This study presented the contribution of monovalent cations (Na⁺ and K⁺) to the adsorptive sodium alginate (SA) fouling in real-time using a quartz crystal microbalance and dissipation (QCM-D). Polyvinylidene fluoride (PVDF) and graphene oxide modified PVDF membrane (GO-PVDF) were selected as representative membrane materials. Atomic force microscopic (AFM) equipped with probes modified with foulant was used for exploring the adhesion force changes between SA and the membrane. The results showed that both Na⁺ and K⁺ can promote the adsorption capacity of SA on the membrane surface. SA fouling in Na⁺ condition was more severe than that in K⁺ circumstance due to higher attraction forces under identical ion strength. In addition, the GO-PVDF membrane is more readily/severely fouled than PVDF by SA when Na⁺ or K⁺ is present. The difference in the interaction forces was further interpreted using XDLVO theory. The results suggested that the Lewis acid-base adhesion free energy (ΔG_flf^AB) between SA decreased gradually with increasing Na⁺ concentration, while in the K⁺ environment, ΔG_flf^AB increased instead. Moreover, the increase of the Lifshitz-van der Waals components (γ_m^LW) of the GO membrane, resulted in a higher attractive interaction in the initial phase of the SA fouling. The results of this study provide a microscopic analysis of the possible fouling mechanism of Na⁺ and K⁺ on membrane fouling and as well as provide insightful reflections for an appropriate approach (whether GO modified or not) to membrane fouling control.

本研究使用石英晶体微量天平和耗散 (QCM-D) 实时^{展示了单价阳离子（Na +}和 K ⁺ ）对吸附性海藻酸钠(SA) 污垢的贡献。选择聚偏二氟乙烯（PVDF）和氧化石墨烯改性PVDF膜（GO-PVDF）作为代表膜材料。配备有污垢修饰探针的原子力显微镜 (AFM) 用于探索 SA 与膜之间的粘附力变化。结果表明，Na ⁺和K ⁺均能促进SA在膜表面的吸附能力。^{Na +}中的 SA 污垢由于在相同离子强度下具有更高的吸引力，因此条件比 K ^{+情况更严重。}此外，当存在 Na ⁺或 K ⁺时，GO-PVDF 膜比 PVDF 更容易/严重地被 SA 污染。使用 XDLVO 理论进一步解释了相互作用力的差异。结果表明，随着Na ⁺浓度的增加，SA间的Lewis酸碱粘附自由能（ΔG _flf ^AB ）逐渐降低，而在K ⁺环境中，ΔG _flf ^AB反而增加。此外，Lifshitz-van der Waals 分量（γ _m ^LW) 的 GO 膜，在 SA 污染的初始阶段导致更高的吸引力相互作用。本研究的结果提供了对 Na ⁺和 K ⁺对膜污染可能的污染机制的微观分析，并为膜污染控制的适当方法（无论是否 GO 改性）提供了深刻的思考。