High performance loose-structured membrane enabled by rapid co-deposition of dopamine and polyamide-amine for dye separation

Textile wastewater poses a significant environmental challenge that demands effective treatment. Membrane separation offers a promising solution, with high-flux tight ultrafiltration membranes recognized as an effective technology for dye separation. Polyamide amine (PAMAM), a dendritic macromolecule renowned for its regular structure, high monodispersity, excellent solubility, and tunable molecular weight, has emerged as a promising material for membrane fabrication. This study introduces a novel, eco-friendly, and time-efficient method for preparing polymer composite membranes through one-step co-deposition of dopamine (DA) and PAMAM, predominantly utilizing Michael addition and Schiff base reactions. The incorporation of ammine-rich PAMAM imparts ultra-high hydrophilicity to the membranes (contact angle of 38°), facilitating strong adhesion of water molecules to the membrane surface. The effects of co-deposition time and concentrations of DA and PAMAM on the separation performance of the resulting membranes were systematically investigated. Notably, the optimal membrane demonstrated a high water flux (126.1 L m^-2h⁻¹ bar⁻¹), primarily due to the incorporation of PAMAM, which resulted in a looser selective separation layer. Furthermore, the membrane demonstrated excellent rejection of methyl blue (MB) at 98.9 % and low rejection os methyl orange (MO) at 13.2 %, making it well-suited for the selective separation of mixed dyes. Our approach offers a sustainable and technologically advanced solution for addressing resource recovery from textile wastewater.