Amidation modified hollow composite microspheres as a self-floating adsorbent for efficient capture of anionic dye DB86 and heavy metal nickel (II)

The co-contamination of dyes and heavy metal ions often used as mordants poses potential risks to environment and public health, and is a challenging problem that needs to be solved in water treatment. Meanwhile, improving the solid–liquid separation capability of adsorbents is of great significance for the application of adsorption technology. Herein, amidation modified hollow composite microspheres were prepared using hollow glass microsphere (HGM) as matrix through hydrolysis and condensation of silane coupling agent (A-1100) and subsequent amidation reaction. The material (HGMNE) not only exhibited good adsorption performance for DB86 and Ni 2+ but also had stable self-floating capability. The adsorption of DB86 by HGMNE is mainly carried out by the electrostatic interaction between positively charged quaternary amine nitrogen and negatively charged DB86, while the adsorption of Ni 2+ is achieved by the carboxyl group in EDTA group through complexation interaction to adsorb Ni 2+ to form Ni complex. This research not only is devoted to the utilization of HGMNE to achieve the co-removal of DB86 and Ni 2+ and flexible self-floating solid–liquid separation but also verifies the feasibility and applicability of the modification method of introducing organic adsorption functional groups through amidation reaction, so as to expand the preparation path of HGM-based adsorbents. Graphical abstract