Graphene quantum dots doped poly(vinyl alcohol) hybrid membranes for desalination via pervaporation

Abstract

Pervaporation desalination by highly hydrophilic materials such as poly(vinyl alcohol) (PVA) based separation membrane is a burgeoning technology of late years. However, the improvement of membrane flux in pervaporation desalination has been a difficult task. Here, a novel hybrid membrane with doped graphene oxide quantum dots (GOQDs) which is rich in hydrophilic groups and small size into the matrix of PVA was prepared to improve the membrane flux. The membranes structures were described by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). And more, Water contact angle, swelling degree, and pervaporation properties were carried out to explore the effect of GOQDs in PVA matrix. In addition, GOQDs content in the hybrid membrane, NaCl concentration, and feed temperature were investigated accordingly. Moreover, the hydrogen bonds between PVA chains were weakened by the interaction between GOQDs and PVA chains. Significantly, the hybrid membrane with optimized doped GOQDs content, 200 mg·L−1, displays a high membrane flux of 17.09 kg·m−2∙h−1 and the salt rejection is consistently greater than 99.6%.