June 24, 2024

Widely used chemicals can now be made without using toxic gas

Jars used for milling the powder

Gouverneur Group, University of Oxford

Chemicals containing the element fluorine and widely used in pharmaceuticals, fertilizers and batteries can now be made by a process that is safer and takes less energy than these substances have been manufactured for centuries.

Fluorine in most fluorochemicals comes from a chunk of salt called fluorspar where the element is bound to calcium. The fluorspar crystals are then removed with strong acid at high temperature to create hydrogen fluoride gas which can then be used in the remaining steps of the fluorochemical production.

However, hydrogen fluoride is highly toxic which makes the whole process hazardous to both the environment and human health. Calum Patel at Oxford University and his colleagues wanted to make fluorine chemicals without using it at all.

Their idea was to grind fluorspar and potassium phosphate salt into a powder rather than reacting it with acid. They put the two salts in a stainless steel jar along with a small steel ball, then used a machine called a ball mill to shake the jar for several hours.

As the jar moved, the steel ball hit the salts repeatedly, grinding them like a hands-free mortar and pestle. This also caused a chemical reaction that produced a new powdered compound that the researchers named Fluoromix.

The researchers could then make compounds containing fluorine through combining Fluoromix with water and other chemical ingredients. To confirm that this could work instead of using the dangerous hydrogen fluoride gas as a source of fluorine in reactions that produce fluorochemicals, they used Fluoromix to make more than 50 different ones, including some ingredients necessary for drug compounds, fertilizers and antibiotics.

Patel says the milling process his team used is new to fluorine chemistry but has been widely used as a more environmentally friendly approach in other chemical manufacturing processes, such as to create parts for novel batteries. This is because it works at room temperature so the process is less energy intensive than producing and using hydrogen fluoride.

David O’Hagan at the University of St Andrews in the UK says the new method could revolutionize an industry that still uses methods dating back to the 1600s. “It’s surprising in a very positive way that you can avoid hydrogen fluoride, and there are many industrial accidents and deaths from hydrogen fluoride. To me, it seems like this could be the beginning of something new for this industry,” he says.

“This seems like a breakthrough, and it’s something of a holy grail to use fluorspar directly in this way that has had little success so far,” he says. James O’Clairig at the University of York in the UK. He says the researchers now need to work out how the new method stacks up against more traditional approaches, both in terms of price and how well it can be adapted to large industrial quantities of fluorspar.


  • chemistry /
  • green technology

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