Chen Zhaoxi, Wang Peng, Pei An, Zhang Gaige, Liu Daoru, Sun Peilin, Chen Guangxu
School of Environment and Energy, National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou, 510006, China.
Small Methods. 2025 Jul 31:e2500962. doi: 10.1002/smtd.202500962.
Alkali-catalyzed hydrolysis effectively depolymerizes waste polyesters and recovers high-purity monomers. Nonetheless, the conventional acid-based neutralization process (ABNP) for polyesters recycling faces economic and efficiency challenges due to substantial alkali consumption. To address these challenges, this study developed an electrochemical recovery and separation system (ERSS), a three-chamber electrolyzer separated by cation exchange membranes (CEM), with an ion separation module (ISM) situated between the anode and cathode of a water electrolysis system. Through water electrolysis, the system can efficiently recover excess KOH from polyester hydrolysates by leveraging directed ion migration under an electric field. Experimentally, the system achieves outstanding performance in real PET hydrolysates, with a KOH Faraday efficiency of 96.4%, yielding 88.4% for ethylene glycol (EG) and 89.3% for p-phthalic acid (PTA). The system operates stably and continuously for 100 h, processing ≈6 liters of hydrolysate. Additionally, it has exceptional KOH recovery across multiple polyester hydrolysates. A techno-economic analysis (TEA) shows that compared to the traditional ABNP, the ERSS significantly reduces chemical input costs in the hydrolysis unit, achieving savings of up to 62.5%. This study provides an efficient and cost-effective solution for the alkaline hydrolysis recycling of waste polyesters, effectively mitigating the economic drawbacks of excessive KOH usage.
碱催化水解能有效使废弃聚酯解聚并回收高纯度单体。尽管如此，用于聚酯回收的传统酸碱中和工艺（ABNP）由于大量碱消耗而面临经济和效率挑战。为应对这些挑战，本研究开发了一种电化学回收与分离系统（ERSS），这是一种由阳离子交换膜（CEM）分隔的三室电解槽，在水电解系统的阳极和阴极之间设有离子分离模块（ISM）。通过水电解，该系统可利用电场下的定向离子迁移从聚酯水解产物中高效回收过量的KOH。实验表明，该系统在实际PET水解产物中表现出色，KOH法拉第效率为96.4%，乙二醇（EG）产率为88.4%，对苯二甲酸（PTA）产率为89.3%。该系统可稳定连续运行100小时，处理约6升水解产物。此外，它对多种聚酯水解产物具有出色的KOH回收能力。技术经济分析（TEA）表明，与传统ABNP相比，ERSS显著降低了水解单元的化学投入成本，节省高达62.5%。本研究为废弃聚酯的碱性水解回收提供了一种高效且经济高效的解决方案，有效缓解了过量使用KOH的经济弊端。
