Synthesis of porous lignin xanthate resin for Pb2+ removal from aqueous solution

• A lignin xanthate resin (LXR) was newly synthesized by a two-step method.
• This method is easy for large-scale production.
• The LXR contains an order porous structure (dp < 100 nm).
• The LXR showed a 4.8 times higher adsorption capacity than alkaline lignin.
• The adsorption of Pb2+ by LXR is spontaneous and endothermic.

A new lignin xanthate resin (LXR) was synthesized by a two-step reaction from alkaline lignin and carbon disulfide. It was characterized by FT-IR, SEM and element analysis. An ordered porous structure is observed on LXR. Batch adsorption including equilibrium isotherms, kinetics, and the effects of pH, dosage and temperature on the adsorption of Pb2+ by LXR were systematically studied. LXR shows a 4.8 times higher adsorption capacity than alkaline lignin at 30 °C that is attributed to the incorporation of xanthate groups and porous structure. Thermodynamic parameters, involving ΔH°, ΔS° and ΔG° were also calculated from graphical interpretation of the experimental data. Negative values of ΔG° indicate the adsorption process of Pb2+ by LXR is spontaneous. The positive value of ΔH° confirms the endothermic adsorption in nature. The high adsorption capacity of LXR, together with its feasible preparation, biocompatibility and environmentally friendliness, open new perspectives in the potential use for wastewater treatment.

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