2017/12/20 by Stella Palkopoulou, Ali Ben Saïd, Palkopoulou, Stella +13
Environmental Science · #Recycling and Waste Management Techniques
paper · doi:10.15454/1.5137834343647146e12
Food contact material safety: polyolefine recycling, a feasability study Recycled plastic packaging are contaminated with various substances when used. After recycling (closed loop recycling), their reuse for food packaging raises food safety problems. Recycling processes must successfully eliminate these contaminants by including a purification step. In literature, abundant data are available for the recycling of polyethylene terephthalate (PET) extrapolating directly to polyolefins the decontamination strategy applied to PET. This article emphasizes that this extrapolation is not justified on the basis of the comparison between the transport properties of contaminants potentially present in PET and in polyolefins (polypropylene and polyethylene). The REPALI 2 project demonstrated i) that the contamination level (sorption during first use and misuses) is much higher than that given for PET (3 ppm) and the actual contaminants are highly diversified in nature for a wide molecular weight range ii) that the acceptable concentration threshold in recycled polyolefins must be much lower than for PET to ensure food safety. Therefore, the extraction yield must be very high. A simple thermal treatment (under vacuum) is inadequate; the batch extraction with supercritical CO2 is very effective but must be optimized for an efficient continuous process. The surrogates to be used to challenge the decontamination process have to include molecules with high molecular weight.