Spinning the world clean


Prof Colin Raston and his colleagues in the Centre for Strategic Nano-Fabrication at the University of Western Australia are setting about cleaning up the world—and chemical industry in particular—through developing a suite of technologies to enable continuous, rather than batch, processing.

“We’re working at getting rid of the round-bottom glass in the laboratory, and the array of tanks and pipes in chemical plants.”

The advantages of continuous processing, says Raston, are that it can be controlled precisely and is easy to scale up from the work bench to production. The initial impetus came from manufacturing nano-particles to within a narrow size distribution. The technology to do this involved the need to build in high levels of control. “Every molecule has to be treated in the same way.”

One of the techniques which the University of Western Australia researchers have been developing is spinning disc processing, where chemicals are injected through feed jets at the centre of the disc and react in the thin film which forms as they are flung across the disc under the influence of centrifugal force. Another technique involves using a rotating tube as a reaction surface.

The efficiency of these processes leads to a smaller energy expenditure and less waste. It fits generally in with the principles of environmentally sustainable, “green” chemistry, Raston says.


Process Intensification Strategies in Nano-chemistry

C. L. Raston
Centre for Strategic Nano-Fabrication, The University of WA, Crawley, WA, Australia

We have investigated the use of continuous flow process intensification (PI) to prepare nano-materials with remarkable control over their properties.

Scalable PI involving dynamic thin films, notably spinning disc processing (SDP) and rotating tube processing (RTP), allows the ability to control the size, shape, agglomeration, phase, coatings, and defects for a wide range of nano-materials, with uniform properties.

The shearing in the thin films SDP is effective in disassembling self organised systems (probing structure), and can be used to laterally slice single wall carbon nano-tubes coated with metal. RTP has an advantage over SDP in being able to control and extend the residence time of the liquid in the processor.

Continuous flow narrow channel reactors have also been used to prepare nano-materials, including nanorods (pre-prepared in a controlled way using RTP), decorated with quantum dots, with the ability to control the size of the quantum dots.