Construction of tight ultrafiltration membrane for efficient dye/salt separation with physical and chemical self-healing property

This work developed a novel self-healing tight UF membrane based on damages to membrane during operation and cleaning via blending AMPS-PANI into the membrane matrix, which can not only endow the membrane with physical and chemical self-healing properties, but also enable the membrane to obtain effective separation performance of inorganic salt and dyes. Taking AMPS-PANI membrane (M4) as an example, the self-healing test showed that the dye/salt rejection rates of M4 membrane recovered to near pre-damage levels (more than 98%) for the physical damage. As for chemical damage, the high-resolution XPS spectra of S 2p of M4 membrane after damage displayed a larger S-C-C peak area than that before damage. The above results prove that the membrane has self-healing ability after physical and chemical damage. The observed physical self-healing property is ascribed to the swelling behavior of AMPS hydrogels, the fluidity of hydrogel chains and strong hydrogen bonding, and owing the chemical self-healing property to the Michael addition reaction between carbon–carbon double bonds and free radicals. The pure water flux, dye/salt rejection rate, structure, mechanical properties and porosity of the self-healing tight UF membrane were systematically investigated to evaluate its feasibility as an actual filtration membrane for textile wastewater. The results of the research indicate that membrane including both physical and chemical self-healing is a promising way to improve water filtration membrane with self-healing ability.