A "greener" fertilizer might be produced by a milling technique

A "greener" fertilizer might be produced by a milling technique ...

DESY''s light source PETRA III has adapted a more sustainable fertilizer, resulting in a rapid, effective process, and cleanas is the fertiliser product, which has the potential to reduce the nitrogen pollution that irritates water systems and contributes to climate change. The research has shown that a purely mechanical method could be utilized in industrial usage.

DESY and IRB have worked to investigate the origins of mechanical techniques for initiating chemical reactions. This method of processing, called mechanochemistry, is quite an old technique, according to Martin Etter, a beamline researcher at PETRA III. It was only now that we were beginning to study these mechanochemical processes more intensively using X-rays and seeing how they might be used to initiate chemical reactions.

Etters beamline is one of the few in the world in which mechanochemistry can be routinely performed and analysed with X-rays from a synchrotron. Etter has spent years developing the beamline and working with users to develop and improve mechanochemical reactions. The result has been a globally renowned experiment system that has been used in research many types of reactions related to materials science, industrial catalysis, and green chemistry.

According to Krunoslav Uzarevic of the IRB in Zagreb, the DESY mechanochemistry setup is likely to be the best in the world. In only a few areas, one can monitor the progress of mechanochemical reactions as well as here at DESY. This result would have been virtually impossible without Martin Etters'' knowledge and this PETRA III setup.

The mechanochemistry team teamed with Jonas Baltrusaitis, a professor of chemical engineering at Lehigh University. The P02.1 setup allows for direct insight into the reaction parameters for the milling vessel. This allows for immediate feedback and analysis of the material''s performance on the fly.

Cocrystal, a solid with a crystal structure that is stabilized by weaker intermolecular interactions in repeated patterns, is known as LEGO structures. In this case, bricks are calcium sulphate, which is derived from the gypsum and the urea. Through the milling process, the urea and calcium sulphate become bonding together.

On its own, urea makes for a very weakly bound crystal that falls apart easily and releases its nitrogen too readily, according to Baltrusaitis. However, with this calcium sulphate through this mechanochemical process, you get a much more robust cocrystal with a slow-release. The advantage of this cocrystal is that its chemical bonds are weak enough to release nitrogen and calcium, but they are also strong enough to prevent the two elements from being unleashed all at once.

For one, the fertilizer has avoided one of the most significant losses of nitrogen fertilizers used since the 1960s. According to Baltrusaitis, the status quo in fertilisers, for food security reasons, is to dump as much nitrogen and phosphorus on crops as possible, while the rest is being cleaned away, causing significant damage to water systems. In the North Sea and the Gulf of Mexico, massive dead zones are rising, where algal blooms fed by excess fertilizer absorb all the available oxygen in the water and thus kill

Besides, the production of common fertilisers is energy-intensive, consuming every year four percent of the global natural gas supply through the HaberBosch process. The new method is an opportunity to alleviate that dependency. If you increase the efficiency of those urea materials by 50%, you must make less urea via HaberBosch, despite all of the related energy consumption concerns, such as natural gas demand. The milling process is fast and very efficient, resulting in a pure fertiliser, without any

While the PETRA III analysis involved milligrams of fertiliser, the researchers at Baltrusaitis and Uzarevic have managed to scale their procedures up with the help of PETRA data. So far, they can, with the same procedure and efficiency, produce hundreds of grams of fertiliser. As a next step, the team hopes to continue scaling up, in order to make an actual proof-of-principle process.

The mechanochemical process is far outlived the product, implying that there is no unwanted byproducts or waste, according to Uzarevic from the IRB. We are optimistic that it will be available elsewhere in the United Kingdom.

The Ruer Boskovic Institut in Zagreb, Croatia, the Lehigh University in Bethlehem (Pennsylvania) in the United States, the chemical company ICL Group, the University of Zagreb, and DESY have all participated in this research.

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