Nature-inspired polyphenol chemistry to fabricate halloysite nanotubes decorated PVDF membrane for the removal of wastewater

The membrane filtration technology is considered as one of the most important approach for removal of hazardous substances from wastewater. Herein, we report a facile surface modification method for preparing a novel membrane via the codepositing tannic acid (TA), polyetheylenimine (PEI), and halloysite nanotubes (HNTs) on the surface of polyvinylidene fluoride (PVDF) membrane. The morphologies and chemical compositions of membrane were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), indicating that the membrane was successfully modified by TA/PEI/HNTs. Compared with pristine membrane, the coated membrane shows the improved hydrophilicity and pure water flux (PWF). The membrane modified by TA/PEI/HNTs achieves higher dyes rejection with 90.7%, 92.8% and 96.0% for direct yellow, direct red and direct blue, respectively. Moreover, the treated membrane exhibits excellent anti-fouling performance after several cycles. In addition, removal capacity for heavy metal ion can be enhanced by the as-prepared membrane with introducing the TA/PEI/HNTs coating. This work provides a facile strategy to carry out the hydrophilic modification of membranes. We hope the as-prepared membrane would have some practical applications for wastewater treatment.