Characterization and adsorption properties of cross-linked yeast/β-cyclodextrin polymers for Pb(ii) and Cd(ii) adsorption

Abstract

In this study, a crosslinked yeast/β-cyclodextrin polymer (Y–β-CDP), for use as an effective adsorbent for removal Pb(II) and Cd(II) ions from aqueous solution, has been innovatively prepared by grafting β-cyclodextrin (β-CD) onto the surface of baker's yeast (BY) and thiomalic acid as a crosslinker. Several characterization techniques, such as SEM equipped with an EDS analyzer, FTIR, XRD, and XPS were employed characterize the Y–β-CDP. The impact of various operating parameters, such as pH, adsorbent dosage, initial concentration of metal ions, contact time and solution temperature, as well as adsorption kinetics, isotherms and thermodynamics were systematically investigated. The adsorption of Pb(II) and Cd(II) on Y–β-CDP reached equilibrium in 25 min, and the kinetic process conforms to the pseudo-second order model. The Langmuir model was used to describe the adsorption isotherm data better than the Freundlich model. The predicted maximum adsorption capacity at 25 °C for Pb(II) and Cd(II) was 150.08 and 102.80 mg g⁻¹, respectively, when the initial concentration of metal ions was 120 mg L⁻¹. The thermodynamic analysis revealed that the adsorption procedure of Pb(II) and Cd(II) onto Y–β-CDP was spontaneous and endothermic. Furthermore, regeneration experiments demonstrated that Y–β-CDP had excellent recyclability. Together, all results suggested that Y–β-CDP could potentially be a promising adsorbent in the purification of water contaminated with heavy metal ions.