment due to high concentrations of pharmaceuticals in wastewater.”

    It’s no surprise then, that over the past few years micropollutants have become more and more of a concern. These chemicals have garnered attention in the media and led to “significant change in the environmental engineering and regulatory landscape” says Gokhale. In March 2023, the U.S. Environmental Protection Agency (EPA) proposed a strict, federal standard that would regulate six different PFAS chemicals in drinking water. Just last October, the EPA proposed banning the micropollutant trichloroethylene, a cancer-causing chemical that can be found in brake cleaners and other consumer products. And as recently as November, the EPA proposed that water utilities nationwide be required to replace all of their lead pipes to protect the public from lead exposure. Internationally, Gokhale notes the Oslo Paris Convention, whose mission is to protect the marine environment of the northeast Atlantic Ocean, including phasing out the discharge of offshore chemicals from the oil and gas industries. 

    With each new, necessary regulation to protect the safety of our water resources, the need for effective water treatment processes grows. Compounding this challenge is the need to make water treatment processes that are sustainable and energy-efficient. 

    The benchmark method to treat micropollutants in water is activated carbon. However, making filters with activated carbon is energy-intensive, requiring very high temperatures in large, centralized facilities. Gokhale says approximately “four kilograms of coal are needed to make one kilogram of activated carbon, so you lose a significant amount of carbon dioxide to the environment.” According to the World Economic Forum, global water and wastewater treatment accounts for 5 percent of annual emissions. In the U.S. alone, the EPA reports that drinking water and wastewater systems account for over 45 million tons of greenhouse gas emissions annually.

    “We need to develop methods which have smaller climate footprints than methods which are being used industrially today,” says Gokhale.

    Supporting a “high-risk” project

    In September 2019, Doyle and his lab embarked on an initial project to develop a microparticle-based platform to remove a broad range of micropollutants from water. Doyle’s group had been using hydrogels in pharmaceutical processing to formulate drug molecules into pill format. When he learned about the J-WAFS seed grant opportunity for early-stage research in water and food systems, Doyle realized his pharmaceutical work with hydrogels could be applied to environmental issues like water treatment. “I would never have gotten funding for this project if I went to the NSF [National Science Foundation], because they would just say, ‘you’re not a water person.’ But the J-WAFS seed grant offered a way for a high-risk, high-reward kind of project,” Doyle says.

    In March 2022, Doyle, Gokhale, and MIT undergraduate Ian Chen published findings from the seed grant work, describing their use of micelles within hydrogels for water treatment. Micelles are spherical structures that form when molecules called surfactants (found in things like soap), come in contact with water or other liquids. The team was able to synthesize micelle-laden hydrogel particles that soak up micropollutants from water like a sponge. Unlike activated carbon, the hydrogel particle system is made from environmentally friendly materials. Furthermore, the system’s materials are made at room temperature, making them exceedingly more sustainable than activated carbon.

    Building off the success of the seed grant, Doyle and his team were awarded a J-WAFS Solutions grant in September 2022 to help move their technology from the lab to the market. With this support, the researchers have been able to build, test, and refine pilot-scale prototypes of their hydrogel platform. System iterations during the solutions grant period have included the use of the zwitterionic molecules, a novel advancement from the seed grant work.  

    Rapid elimination of micropollutants is of special importance in commercial water treatment processes, where there is a limited amount of time water can spend inside the operational filtration unit. This is referred to as contact time, explains Gokhale. In municipal-scale or industrial-scale water treatment systems, contact times are usually less than 20 minutes and can be as short as five minutes. 

    “But as people have been trying to target these emerging micropollutants of concern, they realized they can’t get to sufficiently low concentrations on the same time scales as conventional contaminants,” Gokhale says. “Most technologies focus only on specific molecules or specific classes of molecules. So, you have whole technologies which are focusing only on PFAS, and then you have other technologies for lead and metals. When you start thinking about removing all of these contaminants from water, you end up with designs which have a very large number of unit operations. And that’s an issue because you have plants which are in the middle of large cities, and they don’t necessarily have space to expand to increase their contact times to efficiently remove multiple micropollutants,” he adds.

