GT/ Researcher finds inspiration from spider webs and beetles to harvest fresh water from thin air
Energy & green technology biweekly vol.56, 24th August — 8th September
TL;DR
- A team of researchers is designing novel systems to capture water vapor in the air and turn it into liquid. They have developed sponges or membranes with a large surface area that continually capture moisture from their surrounding environment.
- Molecular photoswitches that can both convert and store energy could be used to make solar energy harvesting more efficient. A team of researchers has used a quantum computing method to find a particularly efficient molecular structure for this purpose. Their procedure was based on a dataset of more than 400,000 molecules, which they screened to find the optimum molecular structure for solar energy storage materials.
- Carbon capture is a promising method to help slow climate change. With this approach, carbon dioxide (CO2) is trapped before it escapes into the atmosphere, but the process requires a large amount of energy and equipment. Now, researchers have designed a capture system using an electrochemical cell that can easily grab and release CO2. The device operates at room temperature and requires less energy than conventional, amine-based carbon-capture systems.
- A new study finds that standalone solar photovoltaic irrigation systems have the potential to meet more than a third of the water needs for crops in small-scale farms across sub-Saharan Africa.
- Methylcyclohexane is very promising as a hydrogen carrier that can safely and efficiently transport and store hydrogen. However, the dehydrogenation process using catalysts has issues due to its durability and large energy loss. Recently, researchers have succeeded in using solid oxide fuel cells to generate electricity directly from methylcyclohexane and recover toluene for reuse. This research is expected to not only reduce energy requirements but also explore new chemical synthesis by fuel cells.
- If coal and natural gas power generation were 2% more efficient, then, every year, there could be 460 million fewer tons of carbon dioxide released and 2 trillion fewer gallons of water used. A recent innovation to the steam cycle used in fossil fuel power generation could achieve this.
- In the ongoing quest for more efficient solar cells, the most current published record for tandem perovskite solar cells is 32.5 percent. In a new paper, researchers report on the improvements in silicon-perovskite tandem cells that have made this possible.
- Researchers have developed a way to make a promising, sustainable alternative to petroleum-based plastics more biodegradable. A team has made a bio-based polymer blend that’s compostable in both home and industrial settings.
- Expensive noble metals often play a vital role in illuminating screens or converting solar energy into fuels. Now, chemists have succeeded in replacing these rare elements with a significantly cheaper metal. In terms of their properties, the new materials are very similar to those used in the past.
- Engineers have developed a new kind of membrane that separates chemicals within wastewater so effectively that they can be reused, presenting a new opportunity for industries to improve sustainability, while extracting valuable by-products and chemicals from wastewater.
- And more!
Green Technology Market
Green technology is an applicable combination of advanced tools and solutions to conserve natural resources and environment, minimize or mitigate negative impacts from human activities on the environment, and ensure sustainability development. Green technology is also referred to as clean technology or environmental technology which includes technologies, such as IoT, AI, analytics, blockchain, digital twin, security, and cloud, which collect, integrate, and analyze data from various real-time data sources, such as sensors, cameras, and Global Positioning System (GPS).
Green technology, also known as sustainable technology, protects the environment by using various forms of sustainable energy. Some of the best examples of green technologies include solar panels, LED lighting, wind energy, electric vehicles, vertical farming, and composting.
The global Green Technology and Sustainability market size to grow from USD 11.2 billion in 2020 to USD 36.6 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 26.6% during the forecast period. The growing consumer and industrial interest for the use of clean energy resources to conserve environment and increasing use of Radio Frequency Identification sensors across industries are driving the adoption of green technology and sustainability solutions and services in the market.
The blockchain segment is estimated to grow at the highest CAGR: Energy-intensive cryptocurrency mining has caused a spike in carbon emission, and hence blockchain is capable of driving innovation in the field of green technology.
Latest Research
Biomimetic surface engineering for sustainable water harvesting systems
by Yi Wang, Weinan Zhao, Mei Han, Jiaxin Xu, Kam Chiu Tam in Nature Water
A team of researchers is designing novel systems to capture water vapour in the air and turn it into liquid.
University of Waterloo professor Michael Tam and his PhD students Yi Wang and Weinan Zhao have developed sponges or membranes with a large surface area that continually capture moisture from their surrounding environment.
