Bulk solvents, widely used in the chemical industry, pose a serious threat to human health and the environment. As a result, there is growing interest in avoiding their use by relying on "mechanochemistry" – an energy-efficient alternative that uses high-frequency milling to drive reactions. Because milling involves the intense impact of steel balls in rapidly moving jars, however, the underlying chemistry is difficult to observe.
Now, for the first time, scientists have studied a milling reaction in real time, using highly penetrating X-rays to observe the surprisingly rapid transformations as the mill mixed, ground, and transformed simple ingredients into a complex product. This research, reported Dec. 2 in Nature Chemistry, promises to advance scientists' understanding of processes central to the pharmaceutical, metallurgical, cement and mineral industries – and could open new opportunities in "green chemistry" and environmentally friendly chemical synthesis.
The international team of researchers was led by Tomislav Frišèiæ of McGill University in collaboration with Ivan Halasz from the University of Zagreb in Croatia, and scientists from the University of Cambridge, the Max-Planck-Institute for Solid State Research in Stuttgart, Germany, and the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
While mechanical action can break chemical bonds -- for example, in the wear and tear of textile fibers -- mechanical force can also be used to synthesize new chemical compounds and materials. In recent years, ball milling has become increasingly popular in the production of highly complex chemical structures. In such synthesis, steel balls are shaken with the reactants and catalysts in a rapidly vibrating jar. Chemical transformations take place at the sites of ball collision, where impact causes instant "hot spots" of localized heat and pressure. This is difficult to model and, without access to real time reaction monitoring, mechanochemistry remained poorly understood.
"When we set out to study these reactions, the challenge was to observe the entire reaction without disturbing it, in particular the short-lived intermediates that appear and disappear under continuous impact in less than a minute", says Frišèiæ, an assistant professor in McGill's Department of Chemistry.
The team of scientists chose to study mechanochemical production of the metal-organic framework ZIF-8 from the simplest and non-toxic components. Materials such as ZIF-8 are rapidly gaining popularity for their ability to capture large amounts of CO2; if manufactured cheaply and sustainably, they could become widely used for carbon capture and storage, catalysis and even hydrogen storage.
"The team came to the ESRF because of our high-energy X-rays capable of penetrating 3 mm thick walls of a rapidly moving reaction jar made of steel, aluminium or plastic. The X-ray beam must get inside the jar to probe the mechanochemical formation of ZIF-8, and then out again to detect the changes as they happened", says Simon Kimber, a scientist at the European Synchrotron Radiation Facility (ESRF) in Grenoble, who is a member of the team. This unprecedented methodology enabled the real-time observation of reaction kinetics, reaction intermediates and the development of their respective nanoparticles.
In principle, this technique could be used to study all types of chemical reactions in a ball mill, and optimize them for processing in a range of industries. "That would translate into good news for the environment, for industry -- and for consumers," Frišèiæ says.
The researchers in the team were supported by the Herchel Smith Fund, the British Council/DAAD, ESRF Grenoble, NanoDTC, the University of Cambridge, the Ministry of Science, Education and Sports of the Republic of Croatia, McGill University and the FRQNT Centre for Green Chemistry and Catalysis.
Chris Chipello | EurekAlert!
International team discovers novel Alzheimer's disease risk gene among Icelanders
24.10.2016 | Baylor College of Medicine
New bacteria groups, and stunning diversity, discovered underground
24.10.2016 | DOE/Lawrence Berkeley National Laboratory
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
24.10.2016 | Power and Electrical Engineering
24.10.2016 | Life Sciences
24.10.2016 | Life Sciences