Researchers at Virginia Tech believe they have found a way to shift that timing dramatically in farmers’ favor. A team at the university has developed a low-cost electrochemical sensor capable of detecting Sclerotinia blight in peanut plants as early as five days after infection. By contrast, the physical symptoms that farmers have traditionally relied upon — the telltale signs of fungal invasion visible on stems and foliage — sometimes do not appear for as long as two months. That gap between infection and visible disease is precisely where the pathogen gains its advantage, spreading silently through a field while a grower remains unaware that anything is wrong.

The research, led by Frank Erukainure, a Ph.D. candidate in the Department of Biological Systems Engineering and an Institute for Critical Technology and Applied Science Doctoral Scholar, was described in a paper published in ACS Agricultural Science & Technology. Erukainure’s work on the project earned him the 2026 Boyd-Scott Graduate Research Award, one of the American Society of Agricultural and Biological Engineers’ top honors for graduate scholarship. The recognition underscores how significant the problem is: Sclerotinia blight is not a marginal nuisance but a persistent threat to one of Virginia’s most valuable row crops.

The stakes are easy to quantify. In 2024, farmers in the southeastern region of Virginia harvested roughly 30,000 acres of peanuts, bringing in a cumulative 37.4 million dollars. Historically, growers have relied on time-consuming physical inspections to detect the fungus, walking their fields and examining plants for signs of disease. The trouble with that approach is that by the time the fungus produces its characteristic structures — irregular, rice grain-sized formations that Erukainure describes as the disease’s most visible calling card — the outbreak is often already beyond easy control. Once those structures appear, the disease spreads quickly across the farm, and the pathogen settles into the soil, where it can survive for years, making eradication extraordinarily difficult.

The technical insight behind the new sensor lies in plant biochemistry. When peanut plants are infected with Sclerotinia minor, they produce abundant quantities of oxalic acid, a chemical compound that accumulates in the plant’s sap. This elevated oxalic acid serves as an early biochemical fingerprint of infection, a molecular distress signal that appears long before any outward symptom. The Virginia Tech sensor is designed to read that signal directly. Peanut plant sap is extracted from the plant and placed on the sensor, which is built from 3D-printed resin substrates fitted with platinum electrodes. The electrochemical platform measures the concentration of oxalic acid in the sample, flagging infections that would otherwise remain hidden for weeks.

The choice of materials is not incidental. By relying on 3D-printed resin and a relatively simple electrode arrangement, the team has kept the sensor inexpensive to produce, a critical consideration for any technology that hopes to reach working farms. Cost, scalability, and the number of sensors a grower would need to monitor large acreages are all questions the researchers are actively evaluating as development continues. These practical factors will shape how the technology is ultimately deployed on plants in real farm environments, and the team is candid that additional field testing is needed before the sensors can move from validated greenhouse trials into routine agricultural use.

The early detection capability itself has already been validated in greenhouse trials, an important milestone that demonstrates the sensor works under controlled conditions. If the fungus is caught early enough, the infected plant can be treated with a fungicide to prevent the disease from spreading to healthy parts of the plant and to neighboring crops. That intervention window — the days between infection and visible symptom onset — is exactly what the sensor opens up. Instead of reacting to an established outbreak, growers could treat a nascent one, protecting both their yields and the soil beneath their fields from long-term contamination.

The peanut blight sensor is not the team’s first foray into plant-mounted diagnostics. In a previous study published in ACS Sensors, Erukainure and his advisor Abhilash Chandel, assistant professor of precision agriculture and data management, demonstrated a wearable microneedle sensor designed to monitor glucose and water stress in crop plants, providing real-time sensor readings directly from living plants. That device attaches to the stem of a plant and streams plant health data to a phone application, giving growers a continuous window into the physiological state of their crops. The team now hopes to develop a similar wearable sensor for detecting Sclerotinia blight in peanut plants, extending the same continuous-monitoring philosophy to fungal disease.

