Shrimp Shell-Inspired Antifouling Chitin Nanofibrous Membrane for Efficient Oil/Water Emulsion Separation with In Situ Removal of Heavy Metal Ions

In nature, shrimp has an outstanding antifouling behavior since its shell possesses underwater superoleophobicity. As a major component of the shrimp shell, chitin might have the potential of self-cleaning and can be exploited for dealing with oily water. Hence, novel filtration membranes derived from shellfish wastes were constructed via filtration of chitin nanofiber suspension. The resultant chitin nanofibrous membrane (CNM) was evaluated as a highly efficient oil/water emulsion separation material for the first time. Similar to shrimp shell, CNM with excellent superhydrophilicity and underwater superoleophobicity displayed extremely low underwater-oil adhesion and self-cleaning performance. With controllable thickness and nanoscale pore size, CNM could effectively separate micrometer- and nanometer-sized oil/water emulsions with a high separation efficiency (>95%) and water flux (>1500 L·m–2·h–1·bar–1). Furthermore, CNM displayed multifunctional water remediation characteristics, i.e., it could simultaneously remove heavy metal ions from water phase in the course of oil/water emulsion separation. The CNM also exhibited excellent mechanical strength, recyclable performance, thermal stability, and pH-resistance. Therefore, CNM with unique characteristics, e.g., sustainability, chemical and thermal resistance, multifunctionality, and excellent oil/water separation efficiency has the high potential in the practical oily water treatment.