Carbon black induced fluorination enables robust membrane distillation for landfill leachate treatment

Membrane wetting and fouling pose significant challenges for membrane distillation (MD), particularly in hypersaline wastewater treatment. To address these issues, a robust low-surface-energy polyvinylidene fluoride (PVDF)-based membrane was developed through carbon black-induced fluorination with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS). Carbon black nanoparticles were deposited on a pristine PVDF membrane via vacuum filtration, forming loosely packed structures that served as anchoring sites for FDTS grafting. FDTS fluorination introduced -CF₃/-CF₂ functional groups and Si-O-Si networks. It not only reduced the surface energy to 2.03 mN/m and decreased the pore size to 0.41 μm, but also significantly enhanced the membrane surface hydrophobicity (water contact angle 144°). Compared with the pristine PVDF and carbon black deposited PVDF membranes, the membrane modified by carbon black-induced fluorination exhibited superior water vapor transmission (6.05 × 10⁻⁶ m³/m²·Pa·s) and antiwetting properties due to its ultralow surface energy and robust air barrier. In MD desalination, the surface fluorinated PVDF membrane demonstrated stable fluxes exceeding 7.0 L/m²·h and almost 100 % rejection performance even when treating highly concentrated solutions (5.5 wt. % NaCl) or organic-polluted solutions. This performance remarkably outperformed the pristine PVDF membrane (flux decline >80 %) and carbon black deposited PVDF membrane (severe wetting). The surface fluorinated PVDF membrane also showed exceptional durability in treating real landfill leachate, maintaining fluxes above 6 L/m²·h over 72 h with minimal salt or organic leakage. Mechanistic investigations revealed that the carbon black-FDTS hybrid layer reinforced the air barrier, effectively mitigating foulant-membrane interactions and preventing pore wetting. This study presents a scalable and practical strategy for engineering antiwetting MD membranes, facilitating the reclamation of hypersaline and complex wastewaters.