Membrane fouling persists to be among key obstacles in liquid membrane-based separation processes, and thereby the underlying understanding has actively been pursued. The two gaps attempted to be addressed here are namely, (i) internal fouling, which has limited studies due to limitations of instruments available; and (ii) fouling by mixtures of oppositely charged particles, as an extension to the studies on effect of surface charge of pure foulants on fouling. With the sub-micron pure constituents (namely, negatively charged carboxylated latex particles and positively charged aminated latex particles) as benchmarks, mixtures of three different compositions of the two particle types were investigated. The membrane was polycarbonate track-etched (PCTE) membrane. Surprisingly, the mixtures gave worse flux decline than that by purely positively charged aminated latex, which contradicts electrostatic considerations. The fouling model indicates that the mixtures exhibited higher pore blockage parameters (α) than either of the pure constituents, which agree with the flux decline trends. On the other hand, the mixtures gave internal cake resistance parameters (R_c/R_m) in between that of the pure constituents, which disagree with the fouling trends. Furthermore, optical coherence tomography (OCT) analysis indicates that the mixtures had taller buildups on the membrane as well as heterogenous internal cakes. Therefore, the steepest flux declines for the mixtures seem to be better correlated with the extensive external fouling as manifested in the taller buildups on the membrane pores, rather than internal fouling since the internal cakes were more porous. The contradictory extensive external and mitigated internal fouling phenomena are unexpected based on electrostatic considerations, and thereby highlight that fouling resulting from mixtures may not be readily extrapolated from understanding based on pure particle feeds.

膜结垢仍然是基于液膜的分离过程中的主要障碍之一，因此人们积极地寻求基本的认识。此处试图解决的两个差距是：（i）内部结垢，由于可用仪器的限制，因此研究有限。（ii）带相反电荷的颗粒的混合物造成的结垢，作为对纯污垢表面电荷对结垢影响的研究的延伸。以亚微米级纯组分（即带负电荷的羧化乳胶颗粒和带正电荷的胺化乳胶颗粒）为基准，研究了两种颗粒类型的三种不同组成的混合物。该膜是聚碳酸酯轨迹蚀刻（PCTE）膜。出奇，与纯正电荷的胺化乳胶相比，该混合物的通量下降更严重，这与静电方面的考虑相矛盾。结垢模型表明混合物表现出较高的孔堵塞参数（α）比任一纯成分都更符合通量下降趋势。另一方面，混合物给出了内部抗滤饼性参数（R _c / R _m）之间的纯成分，这与结垢趋势不同。此外，光学相干断层扫描（OCT）分析表明，混合物在膜以及异质内部滤饼上具有更高的堆积。因此，混合物的最大通量下降似乎与广泛的外部污垢更好地相关，这表现在膜孔上较高的堆积物上，而不是内部污垢，因为内部滤饼更多孔。基于静电的考虑，矛盾的广泛的外部和内部污垢现象是出乎意料的，因此突出表明，基于纯颗粒进料的理解，可能不容易推断出混合物造成的污垢。