Biomimetic Silicification on Membrane Surface for Highly Efficient Treatments of Both Oil-in-Water Emulsion and Protein Wastewater

The worldwide water crisis and water pollution have put forward great challenges to the current membrane technology. Although poly(vinylidene fluoride) (PVDF) porous membranes can find diverse applications for water treatments, the inherent hydrophilicity must be tuned for an energy-/time-saving process. Herein, the surface wettability of PVDF membranes transforming from highly hydrophobicity to highly hydrophilicity was realized via one-step reaction of plant-derived phenol gallic acid and γ-aminopropyltriethoxysilane in aqueous solutions. The surface hydrophilicization can be achieved on porous PVDF membranes by virtue of integration of a mussel-inspired coating and in situ silicification via a "pyrogallol-amino covalent bridge" toward excellent antifouling performance and highly efficient infiltration ability for oily emulsion and protein wastewater treatment. The water flux of a surface-manipulated microfiltration membrane can reach ca. 9246 L m^-2 h^-1 (54-fold increment compared to that of pristine membrane), oil rejection >99.5% in a three-cycle emulsion separation; the modified ultrafiltration membrane demonstrated benign performance in bovine serum albumin protein interception (rejection as high as ca. 96.6% with water flux of ca. 278.2 L m^-2 h^-1) and antifouling potential (increase of ca. 70.8%). Our in situ biomimetic silicification under "green" conditions exhibits the great potential of the developed strategy in fabrication of similar multifunctional membranes toward environmental remediation.

Bio-Inspired Underwater Super Oil-Repellent Coatings for Anti-Oil Pollution

Underwater superoleophobic surfaces have attracted great attention due to their broad applications such as anti-oil adhesion, oil capture and transportation, and oil/water separation. However, it is often fairly complex and time-consuming, involved in the construction of micro/nanostructures and the regulation of chemical compositions; there is an urgent need to develop new strategies to conquer these problems. Inspired by the strong anchoring capability and easy accessibility of plant polyphenols, we can readily and rapidly fabricate tannic acid (TA) coated copper surfaces with the excellent underwater super oil-repellent property. To achieve the optimal condition for TA modification, the influence of immersion time, TA concentration, and pH value on underwater-oil wettability and adhesion has been systematically explored. Furthermore, the underwater super oil-repellent feature can be widely achieved for different oils and on various metal sheets, suggesting the potential applications for plenty of fields such as anti-oil pollution.