A magnetic pH-induced textile fabric with switchable wettability for intelligent oil/water separation

Wastewater discharged in human daily life, and oil spill accidents occurred frequently. The novel interface materials used for controllable oil/water separation have gained more and more attention. In this work, a facile, environmentally friendly approach is presented to fabricate a magnetic textile fabric with pH-controllable wettability between superhydrophobicty and superhydrophilicity. We prepared this magnetic textile fabric by immersing in lauric acid (LA)-TiO2 composites and Fe3O4 nanoparticles. The resulted pH-conrtollable textile fabric possessed selective separation performance for oil/water mixtures with efficiency higher than 99% and high flux for oil (11,000 L h(-1) m(-2)). Moreover, the magnetic material is recyclable, the detailed experiments were conducted in this work for 25 cycles of oil/water mixture separation remaining unchangeable separation efficiency (> 98%). For neutral water (e.g., at pH 7), the novel Fe3O4/LA-TiO2 textile fabric demonstrated superhydrophobicity/superoleophilicity in air. For alkaline water (e.g., at pH 12), the textile fabric showed superhydrophilicity and underwater superoleophobicity. The Fe3O4/LA-TiO2 textile fabric could separate a series of light or heavy oil/water mixtures with high separation efficiency up to 99.1%, high oil flux of 7400-11,000 L h(-1) m(-2) and water flux of 5300-5700 L h(-1) m(-2). In addition, thermal stability (similar to 180 degrees C) and long exposure to ultraviolet rays showed that the textile fabric was stable in harsh environment. The textile fabric can be easily removed through a magnet due to its magnetic properties. It can be concluded from the results that Fe3O4/LA-TiO2 textile fabric is a good candidate for practical applications, such as water restoration and oil-spill treatment.