CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
LAQV-REQUIMTE, Department of Conservation and Restoration, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
Molecules. 2021 Dec 24;27(1):98. doi: 10.3390/molecules27010098.
Plastics recycling remains a challenge due to the relatively low quality of the recycled material, since most of the developed recycling processes cannot deal with the additives present in the plastic matrix, so the recycled products end up in lower-grade applications. The application of volatile organic solvents for additives removal is the preferred choice. In this study, pretreatment of plastic packaging waste to remove additives using biosolvents was investigated. The plastic waste used was high-density polyethylene (HDPE) with blue and orange colorants (pigment and/or dye). The first step was to identify the type of colorants present in the HDPE, and we found that both plastics presented only one colorant that was actually a pigment. Then, limonene, a renewable solvent, was used to solubilize HDPE. After HDPE dissolution, a wide range of alcohols (mono-, di-, and tri-alcohols) was evaluated as antisolvents in order to selectively precipitate the polymer and maximize its purity. The use of limonene as solvent for plastic dissolution, in combination with poly-alcohols with an intermediate alkyl chain length and a large number of hydroxyl (OH) groups, was found to work best as an antisolvent (1,2,3-propanetriol and 1,2,4-butanetriol), leading to a removal of up to 94% and 100% of the blue and orange pigments, respectively. Finally, three cycles of extraction were carried out, proving the capability of the solvent and antisolvent to be recovered and reused, ensuring the economic viability and sustainability of the process. This pretreatment provides a secondary source of raw materials and revenue for the recycling process, which may lead to an increase in the quality of recycled polymers, contributing to the development of an economical and sustainable recycling process.
由于回收材料的质量相对较低，塑料回收仍然是一个挑战，因为大多数发达的回收工艺都无法处理塑料基质中的添加剂，因此回收产品最终只能用于较低等级的应用。使用挥发性有机溶剂去除添加剂是首选。在这项研究中，研究了使用生物溶剂预处理塑料包装废物以去除添加剂。所用的塑料废物是高密度聚乙烯（HDPE），带有蓝色和橙色着色剂（颜料和/或染料）。第一步是确定 HDPE 中存在的着色剂类型，我们发现两种塑料仅有一种实际上是颜料的着色剂。然后，使用可再生溶剂柠檬烯溶解 HDPE。在 HDPE 溶解后，评估了多种醇（单、二和三醇）作为抗溶剂，以选择性沉淀聚合物并最大限度地提高其纯度。发现使用柠檬烯作为塑料溶解溶剂，结合具有中等烷基链长和大量羟基（OH）基团的多醇，作为抗溶剂（1,2,3-丙三醇和 1,2,4-丁三醇）效果最佳，分别导致蓝色和橙色颜料的去除率高达 94%和 100%。最后，进行了三次萃取循环，证明了溶剂和抗溶剂的可回收性和再利用能力，确保了该工艺的经济可行性和可持续性。这种预处理为回收过程提供了原材料的二次来源和收入来源，这可能会提高回收聚合物的质量，有助于开发经济和可持续的回收工艺。
