royalsocietypublishing.org/journal/rsos Research Cite this article: Al-Hetlani E, Amin MO, Bezzu CG, Carta M. 2020 Spirobifluorene-based polymers of intrinsic microporosity for the adsorption of methylene blue from wastewater: effect of surfactants. R. Soc. Open Sci. 7: 200741. http://dx.doi.org/10.1098/rsos.200741 Received: 11 May 2020 Accepted: 13 August 2020 Subject Category: Chemistry Subject Areas: environmental chemistry/materials science/ organic chemistry Keywords: polymers of intrinsic microporosity, spirobifluorene- based polymers of intrinsic microporosity, methylene blue, surfactants, water treatment Authors for correspondence: Entesar Al-Hetlani e-mail: entesar.alhetlani@ku.edu.kw Mariolino Carta e-mail: mariolino.carta@swansea.ac.uk This article has been edited by the Royal Society of Chemistry, including the commissioning, peer review process and editorial aspects up to the point of acceptance. Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c. 5104326. Spirobifluorene-based polymers of intrinsic microporosity for the adsorption of methylene blue from wastewater: effect of surfactants Entesar Al-Hetlani 1 , Mohamed O. Amin 1 , C. Grazia Bezzu 2 and Mariolino Carta 3 1 Department of Chemistry, Faculty of Science, Kuwait University, PO Box 5969, 13060 Safat, Kuwait 2 School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK 3 Department of Chemistry, College of Science, Swansea University, Grove Building, Singleton Park, Swansea SA2 8PP, UK Owing to their high surface area and superior adsorption properties, spirobifluorene polymers of intrinsic microporosity (PIMs), namely PIM-SBF-Me (methyl) and PIM-SBF-tBu (tert- butyl), were used for the first time, to our knowledge, for the removal of methylene blue (MB) dye from wastewater. Spirobifluorene PIMs are known to have large surface area (can be up to 1100 m 2 g -1 ) and have been previously used mainly for gas storage applications. Dispersion of the polymers in aqueous solution was challenging owing to their extreme hydrophobic nature leading to poor adsorption efficiency of MB. For this reason, cationic (cetyl-pyridinium chloride), anionic (sodium dodecyl sulfate; SDS) and non-ionic (Brij-35) surfactants were used 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 were investigated. All surfactants offered a homogeneous dispersion of the polymers in the aqueous dye solution; however, the highest adsorption efficiency was obtained using an anionic surfactant (SDS) and this seems owing to the predominance of electrostatic interaction between its molecules and the positively charges dye molecules. Furthermore, the effect of polymer dosage and initial dye concentration on MB adsorption were also considered. The kinetic data for both polymers were well described by a pseudo-second-order © 2020 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.