School of Architecture & Civil Engineering, Xi'an University of Science and Technology, Yan Ta Road, No. 58, Xi'an, 710054, China; Shaanxi Yulin Changjialiang Shengli Coal Mine Co., Ltd., Niujialiang Town, Yulin, 719000, China; Research Institute of Membrane Separation Technology of Shaanxi Province, Xi'an University of Architecture & Technology, Yan Ta Road, No. 13, Xi'an, 710055, China.
School of Architecture & Civil Engineering, Xi'an University of Science and Technology, Yan Ta Road, No. 58, Xi'an, 710054, China.
Chemosphere. 2023 Oct;337:139334. doi: 10.1016/j.chemosphere.2023.139334. Epub 2023 Jun 26.
Perfluorobutane sulfonic acid (PFBS) is a kind of anthropogenic recalcitrant contaminant that has posed a threat to drinking water safety and brought widespread public health concerns. Nanofiltration (NF) is an effective way to remove PFBS from drinking water, while the removal is influenced by coexisting ions. To investigate the effects and intrinsic mechanisms of coexisting ions on the rejection of PFBS, poly(piperazineamide) NF membrane was utilized in this work. Results showed that most cations and anions in the feedwater could effectively improve PFBS rejection and simultaneously reduce NF membrane permeability. In most cases, the decrease in NF membrane permeability corresponded to an increase in the valence of cations or anions. When cations (Na, K, Ca, and Mg) were present, the rejection of PFBS was effectively improved from 79% to more than 91.07%. Under these conditions, electrostatic exclusion was the dominant NF rejection mechanism. This was also the leading mechanism for 0.1 mmol/L Fe coexisted condition. As the concentration of Fe increased to 0.5-1 mmol/L, intensified hydrolyzation would accelerate the formation of the cake layers. The differences in the cake layer characteristics led to the different rejection trends of PFBS. For anions (SO and PO), both sieving effects and electrostatic exclusion were enhanced. As anionic concentration raised, the NF rejection of PFBS increased to above 90.15%. By contrast, the effect of Cl on PFBS rejection was also affected by coexisting cations in the solution. The dominant NF rejection mechanism was electrostatic exclusion. Accordingly, it is suggested that the usage of negatively charged NF membranes could facilitate the efficient separation of PFBS under ionic coexisting conditions, thereby ensuring the safety of drinking water.
全氟丁烷磺酸（PFBS）是一种人为的难降解污染物，对饮用水安全构成了威胁，并引起了广泛的公众健康关注。纳滤（NF）是去除饮用水中 PFBS 的有效方法，而去除效果受到共存离子的影响。为了研究共存离子对 PFBS 去除的影响和内在机制，本工作采用了聚（哌嗪酰胺）纳滤膜。结果表明，给水中的大多数阳离子和阴离子都能有效地提高 PFBS 的去除率，同时降低纳滤膜的渗透性。在大多数情况下，纳滤膜渗透性的降低与阳离子或阴离子价数的增加相对应。当阳离子（Na、K、Ca 和 Mg）存在时，PFBS 的去除率从 79%有效地提高到 91.07%以上。在这些条件下，静电排斥是主导的纳滤去除机制。这也是在共存 0.1 mmol/L Fe 条件下的主要机制。随着 Fe 浓度增加到 0.5-1 mmol/L，强化水解会加速形成滤饼层。滤饼层特性的差异导致 PFBS 去除率的不同趋势。对于阴离子（SO 和 PO），筛分效应和静电排斥都得到了增强。随着阴离子浓度的升高，PFBS 的纳滤去除率提高到 90.15%以上。相比之下，Cl 对 PFBS 去除的影响也受到溶液中共存阳离子的影响。主导的纳滤去除机制是静电排斥。因此，建议在存在离子共存的情况下使用带负电荷的纳滤膜，可以促进 PFBS 的有效分离，从而确保饮用水的安全。