    Since zwitterionic molecules possess unique properties that confer high porosity, the researchers have been able to engineer a system for quicker uptake of micropollutants from water. Tests show that the hydrogels can eliminate six chemically diverse micropollutants at least 10 times faster than commercial activated carbon. The system is also compatible with a diverse set of materials, making it multifunctional. Micropollutants can bind to many different sites within the hydrogel platform: organic micropollutants bind to the micelles or surfactants while inorganic micropollutants bind to the zwitterionic molecules. Micelles, surfactants, zwitterionic molecules, and other chelating agents can be swapped in and out to essentially tune the system with different functionalities based on the profile of the water being treated. This kind of “plug-and-play” addition of various functional agents does not require a change in the design or synthesis of the hydrogel platform, and adding more functionalities does not take away from existing functionality. In this way, the zwitterionic-based system can rapidly remove multiple contaminants at lower concentrations in a single step, without the need for large, industrial units or capital expenditure. 

    Perhaps most importantly, the particles in the Doyle group’s system can be regenerated and used over and over again. By simply soaking the particles in an ethanol bath, they can be washed of micropollutants for indefinite use without loss of efficacy. When activated carbon is used for water treatment, the activated carbon itself becomes contaminated with micropollutants and must be treated as toxic chemical waste and disposed of in special landfills. Over time, micropollutants in landfills will reenter the ecosystem, perpetuating the problem.

    Arjav Shah, a PhD-MBA candidate in MIT’s Department of Chemical Engineering and the MIT Sloan School of Management, respectively, recently joined the team to lead commercialization efforts. The team has found that the zwitterionic hydrogels could be used in several real-world contexts, ranging from large-scale industrial packed beds to small-scale, portable, off-grid applications — for example, in tablets that could clean water in a canteen — and they have begun piloting the technology through a number of commercialization programs at MIT and in the greater Boston area.

    The combined strengths of each member of the team continue to drive the project forward in impactful ways, including undergraduate students like Andre Hamelberg, the third author on the Nature Water paper. Hamelberg is a participant in MIT’s Undergraduate Research Opportunities Program (UROP). Gokhale, who is also a J-WAFS Fellow, provides training and mentorship to Hamelberg and other UROP students in the lab.

    “We see this as an educational opportunity,” says Gokhale, noting that the UROP students learn science and chemical engineering through the research they conduct in the lab. The J-WAFS project has also been “a way of getting undergrads interested in water treatment and the more sustainable aspects of chemical engineering,” Gokhale says. He adds that it’s “one of the few projects which goes all the way from designing specific chemistries to building small filters and units and scaling them up and commercializing them. It’s a really good learning opportunity for the undergrads and we’re always excited to have them work with us.”

    In four years, the technology has been able to grow from an initial idea to a technology with scalable, real-world applications, making it an exemplar J-WAFS project. The fruitful collaboration between J-WAFS and the Doyle lab serves as inspiration for any MIT faculty who may want to apply their research to water or food systems projects.

    “The J-WAFS project serves as a way to demystify what a chemical engineer does,” says Doyle. “I think that there’s an old idea of chemical engineering as working in just oil and gas. But modern chemical engineering is focused on things which make life and the environment better.” More

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    MIT campus goals in food, water, waste support decarbonization efforts

    With the launch of Fast Forward: MIT’s Climate Action Plan for the Decade, the Institute committed to decarbonize campus operations by 2050 — an effort that touches on every corner of MIT, from building energy use to procurement and waste. At the operational level, the plan called for establishing a set of quantitative climate impact goals in the areas of food, water, and waste to inform the campus decarbonization roadmap. After an 18-month process that engaged staff, faculty, and researchers, the goals — as well as high-level strategies to reach them — were finalized in spring 2023.

