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With the rapidly increased discharges of various complex dyeing wastewaters, adsorbents are required to own more properties such as cost-effectiveness, amphoteric ability, and rapid solid-liquid separation ability, to treat dyeing wastewaters. A multi-functional adsorbent was synthesized by co-grafting m-phenylenediamine and sodium allyl sulfonate on the surface of a low-cost base-material: hollow glass microsphere (HGM). Characterization results indicated the surface roughness and –Si–OH groups of HGM were increased by NaOH corrosion; functional groups such as aromatic-rings, –NH 2 , and –HSO 3 − were grafted on the surface of HGM. The synthesized adsorbent showed amphoteric attraction abilities for anionic acid green 25 and cationic basic fuchsin dyes. Kinetics and isotherms studies suggested the PSO model and Langmuir model were most satisfactory for adsorption processes, the theoretical maximum adsorption capacities for acid green 25 and basic fuchsin reached 454.55 and 588.24 mg g−1, respectively. The mechanism investigations indicated the electrostatic attraction, π-π stacking, and hydrogen bonds were the potential interaction forces between dyes and adsorbents. The synthesized material owns self-floating ability due to the hollow structure of HGM, over 95.7% of adsorbents were collected at water surface via the self-floating process in 12 min, which was beneficial to the solid-liquid separation process and the reuse of adsorbents. The technologies developed by these research efforts can serve as templates for synthesizing multi-functional adsorbents for complex wastewaters decontaminations. [Display omitted] • First demonstration of an amphoteric self-floating adsorbent. • The adsorption capacities of anionic/cationic dyes reached 454.55/588.24 mg g−1. • Electrostatic force, π-π stacking, hydrogen bond were dominant adsorption mechanisms. • Over 95.7% of adsorbents were collected at the water surface within 12 min. • The multi-functional adsorbent is beneficial for cleaner production of dyeing goods. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesized adsorbents captured 94.18 mg g−1 of Co2+ and 62.56 mg g−1 of Ni2+. • <1% of lithium was lost in the cathode leachate during the separation process. • The dominant capture mechanism conversed from physical to chemical adsorption. • The N atoms on the adsorbents were the effective chemical adsorption sites. • Particle movement track in water was predictable via the proposed equation. The effectiveness of lithium recovery determines the future use of the devices powered by lithium-ion batteries (LIBs) under lithium resource shortages. Selective separation of Co2+/Ni2+ from the cathode leachate of LIBs is a key step to reduce the lithium loss in the recovery progress. This study reported a hollow structured self-floating adsorbent synthesized by co-grafting of (3-Aminopropyl)triethoxysilane (APTES) and ethylenediaminetetraacetic acid (EDTA) on hollow glass microsphere (HGM) for selective capture of Co2+/Ni2+ from LIBs cathode leachate. The introduction of the N atom of APTES was crucial for bridging the inorganic HGM and organic EDTA. The organic component of the synthesized adsorbent accounted for 12.82%, which was responsible for the Co2+/Ni2+ adsorptions. Physic- and chemic-adsorptions were the ordinal mechanisms during the three-stages divided adsorption progress. The negative –COO− groups promoted the electrostatic attraction between metal ions and the adsorbents. The N atoms of EDTA were the effective adsorption sites for Co2+ and Ni2+ ions, resulting in chemical chelation of the metal ions with adsorbents followed by ion exchanges of Na+ and Ca2+. The adsorbents captured 94.18 mg g−1 of Co2+ and 62.56 mg g−1 of Ni2+ with a < 1% lithium loss in the LIBs cathode leachate. The self-flotation process of the adsorbent was non-linearly fitted by our original equation for predicting its movement track for further solid–liquid separation. This research proposed a new strategy for the selective adsorption of Co2+/Ni2+ from LIBs cathode leachate with limited lithium loss. [ABSTRACT FROM AUTHOR]