Abstract Chlorination remains a big hurdle in membrane technology as the most commonly used membranes for water purification consist of a polyamide top-layer, which is not fully resistant towards chlorine-induced oxidation. In this work, DOW FILMTEC™ BW30 membrane elements were systematically chlorinated with NaOCl at pilot-scale under acidic conditions (pH4) at 10 bar for 2.5 h. Variations in membrane performance and their physicochemical properties were determined by ATR-FTIR, XPS, WD-XRF, SEM, AFM and zeta-potential measurements. With increasing bleaching concentration, both membrane roughness and chlorine incorporation via N- and ring-chlorination increased, while surface charge remained quasi unaltered. Both water flux and salt passage decreased proportionally over the whole concentration range. Accordingly, positron annihilation lifetime spectroscopy (PALS) revealed a decrease in the size of the top-layer free-volume elements as chlorine concentration increased, confirming, for the first time in a quantitative manner, the so-called tightening effect. The obtained results also show that thin-film composite (TFC) membranes are altered differently when chlorinated under pressure than via simple immersion, as conventionally performed in literature.

中文翻译：

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BW30 TFC膜的真实规模氯化及其理化表征

摘要 氯化仍然是膜技术的一大障碍，因为最常用的水净化膜由聚酰胺顶层组成，不能完全抵抗氯引起的氧化。在这项工作中，陶氏 FILMTEC™ BW30 膜元件在酸性条件 (pH4) 和 10 bar 下以中试规模系统地用 NaOCl 氯化 2.5 小时。膜性能及其物理化学性质的变化由 ATR-FTIR、XPS、WD-XRF、SEM、AFM 和 zeta 电位测量确定。随着漂白浓度的增加，膜粗糙度和氯通过 N 和环氯化的结合增加，而表面电荷保持准不变。在整个浓度范围内，水通量和盐通过率都成比例地下降。因此，正电子湮没寿命光谱 (PALS) 显示，随着氯浓度的增加，顶层自由体积元素的尺寸减小，首次以定量方式证实了所谓的紧缩效应。获得的结果还表明，薄膜复合 (TFC) 膜在压力下氯化时的变化与文献中常规进行的简单浸渍相比有所不同。