Rigid-flexible coupled polyphosphazene supported polyurethane foam for efficient and selective adsorption of anionic dyes from water

We proposed a feasible strategy to prepare a rigid-flexible coupled polyphosphazene supported polyurethane foam (PUF-PCP) adsorbent by in situ polycondensation between hexachlorocyclotriphosphazene and polyethyleneimine on the surface of polyurethane foam (PUF) at room temperature . Owing to combination of the open cell porous structure of PUF support and the superior adsorption capacity of PCP coatings, the PUF-PCP composite adsorbent exhibited good adsorption behavior towards anionic dyes. Especially, the experimental adsorption capacity of PUF-PCP for methyl orange (MO) dye was up to 978.56 mg g −1 at 25 ºC. The relative separation factors of MO for methylene blue , crystal violet and rhodamine B were 224.1, 78.1 and 161.8 respectively, exhibiting an excellent adsorption selectivity of PUF-PCP towards MO. Moreover, the used PUF-PCP adsorbent can be easily collected and regenerated. The adsorption test data were best explained by Langmuir model and pseudo-second-order model. The adsorption process of MO onto PUF-PCP was spontaneous and endothermic. XPS and FT-IR analysis confirmed that electrostatic adsorption and hydrogen bonding were the plausible uptake mechanism of PUF-PCP for MO molecules. The present work demonstrated that PUF-PCP has promising potential in removing environmental anionic pollutants from waterbody.