Dopamine composite nanofiltration membranes prepared by self-polymerization and interfacial polymerization

• Dopamine/TMC membranes were prepared by interfacial polymerization.
• Self-polymerization of dopamine enhanced structural stability.
• Dopamine/TMC membranes exhibited long-term chemical stability.

Based on the molecular structure feature and bioadhesion phenomenon, dopamine was selected to prepare composite membranes. The amine and phenol groups in dopamine, and the catechol groups of polydopamine all could react with acyl chloride groups of trimesoyl chloride (TMC) forming a dense thin film onto porous PES ultrafiltration substrate. The interaction between the thin film and the substrate of the composite membrane was enhanced due to the bioadhesion of polydopamine. The dopamine/TMC composite membranes were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and water contact angle measurement. The preparation parameters of dopamine/TMC composite membranes including pH value of water phase, reaction time, reaction temperature, and monomer concentrations were investigated, respectively. The separation performance of dopamine/TMC composite membranes was in the nanofiltration range. The composite membranes exhibited long-term structural stability in ethanol and chemical stability in sodium hypochlorite solution. Compared with the others in enhancing the structural stability, the bioadhesion method was simple and time-saving.