Chemically stable NH2-MIL-125(Ti)/Sep/PDA composite membranes with high-efficiency for oil/water emulsions separation

Nowadays, oily wastewater is a severe threat to the living environment of humankind. In recent years, MOF materials have shown great application potential in membrane separation and treatment of oily wastewater. In this paper, the mixed cellulose ester membrane (MCEM) was modified by polydopamine, and the NH2-MIL-125 (Ti)/Sep(sepiolite)/PDA composite membrane was prepared by simple vacuum filtration. The composite membrane had super-hydrophilic performance and underwater super-oleophobic performance, and could effectively separate oil-water emulsion separation performance. Also, the composite membrane showed good repeatability. After 10 cycles, the retention rate of petroleum ether-in-water emulsion was still more than 99%, and the flux was more than 2000 L.m(-2).h(-1). Since strong adhesion ability of PDA and the covalent interaction between NH2- MIL-125(Ti) and Sep, the chemically stable NH2-MIL-125(Ti)/Sep/PDA composite membrane was exposed to the strong acid (pH=1), alkali (pH=11), and salt (5% saturated NaCl) solutions showed excellent chemically stable. These outstanding properties made the composite membrane have great potential in the removal of oily wastewater.

Automated summary

This paper introduces a composite membrane prepared by modifying mixed cellulose ester membrane with polydopamine, which has super-hydrophilic and underwater super-oleophobic properties, and can effectively separate oil-water emulsion. The composite membrane shows good chemical stability in strong acid, strong alkali, and salt solutions, and has great potential in the treatment of oily wastewater.