Traditionally, fresh water for consumption is collected from rivers, lakes, groundwater, and oceans (with treatment). The current technologies Dr. Tam is developing are inspired by nature to harvest water from alternative sources as the world is facing a serious challenge with freshwater scarcity.
“A spider’s web is an engineering marvel,” said Tam, a University Research Chair in the field of functional colloids and sustainable nanomaterials. “Water is efficiently captured by the web. The spider doesn’t need to go to the river to drink, as it traps moisture from the air.”
Similarly, Namib desert beetles have no easy access to water but acquire water from thin air by leaning into the wind to capture droplets of water from the fog with their textured body armour. This allows the moisture to accumulate and drip into their mouths.
Tam and his research group are engaged in biomimetic surface engineering for sustainable water harvesting. One technology Tam is designing is called atmospheric water harvesting. To mimic the beetle’s unique surface structure, Tam’s research group is designing a similar surface structure using a cellulose-stabilized wax emulsion to fabricate surfaces that attract tiny water droplets while swiftly releasing larger ones.
Tam is working with net zero carbon materials, such as natural and plant-based materials, to develop sustainable technologies. His research group is developing technologies that capture and repel water droplets by harnessing the power of interfacial science and nanotechnology. He has successfully developed superhydrophobic and waterproof paper. He is also engineering a smart and tunable surface that captures water from the air and dehumidifies it with minimal energy consumption. The next step is to develop a scalable process to engineer such surfaces.
Solar evaporation systems directly harvest solar energy, absorbing water and generating fresh collectible vapour through evaporation. Unique mushroom structures inspired the smart biomimetic structural designs for solar evaporation. The proposed freshwater generation systems are inexpensive, energy-efficient, and environmentally friendly.
Searching the Chemical Space of Bicyclic Dienes for Molecular Solar Thermal Energy Storage Candidates
by Andreas Erbs Hillers‐Bendtsen, Jacob Lynge Elholm, Oscar Berlin Obel, Helen Hölzel, Kasper Moth‐Poulsen, Kurt V. Mikkelsen in Angewandte Chemie International Edition
Molecular photoswitches that can both convert and store energy could be used to make solar energy harvesting more efficient. A team of researchers has used a quantum computing method to find a particularly efficient molecular structure for this purpose. As the team describe, their procedure was based on a dataset of more than 400,000 molecules, which they screened to find the optimum molecular structure for solar energy storage materials.
At present, solar energy is either used directly to generate electricity, or indirectly via the energy stored in heat reservoirs. A third route could involve first storing the energy from the sun in light-sensitive materials and then releasing it as needed. The EU-backed project MOST (“Molecular Solar Thermal Energy Storage”) is exploring molecules such as photoswitches that can absorb and store solar energy at room temperature to create entirely emission-free utilization of solar energy a reality.
The research teams of Kurt V. Mikkelsen at the University of Copenhagen, (Denmark) and Kasper Moth-Poulsen at the Technical University of Catalonia, Barcelona (Spain), have taken a closer look at the photoswitches best suited for this task. They studied molecules known as bicyclic dienes, which switch to a high-energy state when illuminated. The most prominent example of this bicyclic diene system is known as norbornadiene quadricyclane, but a vast number of similar candidates exist. The researchers explain: “The resulting chemical space consists of approximately 466,000 bicyclic dienes that we have screened for their potential applicability in MOST technology.”
Screening a database of this size is typically done by machine learning, but this requires large amounts of training data based on real-world experiments, which the team did not have. Using a previously developed algorithm and a novel evaluation score, “eta,” the screening and evaluation of the database molecules yielded a clear result: all six of the top scoring molecules differed from the original norbornadiene quadricyclane system at a crucial point in the structure. The researchers concluded that this structural change, an expansion of the molecular bridge between the two carbon rings in the bicyclic part, allowed the new molecules to store more energy than the original norbornadiene.
The researchers’ work demonstrates the potential for optimizing solar energy storage molecules. However, the new molecules must first be synthesized and tested under real conditions. “Even though the systems can be synthetically prepared, there is no guarantee that they are soluble in relevant solvents and that they will actually photoswitch in high yield or at all, as we have assumed in eta,” the authors caution.
Despite this, the team have developed a new, large set of training data for machine learning algorithms and have thus shortened the arduous research step prior to synthesis for chemists tackling such systems in the future. The authors envision this much larger repository of bicyclic dienes coming into its own for research into photoswitches for a variety of applications, potentially making it easier for molecules to be tailored to specific requirements.
