Efficient oil-water emulsion treatment via novel composite membranes fabricated by CaCO3-based biomineralization and TA-Ti(IV) coating strategy

Continuous increasing discharge of industrial oily wastewater and frequent occurrence of oil spill accidents have taken heavy tolls on global environment and human health. Organic-inorganicmodifications can fabricate superhydrophilic/ submerged superoleophobic membranes for efficient oil-water separation/treatment though they still suffer from complex operation, non-environmental friendliness, expensive cost or uneven distribution. Herein, a new strategy regarding tannic acid (TA)-Ti(IV) coating and CaCO3-based biomineralization through simple inkjet printing processes was proposed tomodify polyvinylidene fluoride (PVDF) membrane, endowing the membrane with high hydrophilicity (water contact angle (WCA) decreased from86.01 degrees to 14.94 degrees) and underwater superoleophobicity (underwater contact angle (UOCA) > 155 degrees). The optimized TA-Ti(IV)-CaCO3 modified membrane possessed perfect water permeation to various oil/water emulsions (e.g., 355.7 L center dot m(-2)center dot h(-1) for gasoline emulsion) under gravity with superior separation efficiency (>98.8 %), leading the way in oil/water emulsion separation performance of PVDF membranes modified with polyphenolic surfaces to our knowledge. Moreover, the modified membrane displayed rather high flux recovery after eight cycles of filtration while maintaining the original excellent separation efficiency. The modification process proposed in this study is almost independent of the nature of the substrate, and meets the demand for simple, inexpensive, rapid preparation of highly hydrophilic antifouling membranes, showing abroad application prospect for oil-water emulsion separation/treatment.

Automated summary

Continuous discharge of industrial oily wastewater and frequent oil spill accidents have caused significant damage to the global environment and human health. A new strategy utilizing tannic acid (TA)-Ti(IV) coating and CaCO3-based biomineralization through inkjet printing process has been proposed to modify PVDF membranes, resulting in high hydrophilicity and underwater superoleophobicity. The optimized TA-Ti(IV)-CaCO3 modified membrane demonstrated excellent water permeation and separation efficiency for various oil/water emulsions, with high flux recovery and low fouling. This simple and cost-effective modification process shows great potential for oil/water emulsion separation/treatment.