TECHNOLOGY

 

The reactor technology uses a process known as continuous hydrothermal (hot water) synthesis to produce inorganic nanoparticles suspended in water as an aqueous dispersion.

 

Supercritical water is simply the scientific term for hot, pressurised water and it has different properties to those you would normally expect of water, one of which is to allow the synthesis of nanoparticles.  In hydrothermal synthesis the hot, pressurised water is mixed with a metal salt solution, such as iron nitrate solution, and a reaction occurs (the salt is dehydrated) and nanoparticles form.

This synthetic approach has been known for many years but only as a one-pot, batch process, which is low yielding, inherently difficult to scale-up and which has product reproducibility issues; making the process continuous would solve all these problems.

 

 Continuous hydrothermal synthesis is a superior method of forming nanoparticles due to the variety of materials that can be produced and the level of product control achievable; but the problem was that the reactors frequently block, discouraging the commercial use of this technique to produce nanoparticles, until now.



Our Reactor System

 

     

reactor flow
  • The process inside a reactor is simple:
  • Hot, pressurised water flows into the reactor from the top
  • Cold, salt solution is pumped in from the bottom.
  • The two fluids mix efficiently at the interface created by the patent protected nozzle where the reaction occurs
  • Newly formed nanoparticles flow up and out of the reactor with the water. The aqueous dispersion of nanoparticles is cooled and collected.

  • The reactor is described in the Journal of Supercritical Fluids:

  • Edward Lester, Paul Blood, Joanne Denyer, Donald Giddings, Barry Azzopardi and Martyn Poliakoff, 2006 Reaction engineering: The supercritical water hydrothermal synthesis of nano-particles The Journal of Supercritical Fluids, 37 (2), 209-214

 

 

 

 

Formulation

 

As the particles are produced as an aqueous dispersion we avoid the problems of particle agglomeration and can formulate the particles easily.

 

As the particles flow out of the reactor they are in dispersion and are never handled as dry powders, thus avoiding agglomeration.  This is a major advantage over dry powder techniques where the particles clump together, defeating the object of using nanoparticles, and requiring further processing such as milling.

 

Formulation, for example adding a surfactant or transfer to another solvent system, is widely needed for nanoparticle applications.  As we operate a continuous flow process formulation agents can be added online, with customer ready material exiting the reactor in a one-step process.

 

capping feed

 

Nanomaterials can be formulated in aqueous or organic phase directly during production

 

particle coating

 

   

 

Hematite Nanoparticles (average particle size 50nm). These particles have interesting applications as pigments, magnetic imaging, and catalytic applications ironoxide
yag Nano YAG particles (around 80nm) showing good uniformity of size. These particles were used in manufacture of transparent ceramics for laser lens applications.These particles can be easily doped with rare earth elements for enhanced fluorescent properties.