Dual Salt Cation-Swing Process for Electrochemical CO2 Separation
by Fang-Yu Kuo, Sung Eun Jerng, Betar M. Gallant in ACS Central Science
Carbon capture is a promising method to help slow climate change. With this approach, carbon dioxide (CO2) is trapped before it escapes into the atmosphere, but the process requires a large amount of energy and equipment. Now, researchers have designed a capture system using an electrochemical cell that can easily grab and release CO2. The device operates at room temperature and requires less energy than conventional, amine-based carbon-capture systems.
Many industries are turning to electrification to help curb carbon emissions, but this technique isn’t feasible for all sectors. For example, CO2 is a natural byproduct of cement manufacture, and thus a major contributor to emissions on its own. Excess gas can be trapped with carbon-capture technologies, which typically rely on amines to help “scrub” the pollutant by chemically bonding to it. But this also requires lots of energy, heat and industrial equipment — which can burn even more fossil fuels in the process. Carbon capture could itself be electrified by using electrochemical cells, and these devices could be powered by renewable energy sources. So, Fang-Yu Kuo, Sung Eun Jerng and Betar Gallant wanted to develop an electrochemical cell that could easily and reversibly trap CO2 with minimal energy input.
The team first developed an electrochemical cell that could both catch and release emitted carbon by “swinging” positively charged cations across a liquid amine dissolved in dimethyl sulfoxide. When the cell was discharged, a strong Lewis cation interacted with the carbamic acid, releasing CO2 and forming the carbamate amine. When the process was reversed and the cell charged, the cation was removed, and the cell could capture CO2 and reform the carbamic acid in the process.
The researchers optimized the ion-swinging process with a combination of potassium and zinc ions. In a prototype cell, they used these two ions as the basis for the cell’s cathode and anode. This cell required less energy than other, heat-based cells and was competitive with other electrochemical cells in initial experiments. Additionally, they tested the device’s long-term stability and found that nearly 95% of its original capacity was maintained after several cycles of charging and discharging, demonstrating that the system was feasible. The researchers say that this work shows that an electrochemical alternative is possible and could help make continuous CO2 capture-release technologies more practical for industrial applications.
Solar irrigation in sub-Saharan Africa: economic feasibility and development potential
by Giacomo Falchetta, Francesco Semeria, Marta Tuninetti, Vittorio Giordano, Shonali Pachauri, Edward Byers in Environmental Research Letters
In sub-Saharan Africa 80% of agricultural production is from smallholder farmers, who face constraints on increasing farm productivity resulting in a large yield gap. Extensive rain-fed agriculture (90% of all cropland) under unpredictable and erratic rainfall pattern is a leading cause of the low productivity and food insecurity in Africa, together with a low degree of mechanization. This has been reinforcing a persistent poverty trap, triggered by cyclical famines that are jeopardizing local development opportunities.
In a new IIASA-led study as part of the research project Renewables for African Agriculture (RE4AFAGRI), an international team of researchers developed an open-source modeling framework that used various datasets related to agriculture, water, energy, expenses, and infrastructure. This framework was employed to calculate local irrigation needs, determine the necessary size and cost of technology components like water pumps, solar PV modules, batteries, and irrigation systems, and assess the economic prospects and sustainable development impacts of adopting solar pumps.
“We estimate an average discounted investment requirement of USD 3 billion per year, generating potential profits of over USD 5 billion per year from increased yields to smallholder farmers, as well as significant food security and energy access co-benefits,” explains Giacomo Falchetta, lead author of the study and a researcher in the Integrated Assessment and Climate Change Research Group of the IIASA Energy, Climate, and Environment Program. “Reducing the irrigation gap with cost-effective solar pumps can boost food production and improve nutrition, contributing to SDG 2 (Zero Hunger). Furthermore, surplus electricity generated by these systems could serve other energy needs, aligning with SDG 7 (Affordable and Clean Energy).”
Crucially, the authors of the study demonstrate the great importance of business models and investment incentives, crop prices, and PV and battery costs, in shaping the economic feasibility and profitability of solar irrigation.
