Preparation and characterization of sulfonated poly(styrene-alt-maleic anhydride) and its selective removal of cationic dyes

Sulfonated poly(styrene-alt-maleic anhydride) (SSMA) microspheres were prepared from poly(styrene-alt-maleic anhydride) (SMA) by sulfonation reaction and its adsorption behavior as an efficient adsorbent for the removal of organic dyes was systematically studied. The structure and morphology of SMA and SSMA were characterized by 13 C NMR, FTIR, EDS, XPS, SEM and TEM. The adsorption performance of SMA and SSMA toward organic dyes was investigated by batch mode adsorption experiments. Results indicated that the SSMA had much more adsorbability for cationic dyes such as methylene blue (MB) and Rhodamine B (RhB) compared to SMA. The adsorption capacity for MB of SSMA 8h which had been sulfonated 8   h was found to be 671.14   mg/g, while the adsorption capacity of SMA for MB was 344.83   mg/g at 25   °C, showing that the adsorption capacity for cationic dyes was enhanced 94.63% via the sulfonation. The kinetic studies revealed that the sorption followed a pseudo-second-order kinetic model which indicated that the adsorption interaction between adsorbent and adsorbate molecules was chemisorption. Moreover, adsorption isotherm mechanisms were analyzed by Freundlich and Langmuir models.