    The goal development process was managed by a team representing the areas of campus food, water, and waste, respectively, and includes Director of Campus Dining Mark Hayes and Senior Sustainability Project Manager Susy Jones (food), Director of Utilities Janine Helwig (water), Assistant Director of Campus Services Marty O’Brien, and Assistant Director of Sustainability Brain Goldberg (waste) to co-lead the efforts. The group worked together to set goals that leverage ongoing campus sustainability efforts. “It was important for us to collaborate in order to identify the strategies and goals,” explains Goldberg. “It allowed us to set goals that not only align, but build off of one another, enabling us to work more strategically.”

    In setting the goals, each team relied on data, community insight, and best practices. The co-leads are sharing their process to help others at the Institute understand the roles they can play in supporting these objectives.  

    Sustainable food systems

    The primary food impact goal aims for a 25 percent overall reduction in the greenhouse gas footprint of food purchases starting with academic year 2021-22 as a baseline, acknowledging that beef purchases make up a significant share of those emissions. Additionally, the co-leads established a goal to recover all edible food waste in dining hall and retail operations where feasible, as that reduces MIT’s waste impact and acknowledges that redistributing surplus food to feed people is critically important.

    The work to develop the food goal was uniquely challenging, as MIT works with nine different vendors — including main vendor Bon Appetit — to provide food on campus, with many vendors having their own sustainability targets. The goal-setting process began by understanding vendor strategies and leveraging their climate commitments. “A lot of this work is not about reinventing the wheel, but about gathering data,” says Hayes. “We are trying to connect the dots of what is currently happening on campus and to better understand food consumption and waste, ensuring that we area reaching these targets.”

    In identifying ways to reach and exceed these targets, Jones conducted listening sessions around campus, balancing input with industry trends, best-available science, and institutional insight from Hayes. “Before we set these goals and possible strategies, we wanted to get a grounding from the community and understand what would work on our campus,” says Jones, who recently began a joint role that bridges the Office of Sustainability and MIT Dining in part to support the goal work.

    By establishing the 25 percent reduction in the greenhouse gas footprint of food purchases across MIT residential dining menus, Jones and Hayes saw goal-setting as an opportunity to add more sustainable, local, and culturally diverse foods to the menu. “If beef is the most carbon-intensive food on the menu, this enables us to explore and expand so many recipes and menus from around the globe that incorporate alternatives,” Jones says.

    Strategies to reach the climate food goals focus on local suppliers, more plant-forward meals, food recovery, and food security. In 2019, MIT was a co-recipient of the New England Food Vision Prize provided by the Kendall Foundation to increase the amount of local food served on campus in partnership with CommonWealth Kitchen in Dorchester. While implementation of that program was put on pause due to the pandemic, work resumed this year. Currently, the prize is funding a collaborative effort to introduce falafel-like, locally manufactured fritters made from Maine-grown yellow field peas to dining halls at MIT and other university campuses, exemplifying the efforts to meet the climate impact goal, serve as a model for others, and provide demonstrable ways of strengthening the regional food system.

    “This sort of innovation is where we’re a leader,” says Hayes. “In addition to the Kendall Prize, we are looking to focus on food justice, growing our BIPOC [Black, Indigenous, and people of color] vendors, and exploring ideas such as local hydroponic and container vegetable growing companies, and how to scale these types of products into institutional settings.”

    Reduce and reuse for campus water

    The 2030 water impact goal aims to achieve a 10 percent reduction in water use compared to the 2019 baseline and to update the water reduction goal to align with the new metering program and proposed campus decarbonization plans as they evolve.

    When people think of campus water use, they may think of sprinklers, lab sinks, or personal use like drinking water and showers. And while those uses make up around 60 percent of campus water use, the Central Utilities Plant (CUP) accounts for the remaining 40 percent. “The CUP generates electricity and delivers heating and cooling to the campus through steam and chilled water — all using what amounts to a large percentage of water use on campus,” says Helwig. As such, the water goal focuses as much on reuse as reduction, with one approach being to expand water capture from campus cooling towers for reuse in CUP operations. “People often think of water use and energy separately, but they often go hand-in-hand,” Helwig explains.

