Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore.
Environ Sci Pollut Res Int. 2023 Oct;30(49):107419-107434. doi: 10.1007/s11356-023-27906-1. Epub 2023 Jun 19.
Biodegradable microplastics (BMPs) are considered to be environmentally friendly compared to non-biodegradable plastics (NMPs). However, BMPs are likely to become toxic during their transport because of the adsorption of pollutants (e.g., heavy metals) onto them. This study investigated the uptake of six heavy metals (Cd, Cu, Cr, Ni, Pb, and Zn) by a common BMPs (polylactic acid (PLA)) and compared their adsorption characteristics to those of three types of NMPs (polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC)) for the first time. The order of heavy metal adsorption capacity among the four MPs was PE > PLA > PVC > PP. The findings suggest that BMPs contained more toxic heavy metals than some NMPs. Among the six heavy metals, Cr showed considerably stronger adsorption than other heavy metals in both BMPS and NMPs. The adsorption of heavy metals on MPs can be well explained using the Langmuir isotherm model, while the adsorption kinetic curves showed the best fit to the pseudo-second-order kinetic equation. Desorption experiments revealed that BMPs released a higher percentage of heavy metals (54.6-62.6%) in the acidic environment in a shorter time (~ 6 h) compared to NMPs. Overall, this study provides insights into interactions of BMPs and NMPs with heavy metals and their removal mechanisms in aquatic environment.
可生物降解微塑料（BMPs）被认为比不可生物降解塑料（NMPs）更环保。然而，由于污染物（例如重金属）吸附在 BMPs 上，BMPs 在运输过程中很可能会变得有毒。本研究首次调查了六种重金属（Cd、Cu、Cr、Ni、Pb 和 Zn）被一种常见的 BMPs（聚乳酸（PLA））的吸收情况，并比较了它们与三种 NMPs（聚乙烯（PE）、聚丙烯（PP）和聚氯乙烯（PVC））的吸附特性。四种 MPs 中重金属吸附能力的顺序为 PE>PLA>PVC>PP。研究结果表明，BMPs 中所含的有毒重金属比某些 NMPs 多。在六种重金属中，Cr 在 BMPs 和 NMPs 中都表现出比其他重金属更强的吸附能力。重金属在 MPs 上的吸附可以很好地用朗缪尔等温模型来解释，而吸附动力学曲线最符合拟二级动力学方程。解吸实验表明，与 NMPs 相比，BMPs 在较短时间（约 6 小时）内，在酸性环境中释放的重金属百分比更高（54.6-62.6%）。总的来说，本研究提供了有关 BMPs 和 NMPs 与重金属相互作用及其在水生环境中去除机制的见解。
