Novel PVDF membranes comprising n-butylamine functionalized graphene oxide for direct contact membrane distillation

To enhance the mechanical properties and wetting resistance of poly(vinylidene fluoride) (PVDF) membranes for membrane distillation (MD) of seawater, we have added n-butylamine modified graphene oxide (GO-NBA) in PVDF flat-sheet and hollow fiber membranes. For the first time, it is found that the addition of GO-NBA leads to PVDF flat sheet membranes with greater mechanical properties than that of conventional GO because of better compatibility, dispersity and crystalline structure. The addition of the GO-NBA also improves the mechanical properties of PVDF hollow fiber membranes in both tensile and hoop directions. With a small loading of 0.5 wt% GO-NBA in PVDF hollow fiber membranes, the maximum tensile stress, maximum tensile stain and Young's modulus increase by 32%, 63% and 71%, respectively, while the liquid entry pressure (LEP) and burst pressure jump by 67% and 15%, respectively. Under direct contact membrane distillation (DCMD), the 0.5 wt% GO-NBA incorporated membrane shows a flux of 61.9 kg m^-2 h^-1 and a salt rejection of 99.9% using a model seawater as the feed at 80 °C. This work might provide useful insights to fabricate robust MD membranes for seawater desalination.