Eco-friendly poly(dopamine)-modified glass microspheres as a novel self-floating adsorbent for enhanced adsorption of tetracycline

Abstract

Hollow glass microspheres (HGM), as a promising hollow spherical ultra-light material, have the advantages of uniform particle size, regular shape, high mechanical strength and stable physical and chemical properties. It has been widely utilized in many fields but its application in water treatment is yet to be developed. Herein, a novel self-floating composite adsorbent was obtained by forming a poly(dopamine) (PDA) biomass coating on the surface of HGM and introducing sulfonic acid groups. The hollow composite material (HGM@PDA-SO3H) was utilized in the adsorptive elimination of tetracycline (TC) from aqueous solutions. In addition to great adsorption performance, HGM@PDA-SO3H also exhibited satisfactory self-floating solid-liquid separation capability. Langmuir, pseudo second-order and Elovich models correlate isotherms and kinetic data relatively well, respectively. The theoretical saturated TC adsorption amount of HGM@PDA-SO3H evaluated by Langmuir model reached 333.70 mg g−1. Thermodynamic analysis confirmed the spontaneous exothermic property of the adsorption process. There was no serious decline in the adsorption of TC by the material after 5 adsorption cycles, and the adsorbent saturated with contaminants could be easily regenerated via solution desorption, reflecting its satisfactory renewability and stability. Based on the results of batch experiments and characterization analysis, it could be concluded that the corresponding adsorption mechanisms mainly involve electrostatic attraction, hydrogen bonding and π-π stacking interactions. This research aimed to decorate HGM with biomaterials and apply it in the adsorptive purification of TC-contaminated water, which brought some insights and inspiration for the environmental application of HGM, and proved its potential applicability.