In this study, an adsorbent made of alginate (Alg) caged magnesium sulfide nanoparticles (MgS) microbeads were used to treat lead ions (Pb2+ ions). The MgS nanoparticles were synthesized at low temperatures, and Alg@MgS hydrogel microbeads were made by the ion exchange process of the composite materials. The newly fabricated Alg@MgS was characterized by XRD, SEM, and FT-IR. The adsorption conditions were optimized for the maximum removal of Pb2+ ions by adjusting several physicochemical parameters, including pH, initial concentration of lead ions, Alg/MgS dosage, reaction temperature, equilibration time, and the presence of co-ions. This is accomplished by removing the maximum amount of Pb2+ ions. Moreover, the adsorbent utilized more than six times with a substantial amount (not less than 60%) of Pb2+ ions was eliminated. Considering the ability of sodium alginate (SA) for excellent metal chelation and controlled nanosized pore structure, the adsorption equilibrium of Alg@MgS can be reached in 60 min, and the highest adsorption capacity for Pb2+ was 84.7 mg/g. The sorption mechanism was explored by employing several isotherms. It was found that the Freundlich model fits the adsorption process quite accurately. The pseudo-second-order model adequately described the adsorption kinetics.
Keywords: Adsorption equilibrium; Alginate microbeads; Kinetic; Lead removal; Magnesium sulfide nanoparticles.
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