“Using a business model that spreads out all initial expenses more than doubles the number of workable solar irrigation systems, presenting a huge potential to achieving the SDGs in the process,” notes IIASA Transformative Institutional and Social Solutions Research Group Leader Shonali Pachauri. “On the other hand, the study highlights that without strong land and water resource management infrastructure and governance, a widespread deployment of solar pumps may drive an unsustainable exploitation of water sources and reduce environmental flows. Consequently, both investing in infrastructure, such as reservoirs for water management during seasonal variations, and enhancing water resource governance, are critical factors for ensuring the sustainability of widespread solar pump deployment.”
The analysis and the novel open-source modeling framework can support public and private actors working along the water-energy-food-economy nexus in identifying economically feasible areas and quantifying the potential net economic benefit of developing solar irrigation, and can thus foster investment in the sector.
Dehydrogenation of methylcyclohexane using solid oxide fuel cell — A smart energy conversion
by Akihiko Fukunaga, Asami Kato, Yuki Hara, Takaya Matsumoto in Applied Energy
Methylcyclohexane is very promising as a hydrogen carrier that can safely and efficiently transport and store hydrogen. However, the dehydrogenation process using catalysts has issues due to its durability and large energy loss. Recently, Japanese researchers have succeeded in using solid oxide fuel cells to generate electricity directly from methylcyclohexane and recover toluene for reuse. This research is expected to not only reduce energy requirements but also explore new chemical synthesis by fuel cells.
Methylcyclohexane (MCH), a type of organic hydride, is expected to be an excellent hydrogen carrier because it remains liquid at room temperature, is easy to transport, has low toxicity, and has a higher hydrogen density than high-pressure hydrogen. Dehydrogenation — the process of removing hydrogen atoms from molecules — in the presence of a catalyst, yields hydrogen and the byproduct toluene, which can then be used to generate electricity to produce CO2-free power. However, the dehydrogenation reaction is an endothermic reaction, and energy loss as well as the facilities required for the reaction are issues.
Recently, a team of researchers from Japan, led by Professor Akihiko Fukunaga from the Department of Applied Chemistry at Waseda University, has succeeded in generating electricity directly from MCH using solid oxide fuel cells (SOFC).
The research team tried to perform two processes simultaneously in a fuel cell: dehydrogenation from organic hydrides, which is an endothermic reaction, and electricity generation, which is an exothermic reaction. To achieve this, they used an anode-supported solid oxide fuel cell with a higher operating temperature than that of a polymer electrolyte fuel cell. They operated it at a temperature that did not allow pyrolysis of organic hydrides and under conditions that prevented carbon deposition at the electrodes. The production ratio of toluene to benzene was 94:6. This achievement demonstrated the possibility of generating electricity without using dehydrogenation facilities which were conventionally required and using less energy than that required for dehydrogenation reactions using catalysts.
In addition, “It was elucidated that by changing the conditions, oxygen groups could be introduced into the aromatic skeleton using a fuel cell” reveals Fukunaga.
These results indicate that the MHC reacts with the conducting oxygen ions in the SOFC to successfully generate electricity. Thus, power can be generated directly from MHC, and the energy required for direct power generation is lesser than that required for the conventional catalyst-assisted dehydrogenation reaction of MCH.
“Fuel cells have been studied and developed as devices that produce highly efficient, carbon-free electricity through the electrochemical reaction of hydrogen and oxygen. In this study, we have demonstrated that this device can be applied to control dehydrogenation reactions from organic hydrides and oxygen substitution reactions of aromatic rings. In the future, new synthetic chemistry may be created by applying fuel cells.” concludes Fukunaga. Here’s hoping that the proposed technology will pave the way to a sustainable hydrogen-based society!
Ultra-resilient multi-layer fluorinated diamond like carbon hydrophobic surfaces
by Muhammad Jahidul Hoque, Longnan Li, et al in Nature Communications
If coal and natural gas power generation were 2% more efficient, then, every year, there could be 460 million fewer tons of carbon dioxide released and 2 trillion fewer gallons of water used. A recent innovation to the steam cycle used in fossil fuel power generation could achieve this.
Researchers at the University of Illinois Urbana-Champaign have developed a coating for steam condensers used in fossil fuel steam-cycle generation that is made with fluorinated diamond-like carbon, or F-DLC. The researchers reported that this coating could boost the overall process efficiency by 2%. In addition, they demonstrated the coating’s suitability for industrial use by performing the longest durability test ever reported.
