Jeswani Harish K, Perry Mitchell R, Shaver Michael P, Azapagic Adisa
Sustainable Industrial Systems, Department of Chemical Engineering, The University of Manchester, Manchester, UK.
Department of Materials, School of Natural Sciences, The University of Manchester, Manchester, UK; Sustainable Materials Innovation Hub, Henry Royce Institute, The University of Manchester, Manchester, UK.
Sci Total Environ. 2023 Dec 10;903:166311. doi: 10.1016/j.scitotenv.2023.166311. Epub 2023 Aug 15.
Most of plastic packaging waste does not degrade over time, which can lead to harmful effects on aquatic life and humans, highlighting the need for packaging materials that are easily degradable. Poly(mandelic acid) (PMA) is a biodegradable polymer that has been proposed as an alternative to polystyrene for use in packaging. However, its potential to replace the existing packaging materials also depends, among other factors, on the environmental sustainability of its production. This study aims to estimate and compare the life cycle environmental impacts of the production of PMA via polymerisation of 5-phenyl-1,3-dioxolane-4-one (Ph-DOX) and o-carboxyanhydride (OCA) monomers. For each route, the impacts are evaluated for 18 ReCiPe categories for reported laboratory scales and potential scaled-up commercial production. The results suggest that most of the impacts of PMA production via the Ph-DOX route are significantly lower (≥20%) than that of the OCA route for both the laboratory and large scales. However, compared to polystyrene, the impacts of large-scale PMA production via the (better of the two) Ph-DOX route are more than five times higher. This is largely due to the use of benzaldehyde, enzymes, hydrocyanic acid and sodium phosphate in the production of mandelic acid and the solvents utilised in monomer synthesis. A sensitivity analysis shows that the bio-transformation of bio-glycerol to produce mandelic acid would reduce 16 out of 18 life cycle impacts of PMA by 6-77%. The impacts are also sensitive to the assumptions used in the scaling-up of laboratory data for solvents. However, the results indicate clearly that, despite all the uncertainties in the scaling-up method, the proposed production routes for PMA would still have several times higher environmental impacts than polystyrene. Therefore, further research would be needed to improve significantly the production process for (bio-)mandelic acid, synthesis of monomers and their polymerisation before PMA can be considered an environmentally sustainable option for packaging applications.
大多数塑料包装废弃物不会随时间降解，这可能对水生生物和人类产生有害影响，凸显了对易于降解的包装材料的需求。聚（扁桃酸）（PMA）是一种可生物降解的聚合物，已被提议作为聚苯乙烯的替代品用于包装。然而，它替代现有包装材料的潜力还取决于其他因素，包括其生产的环境可持续性。本研究旨在估算和比较通过5-苯基-1,3-二氧戊环-4-酮（Ph-DOX）和邻羧基酸酐（OCA）单体聚合生产PMA的生命周期环境影响。对于每种路线，针对已报道的实验室规模和潜在的扩大规模商业生产，评估了18个ReCiPe类别的影响。结果表明，无论是实验室规模还是大规模生产，通过Ph-DOX路线生产PMA的大多数影响都比OCA路线显著低（≥20%）。然而，与聚苯乙烯相比，通过（两者中较好的）Ph-DOX路线大规模生产PMA的影响高出五倍多。这主要是由于在扁桃酸生产中使用了苯甲醛、酶、氢氰酸和磷酸钠以及单体合成中使用的溶剂。敏感性分析表明，生物甘油生物转化生产扁桃酸将使PMA的18个生命周期影响中的16个降低6-77%。这些影响对溶剂实验室数据放大过程中使用的假设也很敏感。然而，结果清楚地表明，尽管放大方法存在所有不确定性，但PMA的提议生产路线的环境影响仍将比聚苯乙烯高出几倍。因此，在PMA被视为包装应用的环境可持续选择之前，需要进一步研究以显著改进（生物）扁桃酸的生产工艺、单体合成及其聚合。
