Trash to Treasure: Microwave-Assisted Conversion of Polyethylene to Functional Chemicals
Trash to Treasure: Microwave-Assisted Conversion of Polyethylene to Functional Chemicals
复制标题
DOI：
10.1021/acs.iecr.7b04091
复制
发表时间：
2017-12-20
影响因子：
4.2
通讯作者：
Hakkarainen, Minna
中科院分区：
文献类型：
--
作者：
Backstrom, Eva;Odelius, Karin;Hakkarainen, Minna
开发了一种有效的微波辅助低密度聚乙烯（LDPE）废物回收工艺。为了实现旨在生产二羧酸的快速有效的氧化降解，硝酸被用作氧化剂。不同的条件进行了评估，其中循环时间和氧化剂的浓度是不同的，并通过FTIR，NMR和HPLC对最终产物进行了表征。在相对稀的硝酸溶液（0.1g/mL）中在180 ℃下微波照射仅1小时后，LDPE粉末完全降解。这种转化导致很少有明确的水溶性产物，主要是琥珀酸、谷氨酸和己二酸，以及少量的较长的二羧酸、乙酸和丙酸。通过调节反应时间、温度和氧化剂的量，可以在一定程度上调节所获得的二元羧酸的长度。最后，通过回收LDPE冷冻袋作为模型LDPE废物来验证所开发的工艺。冷冻袋主要转化为二羧酸，产率为71%，该过程的碳效率为37%。因此，开发的方法可以促进循环经济，并为提高塑料废物的价值提供新的可能性。
An effective microwave-assisted process for recycling low-density polyethylene (LDPE) waste into value-added chemicals was developed. To achieve fast and effective oxidative degradation aimed at production of dicarboxylic acids, nitric acid was utilized as an oxidizing agent. Different conditions were evaluated, where recycling time and concentration of oxidizing agent were varied and the end products were characterized by FTIR, NMR, and HPLC. After just 1 h of microwave irradiation at 180 degrees C in relatively dilute nitric acid solution (0.1 g/mL), LDPE powder was totally degraded. This transformation led to few well-defined water-soluble products, mainly succinic, glutaric, and adipic acids, as well as smaller amounts of longer dicarboxylic acids, acetic acid, and propionic acid. The length of the obtained dicarboxylic acids could to some extent be tuned by adjusting the reaction time, temperature, and amount of oxidizing agent. Finally, the developed process was verified by recycling LDPE freezer bags as model LDPE waste. The freezer bags were converted mainly into dicarboxylic acids with a yield of 71%, and the carbon efficiency of the process was 37%. The developed method can, thus, contribute to a circular economy and offers new possibilities to increase the value of plastic waste.