Mechanochemistry, the art of smashing molecules together to trigger reactions through sheer force, offers a revolutionary path in chemistry. By sidestepping solvents, it champions eco-friendly practices with minimal waste production. Moreover, contrary to traditional industrial practices, it works on low temperatures and pressures, which translates into less energy consumption and highly efficient and cost-effective chemical reactions, aligning with the principles of green chemistry and the circular economy.
Another breakthrough of mechanochemical methods is unlocking pathways to “impossible reactions”, akin to photochemistry and electrochemistry. This means creating and inventing a new set of rules for reactions, which will push the boundaries of chemistry and lead to unexplored and unexpected products. Its unique advantages in terms of versatility, efficiency, and sustainability make mechanochemistry an especially attractive option for industry. That’s why mechanochemistry is moving from lab to fab and finding its way into more and more fields of application. Let’s discover some of the most relevant industrial use cases.
Pharmaceutical manufacturing
If you are familiar with IMPACTIVE, you’ll surely know that the pharmaceutical industry is a protagonist of the mechano-revolution. For pharma industries, mechanochemistry is an opportunity to diversify drug portfolios, democratise the development of life-saving medicines, reduce the reliance on shaky supply chains, and strengthen European leadership during emergencies. The future of mechanochemistry is incredibly bright, and the present provides some exciting examples. Mechanochemical methods, including liquid-assisted grinding (LAG), have shown remarkable success in screening for new polymorphs, salts, or cocrystals of both real and model active pharmaceutical ingredients (APIs). What’s truly exciting is their ability to scale up production of these compounds using batch or continuous processing methods.
Although the amount of reported mechanochemical API syntheses remains limited, there is a growing body of procedures for generating pharmaceutically relevant fragments and functionalities through mechanochemistry. Here at IMPACTIVE we scaled up to the kilogram range the synthesis of a pharmaceutical cocrystal, combining ibuprofen and nicotinamide, and we identified some mechanochemical alternatives to three traditional, solvent-based reactions. And much more is coming soon — that’s our specialty at IMPACTIVE.
Biomass transformation
Transitioning to a low-carbon economy demands innovative solutions, and mechanochemical methods emerge as a sustainable strategy. Thanks to mechanochemistry, we can transform biomass into an array of valuable resources such as biofuels, biochemicals, and bioproducts. Fine milling of biomass, such as straw or agricultural by-products, is already used to enhance their usefulness or to aid further processing. In this field, mechanochemistry plays a role at the beginning of the supply chain: it’s applied in biomass pretreatment, to break the chemical linkages between its components, and prepare it for further chemical or biochemical reactions. Mechanochemical activation provides accelerated reaction rates and creates a high-energy microenvironment by applying pressure and heat through friction. This not only boosts efficiency but also makes biomass transformation more cost-effective.
Recycling technology
Although ball-mils, extruders and other mechanochemical tools are used throughout the recycling field, two industrial uses stand out: the recovery metals and semi-metals from used equipment, and the recycling of plastics. Metal extraction stands out as one of the most energy-intensive and environmentally harmful processes in the chemical industry. But we need more and more lithium-ion batteries, among other metal-intensive applications, along with increasing amounts of battery waste. Fortunately, several studies have shown that lithium and other cathode metals can be recycled. Regarding plastic recycling, there are several mechanochemical approaches that work. For example, polymers with a low ceiling temperature can be completely depolymerized to monomers using polymer mechanochemistry. Turning plastic bags into useful chemicals is now possible thanks to mechanochemistry! Hajime Ito and his team found a way to do it .
Agrochemicals
Chemical substances are widely utilised to increase food production worldwide: they enhance crop production, protect plants from pests and diseases, and improve soil quality. As economies improve in developing countries, farming methods tend to move from traditional, lower-cost chemistry to more advanced solutions. And here is where mechanochemistry steps in.
Let’s travel to Mongolia. Specifically, to the Burenkhaan deposit of phosphorite ores. Here, they turn phosphorite ores into phosphate fertilisers. And to do so, they use mechanochemistry. Phosphorus is a crucial nutrient for plant growth, primarily found in natural phosphate minerals like apatite. However, apatite’s solubility is typically low in soil and natural phosphates have first to be converted to the water-soluble form by their decomposition in acids. But under the influence of mechanical activation, the reactivity of apatites is strongly increased. Proven over 15 years of agrochemical testing, mechanochemically pretreated phosphate fertilizers demonstrate prolonged efficacy akin to their wet chemical counterparts.
Energy storage materials
Energy storage is undergoing a revolution, and mechanochemistry plays a pivotal role in advancing energy storage technologies. Particularly, mechanochemistry can be a powerful ally for perovskites: a family of materials that show immense promise as active materials for light harvesting, thanks to their excellent light absorption abilities and charge-carrier mobilities. Lead halide perovskite materials are promising next-generation solar photovoltaic materials, achieving remarkable power conversion efficiencies exceeding 25%.
Moreover, mechanochemical techniques provide a solvent-free, scalable route to produce solid electrolytes and cathode composites essential for solid-state batteries. This approach not only enhances the sustainability of energy storage solutions but also contributes to the circular economy by facilitating the recycling of these devices.
Metallurgy
In the field of metals, extractive metallurgy excels by far in the use of mechanochemistry, especially in hydrometallurgy, which involves extracting metals from ores using aqueous methods. Mechanochemical processes are becoming more prominent in the very important step of leaching. This step is crucial to extract the metals from their ores as it selectively dissolves the valuable metals, usually thanks to the use of chemicals, while the impurity remains insoluble. Mechanochemistry offers several beneficial effects compared to traditional methods such as enhanced selectivity, improved metal recovery, and kinetics, among others.
Several technologies have been developed for this metallurgical processing. For instance, the mechanochemical process (MELT) originated in Slovakia for hydrometallurgical treatment targets tetrahedrite to selectively extract antimony metal in a liquid state while preserving copper in a solid state. Another example is the Activox process, developed in Australia as an alternative to the pretreatments of sulphidic concentrates by roasting and bacterial oxidation. It has been applied to the recovery of nonferrous and precious metals from concentrates and calcines by combining ultra fine milling with a low temperature and low-pressure oxidative leach.
Material manufacturing
Exploring mechanochemical phenomena is driven by their potential to create new materials and enhance the efficiency of existing and future technologies. Mechanochemistry is a broad field that is applicable to mechanical alloying. Tons of oxide dispersion strengthened alloys have been produced commercially. These alloys consist of a metal matrix with nanoscale oxide particles dispersed within it which provides them with a greater mechanical properties such as tensile and creep strength at high temperatures. This means that they can be used in critical components and highly stressed structures, such as in aerospace or even nuclear industries.
Mechanical activation finds diverse applications in inorganic synthesis and ceramic technology, serving to enhance solubility, reactivity, and even reduce consolidation temperatures. Ball milling can be the primary step of the process in other cases, such as the preparation of complex oxides and refractory compounds. High-energy milling is investigated also for building materials.
A promising future
In conclusion, mechanochemistry stands as a beacon of innovation on the borderline between chemistry, materials science and environmental science. As we continue to delve deeper into this promising approach, we embark on a journey marked by unprecedented opportunities to reshape the landscape of industry, catalysing progress towards a greener, more resilient future.
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