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• Self-floating adsorbents can reach surface solid-liquid separation spontaneously. • The two-step synthesis process of SFA is simple and efficient. • Single-layer grafting allows the adsorption to reach equilibrium within 10 min. • Concentrate low concentration dyes to industrially usable levels by desorb method. In the case of a sharp increase in the price of dyes, the dyes concentration of in wastewater is important for environmental protection and industrial costs reduction. In this study, we grafted single-layer amino groups onto the surface of the hollow glass microspheres by a two-step simple synthesis, and the anionic dyes adsorption process reaches equilibrium within 10 min. The as-synthesized adsorbent has self-floating ability to achieve high-efficiency surface solid-liquid separation with water. SEM, EDS, S BET , FT-IR, XPS, TGA characterizations results demonstrated the successful grafting of amino groups and the important role of the pretreatment process in the two-step synthesis. The results of adsorption isotherms and kinetics show the adsorption process belongs to single-layer adsorption with equal adsorption sites, and the adsorption capacities for acid orange 7 and amaranth reach 428.99 mg g−1 and 145.62 mg g−1, respectively. Regeneration of the adsorbent and concentration of the dye solutions can be achieved by dispersing the separated adsorbent in alkaline solution, the maximum concentrated concentration of acid orange 7 and amaranth was 6321.57 mg L−1 and 2431.84 mg L−1, respectively. This study provides new insights for the solid-liquid separation of water treatment agents and the resource regenerating of dyeing wastewater. [ABSTRACT FROM AUTHOR]