“The reality is that fossil fuels aren’t going away for at least 100 years,” said Nenad Miljkovic, a professor of mechanical science & engineering at UIUC and the project lead. “A lot of CO2 is going to be emitted before we get to a place where we can lean on renewables. If our F-DLC coating were adopted globally, it would noticeably curtail carbon emissions and water usage for the existing power infrastructure.”
Fossil fuel power generation depends on a process called the steam cycle, in which fuel is burned to boil water, the resulting steam spins a turbine and the turbine drives an electric generator. The steam then reaches a condenser which both reclaims water from the steam and maintains a pressure difference across the turbine so the steam flows. Improving the condensers’ heat transfer properties would allow a pressure difference to be maintained while burning less fuel.
The researchers’ new F-DLC coating improves heat transfer because the material is hydrophobic. When the steam condenses into water, it does not form a thin film that coats the surface, like water does on many clean metals and their oxides. Instead, the water forms droplets on the F-DLC surface, putting the steam into direct contact with the condenser and allowing heat to be directly transferred. The researchers found that this improved the heat transfer properties by a factor of 20, which translates to a 2% overall process boost.
“It’s remarkable that we can achieve this with F-DLC, something that just uses carbon, fluorene and a little bit of silicon,” said Muhammad Hoque, a postdoctoral research associate and the study’s lead author. “And it can coat pretty much any common metal, including copper, bronze, aluminum and titanium.”
To demonstrate F-DLC’s durability, the researchers subjected coated metals to steam condenser conditions for 1,095 days, the longest test reported in the literature. The coated metals maintained their hydrophobic properties for this entire length of time. The researchers also found that the coated metals maintained their hydrophobic properties after 5,000 scratches in an abrasion test.
The research team is now collaborating with UIUC’s Abbott Power Plant to study the coating’s performance for six months of steady condensation exposure under industrial conditions.
“If all goes well, we hope to show everyone that this is an effective solution that is economically viable,” Miljkovic said. “We want our solution to be adopted, because, although the development of renewable energy should absolutely be a priority, it’s still very worthwhile to continue improving what we have now.”
Interface engineering for high-performance, triple-halide perovskite–silicon tandem solar cells
by Silvia Mariotti, Eike Köhnen, Florian Scheler, et al in Science
29, 30, 32… — these are not random numbers, but the efficiency of solar cells, measured by the percentage of incidental sunlight they convert into electrical power. The ellipsis at the end of the line is also not a coincidence, as the efficiency of tandem solar cells has already exceeded 32%. “There is a kind of race going on among research teams around the world. In the last year, the solar cell efficiency record has been broken three or four times, it’s just the publication of scientific papers that takes time,” says Dr Artiom Magomedov, a researcher at Kaunas University of Technology, Lithuania.
According to Dr Magomedov, the co-author of a recent paper, the most current published record for tandem perovskite solar cells is 32.5 percent. The paper reports on the improvements in silicon-perovskite tandem cells that have made this possible.
“Tandem solar cells have more than ten layers, so it is technologically very challenging to ensure their smooth operation. The development of such solar cells involves a large number of researchers. For example, our research team is responsible for one of the layers, which is made of hole-transporting materials,” explains Dr Magomedov, a researcher at Kaunas University of Technology (KTU), Lithuania.
Back in 2018, a group of KTU chemists synthesised a material that forms a molecule-thick layer, also known as a monolayer, which evenly covers a variety of surfaces. Several highly efficient solar cells have already been developed using this material. According to Dr Magomedov, one of the authors of the invention, the KTU innovation has become a commonplace among scientists developing the latest solar technologies. The recent scientific article is Dr Magomedov’s second co-authored publication, and is serving as a follow-up to the previous one, proposing a solution to the challenge at hand.
“Although our materials help achieve the highest efficiency, it is difficult to form another layer on top. After our previous paper in Science, we received a lot of attention and comments about how our materials act in different contexts. In the current paper, we show one way to address the problems,” says Dr Magomedov.
More details about the improvement proposed by the KTU research team, which, together with the solutions developed by other scientists around the world, has led to the construction of an ultra-high-efficiency tandem solar cell, can be found in the scientific article. The ultra-high efficiency tandem solar cell was constructed by a research group led by Prof Steve Albrecht from Helmholtz-Zentrum Berlin, in Germany.
