Currently the recycling of films is greatly held back by the absence of a technology that can decontaminate post consumer polyolefin (LDPE, LLDPE,HDPE,PP) films back to food-grade and create high value end-markets for these recycled plastics back into films which is critical to boosting the recycling rate of films. The vision of this project is to fill this gap with an efficient, commercial process that can be integrated into mechanical recycling operations, targeted at high-quality film applications, to ensure that recycling targets can be met.

COtooCLEAN, is a disruptive waterless cleaning process for polyolefin films based on low-pressure super-critical CO2 (scCO2) in combination with green co-solvents that can, in a single step, remove oils, fats and printing inks and effectively decontaminate polyolefin films under EFSA Challenge Test conditions back to food contact levels.

The COtooCLEAN technology, in preliminary research, has shown many promising results and would greatly benefit from the optimisation of the processing conditions to design a prototype plant for use in decontamination and cleaning of films in commercial recycling operations.

The industrial decontamination of post-consumer polyolefin films is currently performed using a mixture of aqueous or organic solvent washing, drying and thermal desorption. These processes have a high cost both in terms of the energy required and their environmental impact and are unable to reach food-grade compliance.

ScCO2 is a non-toxic, non-flammable, non-corrosive solvent and can be selective about the contaminants it removes by the use of co-solvents. It's potential to recycle film back to food-grade quality will not only offer a new recycling stream, but will also facilitate significant reductions in waste to landfill, displacement of virgin resin with significant savings in resources and reductions in carbon emissions and water usage.

ScCO2 is widely used in the extraction of food flavours and components such as caffeine. Impressively, a simple phase change can isolate dissolved contaminants and free the CO2 for re-use as a solvent once again. In this way it does not produce aqueous waste containing impurities and contaminants, or decontamination solvents that could themselves be hazardous materials as seen in competitive processes.

A commercialised COtooCLEAN process has the potential to provide a unique technology that fills the gap in food-grade recycling of films.

The Project is led by Nextek Ltd with deep commercial and technical support from Unilever, Amcor, Viridor, Allied Bakeries, SUPREX, University of Nottingham, Chemistry Department and BioComposites Centre, Bangor University .