Robust superhydrophilic/underwater superoleophobic cotton fabric decorated by β-FeOOH and PVA with excellent oil-water separation and photodegradation properties

The oils and organic dyes in wastewater have caused serious damage to the environment, thus, it is very urgent to develop a multifunctional wastewater treatment material by a simple and environment-friendly method. Herein, a layer of polyvinyl alcohol (PVA)-Fe3+-citric acid (CA) crosslinked structure combined with β-FeOOH particles was firmly anchored on a cotton fabric (CF) through a simple dip-coating and in-situ mineralization method to obtain a robust multifunctional superhydrophilic/underwater superoleophobic CF (β-FeOOH/PVA/Fe-CA-CF). β-FeOOH/PVA/Fe-CA-CF could separate different immiscible oil/water mixtures with a separation efficiency of exceeding 98.26% and high flux of 25,347 L/m2·h only by gravity, especially, it also could separate oil-in-water emulsions with a separation efficiency up to 94.07%. Moreover, β-FeOOH/PVA/Fe-CA-CF displayed an outstanding photocatalytic degradation capacity to organic dyes and the removal efficiency of methylene blue (MB) could reach 98.5% in 20 min. Meanwhile, the modified CF exhibited satisfactory chemical stability, high temperature and abrasion resistance. More importantly, β-FeOOH/PVA/Fe-CA-CF possessed excellent reusability, whose separation efficiency for petroleum ether/water mixture could reach 96.5% after 20 cycles and removal efficiency of MB was still up to 89% after 12 cycles. Therefore, this work provides a facile strategy for the design of multifunctional biodegradable wastewater treatment materials with high durability.