Chandel frames the broader shift in stark terms: technologies like these are transforming plant production. By monitoring plant health in real time, he argues, such sensors enable proactive intervention, improving crop resilience, productivity, and sustainability. The vision is one in which disease management moves from periodic, labor-intensive scouting to continuous, data-driven surveillance — a model familiar from precision medicine, applied instead to the physiology of crops. For a disease like Sclerotinia blight, whose survival structures can lurk in soil for years and sabotage subsequent growing seasons, the value of catching an infection at day five rather than day sixty is difficult to overstate.

The next step is already on the calendar. The researchers plan to connect with farmers in the Tidewater region of Virginia to pilot test the sensors in the coming year, a crucial transition from controlled greenhouse experiments to the messier realities of commercial production. That pilot phase will determine how the technology performs across variable field conditions, how growers integrate it into existing management routines, and whether the promise of early detection translates into measurably healthier harvests. If it does, a modest 3D-printed sensor with platinum electrodes could become an essential tool in protecting a crop that Virginia has grown for two hundred years — and in demonstrating that the future of plant disease management may be measured not in seasons, but in days.

Subject of Research: Electrochemical biosensor detection of Sclerotinia blight fungal infection in peanut crops

Article Title: Protecting the peanut: Sensors help fend off fungus

Article References: Protecting the peanut: Sensors help fend off fungus. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: peanuts, Sclerotinia blight, Sclerotinia minor, electrochemical sensor, oxalic acid, plant disease detection, precision agriculture, Virginia Tech, fungicide, wearable plant sensors, crop yield loss, 3D-printed sensors

The core problem with recycled aggregates is well understood. When old concrete is crushed, fragments of the original natural stone remain encrusted with hydrated cement paste, the soft, capillary-rich residue of the demolished structure. This adhered mortar is far weaker and more porous than the parent rock, so it acts as a built-in weak zone. Water penetrates readily, the interfacial transition zone between aggregate and new cement paste is compromised, and the resulting concrete loses compressive strength, tensile strength, and long-term durability. Previous strategies have attacked the problem in various ways: mechanical grinding, thermal treatment, carbonation, polymer impregnation, and, most directly, acid soaking. But the acids used so far have mostly been strong inorganic acids such as hydrochloric acid and sulfuric acid, and the literature shows these can do as much harm as good, dissolving cementitious phases deep inside the aggregate and undermining its structural integrity.

The Indian team, led by Anchal Aggarwal together with Sanjeew Kumar Singh and Gaurav Goel, took a different chemical route. They chose oxalic acid, an organic acid with the formula C2H2O4, best known as the compound that gives rhubarb its sharp taste and, less glamorously, as a chief constituent of kidney stones. The choice is chemically shrewd. When oxalic acid meets the calcium-rich phases of cement mortar, it does not simply dissolve them; it reacts with calcium ions to precipitate calcium oxalate, an insoluble crystalline salt that deposits directly on the aggregate surface. Rather than etching the aggregate away, the treatment converts the troublesome outer mortar into a dense, mineralized skin. The researchers describe this as surface activation rather than surface removal, a conceptual shift that turns out to be the key to the method’s success.

To understand exactly what the acid was doing at the microscale, the team subjected the treated aggregates to a battery of advanced characterization techniques, including X-ray diffraction, field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy with elemental mapping. Together, these tools painted a consistent picture. The treated surfaces were coated with calcium oxalate crystals, calcium had been redistributed across the interfacial region, and pozzolanic crystalline deposits had formed, all of which contribute to a denser, better-bonded interface between the recycled aggregate and the surrounding cement paste in fresh concrete. In effect, the treatment builds a chemically compatible bridge between old mortar and new cement rather than leaving a porous, weak seam.

