Fabrication of PVDF@MOF-303 membrane with Mortise-Tenon structure by the polyphenol analogue-assisted growth strategy for oil-water separation and heavy metal adsorption

Abstract

This study applied a novel strategy to modify an inert fluorine-containing surface by combining alkaline lignin (AL) and silk fibroin (SF), introducing many active sites. The intercalation sites of SF during the formation of the AL coating allow the shape of the Mortise-Tenon metal-organic framework (MOF). MOF-303 with a Mortise-Tenon structure was grown on the surface of the membrane. The PVDF@MOF-303 membrane possesses superhydrophilic/underwater superoleophobic properties. The modified membrane showed perfect resistance to oil adhesion. Stable oil-in-water emulsions and toxic heavy metal ions can be separated by the PVDF@MOF-303 membrane with a Mortise-Tenon structure. This membrane has achieved outstanding oil-in-water emulsion separation efficiency (over 99.2 %) and flux (over 4200.0 L m−2 h−1 bar−1). After ten repeated experiments, a separation efficiency of 93.0 % was obtained. This membrane was used for heavy metal adsorption with high capacity (over 3374.4 mg m−2) and efficiency (over 99.6 %). Even more importantly, harmful heavy metal ions soluble in water can be effectively removed during emulsion separation. It can modify other substrates due to the easy preparation method and efficient performance described in this report.