Investigating sustainable approaches to reduce VOCs and odor from mechanically recycled polypropylene

Abstract

Post-consumer recycled polypropylene (PCR-PP) often contains volatile organic compounds (VOCs) and odorous compounds, limiting its use in high-value applications. This study investigates three treatment methods – polyethylene glycol (PEG) extraction, heated air purging, and additivation with zeolites to reduce VOCs in PCR-PP. Gas chromatography-mass spectrometry (GC-MS) was used to quantify VOC reduction, with additivation with zeolites achieving the highest reduction (89%), followed by heated air purging (78%) and PEG extraction (73%). Heated air purging was particularly effective for low-boiling-point VOCs, while additivation with zeolites demonstrated broad efficacy across VOC types. PEG extraction, although slightly less effective, provides an alternative method with potential for specific applications. Importantly, none of the methods significantly altered the melt flow index (MFI), maintaining suitability for extrusion processes. Energy consumption analysis highlighted additivation with zeolites as the most energy efficient approach (25 kJ kg⁻¹), followed by heated air purging (72 kJ kg⁻¹) and PEG extraction (159 kJ kg⁻¹). By effectively reducing contaminants without compromising material properties, these approaches enable PCR-PP to meet the quality standards required for non-food packaging applications, such as cosmetics and household products. This research highlights the critical role of advanced decontamination processes in improving the sustainability and market viability of recycled plastics, addressing challenges in the transition to a circular economy and reducing environmental and health risks associated with VOCs in recycled PP.