污泥是微塑料(MPs)向环境扩散的重要载体,因此,从污泥中高效去除MPs是迫切需要的。在这项研究中,提出了热液碳化(HTC),并评估了其从污水污泥中去除MP的潜力。光学显微镜和显微FTIR分析表明,污泥中MPs的浓度显著降低,在HTC温度为260°C时显示79%的降低。通过HTC实验研究了缩聚物和加成聚合物的潜在分解机理,使用聚对苯二甲酸乙二醇酯-微塑料(PET-MPs)和聚丙烯-微塑料(PP-MPs)。在HTC的过程中,PET-MPs的崩解效率显著高于PP-MPs,由于PET酯键容易通过水解被单体化。此外,残余PP-MPs的物理化学性质分析表明,暴露于热导致PP进行热解反应,导致聚合物分子链的随机断裂。总的来说,这些结果为HTC在去除污水污泥中的MPs的关键作用提供了初步的见解,为未来降低污水污泥中MP带来的风险提供了一种新的解决方案。
Sewage sludge is an important vehicle for the diffusion of microplastics (MPs) into the environment, and thus, efficient removal of MPs from sludge is in urgent need. In this study, hydrothermal carbonization (HTC) is proposed and its potential for the removal of MPs from sewage sludge is assessed. Optical microscopy and micro-FTIR analysis showed that the concentrations of MPs in sewage sludge decreased significantly, exhibiting a 79% reduction with a HTC temperature of 260 °C. The potential decomposition mechanism of condensation polymers and addition polymers were investigated through HTC experiments, using polyethylene terephthalate-microplastics (PET-MPs) and polypropylene-microplastics (PP-MPs). During the HTC process, the disintegration efficiency of PET-MPs was significantly higher than PP-MPs, due to the PET ester bond being easily monomerized by hydrolysis. Furthermore, analyses of physicochemical properties of the residual PP-MPs indicated that exposure to heat cause PP to undergo pyrolysis reaction, resulting in the random rupture of polymer molecular chains. Overall, these results provide the first insight into the critical role of HTC in the removal of MPs from sewage sludge, providing a novel solution for reducing the risk posed by MPs in sewage sludge in the future.