Hydrothermal carbon nanospheres assisted-fabrication of PVDF ultrafiltration membranes with improved hydrophilicity and antifouling performance

The hydrophobicity of polyvinylidene fluoride (PVDF) membrane in nature can result in permeability decline and critical membrane fouling, limiting its further development and application in the field of purification and separation. Novel composite PVDF ultrafiltration membranes containing 0.1-0.6 wt% of synthesized hydrothermal carbon nanospheres (CNS) were prepared with phase inversion method. The CNS had the mean diameter between 170 and 177 nm and the reactive oxygen functionalities such as hydroxyl, carbonyl, and carboxylic groups on outer carbon surface. The various characterizations revealed that the amount of CNS had a significant effect on composite membrane properties. The membrane of PVDF-2 exhibited the superior properties because of its lowest surface roughness and highest hydrophilicity, thermal stability, surface energy, porosity and mean pore size. Evaluations by pure water flux, bovine serum albumin (BSA) rejection and antifouling performance test further demonstrated the enhancement of membrane performance properties by the introduction of CNS into PVDF. The highest pure water flux, BSA rejection and flux recovery ratio (FRR) were achieved with the composite membrane blended with an amount of 0.2 wt% CNS (PVDF-2), reaching 956.72 L m(-2) h(-1), 95.8% and 83.21% respectively. The overall improved permeability and antifouling performance suggested a great potential application of carbonaceous spheres being used in composite PVDF membrane fabrication.