A novel magnetic adsorbent based on waste litchi peels for removing Pb(II) from aqueous solution

• A novel magnetic adsorbent was synthesized with litchi peels and Fe3O4.
• The preparation and characterization of the magnetic litchi peel were introduced.
• The application of the magnetic litchi peel for Pb(II) removal was presented.
• The magnetic bio-adsorbent can be separated rapidly from the mixed solutions.

A new magnetic bioadsorbent, magnetic litchi peel (MLP), was synthesized by coating powdered litchi peel with Fe3O4, and was used for removing Pb(II) from aqueous solutions. The influencing factors, adsorption isotherms, kinetics, and thermodynamics of Pb(II) adsorption by MLP were investigated using batch assays. Optimum Pb(II) adsorption by MLP was achieved using a contact time of 120 min, an adsorbent dose of 5 g/L, and pH of 6.0. The adsorption equilibrium data conformed to the Langmuir isotherm model, yielding a maximum Pb(II) adsorption capacity of 78.74 mg/g. The adsorption kinetics for Pb(II) adsorption by MLP followed a pseudo-second-order model. The thermodynamic results suggested that Pb(II) adsorption by MLP was spontaneous and exothermic. Additionally, the magnetic adsorbent was easily and rapidly separated out of solution under an external magnetic field.

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