Sulfonated halloysite nanotubes/polyethersulfone nanocomposite membrane for efficient dye purification

First, styrene was grafted onto the surface of halloysite nanotubes (HNTs) via distillation-precipitation polymerization and the above modified HNTs were sulfonated by concentrated sulfuric acid to prepare highly crosslinked HNTs-SO3H. Then, HNTs-SO3H was used as a novel inorganic filler to fabricate polyethersulfone (PES) nanofiltration hybrid membrane via classical phase inversion method. The morphology and separation performance of the above membranes were characterized by scan electron microscope (SEM), transmission electron microscope (TEM), water contact angle and mechanical measurement. The results revealed that water flux of the hybrid membranes was improved greatly after adding HNTs-SO3H. Especially, the hybrid membranes showed higher rejections for Reactive Black 5 (above 90%) and Reactive Red 49 (80-90%). Meanwhile, the rejection for salts declined to under 10% and the order for different salt solutions was Na2SO4 > MgSO4 > MgCl2 > NaCl, indicating the characteristics of negatively charged nanofiltration membranes. (C) 2015 Elsevier B.V. All rights reserved.