The mechanical evidence was equally striking. In impact tests, oxalic acid-treated aggregates outperformed aggregates treated with sulfuric acid by 4.6 percent and hydrochloric acid-treated aggregates by 5.9 percent, confirming that the organic treatment preserves and even enhances aggregate integrity where inorganic acids degrade it. Water absorption, the single most telling indicator of aggregate porosity, told a similar story. Untreated recycled aggregates absorbed 3.68 percent water by weight, a figure that dropped to 2.80 percent after sulfuric acid treatment and 2.75 percent after hydrochloric acid treatment. Oxalic acid pushed the figure down to 2.45 percent, evidence of genuine surface pore refinement and reduced accessible porosity rather than mere surface cleaning.

The most consequential results came when the treated aggregates were cast into concrete and tested at 28 days. Compared with concrete made from untreated recycled aggregates, the oxalic acid-treated material showed a 29.5 percent increase in compressive strength and a 35.2 percent increase in splitting tensile strength. Those are not incremental gains; they represent the difference between recycled aggregate concrete that must be derated and blended with virgin stone and concrete that can genuinely compete with conventional mixes in structural applications. The authors attribute the superior performance to the combined effects of adhered mortar modification and the formation of a calcium oxalate-rich surface, emphasizing that the benefit comes not from simply washing the old mortar away but from chemically transforming it into something useful.

Beyond raw performance, the choice of oxalic acid carries practical and safety advantages that could matter enormously for industrial adoption. Concentrated hydrochloric and sulfuric acids are among the most hazardous reagents in routine industrial use, demanding corrosive-resistant equipment, specialized storage, and rigorous worker protection protocols. Oxalic acid, while still requiring sensible handling, is comparatively less hazardous to store and manage, which lowers both operational costs and the regulatory burden of scaling the process to the enormous throughputs that aggregate processing plants demand. For an industry that consumes billions of tons of material annually, even modest simplifications in chemical handling translate into significant economic and safety dividends.

The environmental case was reinforced by a preliminary screening-level carbon and life-cycle assessment, which indicated a potential environmental advantage for the oxalic acid route relative to conventional treatments. Life-cycle thinking is essential here, because a treatment that improves concrete strength but imposes a heavy chemical or energy footprint would simply shift the environmental burden rather than reduce it. The screening assessment suggests that the mild conditions, lower hazards, and improved durability of the resulting concrete combine to make the overall proposition favorable, though the authors are careful to frame this as a preliminary, screening-level result rather than a definitive full life-cycle audit.

The work also fits into a broader and rapidly evolving research landscape. Other groups have pursued accelerated carbonation of recycled aggregates, slag-coated carbonation, nano-silica hydrophobic treatments, cement slurry coating, and thermo-mechanical upgrading, each with its own trade-offs in cost, energy, and scalability. Calcium oxalate chemistry itself has been gaining attention in materials science, from biomimetic conservation treatments for carbonate building stones to newly developed oxalate-activated calcium silicate cements, suggesting that the Indian team’s approach taps into a wider vein of promising mineral chemistry. What distinguishes the new study is its application of that chemistry directly to the adhered mortar problem, converting the recycled aggregate’s greatest liability into a strengthening feature.

If the process can be scaled economically, the implications for urban mining and circular construction are considerable. Cities effectively sit atop vast above-ground mines of demolished concrete, and technologies that upgrade this waste into high-performance raw material could simultaneously relieve landfill pressure, reduce demand for virgin sand and gravel extraction, and cut the carbon intensity of new construction. The authors position oxalic acid treatment as a sustainable route to producing high-performance recycled aggregates for circular concrete applications, and their data lend that claim real substance. Much work remains, from optimizing acid concentration and treatment duration to validating long-term durability in field structures, but the central insight is likely to endure: sometimes the best way to deal with a weak surface is not to remove it, but to grow a better one in its place.