    Data also play a central part in the water impact goal — that’s why a new metering program is called for in the implementation strategy. “We have access to a lot of data at MIT, but in reviewing the water data to inform the goal, we learned that it wasn’t quite where we needed it,” explains Helwig. “By ensuring we have the right meter and submeters set up, we can better set boundaries to understand where there is the potential to reduce water use.” Irrigation on campus is one such target with plans to soon release new campuswide landscaping standards that minimize water use.

    Reducing campus waste

    The waste impact goal aims to reduce campus trash by 30 percent compared to 2019 baseline totals. Additionally, the goal outlines efforts to improve the accuracy of indicators tracking campus waste; reduce the percentage of food scraps in trash and percent of recycling in trash in select locations; reduce the percentage of trash and recycling comprised of single use items; and increase the percentage of residence halls and other campus spaces where food is consumed at scale, implementing an MIT food scrap collection program.

    In setting the waste goals, Goldberg and O’Brien studied available campus waste data from past waste audits, pilot programs, and MIT’s waste haulers. They factored in state and city policies that regulate things like the type and amount of waste large institutions can transport. “Looking at all the data it became clear that a 30 percent trash reduction goal will make a tremendous impact on campus and help us drive toward the goal of completely designing out waste from campus,” Goldberg says. The strategies to reach the goals include reducing the amount of materials that come into campus, increasing recycling rates, and expanding food waste collection on campus.

    While reducing the waste created from material sources is outlined in the goals, food waste is a special focus on campus because it comprises approximately 40 percent of campus trash, it can be easily collected separately from trash and recycled locally, and decomposing food waste is one of the largest sources of greenhouse gas emissions found in landfills. “There is a lot of greenhouse gas emissions that result from production, distribution, transportation, packaging, processing, and disposal of food,” explains Goldberg. “When food travels to campus, is removed from campus as waste, and then breaks down in a landfill, there are emissions every step of the way.”

    To reduce food waste, Goldberg and O’Brien outlined strategies that include working with campus suppliers to identify ordering volumes and practices to limit waste. Once materials are on campus, another strategy kicks in, with a new third stream of waste collection that joins recycling and trash — food waste. By collecting the food waste separately — in bins that are currently rolling out across campus — the waste can be reprocessed into fertilizer, compost, and/or energy without the off-product of greenhouse gases. The waste impact goal also relies on behavioral changes to reduce waste, with education materials part of the process to reduce waste and decontaminate reprocessing streams.

    Tracking progress

    As work toward the goals advances, community members can monitor progress in the Sustainability DataPool Material Matters and Campus Water Use dashboards, or explore the Impact Goals in depth.

    “From food to water to waste, everyone on campus interacts with these systems and can grapple with their impact either from a material they need to dispose of, to water they’re using in a lab, or leftover food from an event,” says Goldberg. “By setting these goals we as an institution can lead the way and help our campus community understand how they can play a role, plug in, and make an impact.” More

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    Accelerated climate action needed to sharply reduce current risks to life and life-support systems

    Hottest day on record. Hottest month on record. Extreme marine heatwaves. Record-low Antarctic sea-ice.

    While El Niño is a short-term factor in this year’s record-breaking heat, human-caused climate change is the long-term driver. And as global warming edges closer to 1.5 degrees Celsius — the aspirational upper limit set in the Paris Agreement in 2015 — ushering in more intense and frequent heatwaves, floods, wildfires, and other climate extremes much sooner than many expected, current greenhouse gas emissions-reduction policies are far too weak to keep the planet from exceeding that threshold. In fact, on roughly one-third of days in 2023, the average global temperature was at least 1.5 C higher than pre-industrial levels. Faster and bolder action will be needed — from the in-progress United Nations Climate Change Conference (COP28) and beyond — to stabilize the climate and minimize risks to human (and nonhuman) lives and the life-support systems (e.g., food, water, shelter, and more) upon which they depend.

