s Sodium Alginate Modified Hydroxyapatite Nanotubes as a Novel Ecofriendly Additive for Preparation of Polyethersulfone Hybrid Ultrafiltration Membranes

Background: Hydrophilic nanomaterials have been extensively exploited their applications in the field of hybrid water treatment membranes. However, some of the modification process to nanomaterials may be complicated, and the nonselective pores caused by the poor compatibility between nanoparticles and the polymer matrix impair the rejection efficiency for ultrafiltration application. Thus, it is highly desirable to develop a kind of effective nano dopant with favorable compatibility by a facile way for the preparation of ultrafiltration membranes. Objective: The aim of this study was to fabricate a novel environmentally friendly and low-cost nano additive with good compatibility for the preparation of ultrafiltration membranes. Methods: Hydroxyapatite nanotubes were prepared via a biomimetic process, and then SA was coated on the surface of hydroxyapatite nanotubes. Subsequently, a series of hybrid ultrafiltration membranes were fabricated with different amounts of modified HANTs and polyethersulfone (PES). Results: Exhaustive characterizations were conducted for the membranes, including hydrophilicity, porosity, mean pore size, morphologies and UF performance test. The highest water flux of the hybrid membranes displayed 1.9 times that of the original PES membrane. Meanwhile, the hybrid membrane with 0.2% hydroxyapatite nanotubes obtained elevated antifouling ability, achieving a flux recovery ratio of 85.6%. Conclusion: The facile coating of SA endowed the nanotubes improved hydrophilicity and meanwhile enhanced the compatibility between PES and HANTs. This work provides a facile way in the construction of green nanofillers and promising results in the preparation of hybrid UF membranes.