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

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 Pb 2+ 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 Δ H °, Δ S ° and Δ G ° were also calculated from graphical interpretation of the experimental data. Negative values of Δ G ° indicate the adsorption process of Pb 2+ by LXR is spontaneous. The positive value of Δ H ° 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.