Silicon solar cells have a peak potential efficiency of only 29%; the world needs more and more alternative energy sources due to the climate change crisis. Tandem solar cells consist of two types of photoactive layers — a perovskite solar element is placed on top of silicon. The silicon layer collects infrared light, while the perovskite collects blue light from the visible spectrum, increasing the efficiency of the solar cell. However, according to Dr Magomedov, it will still take time for the new generation of solar cells to replace those in use today.
“In theory, electricity made by tandem solar cells would be cheaper because the additional materials used are cheaper. However, in practice, the final commercial product does not exist, the technological processes are not ready for mass production. Moreover, the cell itself, which is only being developed in laboratories so far, also raises unanswered questions. For example, not all materials are suitable for mass production, which means that alternatives have to be found,” explains the KTU scientist.
One of the biggest challenges in the production of these cells so far, he says, is their stability. Solar cells are expected to last for 25 years, during which time they will lose 10% of their efficiency. However, testing over such a long period of time is difficult, so there is no definitive answer as to how the new generation of solar cells will wear out.
The synthesis and analysis of chemical materials for solar technologies has been Dr Magomedov’s topic since the beginning of his undergraduate studies, when he joined a research group led by KTU Professor Vytautas Getautis. As the need for new materials for solar cells emerged, the talented chemists used their competences and established themselves in the niche that opened up, gaining international recognition.
“We are probably the most specialised research group in the world,” jokes Dr Magomedov.
He says that good results are motivating, offer exciting prospects for collaboration and open up new research opportunities. It is great to contribute to a global scientific breakthrough. In addition, Dr Magomedov said, the development of solar technologies is a very topical issue in the context of today’s world, and the inventions can be widely applied.
“Broadly speaking, we are working with new electronics with a very wide range of applications. And of course, in the topic of solar technology itself, the solar energy storage and batteries issue is inevitably coming up,” says Dr Magomedov.
Currently, a research group of KTU chemists led by Prof Getautis is involved in a project to develop a pilot production line for tandem silicon-perovskite solar cells, and is looking for ways to apply the developed materials to other technologies, such as light emitting diodes. In parallel, fundamental questions are also being explored, such as why semiconductors developed in the lab work the way they do.
Breaking It Down: How Thermoplastic Starch Enhances Poly(lactic acid) Biodegradation in Compost─A Comparative Analysis of Reactive Blends
by Pooja C. Mayekar, Wanwarang Limsukon, Anibal Bher, Rafael Auras in ACS Sustainable Chemistry & Engineering
Researchers from Michigan State University’s top-ranked School of Packaging have developed a way to make a promising, sustainable alternative to petroleum-based plastics more biodegradable.
A team led by Rafael Auras has made a bio-based polymer blend that’s compostable in both home and industrial settings.
“In the U.S. and globally, there is a large issue with waste and especially plastic waste,” said Auras, MSU professor and the Amcor Endowed Chair in Packaging Sustainability.
Less than 10% of plastic waste is recycled in the U.S. That means the bulk of plastic waste ends up as trash or litter, creating economic, environmental and even health concerns.
“By developing biodegradable and compostable products, we can divert some of that waste,” Auras said. “We can reduce the amount that goes into a landfill.”
Another bonus is that plastics destined for the compost bin wouldn’t need to be cleaned of food contaminants, which is a major obstacle for efficient plastic recycling. Recycling facilities routinely must choose between spending time, water and energy to clean dirty plastic waste or simply throwing it out.
“Imagine you had a coffee cup or a microwave tray with tomato sauce,” Auras said. “You wouldn’t need to rinse or wash those, you could just compost.”
The team worked with what’s known as polylactic acid, or PLA, which seems like an obvious choice in many ways. It’s been used in packaging for over a decade, and it’s derived from plant sugars rather than petroleum. When managed properly, PLA’s waste byproducts are all natural: water, carbon dioxide and lactic acid. Plus, researchers know that PLA can biodegrade in industrial composters. These composters create conditions, such as higher temperatures, that are more conducive to breaking down bioplastics than home composters. Yet, the idea of making PLA compostable at home seemed impossible to some people.
“I remember people laughing at the idea of developing PLA home composting as an option,” said Pooja Mayekar, a doctoral student in Auras’ lab group and the first author of the new report. “That’s because microbes can’t attack and consume PLA normally. It has to be broken down to a point where they can utilize it as food.”
Although industrial compost settings can get PLA to that point, that doesn’t mean they do it quickly or entirely.
“In fact, many industrial composters still shy away from accepting bioplastics like PLA,” Auras said.
