In a practical project of polyvinylidene fluoride (PVDF) ultrafiltration membrane for polymer flooding wastewater treatment, the deterioration of membrane performance was observed after 4 years of operation. The aging effects of sodium hypochlorite (NaClO) on PVDF ultrafiltration membranes were systematically studied, including the membrane properties, filtration performance, and fouling behaviors. During the NaClO aging process, chemical transformations of polyvinylpyrrolidone (PVP) additives dominated the changes in membrane intrinsic characteristics, and the kinetic behavior of PVP decomposition was proposed, which was closely related to the evolution of the membrane pore size. For aged membranes, due to the changes in intrinsic characteristics, the antifouling performance significantly declined: the pseudo-stable flux with feeding solution and flux recovery after physical cleaning decreased by ~55% and ~62%, respectively, after 20 days of aging. The intermolecular forces in combination with the interfacial free energies were used to evaluate the fouling behaviors of aged membranes. The increased energies indicated the more spontaneous foulant‒membrane adhesion and stabilized fouling layers, which deteriorated the irreversible fouling resistance, increased the initial fouling rates and reduced the flux recovery after physical cleaning. Compared to intermolecular forces, foulant‒membrane interfacial free energies can serve as the more sensitive and reliable indicators of membrane fouling.

在一个聚偏二氟乙烯（PVDF）超滤膜用于聚合物驱油废水处理的实际项目中，运行4年后观察到膜性能下降。系统研究了次氯酸钠（NaClO）对PVDF超滤膜的老化作用，包括膜性能，过滤性能和结垢行为。在NaClO老化过程中，聚乙烯吡咯烷酮（PVP）添加剂的化学转化控制了膜固有特性的变化，并提出了PVP分解的动力学行为，这与膜孔径的变化密切相关。对于老化的膜，由于其固有特性的变化，其防污性能显着下降：老化20天后，进料溶液的准稳定通量和物理清洗后的通量回收率分别降低了约55％和〜62％。分子间力结合界面自由能被用来评估老化膜的结垢行为。能量的增加表明更自然的污垢-膜附着力和稳定的污垢层，这恶化了不可逆的污垢抵抗力，增加了初始污垢率并降低了物理清洁后的焊剂回收率。与分子间力相比，污垢-膜的界面自由能可以作为膜污染的更灵敏和可靠的指标。分子间力结合界面自由能被用来评估老化膜的结垢行为。能量的增加表明更自然的污垢-膜附着力和稳定的污垢层，这恶化了不可逆的污垢抵抗力，增加了初始污垢率并降低了物理清洁后的焊剂回收率。与分子间力相比，污垢-膜的界面自由能可以作为膜污染的更灵敏和可靠的指标。分子间力结合界面自由能被用来评估老化膜的结垢行为。能量的增加表明更自然的污垢-膜附着力和稳定的污垢层，这恶化了不可逆的污垢抵抗力，增加了初始污垢率并降低了物理清洁后的焊剂回收率。与分子间力相比，污垢-膜的界面自由能可以作为膜污染的更灵敏和可靠的指标。增加了初始结垢率并降低了物理清洁后的焊剂回收率。与分子间力相比，污垢-膜的界面自由能可以作为膜污染的更灵敏和可靠的指标。增加了初始结垢率并降低了物理清洁后的焊剂回收率。与分子间力相比，污垢-膜的界面自由能可以作为膜污染的更灵敏和可靠的指标。