An artificial mineral made with sugar could sponge up oil spills and replace cyanide in gold mining
A new class of materials developed by chemists at the University of Melbourne could spawn an industry for custom catalysts, molecular sieves and materials for nanotechnology. Their latest invention was made almost by accident.
“I started with simple sugars like glucose and galactose, and metals including cobalt and zinc,” says Mick Moylan, a research chemist at the University of Melbourne. “I found that I’d made crystals with microscopic pores and channels that are less than a millionth of a millimetre wide.”
Mick has been testing the ability of these sponges to suck up pollution. “The pores are about the same size as some common environmental contaminants,” he says. “Their abilities have not been fully tested, but they can absorb some oily chemicals and corrosives into the tiny pores.”
The materials are made by treating some sugar derivatives with metal salts. The result is similar to a scaffold where steel rods are held together by joints. In the molecular sense, metal atoms form the “joints” and sugar derivatives form the rods.
Mick’s creations are the latest of a new group of compounds called coordination polymers was reported in the international journal Agnewandte Chemie International Edition 2003, 42, 1848-51. (Agnewandte Chemie is the journal of the German Chemical Society).
If Mick and his colleagues are successful their new compounds will challenge the use of zeolites in industry. Zeolites are naturally occurring minerals used in many applications including pet litter, animal feed, horticultural applications (soil conditioners and growth media), and wastewater treatment. Synthetic versions are used as catalysts, detergents and molecular sieves.
“Zeolites are hard to customise,” says Mick. “The pore size and openings are restricted, and the properties of the pores are difficult to modify
“Our new compounds are still porous like zeolites but the pore size, shape and wall linings can be tailor-made, meaning the number of reactions and combinations is increased dramatically.”
Born in Bundaberg, Mick is excited about working with the sugar derivatives. “They’re a natural, renewable, abundant and biodegradable resource. If we can commercially develop useful high technology materials based on sugars, it would be great for canegrowers.”
Mick is presenting his research to the public for the first time thanks to Fresh Science, a national program to bring public attention to the remarkable unsung achievements of young Australian scientists. Mick will be speaking to the public and school students about his work on Tuesday 19 and Wednesday 20 August at the Melbourne Museum.
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Some of the sugar-metal structures made by Mick Moylan
PhD student School of Chemistry, University of Melbourne
Pollution’s Sweet Solution
Coordination Polymers and Oligomers
I have produced materials that contain tiny pores by treating sugar derivatives with metals. These pores are roughly the size of a small pollutant molecule or a heavy metal atom, less than a millionth of a millimetre wide. The materials I have made act like sponges. They can suck up environmental contaminants, trapping them safely in the pores.
My research group in the University of Melbourne’s School of Chemistry have been working for the last two years to develop new materials by treating sugar derivatives with different metals.
This work is part of a broader project that aims to control the make-up and organisation of extremely small spaces. We do this using an approach that is very similar to the construction of scaffolding on a building site, but on a much smaller scale. Scaffolding consists of steel rods that are held together by joints. Our molecular scaffolding uses stick-like chemicals that have metal binders at both ends as the “rods” and metal atoms as the “joints”.
In my project, I use some sugar derivatives as the rods. Sugars are attractive as building blocks for materials because they are a safe and renewable resource that would be cheap to produce on a large scale. The manufacture of a commercially successful material from sugar would also benefit Australia’s sugarcane growers. The sugar derivatives that I use are very good at connecting to some metals because they have “pincers” at each end of the molecules that can grab the metal atoms and hold them tightly. This pincing effect can produce materials that are strong and durable.
By carefully controlling the rate that the rods and joints arrange themselves I can sometimes get the materials to form crystals that can be analysed using a technique known as x-ray diffraction. The diffraction instrument shoots an x-ray beam at a crystal and detects the pattern formed as the x-rays bounce off it. By analysing the pattern, I can determine the way the crystal’s components are arranged.
The pores in my materials are located between the rods and joints of the scaffold. The full capabilities of the materials have not yet been determined, but early tests show that they can absorb a range of pollutants, including oily chemicals, some corrosives and some heavy metals. Aside from cleaning up pollution, they may be useful in industrial processes where one component is separated from a mixture. For example, when gold is mined, it is separated from the rubble using cyanide. Cyanide is used because it is cheap and very good at extracting gold. It is also very poisonous and extremely dangerous if it escapes into the environment. If cyanide was replaced with a cheap and environmentally friendly alternative, it would have great benefits for the mining industry.
Qualifications: BSc (Hons), University of Melbourne, 2000, BA, (incomplete), University of Melbourne, 1995-2000