    Quantifying the risks posed by simply maintaining existing climate policies — and the benefits (i.e., avoided damages and costs) of accelerated climate action aligned with the 1.5 C goal — is the central task of the 2023 Global Change Outlook, recently released by the MIT Joint Program on the Science and Policy of Global Change.

    Based on a rigorous, integrated analysis of population and economic growth, technological change, Paris Agreement emissions-reduction pledges (Nationally Determined Contributions, or NDCs), geopolitical tensions, and other factors, the report presents the MIT Joint Program’s latest projections for the future of the earth’s energy, food, water, and climate systems, as well as prospects for achieving the Paris Agreement’s short- and long-term climate goals.

    The 2023 Global Change Outlook performs its risk-benefit analysis by focusing on two scenarios. The first, Current Trends, assumes that Paris Agreement NDCs are implemented through the year 2030, and maintained thereafter. While this scenario represents an unprecedented global commitment to limit greenhouse gas emissions, it neither stabilizes climate nor limits climate change. The second scenario, Accelerated Actions, extends from the Paris Agreement’s initial NDCs and aligns with its long-term goals. This scenario aims to limit and stabilize human-induced global climate warming to 1.5 C by the end of this century with at least a 50 percent probability. Uncertainty is quantified using 400-member ensembles of projections for each scenario.

    This year’s report also includes a visualization tool that enables a higher-resolution exploration of both scenarios.

    Energy

    Between 2020 and 2050, population and economic growth are projected to drive continued increases in energy needs and electrification. Successful achievement of current Paris Agreement pledges will reinforce a shift away from fossil fuels, but additional actions will be required to accelerate the energy transition needed to cap global warming at 1.5 C by 2100.

    During this 30-year period under the Current Trends scenario, the share of fossil fuels in the global energy mix drops from 80 percent to 70 percent. Variable renewable energy (wind and solar) is the fastest growing energy source with more than an 8.6-fold increase. In the Accelerated Actions scenario, the share of low-carbon energy sources grows from 20 percent to slightly more than 60 percent, a much faster growth rate than in the Current Trends scenario; wind and solar energy undergo more than a 13.3-fold increase.

    While the electric power sector is expected to successfully scale up (with electricity production increasing by 73 percent under Current Trends, and 87 percent under Accelerated Actions) to accommodate increased demand (particularly for variable renewables), other sectors face stiffer challenges in their efforts to decarbonize.

    “Due to a sizeable need for hydrocarbons in the form of liquid and gaseous fuels for sectors such as heavy-duty long-distance transport, high-temperature industrial heat, agriculture, and chemical production, hydrogen-based fuels and renewable natural gas remain attractive options, but the challenges related to their scaling opportunities and costs must be resolved,” says MIT Joint Program Deputy Director Sergey Paltsev, a lead author of the 2023 Global Change Outlook.

    Water, food, and land

    With a global population projected to reach 9.9 billion by 2050, the Current Trends scenario indicates that more than half of the world’s population will experience pressures to its water supply, and that three of every 10 people will live in water basins where compounding societal and environmental pressures on water resources will be experienced. Population projections under combined water stress in all scenarios reveal that the Accelerated Actions scenario can reduce approximately 40 million of the additional 570 million people living in water-stressed basins at mid-century.

    Under the Current Trends scenario, agriculture and food production will keep growing. This will increase pressure for land-use change, water use, and use of energy-intensive inputs, which will also lead to higher greenhouse gas emissions. Under the Accelerated Actions scenario, less agricultural and food output is observed by 2050 compared to the Current Trends scenario, since this scenario affects economic growth and increases production costs. Livestock production is more greenhouse gas emissions-intensive than crop and food production, which, under carbon-pricing policies, drives demand downward and increases costs and prices. Such impacts are transmitted to the food sector and imply lower consumption of livestock-based products.

    Land-use changes in the Accelerated Actions scenario are similar to those in the Current Trends scenario by 2050, except for land dedicated to bioenergy production. At the world level, the Accelerated Actions scenario requires cropland area to increase by 1 percent and pastureland to decrease by 4.2 percent, but land use for bioenergy must increase by 44 percent.

