Anionic ammonium polyphosphate coated underwater superoleophobic cotton fabric for effective oil/water separation

Abstract

Considering the great threat of oil spilling to human safety and ecological balance, treatment of oily wastewater became a worldwide challenge. Inspired by the underwater superoleophobic property of fish scale surface, we fabricated the superhydrophilic and underwater superoleophobic cotton fabric (CF) through grafting modification of ammonium polyphosphate (APP) followed by surface deposition of Fe3O4 nanoparticles via micro-dissolution method. The incorporation of APP, which contained numerous anionic groups, was found to be advantageous in enhancing the water holding capacity of fabric. More significantly, the micro-nanoscale rough structure resulting from Fe3O4 nanoparticles was pivotal in achieving superwetting ability towards water. The synergistic effect of hydrophilic chemical and rough structure significantly improved the superhydrophilicity and underwater superoleophobicity of the CF. The as-prepared fabric not only exhibited applicability for separating oil/water mixture, but also demonstrated exceptional performance in the separation of emulsions with relatively high water flux. The presence of numerous anionic groups was crucial in facilitating water flux during emulsions separation by screening electrostatic repulsion. Furthermore, benefiting from the self-glue effect of micro-dissolved CF, the as-prepared fabric exhibited remarkable stability against harsh conditions such as mechanical abrasion, immersion in acid or alkali solution, high temperature and frequent laundering. In general, this study would contribute to the development of fabric-based materials for oily wastewater separation with excellent separation performance and high stability.