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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]

Environmentally friendly magnetic sodium alginate beads with glutaraldehyde cross-linking catalyzed by acetic acid-hydrochloric acid were successfully designed (FSSi@SA), and the magnetic bio-sorbents after amide reaction (FSSi@SA-sula) were utilized to absorb fluoroquinolone antibiotics in water. After amidation, FSSi@SA-sula exhibited strong pH adaptability (pH = 6.0–12.0). Langmuir and pseudo-first-order models can better describe the isotherm and kinetic process well, respectively. Under the optimization conditions with pH = 7 and temperature of 318.15 K, the maximum adsorption capacities of FSSi@SA-sula on the third-generation FQs ciprofloxacin (CIP) and the fourth-generation FQs moxifloxacin (MOX) respectively reached 365.66 and 149.57 mg g−1. The thermodynamics research indicated that the as-prepared FSSi@SA-sula is spontaneous and feasible. And after five adsorption cycles, the loss of adsorption capacity was less than 20% for both CIP and MOX, demonstrating the fine reusability and stability of the designed magnetic bio-sorbent. This study provides some ideas for facile synthesis of acid-catalyzed sodium alginate-glutaraldehyde cross-linking, which has promising applications in grafting various types of groups onto the retained carboxyl groups of sodium alginate spheres for the various contaminants removal in wastewater. [Display omitted] • FSSi@SA-sula beads were prepared by acid-catalyzed glutaraldehyde cross-linking. • FSSi@SA-sula showed excellent adsorption and reusability for CIP and MOX. • Langmuir and pseudo-first-order models better fitted adsorption process. • The mechanisms include electrostatic interactions, hydrogen bonding and n-π EDA. • Provided new ideas for facile synthesis of functional sodium alginate adsorbents. [ABSTRACT FROM AUTHOR]

The selective separation and recovery of valuable metals from complex polluted wastewater is of great significance to the protection of water resources and the realization of resource recycling. Herein, the chitosan-coated magnetic silica core-shell nanoparticles (FO@SD@CS) were fabricated and applied as adsorbents for highly selective removal of precious metals silver ions (Ag(I)) from complex wastewater. In multi-ion compound polluted solutions, FO@SD@CS showed excellent selective adsorption of Ag(I) in a wide pH range, and an enhancement of the highly selective adsorption capacity of Ag(I), which was increased from 85.86 to 126.74 mg g−1 when the concentrations of methyl blue (MB) coexisted in the solution from 0 to 40 mg L−1 at pH 6.0. The results of Ag(I) single system batch adsorption experiments illustrated that the adsorption behavior of FO@SD@CS to Ag(I) shows obvious pH responsiveness, the adsorption capacity of Ag(I) increases with the increasing of pH value. The results of the adsorption isotherm and kinetics demonstrated that Langmuir and pseudo-second-order kinetics can better describe the adsorption behavior of Ag(I) on FO@SD@CS, indicating that the adsorption process was controlled by chemisorption and the maximum monolayer adsorption capacity reached 116.28 mg g−1 at room temperature. Additionally, in the dye-metal binary system, the coexisting MB promoted the adsorption capacity of FO@SD@CS to Ag(I) from 116.28 to 156.25 mg g−1, showing a synergistic adsorption effect. This study shows that the enhanced selective separation and recovery of metal ions from wastewater based on anion-synergistic not only provides new ideas for wastewater treatment, but also has important significance for water resources reuse. [Display omitted] • A magnetic adsorbent with core-shell structure was successfully prepared. • FO@SD@CS exhibited higher acid resistance than uncoated silica adsorbent. • FO@SD@CS showed high selectivity in capturing silver from multi-ion solutions. • Coexisting MB enhanced the selective adsorption of Ag(I) in complex wastewater. • Possible adsorption mechanisms in both single and binary systems were proposed. [ABSTRACT FROM AUTHOR]