Membrane Technology Group (division cMACS), Faculty of Bioscience Engineering , KU Leuven , Celestijnenlaan 200F , P.O. Box 2454, 3001 Leuven , Belgium.
Institut für Angewandte Physik und Messtechnik , Universität der Bundeswehr München , 85577 Neubiberg , Germany.
Environ Sci Technol. 2019 Aug 6;53(15):8640-8648. doi: 10.1021/acs.est.8b07226. Epub 2019 Jul 22.
The chlorine resistance of nanofiltration and reverse osmosis membranes is of high importance in the water treatment industry. Elastic recoil detection (ERD) is now presented as a powerful tool to uniquely provide elemental depth profiles, including hydrogen, of NaOCl-treated polyamide-based thin-film composite (TFC) membranes. The influence of pressure, pH, and chlorine feed concentration on the volume-averaged Cl uptake, the location of chlorine throughout the membrane, and the -gradient in the Cl/N ratio is demonstrated. The results suggest that (i) higher volume-averaged Cl uptakes are achieved at higher chlorine doses and at acidic pH; (ii) chlorination is mostly restricted to the top layer; (iii) a gradient in the Cl/N ratio exists along the membrane depth; and (iv) the shape of this gradient is influenced by the chlorination pH and the applied pressure. Conclusions on the chlorination mechanisms could also be deduced. Conversely, no conclusive relationships between H fractions and Cl uptake could be drawn, even though changes in the H content after chlorination were observed. To corroborate these results and fully exploit the potential of ERD, the exact microstructure of the (chlorinated) TFC membranes should be better understood.
纳滤和反渗透膜的耐氯性在水处理行业非常重要。弹性背散射探测（ERD）现在被证明是一种强大的工具，可以独特地提供包括氢在内的元素深度分布，用于处理过次氯酸钠的聚酰胺基薄膜复合（TFC）膜。研究了压力、pH 值和氯进料浓度对体积平均 Cl 摄取量、氯在整个膜中的位置以及 Cl/N 比的 -梯度的影响。结果表明：（i）氯剂量越高和酸性 pH 值时，体积平均 Cl 摄取量越高；（ii）氯化作用主要局限于最上层；（iii）在膜深度上存在 Cl/N 比的梯度；（iv）该梯度的形状受氯化 pH 值和所施加压力的影响。还可以推断出氯化机制的结论。相反，即使在氯化后观察到 H 含量发生变化，也无法得出 H 分数与 Cl 摄取量之间的明确关系。为了证实这些结果并充分利用 ERD 的潜力，应该更好地理解（氯化）TFC 膜的精确微观结构。
