WEEE Research Centre of Shanghai Polytechnic University, Shanghai, 201209, China.
WEEE Research Centre of Shanghai Polytechnic University, Shanghai, 201209, China; Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University, Shanghai, 201209, China.
Chemosphere. 2020 Apr;245:125645. doi: 10.1016/j.chemosphere.2019.125645. Epub 2019 Dec 16.
Recycling is the primary method to handle electronic waste plastics, however, little attention has been paid to the risk posed by heavy metal migration in waste plastic products. The effect of multistage recycling processes on heavy metal migration and the environmental risk posed by heavy metals during recycling processes were investigated by: (1) Recycling waste plastics and determining the heavy metal contents in secondary products; (2) Using toxic leaching experiments to assess environmental risks of heavy metal migration in secondary products; and (3) Evaluating the effect of recycling processes on the mechanical properties and microstructure of plastics. Results showed that the contents of some harmful heavy metals in processed products exceeded the Safety of Toys Standard. Toxic leaching tests showed that Ni, Cu, Zn, Pb, and Sb migrated outward during secondary products use. With increased recycling times, concentrations of migrated Ni, Cu, Zn, Pb, and Sb increased, and the leached concentrations exceeded the limits stipulated in the Groundwater Quality Standard. Increased recycling times also accelerated waste plastics aging and caused the deterioration of mechanical properties. Furthermore, adhesion between layers decreased, stratification and cracking in polymers appeared, and adhesion of waste plastics to additives decreased. Therefore, the environmental risks of waste plastic recycling should be carefully considered.
回收是处理电子废物塑料的主要方法，但很少有人关注废物塑料产品中重金属迁移带来的风险。通过以下方法研究了多阶段回收过程对重金属迁移的影响以及回收过程中重金属带来的环境风险：（1）回收废塑料并确定二次产品中的重金属含量；（2）利用有毒浸出实验评估重金属在二次产品中的迁移对环境的风险；（3）评估回收过程对塑料机械性能和微观结构的影响。结果表明，加工产品中一些有害重金属的含量超过了《玩具安全标准》。有毒浸出实验表明，Ni、Cu、Zn、Pb 和 Sb 在二次产品使用过程中向外迁移。随着回收次数的增加，迁移的 Ni、Cu、Zn、Pb 和 Sb 的浓度增加，浸出浓度超过了《地下水质量标准》规定的限值。回收次数的增加还加速了废塑料的老化，导致机械性能恶化。此外，层间附着力降低，聚合物分层和开裂，废塑料与添加剂的附着力降低。因此，应谨慎考虑废塑料回收的环境风险。
