Wood-derived fiber/BiOBr/AgBr sponges by in situ synthesis for separation of emulsions and degradation of dyes

Abstract The removal of emulsified oil and organic dyes from wastewater is of extreme challenge owing to their difference of physical and chemical properties. Here we choose cellulose fibers derived from wood as supporting materials and the irregular flake-like BiOBr and sphere-like AgBr are in situ grown on the fibers via freeze-drying, which successfully create wood-derived fiber/BiOBr/AgBr (WFBA) sponge for wastewater treatment. The obtained WFBA sponge reveals favorable mechanical strength at a strain of 60% and 50 cycles of compression tests. In view of the superhydrophilicity and underwater superoleophobicity of WFBA sponge, it can be used for separating surfactant-stabilized kerosene-in-water emulsions with oil rejection ration higher than 99.91%, and simultaneously adsorbing organic dyes with removal efficiency >99.99%. Furthermore, the polluted WFBA sponge is capable of realizing dye degradation under Xe lamp, solar light and fluorescent lamp due to its enhanced photocatalytic activity. Thus, the regenerated sponge can take full advantage of functionalities of emulsion separation and dye adsorption, as presented by that the oil rejection ration still keeps as high as 98.23% and removal dye efficiency remained over 99.90% after five cycles of filtration. This study provides a feasible and scalable approach to engineer versatile materials for wastewater treatment.