Subject of Research: Oxalic acid surface activation of recycled construction and demolition waste aggregates for high-performance circular concrete

Article Title: Upcycling of construction and demolition waste by oxalic acid surface activation of recycled aggregates: a novel processing approach

Article References: Aggarwal, A., Singh, S. K., & Goel, G. (2026). Upcycling of construction and demolition waste by oxalic acid surface activation of recycled aggregates: a novel processing approach. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38250-5

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38250-5

Keywords: construction and demolition waste, recycled aggregates, oxalic acid, calcium oxalate, concrete, circular economy, surface activation, water absorption, compressive strength, life-cycle assessment, sustainable construction, adhered mortar

The conventional way of making manganese-cerium mixed oxides starts with soluble metal salts, typically nitrates, which are combined through coprecipitation or impregnation. Those routes carry real drawbacks: the procedures are multi-step and difficult to control, the salt solutions generate their own pollutant streams, and the active metal loading on the final support tends to be low. The research team, led by Min Kang and Jian Yu with collaborators at several Chinese institutions, sidestepped the problem by starting from manganese carbonate and cerium carbonate, cheap and stable crystalline solids that are already produced at industrial scale. The trick was finding a way to persuade two stubbornly insoluble carbonates to mix intimately at the molecular level, and the answer turned out to be a humble kitchen-adjacent chemical: oxalic acid.

When the powdered carbonate precursors are treated with oxalic acid, a remarkable transformation occurs. The crystalline carbonates dissolve and reprecipitate as viscous, amorphous oxalate species in which manganese and cerium are chemically intermingled rather than merely sitting side by side as separate grains. This chemical mixing, which the authors distinguish from simple physical blending, is the heart of the method. Structural characterization by X-ray diffraction showed that the oxalate intermediates lose their long-range order, while thermogravimetric analysis revealed a second crucial benefit: the homogeneous oxalate precursors decompose at a lower temperature, between 250 and 300 degrees Celsius, compared with physically mixed carbonates. During that decomposition they also release more carbon dioxide gas, and it is this escaping gas that does the sculpting.

As the oxalate precursor breaks down and CO2 streams out of the shrinking solid, it leaves behind a porous manganese-cerium oxide framework riddled with voids. Measurements of surface area and pore volume using the Brunauer-Emmett-Teller method confirmed that the chemically mixed catalyst possesses a significantly larger specific surface area and pore volume than material made by physically mixing the same carbonates. The morphology that emerges is strip-shaped, a form the authors highlight as suitable for industrial catalyst bodies, which are often shaped into pellets, plates, or honeycombs that must withstand gas flow without excessive pressure drop. Large pores matter in real flue gas service because they allow molecules to diffuse quickly to active sites and are less prone to clogging by dust and aerosols.

Why does intimate mixing of manganese and cerium matter so much for the catalysis itself? The answer lies in the electronic handshake between the two oxides. When manganese oxide domains and cerium oxide domains are finely interspersed, the interface generates abundant defect sites, including oxygen vacancies where an oxygen atom is missing from the crystal lattice. These vacancies, together with highly mobile surface active oxygen species, form the reactive heart of the catalyst. X-ray photoelectron spectroscopy indicated a higher proportion of surface active oxygen in the chemically mixed sample, and the manganese and cerium atoms engage in a facile redox cycle, shuttling electrons back and forth as the reaction proceeds. Ammonia temperature-programmed desorption experiments showed an increased density of acid sites, which anchor the ammonia reductant molecules needed for the selective catalytic reduction reaction.

In the selective catalytic reduction process, ammonia is injected into the flue gas and reacts with nitric oxide over the catalyst surface to produce harmless nitrogen and water. The performance figures reported for the carbonate-derived MnCeOx catalyst are striking. At 150 degrees Celsius, a temperature at which many commercial vanadia-based catalysts are essentially dormant, the material achieved close to 100 percent denitrification efficiency. More important for any real installation, the catalyst held its activity over a 168-hour continuous test, maintaining conversion above 94 percent even under demanding conditions: 30 volume percent water vapor, a level typical of wet flue gases, and a sulfur dioxide concentration of 50 milligrams per normal cubic meter. Sulfur and water resistance has historically been the Achilles heel of manganese-based low-temperature catalysts, because sulfur dioxide reacts with surface sites to form stable sulfates and water competes with ammonia for adsorption.

