Polyvinyl chloride (PVC) plastics are easily embrittled and decomposed to microplastics in an aquatic environment. The plasticizers such as bisphenol A (BPA), bisphenol S (BPS) and their analogues might be released and adsorbed by the PVC microplastics causing consequential pollution to the ecosystem. Herein, a systematic study was performed to determine the adsorption mechanisms of five bisphenol analogues (BPA, BPS, BPF, BPB and BPAF) on PVC microplastics. The maximum adsorption efficiency reached 0.19 ± 0.02 mg·g −1 (BPA), 0.15 ± 0.01 mg·g −1 (BPS), 0.16 ± 0.01 mg·g −1 (BPF), 0.22 ± 0.01 mg·g −1 (BPB), and 0.24 ± 0.02 mg·g −1 (BPAF) at PVC dosage of 1.5 g·L −1 . The kinetics study shows that the adsorption processes can be divided into three stages including external mass transport, intraparticle diffusion and dynamic equilibrium. The isotherm modeling shows a better fit of the adsorption results to the Freundlich isotherm compared to the Langmuir model. The thermodynamic study indicates the adsorption of all bisphenols as exothermic processes. Furthermore, the adsorption mechanisms of bisphenols were explicated intensively, with respect to hydrophobic interactions, electrostatic forces, and noncovalent bonds. A positive effect of hydrophobic interactions was identified for bisphenols adsorption on PVC microplastics, but an obvious inhibition by electrostatic repulsions was revealed for BPF due to its ionization in the neutral solution. In addition, noncovalent bonds (hydrogen and halogen bonds) may promote the adsorption of bisphenols on PVC microplastics. Finally, the desorption and competitive adsorption of five bisphenol analogues on the microplastics were provided together with a perspective for future works.
Yuan Wang,Haihong Zhong,Qianqian Xu,Miao Dong,Jianxin Yang,Weiting Yang,Yongjun Feng,Zhong-Min Su
Electrochemically upcycling polyvinyl chloride (PVC) into high-value small molecules represents a sustainable strategy for mitigating plastic pollution. Herein, a cost-effective self-supporting electrode with abundant vacancies, i.e. , NiFe-layered double hydroxide nanoarrays in-situ grown on the surface of carbon paper (denoted as NiFe V -LDH/CP), is developed for the electro-Fenton degradation of PVC microplastics (MPs). The NiFe V -LDH catalyst shows a high selectivity of 76 % towards H 2 O 2 production via two-electron oxygen reduction reaction (2e - ORR). Density functional theory (DFT) calculations reveal that the energy barrier of rate-determining step (*H 2 O 2 desorption) decreases over the vacancy-enriched NiFe V -LDH related to the pristine NiFeZn-LDH. The influence of vacancy concentration, reaction temperature and initial concentration of PVC MPs were systematically investigated. Under optimized conditions, the NiFe V -LDH/CP electrode exhibits an outstanding degradation performance of PVC MPs via direct cathodic reduction and oxidation by hydroxyl radicals. This work demonstrates that the electro-Fenton technology using LDH-based self-supporting electrodes is a promising and environmentally-friendly approach for waste plastic treatment.
危险品化学品经营许可证（带存储）