    Climate trends

    Under the Current Trends scenario, the world is likely (more than 50 percent probability) to exceed 2 C global climate warming by 2060, 2.8 C by 2100, and 3.8 C by 2150. Our latest climate-model information indicates that maximum temperatures will likely outpace mean temperature trends over much of North and South America, Europe, northern and southeast Asia, and southern parts of Africa and Australasia. So as human-forced climate warming intensifies, these regions are expected to experience more pronounced record-breaking extreme heat events.

    Under the Accelerated Actions scenario, global temperature will continue to rise through the next two decades. But by 2050, global temperature will stabilize, and then slightly decline through the latter half of the century.

    “By 2100, the Accelerated Actions scenario indicates that the world can be virtually assured of remaining below 2 C of global warming,” says MIT Joint Program Deputy Director C. Adam Schlosser, a lead author of the report. “Nevertheless, additional policy mechanisms must be designed with more comprehensive targets that also support a cleaner environment, sustainable resources, as well as improved and equitable human health.”

    The Accelerated Actions scenario not only stabilizes global precipitation increase (by 2060), but substantially reduces the magnitude and potential range of increases to almost one-third of Current Trends global precipitation changes. Any global increase in precipitation heightens flood risk worldwide, so policies aligned with the Accelerated Actions scenario would considerably reduce that risk.

    Prospects for meeting Paris Agreement climate goals

    Numerous countries and regions are progressing in fulfilling their Paris Agreement pledges. Many have declared more ambitious greenhouse gas emissions-mitigation goals, while financing to assist the least-developed countries in sustainable development is not forthcoming at the levels needed. In this year’s Global Stocktake Synthesis Report, the U.N. Framework Convention on Climate Change evaluated emissions reductions communicated by the parties of the Paris Agreement and concluded that global emissions are not on track to fulfill the most ambitious long-term global temperature goals of the Paris Agreement (to keep warming well below 2 C — and, ideally, 1.5 C — above pre-industrial levels), and there is a rapidly narrowing window to raise ambition and implement existing commitments in order to achieve those targets. The Current Trends scenario arrives at the same conclusion.

    The 2023 Global Change Outlook finds that both global temperature targets remain achievable, but require much deeper near-term emissions reductions than those embodied in current NDCs.

    Reducing climate risk

    This report explores two well-known sets of risks posed by climate change. Research highlighted indicates that elevated climate-related physical risks will continue to evolve by mid-century, along with heightened transition risks that arise from shifts in the political, technological, social, and economic landscapes that are likely to occur during the transition to a low-carbon economy.

    “Our Outlook shows that without aggressive actions the world will surpass critical greenhouse gas concentration thresholds and climate targets in the coming decades,” says MIT Joint Program Director Ronald Prinn. “While the costs of inaction are getting higher, the costs of action are more manageable.” More

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    In a surprising finding, light can make water evaporate without heat

    Evaporation is happening all around us all the time, from the sweat cooling our bodies to the dew burning off in the morning sun. But science’s understanding of this ubiquitous process may have been missing a piece all this time.

    In recent years, some researchers have been puzzled upon finding that water in their experiments, which was held in a sponge-like material known as a hydrogel, was evaporating at a higher rate than could be explained by the amount of heat, or thermal energy, that the water was receiving. And the excess has been significant — a doubling, or even a tripling or more, of the theoretical maximum rate.

    After carrying out a series of new experiments and simulations, and reexamining some of the results from various groups that claimed to have exceeded the thermal limit, a team of researchers at MIT has reached a startling conclusion: Under certain conditions, at the interface where water meets air, light can directly bring about evaporation without the need for heat, and it actually does so even more efficiently than heat. In these experiments, the water was held in a hydrogel material, but the researchers suggest that the phenomenon may occur under other conditions as well.

    The findings are published this week in a paper in PNAS, by MIT postdoc Yaodong Tu, professor of mechanical engineering Gang Chen, and four others.

