Molecular Mechanisms of Ultrafiltration Membrane Fouling in Polymer-Flooding Wastewater Treatment: Role of Ions in Polymeric Fouling
Molecular Mechanisms of Ultrafiltration Membrane Fouling in Polymer-Flooding Wastewater Treatment: Role of Ions in Polymeric Fouling
复制标题
聚合物驱废水处理中超滤膜污垢的分子机制：离子在聚合物污垢中的作用
DOI：
10.1021/acs.est.5b04098
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发表时间：
2016-02-02
影响因子：
11.4
通讯作者：
Liu, Zhiyuan
中科院分区：
文献类型：
--
作者：
Liu, Guicai;Yu, Shuili;Liu, Zhiyuan
利用原子力显微镜（AFM）研究了聚合物（即阴离子聚丙烯酰胺（APAM））对聚偏氟乙烯（PVDF）超滤（UF）膜的污染及其与分子间相互作用的关系。AFM力谱测量值与计算的浓度极化层（CPL）和凝胶层（GL）上的污垢阻力之间存在明显的关系。测得的最大附着力（F-ad,F-max）与CPL阻力（R-p）密切相关，而APAM链的分子填充性能（主要基于AFM力谱曲线的形状）与GL阻力（R-g）相关。钙离子（Ca2+）和钠离子（Na+）造成的污染更为严重。在Ca2+存在的情况下，较大的R-p对应于较高的杂质（杂质F-ad，F-max），导致较高的通量损失。此外，Ca2+的R-g较小，但化学清洗后的通量回收率最低，说明Ca2+对GL清洗的挑战更大。在Na+中，污染行为复杂且具有浓度依赖性。带有Na+的GL结构可能对应于APAM链之间的分子堆积状态，在膜污染和GL清洁中起重要作用。
Polymer (i.e., anionic polyacrylamide (APAM)) fouling of polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes and its relationships to intermolecular interactions were investigated using atomic force microscopy (AFM). Distinct relations were obtained between the AFM force spectroscopy measurements and calculated fouling resistance over the concentration polarization layer (CPL) and gel layer (GL). The measured maximum adhesion forces (F-ad,F-max) were closely correlated with the CPL resistance (R-p), and the proposed molecular packing property (largely based on the shape of AFM force spectroscopy curve) of the APAM chains was related to the GL resistance (R-g). Calcium ions (Ca2+) and sodium ions (Na+) caused more severe fouling. In the presence of Ca2+, the large R-p corresponded to high foulant-foulant F-ad,F-max) resulting in high flux loss. In addition, the R-g with Ca2+ was minor, but the flux recovery rate after chemical cleaning was the lowest, indicating that Ca2+ created more challenges in GL cleaning. With Na+, the fouling behavior was complicated and concentration-dependent. The GL structures with Na+, which might correspond to the proposed molecular packing states among APAM chains, played essential roles in membrane fouling and GL cleaning.