聚乳酸塑料合成、生物降解及其废弃物处置的研究进展

Synthesis, biodegradation and waste disposal of polylactic acid plastics: a review

摘要:

随着国内外禁塑令和限塑令的升级，以聚乳酸(polylactic acid, PLA)为代表的生物基塑料成为传统石油基塑料市场的主要替代品，备受产业界的青睐。然而，公众对生物基塑料的认识仍存在诸多误解。事实上，生物基塑料的降解需要在特定条件下才能实现，泄入到自然环境中同样难以降解，会对人体、生物多样性和生态系统功能造成危害，这与传统石油基塑料相似。近年来，随着我国PLA产能和市场规模不断的提高，亟需进一步加强对PLA等生物基塑料降解性能的认识，挖掘PLA生物降解资源，关注和研究生物基塑料回收处理模式。基于上述背景，本文首先介绍了PLA塑料的性质及合成方式，以及PLA塑料的产业化与市场规模；其次，对目前聚乳酸塑料微生物与酶法降解的研究进展进行了综述，并对其生物降解机制进行了探讨；最后，提出了微生物原位处理和酶法闭环回收两种聚乳酸塑料废弃物生物处置方法，并对PLA生物基塑料的发展前景和趋势进行了展望。

关键词:生物基塑料;聚乳酸;降解机制;酶;回收利用

Abstract:

With the escalation of plastic bans and restrictions, bio-based plastics, represented by polylactic acid (PLA), have become a major alternative to traditional plastics in the current market and are unanimously regarded as having potential for development. However, there are still several misconceptions about bio-based plastics, whose complete degradation requires specific composting conditions. Bio-based plastics might be slow to degrade when it is released into the natural environment. They might also be harmful to humans, biodiversity and ecosystem function as traditional petroleum-based plastics do. In recent years, with the increasing production capacity and market size of PLA plastics in China, there is an urgent need to investigate and further strengthen the management of the life cycle of PLA and other bio-based plastics. In particular, the in-situ biodegradability and recycling of hard-to-recycle bio-based plastics in the ecological environment should be focused. This review introduces the characteristics, synthesis and commercialization of PLA plastics, summarizes the current research progress of microbial and enzymatic degradation of PLA plastics, and discusses their biodegradation mechanisms. Moreover, two bio-disposal methods against PLA plastic waste, including microbial in-situ treatment and enzymatic closed-loop recycling, are proposed. At last, the prospects and trends for the development of PLA plastics are presented.

Key words:bio-based plastics;polylactic acid;degradation mechanism;enzyme;recycling