磺化聚砜改性阳离子交换膜用于高盐乙二醇废液电渗析脱盐

Sulfonated Polysulfone Modified Cation Exchange Membrane for Electrodialysis Desalination of Hypersaline Ethylene Glycol Wastewater

深水油气田开采过程中普遍需要使用乙二醇(EG)作为水合物抑制剂,副产大量高盐乙二醇废液(SEGW),对其进行除盐回用具有重要的经济价值和生态环境效益。SEGW回收系统的脱盐工序通常采用热法蒸馏,以离子选择性电迁移为除盐机制的电渗析(ED)技术有望显著简化脱盐工艺、降低投资成本和运行能耗,具有较好应用潜力。但常规ED技术用于SEGW脱盐时存在着盐迁移和EG泄漏间的trade-off效应,阻碍了实际应用。为了减少ED脱盐过程中EG的损失,提出采用磺化聚砜(SPSF)对阳离子交换膜(CEM)进行表面改性,SPSF改性层的引入使得CEM表面形成致密离子传输通道,基于空间位阻和电荷效应促使EG分子与水合阳离子的迁移速率形成显著差异,赋予了改性CEM良好的阻醇脱盐性能。实验结果表明,对于EG含量为60%的SEGW,改性膜在达到与原膜同等脱盐效率时可降低61%的EG损失。

It is generally necessary to use ethylene glycol(EG) as a hydrate inhibitor in the exploitation of deep-water oil and gas fields,and a large amount of hypersaline ethylene glycol wastewater(SEGW) is produced by-products.Desalination and reuse of SEGW have important economic value and environmental benefits.The desalination process of the SEGW recovery system usually uses thermal distillation.Electrodialysis(ED) technology with ion-selective electromigration as the desalination mechanism is expected to significantly simplify the desalination process,reduce investment costs and operating energy consumption,and have good application potential.However,the trade-off effect between salt migration and EG leakage exists in the conventional ED technology for SEGW desalination,which hinders its practical application.In order to reduce EG-leak during ED desalination,this paper proposed use of the sulfonated polysulfone(SPSF) to modify the surface of the cation exchange membrane(CEM).The introduction of the SPSF-modified layer caused the CEM surface to form a dense ion transport channel.Based on the steric hindrance and charge effects,the migration rate of EG molecules and hydrated cations was significantly different,which gave the modified CEM good EG-blocking and desalination properties.The experimental results showed that for SEGW with an EG content of 60 wt%,the modified CEM reduced the EG leakage by 61% when it reached the same desalination efficiency as the original CEM.