Use of Nano-TiO2 self-assembled flax fiber as a new initiative for immiscible oil/water separation

In this study, an environmental friendly, reusable and low-cost functionalized flax fiber was fabricated to separate immiscible oil and water. Flax fibers were modified by plasma-induced poly(acrylic acid) (PAA) polymerization followed by nano-TiO2 self-assembly. A two-level fractional factorial design was engaged to analyze the modification influencing parameters and their interactions. The modified fiber was comprehensively characterized by synchrotron-based Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF). For the first time, the concentration distribution of functional groups and TiO2 nanoparticles (TiO2 NPs) were explored on flax fiber surface. The TiO2 NPs were found unevenly fixed on flax fiber surface with high concentration on abundant substrate. The hydrophilicity of nano-TiO2 self-assembled flax fiber was significantly improved, with water contact angle decreasing from 97.4° to 25.9° and almost doubled maximum oil holding pressure. The modified flax fiber showed stable performance of oil/water separation in alkaline and salty conditions and could be used for multiple cycles. The modified flax fiber could be further constructed into oil barrier with special wettability to separate oil.