The authors attribute the exceptional sulfur tolerance to the same structural features that drive the high activity. The large pore volume gives sulfur species less opportunity to block the network of channels, and the sheer abundance of exposed active sites means that even if some are deactivated by sulfate formation, plenty remain available to keep the reaction going. The strong Mn-Ce interaction also appears to moderate the severity of sulfation on the manganese sites themselves, a phenomenon that previous studies of Mn-Ce systems have linked to cerium’s oxygen storage and release capacity. Cerium oxide is famous as an oxygen buffer, absorbing and releasing oxygen as conditions fluctuate, and that buffering stabilizes the redox state of neighboring manganese atoms under the reducing and oxidizing swings of a working flue gas stream.

The comparative experiments in the study sharpen the message about preparation chemistry. Samples made by physically mixing the two carbonates and calcining them at either 300 or 400 degrees Celsius performed markedly worse than the chemically mixed counterparts calcined at the same temperatures. The difference traces back to the precursor stage: physical mixing leaves manganese and cerium in separate crystalline carbonate grains, so even after decomposition the two oxides remain poorly interleaved, with fewer interface sites, fewer defects, and less active oxygen. The oxalic acid route effectively performs the mixing at the molecular scale before any heat is applied, which is why the resulting oxide inherits such a favorable architecture. Calcination temperature mattered as well, with the 300-degree samples retaining the fine dispersion that higher temperatures begin to erode through sintering.

There is also a green-chemistry dimension to the work that extends beyond the catalyst’s performance. By replacing soluble metal salts with carbonates, the synthesis avoids nitrate-containing waste streams and the corrosive, fuming solutions that industrial plants must handle and treat. Oxalic acid is inexpensive, widely available, and acts here as a chemical molding additive that shapes the precursor into workable strips. The lower decomposition temperature of the oxalate route, 250 to 300 degrees Celsius rather than the higher temperatures often needed to fully break down carbonates, translates directly into lower energy consumption during the calcination step, which for a catalyst produced in tonnage quantities is a meaningful cost and emissions saving. The released carbon dioxide is the only major gaseous byproduct of the precursor transformation.

The broader context makes the advance timely. Low-temperature denitrification is increasingly demanded by industries such as coking, cement, glass, and steel, where exhaust gases leave stacks at temperatures far below the window in which conventional catalysts operate, and where reheating the gas is economically prohibitive. Manganese-based catalysts have long been recognized as the most promising family for sub-200-degree operation, but translating laboratory powders into durable industrial bodies has remained the bottleneck. By demonstrating a route that starts from cheap carbonates, uses a simple acid treatment, yields a strip-shaped body suited to industrial forming, and delivers near-complete NOx conversion with robust resistance to water and sulfur, the researchers have addressed several of those bottlenecks at once. If the approach scales as its chemistry suggests it should, the humble carbonate, long treated as a dull industrial commodity, may find a new starring role in cleaning the air above the world’s heaviest industries.

Subject of Research: Carbonate-derived MnCeOx catalysts for low-temperature selective catalytic reduction of NOx in flue gas

Article Title: The Fabrication of Strip-Shaped Industrial MnCeOx Catalyst Derived from Carbonates for Flue Gas Denitrification

Article References: Kang, M., Xu, M., Xiao, P., Xiao, Y., Li, C., Fu, W., Xu, Y., Yu, Z., & Yu, J. (2026). The Fabrication of Strip-Shaped Industrial MnCeOx Catalyst Derived from Carbonates for Flue Gas Denitrification. Catalysis Letters, 156(9), Article 268. https://doi.org/10.1007/s10562-026-05520-3

Image Credits: AI Generated

DOI: 10.1007/s10562-026-05520-3

Keywords: MnCeOx catalyst, flue gas denitrification, NH3-SCR, carbonate precursors, oxalic acid, low-temperature catalysis, nitrogen oxides, sulfur resistance, oxygen vacancies, industrial catalysts, manganese oxide, cerium oxide

