Dip‐Coated Cu ² ⁺ /Chitosan/Acrylamide Hydrogel on PVDF Membranes for Dye Removal

Industrial discharge of persistent textile dyes poses severe threats to aquatic ecosystems and water resources, while commercial polyvinylidene fluoride (PVDF) membranes are constrained by hydrophobicity and fouling, limiting their dye removal efficacy. A Cu 2 + /acrylamide (AM)/chitosan (CS) hydrogel‐modified PVDF membrane (PVDF‐YM) was successfully fabricated using a simple dip‐coating approach. SEM, FTIR, XPS, BET/BJH, and water contact angle analyses confirmed the successful deposition of a hydrated Cu 2 + /AM/CS hydrogel coating, enhanced membrane hydrophilicity, and introduced nano/mesoporous domains within the coating layer. The modified membrane exhibited a pure water flux of ∼150 L·m − 2 ·h − 1 and solution permeate fluxes of ∼128 and ∼147 L·m − 2 ·h − 1 during RhB and MB filtration, respectively. High dye rejection efficiencies of 95.75% for RhB and 97.63% for MB were achieved. After five adsorption–desorption cycles, the RhB removal efficiency remained above 72%, indicating good short‐term reusability under the tested conditions. XPS and adsorption analyses suggest that Cu 2 + ‐assisted interactions stabilize the AM/CS hydrogel coating and provide functional dye‐retention domains. Dye removal is mainly attributed to adsorption‐assisted retention within/on the hydrated hydrogel layer, nano/mesopore‐confined diffusion, and coating‐induced mass‐transfer resistance. Overall, this simple and eco‐friendly strategy provides a promising route for improving PVDF membrane performance in dye wastewater treatment.