Engineering a covalently constructed omniphobic/slippery membrane for high-performance membrane distillation
The functional loss of membranes caused by pore wetting,mineral scaling,or structural instability is a critical challenge in membrane distillation(MD),severely impacting its long-term operational stability.In light of this,we provide a novel strategy to fabricate an omniphobic/slippery MD membrane via"covalent"grafting modification.Specifically,spherical silica nanoparticles were covalently bonded to the surfaces of polyvinylidene fluoride(PVDF)membranes using polydopamine(PDA)interlayer,followed by direct surface fluorination through thiol-ene click chemistry.Contact angle(CA)measurements reveal that the resulting membrane(PDA/PVDF-C)exhibits an ultrahigh water contact angle(163.5°±0.9°)and low sliding angle(5.6°±1.2°).Besides,the membrane shows excellent wetting resistance toward various liquids with low surface tension surface tension liquids,and outstanding anti-wetting properties for the short-term treatment of high-salinity brines containing surfactants.Due to its unique omniphobic/slippery characteristics,the membrane can durably and stably handle high-salinity brines containing surfactants,delaying the formation of gypsum scale.The membrane exhibits an initial flux of approximately 23.5 L/(m2·h)and maintains a salt rejection of up to 99％during the whole operation.Overall,this study presents a novel and effective approach for fabricating high-performance membrane distillation(MD)membranes with high performance even under harsh operating conditions.
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