School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China.
National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology, Shanghai 200237, PR China.
Environ Sci Technol. 2021 May 4;55(9):6329-6339. doi: 10.1021/acs.est.1c00206. Epub 2021 Apr 13.
The potential coexistence and interaction of bromine and polyamide membranes during membrane-based water treatment prompts us to investigate the effect of bromine on membrane performance. For fully aromatic polyamide membrane NF90 exposed under a mild bromination condition (10 mg/L), bromine incorporation resulted in more negatively charged (-13 vs -25 mV) and hydrophobic (55.2 vs 58.9°) surfaces and narrower pore channels (0.3 vs 0.29 nm). The permeabilities of water and neutral solutes were reduced by 64 and 69-87%, respectively, which was attributed to the decreased effective pore radius and hydrophilicity. NaCl permeability was reduced by 90% as a synergistic result of enhanced size exclusion and charge repulsion. The further exposure (100 and 500 mg/L bromine) resulted in a more hydrophobic surface (61.7 and 65.5°) and the minor further reduction for water and solute permeabilities (1-9%). Compared with chlorine, the different incorporation efficiency and properties (e.g., atomic size, hydrophilicity) of bromine resulted in opposite trends and/or different degrees for the variation of physicochemical properties and filtration performance of membranes. The bromine incorporation, the shift and disappearance of three characteristic bands, and the increased O/N ratio and calcium content indicated the degradation pathways of N-bromination and bromination-promoted hydrolysis under mild bromination conditions (480 mg/L·h). The further ring-bromination occurred after severe bromine exposure (4800-24,000 mg/L·h). The semi-aromatic polyamide membrane NF270 underwent a similar but less significant deteriorated filtration performance compared with NF90, which requires a different explanation.
溴素与聚酰胺膜在膜基水处理过程中可能共存和相互作用，促使我们研究溴素对膜性能的影响。对于在温和溴化条件（10mg/L）下暴露的全芳香族聚酰胺膜 NF90，溴素的掺入导致表面带更多负电荷（-13 对-25 mV）和疏水性（55.2 对 58.9°），且孔径通道更窄（0.3 对 0.29nm）。水和中性溶质的透过率分别降低了 64%和 69-87%，这归因于有效孔径半径和亲水性的降低。NaCl 的透过率降低了 90%，这是尺寸排阻和电荷排斥增强的协同结果。进一步的暴露（100 和 500mg/L 溴素）导致表面更加疏水性（61.7 和 65.5°），水和溶质透过率进一步降低（1-9%）。与氯相比，溴素的不同掺入效率和性质（例如原子大小、亲水性）导致膜的物理化学性质和过滤性能的变化呈现相反的趋势和/或不同程度的变化。溴素的掺入、三个特征带的移动和消失、O/N 比和钙含量的增加表明在温和溴化条件（480mg/L·h）下存在 N-溴化和溴化促进水解的降解途径。在严重的溴素暴露（4800-24,000mg/L·h）后，发生了进一步的环溴化。半芳香族聚酰胺膜 NF270 与 NF90 相比，过滤性能的劣化具有相似但不那么显著的特征，这需要不同的解释。