Oxalic acid is hardly a novelty. The simple dicarboxylic compound has served industries from pharmaceuticals to textiles for generations, and it was first synthesized in 1776 by the Swedish chemist Carl Wilhelm Scheele through the oxidation of sugar with nitric acid. Today it is produced almost exclusively through petrochemical routes that involve volatile intermediates and substantial carbon dioxide emissions. That matters for metal recycling, because oxalic acid’s green credentials collapse when its entire life cycle is considered. A recent assessment found that, weighed against its toxicity and recovery performance, conventionally produced oxalic acid failed to qualify as a green chemical. The paradox is what motivated Aylin Nur Erkmen of FH Münster University of Applied Sciences and her colleagues to ask whether the molecule could instead be brewed by living cells.

Filamentous fungi had long been suspected of doing exactly that. As early as 1893, the microbiologist Carl Wehmer identified Aspergillus niger as an oxalic acid accumulator, distinguishing it from Penicillium species that follow different metabolic fates. Decades later, researchers mapped the underlying biochemistry to a cytoplasmic, tricarboxylic-acid-independent pathway driven by the enzyme oxaloacetate hydrolase, which cleaves oxaloacetate into oxalate. Crucially, that enzyme only operates efficiently when the surrounding pH remains above 4, a detail that turns out to be the linchpin of the entire process. Industrial citric acid fermentation has historically treated oxalic acid as an unwanted by-product to be suppressed; the German team inverted that logic entirely.

The researchers began with a head-to-head comparison of two Aspergillus niger strains in small shake-flask cultures. Over a 240-hour fermentation, the ATCC 1015 strain secreted a mean peak of 71.0 millimolar oxalic acid, clearly outpacing the CECT 2807 strain, which managed only 37.9 millimolar under the same conditions. The difference tracks closely with how fast each strain acidified its environment: ATCC 1015 drove the pH down to about 3.8 within 72 hours, while its competitor hovered near 4.5. Because oxaloacetate hydrolase is suppressed at low pH, the team then intervened, periodically raising the culture pH back toward neutral. The effect was dramatic. Cultures with intermittent pH adjustment on days one, four and seven reached a final titer of 90.4 millimolar, roughly seven times the yield of unregulated cultures by the 168-hour mark. Keeping the medium above the critical pH 4 threshold, the authors conclude, is not merely helpful but essential.

Carbon source selection proved equally consequential. When the fungus was grown on glucose, sucrose or lactose, glucose produced the highest titer, 136.9 millimolar, with a product yield on substrate of about 0.4 grams per gram, outperforming sucrose by a factor of 1.6 and lactose by nearly five. The explanation lies in metabolic plumbing: glucose enters glycolysis directly, channeling carbon efficiently toward oxaloacetate, the immediate precursor of oxalate. More complex sugars like sucrose and lactose require enzymatic breakdown steps first, diverting flux toward other metabolites. Prior work has suggested that glucose can theoretically support yields approaching 75 percent of the maximum, making the monosaccharide the obvious choice for scale-up.

The decisive test came in a 10-liter stirred-tank bioreactor, where the team compared conventional batch fermentation against a fed-batch strategy with pulsed glucose feeding every 72 hours. Batch operation, seeded with a high initial glucose load of 150 grams per liter, struggled through a prolonged lag phase; substantial acid secretion began only after roughly 192 hours, and the culture only hit its stride once residual glucose dipped below about 20 grams per liter, a sign of carbon catabolite repression lifting. Fed-batch operation avoided that pitfall by keeping glucose below the inhibitory threshold throughout, producing a cyclical, sustained surge of acid after each pulse. The result was a peak oxalic acid titer of 260.1 millimolar over 14 days, with a volumetric production rate of 0.061 grams per liter per hour, more than 1.6 times the batch rate.