    The phenomenon might play a role in the formation and evolution of fog and clouds, and thus would be important to incorporate into climate models to improve their accuracy, the researchers say. And it might play an important part in many industrial processes such as solar-powered desalination of water, perhaps enabling alternatives to the step of converting sunlight to heat first.

    The new findings come as a surprise because water itself does not absorb light to any significant degree. That’s why you can see clearly through many feet of clean water to the surface below. So, when the team initially began exploring the process of solar evaporation for desalination, they first put particles of a black, light-absorbing material in a container of water to help convert the sunlight to heat.

    Then, the team came across the work of another group that had achieved an evaporation rate double the thermal limit — which is the highest possible amount of evaporation that can take place for a given input of heat, based on basic physical principles such as the conservation of energy. It was in these experiments that the water was bound up in a hydrogel. Although they were initially skeptical, Chen and Tu starting their own experiments with hydrogels, including a piece of the material from the other group. “We tested it under our solar simulator, and it worked,” confirming the unusually high evaporation rate, Chen says. “So, we believed them now.” Chen and Tu then began making and testing their own hydrogels.

    They began to suspect that the excess evaporation was being caused by the light itself —that photons of light were actually knocking bundles of water molecules loose from the water’s surface. This effect would only take place right at the boundary layer between water and air, at the surface of the hydrogel material — and perhaps also on the sea surface or the surfaces of droplets in clouds or fog.

    In the lab, they monitored the surface of a hydrogel, a JELL-O-like matrix consisting mostly of water bound by a sponge-like lattice of thin membranes. They measured its responses to simulated sunlight with precisely controlled wavelengths.

    The researchers subjected the water surface to different colors of light in sequence and measured the evaporation rate. They did this by placing a container of water-laden hydrogel on a scale and directly measuring the amount of mass lost to evaporation, as well as monitoring the temperature above the hydrogel surface. The lights were shielded to prevent them from introducing extra heat. The researchers found that the effect varied with color and peaked at a particular wavelength of green light. Such a color dependence has no relation to heat, and so supports the idea that it is the light itself that is causing at least some of the evaporation.

    The puffs of white condensation on glass is water being evaporated from a hydrogel using green light, without heat.Image: Courtesy of the researchers

    The researchers tried to duplicate the observed evaporation rate with the same setup but using electricity to heat the material, and no light. Even though the thermal input was the same as in the other test, the amount of water that evaporated never exceeded the thermal limit. However, it did so when the simulated sunlight was on, confirming that light was the cause of the extra evaporation.

    Though water itself does not absorb much light, and neither does the hydrogel material itself, when the two combine they become strong absorbers, Chen says. That allows the material to harness the energy of the solar photons efficiently and exceed the thermal limit, without the need for any dark dyes for absorption.

    Having discovered this effect, which they have dubbed the photomolecular effect, the researchers are now working on how to apply it to real-world needs. They have a grant from the Abdul Latif Jameel Water and Food Systems Lab to study the use of this phenomenon to improve the efficiency of solar-powered desalination systems, and a Bose Grant to explore the phenomenon’s effects on climate change modeling.

    Tu explains that in standard desalination processes, “it normally has two steps: First we evaporate the water into vapor, and then we need to condense the vapor to liquify it into fresh water.” With this discovery, he says, potentially “we can achieve high efficiency on the evaporation side.” The process also could turn out to have applications in processes that require drying a material.

    Chen says that in principle, he thinks it may be possible to increase the limit of water produced by solar desalination, which is currently 1.5 kilograms per square meter, by as much as three- or fourfold using this light-based approach. “This could potentially really lead to cheap desalination,” he says.

    Tu adds that this phenomenon could potentially also be leveraged in evaporative cooling processes, using the phase change to provide a highly efficient solar cooling system.

    Meanwhile, the researchers are also working closely with other groups who are attempting to replicate the findings, hoping to overcome skepticism that has faced the unexpected findings and the hypothesis being advanced to explain them.

    The research team also included Jiawei Zhou, Shaoting Lin, Mohammed Alshrah, and Xuanhe Zhao, all in MIT’s Department of Mechanical Engineering. More