Spirobifluorene-based polymers of intrinsic microporosity for the adsorption of methylene blue from wastewater: effect of surfactants

Owing to their high surface area and superior adsorption properties, spirobifluorene PIMs namely, PIM-SBF-Me (methyl) and PIM-SBF-tBu (tert-butyl) were used for the first time for the removal of methylene blue (MB) dye from wastewater. Spirobifluorene PIMs are known to have large surface area (can be up to 1100 m2/g) and have been previously used mainly for gas storage applications. Dispersion of the polymers in aqueous solution was challenging due to their extreme hydrophobic nature leading to poor adsorption efficiency of MB. For this reason, cationic (CPC), anionic (SDS) and nonionic (Brij-35) surfactants were utilized and tested with the aim of enhancing the dispersion of the hydrophobic polymers in water and hence improving the adsorption efficiencies of the polymers. The effect of surfactant type and concentration was investigated. All surfactants offered a homogenous dispersion of the polymers in the aqueous dye solution, however, the highest adsorption efficiency was obtained us...