Efficient production technique for a novel ‘green’ fertiliser

Advanced milling technique produces slow-release soil nutrient crystals

A purely mechanical method can produce a novel, more sustainable fertiliser in a less polluting way. That is the result of a method optimised at DESY’s light source PETRA III. An international team used PETRA III to optimise the production method that is an adaptation of an ancient technique: by milling two common ingredients, urea and gypsum, the scientists produce a new solid compound that slowly releases two chemical elements critical to soil fertilisation, nitrogen, and calcium. The milling method is rapid, efficient, and clean—as is the fertiliser product, which has the potential to reduce the nitrogen pollution that fouls water systems and contributes to climate change. The scientists also found that their process is scalable; therefore, it could be potentially implemented industrially. The results by scientists from DESY; the Ruđer Bošković Institute (IRB) in Zagreb, Croatia; and Lehigh University in the USA have been published in the journal Green Chemistry. The new fertiliser still needs to be tested in the field.

For several years, scientists from DESY and IRB, have been collaborating to explore the fundamentals of mechanical methods for initiating chemical reactions. This method of processing, called mechanochemistry, uses various mechanical inputs, such as compressing, vibrating, or, in this case, milling, to achieve the chemical transformation. “Mechanochemistry is quite an old technique,” says Martin Etter, beamline scientist at the P02.1 beamline at PETRA III. “For thousands of years, we’ve been milling things, for example, grain for bread. It’s only now that we’re starting to look at these mechanochemical processes more intensively using X-rays and seeing how we can use those processes to initiate chemical reactions.”

Etter’s beamline is one of the few in the world where mechanochemistry can be routinely performed and analysed using X-rays from a synchrotron. Etter has spent years developing the beamline and working with users to fine-tune methods for analysing and optimising mechanochemical reactions. The result has been a globally renowned experiment setup that has been used in studying many types of reactions important to materials science, industrial catalysis, and green chemistry.

Read more on the DESY website

Image: The co-crystals of the novel fertiliser (symbolised here with gypsum) release their nutrients much more slowly

Credit: DESY, Gesine Born