Interfacial regulation enhances antiscalant performance in membrane distillation for shale gas produced water treatment.

Mineral scaling and organic fouling severely limit the application of membrane distillation (MD) in shale gas produced water (SGPW) treatment, while conventional antiscalants (AS) often fail to effectively translate bulk complexation into interfacial anti-deposition performance. In this study, an AS-assisted negative pressure membrane distillation (NPMD) strategy was proposed to couple Ca2+ binding regulation with membrane interfacial control. Molecular dynamics simulations showed that NPMD maintained Ca-AS complexation while suppressing Ca-humic aggregation, shifting foulants from membrane surface co-deposition toward more dispersed bulk-phase complexation. Real SGPW treatment demonstrated that, compared to an untreated SGPW system, AS-assisted NPMD increased the normalized flux from 0.22 to 0.68 and reduced the permeate conductivity from 56.42 to 8.05 μS/cm at 75% recovery. Meanwhile, the surface contents of O, Ca, Ba and Si decreased by 57.9%, 71.4%, 90.9% and 90.0%, respectively, while membrane hydrophobicity recovered by 44.2%, greatly reducing the risks of membrane fouling and wetting. Integrated interfacial analysis including front-face fluorescence and interaction energy further confirmed that the performance enhancement originated from reduced humic enrichment on the membrane surface and weakened membrane-foulant interactions. This work establishes a molecular interfacial regulation strategy for improving AS efficiency and provides a scalable route for high-recovery MD desalination of complex hypersaline wastewater.