Interfacial demulsification and antifouling of oil/water separation membrane by dynamically self-releasing hydroxide ions

Abstract

Advanced membranes are urgently needed in concentration, purification and separation of various industrial emulsions. However, their performance is impeded by issues such as membrane fouling and the inherent trade-off between separation efficiency and permeation flux. In this work, an interfacial demulsification and antifouling membrane was achieved through self-releasing high concentration of hydroxide ions on the membrane surface in a dynamic manner. These hydroxide ions can facilitate the emulsified oil droplets on the membrane surface to demulsify by greatly decreasing their Debye length and suppressing their electric double layer repulsion. In this way, the emulsified oil droplets could aggregate into large ones and rapidly detach from the membrane surface, mitigating the challenges of membrane fouling and trade-off. Thus, the membrane exhibits outstanding antifouling ability, achieving high efficiency (99.79 %) and flux (3046 L m⁻² h⁻¹ bar⁻¹) in long-term oil/water emulsion separation. This ionic self-releasing membrane is easy to manage, requires no reagent consumption, and causes no pollution. This work provides a promising solution and valuable insights into membrane separation and emulsion-related systems.