Scalable Highly Ionized Sub‐10 Nm Nanofiltration Membranes Enabled by Interfacial Water on Layered Double Hydroxides

ABSTRACT The rapid and efficient separation of nanoscale targets in liquid matrices presents a critical yet formidable challenge. Polyamide (PA) membranes, while recognized as the benchmark for industrial‐scale nanoscale separation, face ongoing limitations in performance optimization. Although advances in nanomaterials have enabled breakthroughs in PA membrane performance, scalable production remains hindered by integration challenges. Here, we present a scalable strategy to fabricate ultra‐thin (<10 nm) nanofiltration membranes by constructing a layered double hydroxide (LDH) nanoplate‐enhanced piperazine (PIP) intermediate layer via interfacial polymerization (IP) with trimesoyl chloride. Hydrogen‐bond networks between PIP and LDH, combined with ordered water structures induced by LDH hydroxyl groups, restricted PIP diffusion, thus yielding ultrathin membranes with high ionization. Moreover, the rough LDH intermediate layer promoted a rougher membrane surface, enhancing the effective filtration area and permeability. The optimized membranes achieved a pure water permeance of 89.6 ± 3.5 L m −2 h −1 bar −1 and a Na 2 SO 4 rejection rate of 95.7%, achieving one of the best‐reported levels. Leveraging the accessibility of LDH colloids and the scalable fabrication process, this strategy enables the production of large‐area membranes via spraying and IP, making it highly promising for purifying and recovering antibiotics.