Abstract:

The active layer of thin-film composite (TFC) membranes was modified in situ by introducing an additive in the aqueous phase to regulate the interfacial polymerization process in order to break through the "trade-off" effect and improve the anti-pollution performance of the membrane. Initially, the polysulfone (PSF) support layer was prepared via phase inversion. Subsequently, β-cyclodextrin (β-CD) was incorporated into the aqueous phase during interfacial polymerization to construct TFC-β-CD modified forward osmosis membranes. There were hydrophilic hydroxyl groups outside β-CD, which can be interfacial polymerized with acyl chloride groups to produce polyester structure and be firmly retained in the membrane. Moreover, the nanocavity structure carried by β-CD was an efficient mass transfer channel so that it can improve the membrane water flux while maintaining a high retention rate. The surface structure, composition and roughness of the membranes before and after modification were analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The mass transfer properties and structural parameters of the membranes were examined using a cross-flow experimental setup, and the antifouling performance for organics and fouling reversibility were evaluated. The results indicated that the water contact angle of the TFC-β-CD (1.5) modified membrane decreased from (62.6±1.52)° to (44.9±0.52)°, demonstrating a significant enhancement in hydrophilicity and a reduction in roughness. During the antifouling experiments, compared to the TFC membrane, the flux recovery of the TFC-β-CD modified membrane was above 90% when the feed solution was three model organics respectively with Ca²⁺. When the feed solution contained Ca²⁺, the irreversible fouling of the TFC-β-CD modified membrane was less severe, exhibiting better antifouling properties.

Key words: membranes, thin-film composite forward osmosis membrane, β-cyclodextrin, in-situ modification, antifouling

摘要：

采用在水相中引入添加剂调控界面聚合过程的方法对聚酰胺薄膜复合材料（TFC）的活性层进行原位改性，以突破渗透性与选择性之间的“trade-off”效应以及提升膜的抗污染性能。首先，通过相转化制备聚砜（PSF）支撑层，在此基础上通过在界面聚合中掺入水相添加剂β-环糊精（β-CD）原位构筑TFC-β-CD改性正渗透膜。β-CD外部存在亲水性羟基基团，可与酰氯基团进行界面聚合产生聚酯结构而被牢固保留在膜中，并且其携带的纳米空腔结构是一种高效传质通道，使其在提升膜水通量的同时保持高截留率。通过扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和原子力显微镜（AFM）分析了改性前后的膜表面结构、组成和粗糙度，利用错流式实验装置考察了膜的传质性能和结构参数，并探究了膜的抗有机污染性能和膜污染可逆性。结果表明：TFC-β-CD（1.5）改性膜的水接触角由（62.6±1.52）°下降至（44.9±0.52）°，亲水性显著提升，且粗糙度降低。在有机污染实验中，与TFC膜相比，当3种特征污染物的原料液不含Ca²⁺时，TFC-β-CD改性膜的通量恢复率在90%以上，当原料液含Ca²⁺时，TFC-β-CD改性膜的不可逆污染程度较轻，具有较好的抗污染性能。

关键词: 膜, 薄膜复合材料正渗透膜, β-环糊精, 原位改性, 抗污染