Micro-dissolved fabrication of robust superhydrophilic and underwater superoleophobic membranes based on cotton fabrics for oil/water separation.

The superhydrophilic and underwater superoleophobic membranes based on textile possessed excellent separation efficiency as well as outstanding anti-oil fouling property, while the poor stability caused by nanoparticle (NP) shedding had severely limited the practical application in oily water separation. In this paper, a feasible method of fabricating the robust membranes based on cotton fabric (CF), which was decorated with TiO₂ NP and citric acid (CA) through micro-dissolution method, was reported. Firstly, the CF was slightly dissolved in the NaOH/Urea solution at low temperature, accelerating the destruction of the cellulose macromolecule on the superficial layers of the fabrics. Then, the vacuum filtration process promoted the TiO₂ NP to distribute uniformly on the CF surface. In the subsequent coagulation process, the TiO₂ NP were firmly anchored on the fabric surface because of self-glue effect of micro-dissolved CF. Finally, the esterification reaction between CA and CF was carried out to enhance the hydrophilic property of CF. The prepared membranes were characterized by fourier transform infrared spectroscopy, scanning electron microscopy (SEM), X-ray diffraction and thermogravimetric analysis. Additionally, the separation performance and stability of membranes were systematically evaluated. The results of SEM indicated that the TiO₂ NP were uniformly anchored on the membrane surface. Especially, the prepared membranes could not only separate traditional oil/water mixture but also treat complicated oil-in-water (O/W) emulsion with excellent separation efficiency. What's more, the membranes could withstand various harsh condition and exhibit excellent application stability. In terms of separation performance and stability, the CA/TiO₂ decorated cotton fabrics have the potential to be used in the practical oily water separation. [ABSTRACT FROM AUTHOR]