Cleaning of lubricant-oil-contaminated plastic using liquid carbon dioxide

• The average % lubricant oil in waste plastics was found to be 2.49%.
• The feasibility of liquid CO2 cleaning for contaminated plastics was evaluated.
• For liquid CO2 cleaning, the highest cleaning efficiency was achieved for CO2 at 6.5 MPa and 5 °C.
• Process design of liquid CO2 cleaning for 30 kg of plastics/day was proposed.
• With the use of hexane as a co-solvent, the operating cost was 5.7 times more expensive.

The feasibility of using liquid carbon dioxide for cleaning contaminated plastics was evaluated. Flow sheets for the CO2 cleaning processes have been conceptualized and the material and energy balances were conducted using ASPEN Plus. The average % lubricant oil in waste plastics was found to be 2.49%. Although the CO2 cleaning process with hexane as a co-solvent resulted in a higher cleaning efficiency than the process without co-solvent, it consumed 2.2 times more energy. Based on cleaning 30 kg of plastics, the operating cost of the process with hexane was 5.7 times higher than that of the process without hexane.

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