In its experiments, supported by the U.S. Department of Agriculture and MSU AgBioResearch, the team showed that PLA can sit around for 20 days before microbes start digesting it in industrial composting conditions. To get rid of that lag time and enable the possibility of home composting, Auras and his team integrated a carbohydrate-derived material called thermoplastic starch into PLA. Among other benefits, the starch gives composting’s microbes something they can more easily chow down on while the PLA degrades.
“When we talk about the addition of starch, that doesn’t mean we just keep dumping starch in the PLA matrix,” Mayekar said. “This was about trying to find a sweet spot with starch, so the PLA degrades better without compromising its other properties.”
Fortunately, postdoctoral researcher Anibal Bher had already been formulating different PLA-thermoplastic starch blends to observe how they preserved the strength, clarity and other desirable features of regular PLA films. Working with doctoral student Wanwarang Limsukon, Bher and Mayekar could observe how those different films broke down throughout the composting process when carried out at different conditions.
“Different materials have different ways of undergoing hydrolysis at the beginning of the process and biodegrading at the end,” Limsukon said. “We’re working on tracking the entire pathway.”
The team ran these experiments using systems that Auras and lab members, past and present, largely built from scratch during his 19 years with MSU. The equipment the researchers have access to outside their own lab in the School of Packaging also makes a difference.
“Working with Dr. Auras, the School of Packaging, MSU — it’s great,” Bher said. “Because, at some point, we want to be making actual products. We are using facilities around campus to make materials and test their properties. MSU offers a lot of resources.”
Photoredox-active Cr(0) luminophores featuring photophysical properties competitive with Ru(II) and Os(II) complexes
by Narayan Sinha, Christina Wegeberg, Daniel Häussinger, Alessandro Prescimone, Oliver S. Wenger in Nature Chemistry
Expensive noble metals often play a vital role in illuminating screens or converting solar energy into fuels. Now, chemists at the University of Basel have succeeded in replacing these rare elements with a significantly cheaper metal. In terms of their properties, the new materials are very similar to those used in the past.
We’re familiar with chromium from everyday applications such as chromium steel in the kitchen or chrome-plated motorcycles. Soon, however, the element may also be found in the screens of ubiquitous mobile phones or used to convert solar energy. Researchers led by Professor Oliver Wenger from the Department of Chemistry at the University of Basel have developed chromium compounds that can replace the noble metals osmium and ruthenium — two elements that are almost as rare as gold or platinum — in luminescent materials and catalysts. The team reports that the luminescent properties of the new chromium materials are nearly as good as some of the osmium compounds used so far. Relative to osmium, however, chromium is about 20,000 times more abundant in the earth’s crust — and much cheaper.
The new materials are also proving to be efficient catalysts for photochemical reactions, including processes that are triggered by exposure to light, such as photosynthesis. Plants use this process to convert energy from sunlight into energy-rich glucose and other substances that serve as fuel for biological processes.
If the new chromium compounds are irradiated with a red lamp, the energy from the light can be stored in molecules which can then serve as a power source. “Here, there’s also the potential to use our new materials in artificial photosynthesis to produce solar fuels,” explains Wenger.
To make the chromium atoms glow and enable them to convert energy, the researchers built them into an organic molecular framework consisting of carbon, nitrogen, and hydrogen. The team designed this organic framework to be particularly stiff, so that the chromium atoms are well packaged. This tailor-made environment helps to minimize energy losses due to undesired molecular vibrations and to optimize the luminescent and catalytic properties. The disadvantage of the new materials is that chromium requires a more complex framework than noble metals — and further research will therefore be needed in the future.
Encased in its rigid organic framework, chromium proves to be much more reactive than noble metals when exposed to light. This paves the way for photochemical reactions that are otherwise difficult to initiate. A potential application could be in the production of active pharmaceutical ingredients.
For a long time, the search for sustainable and cost-effective materials without noble metals focused primarily on iron and copper. Other research groups have already achieved promising results with both of these elements, and chromium has also been incorporated into luminescent materials in the past.
In many cases, however, the luminescent and catalytic properties of these materials lagged far behind those of materials containing rare and expensive noble metals — therefore failing to represent a real alternative. The new materials made of chromium are different because they contain a form of chromium that is particularly similar to noble metals, thereby achieving luminescent and catalytic efficiencies that come very close to materials containing such metals.