Yet the scale-up experiments also exposed two stubborn complications. First, the phosphate buffering used to protect against acid-induced product inhibition turned out to be a double-edged sword: excess phosphate fueled exuberant biomass growth at the direct expense of acidogenesis, delaying the onset of exponential oxalate production until roughly 312 hours, when the phosphate surplus had been depleted. The authors interpret this as a metabolic switch consistent with phosphate-starvation-driven acid synthesis and suggest that future work should pinpoint the precise phosphorus threshold that triggers the shift from growth to acid production. Second, operating the bioreactor at pH 6 to favor oxaloacetate hydrolase inadvertently created ideal conditions for glucose oxidase, an enzyme that converts glucose into gluconic acid. The culture accumulated 226.1 millimolar of gluconic acid alongside the oxalate, which does not reduce the final titer but complicates downstream separation of the two organic acids in an industrial setting.

These hurdles did not prevent the team from framing the process as a genuine industrial candidate, and the reasoning is strategic rather than purely about yield. The volumetric product formation rates reported here trail benchmarks from highly specialized fermentation systems, but those systems carry extreme complexity and high capital expenditure. The goal was instead a simplified, robust framework that can reliably supply enough biogenic leaching agent for real-world metal recovery operations without the operational fragility of a bespoke fermentation plant. The authors argue that a consistent supply of oxalic acid matters more for recycling economics than squeezing out the absolute maximum titer, and the fed-batch protocol they describe delivers that consistency at modest technical cost.

The destination for this biologically brewed acid is the gallium locked inside waste light-emitting diodes and other electronic components. Gallium is indispensable for LEDs, smartphones and tablets, and its long-term supply is increasingly viewed as precarious. Oxalic acid is unusually well suited to the task because it performs two jobs at once: it dissolves metal-bearing phases and forms robust octahedral coordination complexes with hard trivalent metals such as aluminum, iron and gallium, while selectively precipitating divalent ions, including rare earth elements. Earlier work by the same group showed that under optimized conditions, oxalic acid could recover up to 37 percent of gallium from waste minerals. Related research has achieved gallium recoveries exceeding 90 percent from waste surface-mounted LEDs at 90 degrees Celsius using 700 millimolar acid.

What makes the study resonate beyond the lab is the broader industrial and political context. The European Union has committed to climate neutrality by 2050 and is pushing to replace fossil feedstocks with sustainable alternatives for material production, while the global demand for oxalic acid stands at roughly 350,000 tons per year. Fermentation based on renewable sugars offers a route to satisfy that demand without petrochemical emissions, and it plugs directly into a circular economy vision in which yesterday’s electronics become tomorrow’s metal mines. Fungal leaching fluids may also carry synergistic secondary metabolites that enhance metal extraction beyond what pure acid alone can achieve, a phenomenon documented in earlier bioleaching studies with other microorganisms. There is still work to do: biological variability inherent to filamentous fungi, visible in the wide error bars across replicates, will demand larger reproducibility studies and possibly morphological stabilization strategies before industrial batches can be standardized. But the trajectory is clear. A mold that chemists once berated for contaminating citric acid fermentations is now being cultivated, carefully and deliberately, as the engine of a greener metallurgy, one whose raw material is glucose and whose product may help defuse the e-waste crisis one fermented liter at a time.

Subject of Research: Fermentation-based biogenic oxalic acid production for sustainable critical metal recovery from electronic waste

Article Title: Fermentation-based oxalic acid production aimed at sustainable critical metal recovery from electronic waste

Article References: Fermentation-based oxalic acid production aimed at sustainable critical metal recovery from electronic waste. (n.d.). https://doi.org/10.1007/s00253-026-14040-4

Image Credits: AI Generated

DOI: 10.1007/s00253-026-14040-4

Keywords: oxalic acid, Aspergillus niger, fermentation, electronic waste, critical metals, gallium, fed-batch, bioleaching, bioprocess engineering, circular economy, rare earth elements, pH control