Preparation of cellulose/chitosan superoleophobic aerogel with cellular pores for oil/water separation

Abstract

Nanofibrillated cellulose (NFC)/chitosan (CS) composite aerogel with underwater superoleophobicity was prepared by freeze-drying for oil/water separation. The soft-ice freezing technique was employed to construct cellular pores for improving the mechanical performance while enhancing mass transfer of freeze-drying. The dielectric-aided microwave heating was adopted to enhance heat transfer of freeze-drying. The results showed that the prepared NFC/CS aerogel exhibited an excellent mechanical property with a stress of 87.16 kPa at 80% strain, and underwater superoleophobicity with all oil contact angles above 150˚. The proposed drying method could save over 40% of drying time, achieving a simultaneous mass and heat transfer enhancement of freeze-drying. The prepared aerogel provided separation efficiencies of all above 99.96% and average permeate fluxes of 0.817 and 0.826 L·m−2·s−1 after 20 cycles for oil/water and oil/seawater separations. The research results are expected to provide an economical and sustainable solution for the industrial oily wastewater treatment.