“At the moment, it seems unclear which metal will ultimately win the race when it comes to future applications in luminescent materials and artificial photosynthesis,” says Wenger. “What is certain, however, is that the postdocs Dr. Narayan Sinha and Dr. Christina Wegeberg have made important progress together.”
Next, Wenger and his research group aim to develop their materials on a larger scale to allow broader testing of potential applications. By making additional improvements, they hope to achieve light emission in different spectral colors from blue to green to red. They also want to further optimize the catalytic properties in order to bring us a major step closer to converting sunlight into chemical energy for storage — as in photosynthesis.
Shielding effect enables fast ion transfer through nanoporous membrane for highly energy-efficient electrodialysis
by Jiuyang Lin, Wenyuan Ye, Shuangling Xie, et ai in Nature Water
Engineers have developed a new kind of membrane that separates chemicals within wastewater so effectively that they can be reused, presenting a new opportunity for industries to improve sustainability, while extracting valuable by-products and chemicals from wastewater.
Created for use in wastewater treatment, the thin-film composite nanoporous membrane known as a TFC NPM, exhibits an ‘unprecedented’ capability to separate salts and other chemical components from water, and could lead to more sustainable treatment and management of water in a range of industries.
A research paper details the membrane’s performance and explains how its unique properties, aspects of which are inspired by mussels, could pave the way for more sustainable management of water within industries such as pharmaceuticals, oil and gas, textiles and food processing. The paper is authored by academics from the UK’s University of Bath alongside colleagues based in China, South Korea, Singapore, Australia and Belgium.
They say the membrane could replace current equivalents used in electrodialysis, a process used to treat water by transporting ions through membranes from one solution to another under an electrical current. Existing membranes are expensive and can achieve separation efficiencies of 90–95%. The authors of the new work say the new TFC NPM can improve on this significantly, with efficiencies of more than 99%, while using less energy at a lower cost.
Dr Ming Xie, lecturer in Chemical Engineering at the University of Bath and one of the paper’s authors, says the membrane could lead to a shift in thinking around wastewater treatment. He says: “Traditionally, many industries have regarded the wastewater they create as a trade waste that is a necessary cost of business. Technologies such as the membrane we have created can help us take steps toward lowering carbon emissions by reducing the energy requirement of wastewater treatment, while finding ways to efficiently separate the components in it such as chemicals, salts, energy, biomass and nutrients, before reusing them as high-value by-products.”
The researchers took inspiration from mussels when designing the coating on the membrane surface, which is made up of the polymer polyethyleneimine (PEI) and polydopamine (PDA), a compound which mussels excrete and use to stick to rocks or wood in wet conditions. The coating’s stickiness makes the membrane highly selective, allowing water to pass through but blocking other compounds and organic materials. This multi-stage process results in improved filtration of the water, and a highly efficient, low-energy way to fractionate (or separate) chemicals individually.
Electrodialysis is a technology that has shown its adaptability to several applications, in this case, management of highly saline waste streams. In the electrodialysis process, electrical potential is used to drive the positive and negative ions of dissolved salts through separate semipermeable synthetic membrane.
During tests, the researchers used four antibiotics — ceftriaxone sodium, cefotaxime sodium, carbenicillin disodium and ampicillin sodium — to prove the PDA/PEI-coated membrane’s electro-driven filtration performance. The membrane showed unprecedentedly high recovery efficiency in removing the antibiotics from saltwater solutions (water and NaCl sodium chloride) — with more than 99.3% desalination efficiency and more than 99.1% recovery of the antibiotics. If incorporated in industrial wastewater treatment, the membrane has the capability to carry out highly effective electrodialytic fractionation (separation) of various organic/NaCl mixed solutions, more effectively than standard existing processes.
Co-author, Dr Dong Han Seo from Department of Energy Engineering, Korea Institute of Energy Technology, said “This work demonstrates the state of the art electrodialysis to address the grand challenge in the pharmaceutical industry to bio based wastewater treatment, to enable effective recovery of the high value chemicals while obtaining reusable water in the other end using a low energy consumption.”
Dr Jiuyang Lin from the Chinese Academy of Sciences, also a co-author, said: “This simple yet effective coating provides long term stability and guarantees low energy consumption regardless of the wastewater conditions. This is a breakthrough finding electrodialysis for wastewater treatment involving clever design of membrane, simulation and analysis.”
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