The Green Chemistry Centre of Excellence promotes the application of green and sustainable technologies particularly those that can be used to deliver products that meet consumer and legislation requirements.
The European Union directtive on natural ingredients only permits the use of the natural label for materials extracted using water, ethanol or carbon dioxide. The use of these 'natural solvents' can provide environmentally sustainable and economically attractive alternatives to conventional organic solvents in a wide range of applications.
The natural solvent technology platform focuses on the use of both natural and bio-derived solvents in applications including extraction and fractionation of waxes from waste biomass. Important organic chemistry (including amidations and esterifications), product cleaning, material development, impregnation and utilisation of computer models to predict the effects of solvents in chemical reactions are also key facets of our work.
Some of the applications already developed using natural and bio-dervided solvents include:
Extraction can be carried out using CO2 in a liquid or supercritical state and the choice largely depends on the solubility of the molecules to be extracted. Liquid CO2 is significantly less polar than supercritical CO2 and is applicable only to small non- polar molecules.
Liquid CO2 finds commercial use in the extraction of essential oils and oleoresins. CO2 exists as a supercritical fluid and the manipulation of temperature and pressure produces a highly tuneable solvent that can be used to selectively extract a wide range of molecules, because of this, most commercial extraction plants are designed to operate using supercritical CO2.
In its supercritical state, CO2 has low surface tension and viscosity and therefore high mass transfer rates can be achieved. This provides ideal conditions for extracting compounds with a high degree of recovery in a short period of time and with easy separation of products.
All trials are supported by physical and chemical analysis of feedstocks and products. The Green Chemistry Centre of Excellence has excellent facilities including GC, GC-MS, HPLC and IR techniques. More advanced analysis can be provided through the Centre of Excellence in Mass Spectrometry and Multi-nuclear NMR at the University of York.
Trials can be carried out as individual short term projects or as part of a longer-term study. A full report of the trials and samples are supplied. To find out more about the application of these technologies in your business or research area contact the Green Chemistry Centre of Excellence.
Funding for this initiative has been provided by the University of York’s Enterprise and Innovation Office.
The natural solvent technology platform also operates a state of the art semi-preparative supercritical chromatrography system.
An important part of the platforms' activities is to investigate chemical reactions in alternative green solvents. This includes the use of biocatalysis in supercritical CO2. Extracted products can be modified by this method allowing them to retain the natural status and therefore realize a market premium. Biocatalysis in CO2 can be carried out at lower pressures, reducing energy requirements. Other advantages include improved reaction rates, high enantioselectivity by varying temperature and pressure, improved enzyme stability, easy product recovery and isolated enzymes or whole cells can be used. Traditional heterogeneous catalysts and biocatalytic processes can be employed in continuous flow supercritical reactor systems.
The use of computer programmes to predict the properties of reaction media including bio-derived solvents is of great interest to the group. Models developed allow us to predict which solvents offer the most favourable properties to enhance rates of reaction and also reduce the environmental impact of processes. Such tools have wide ranging applications in all sectors of the chemical industry.
|Natural Solvents Technology Platform Leader|
|Dr Rob McElroy||Postdoctoral Researcher|
|Mr James Sherwood||Research Student|
|Mr Tom Attard||Research Student|
|Mr Kevin Jiang||Research Student|
|Mr Abdul Alheihaibi||Research Student|
|Mr Neil Harris||Research Student|
|Mr Saimeng Jin||Research Student|
|Ms Giulia Paggiola||Research Student|