Novel dual modified alkali lignin based adsorbent for the removal of Pb2+ in water

• The high adsorption capacity adsorbent was prepared by dual modified alkali lignin. • The adsorption of modified lignin is electrostatic attraction and complexation. • The modified lignin has good selectivity for Pb 2+ . • The maximum adsorption capacity of modified lignin for Pb 2+ could reach 208.3 mg/g. In the present study, a dual - modified lignin (DML) adsorbent, which exhibits a high adsorption capacity for Pb 2+ , was prepared through the reaction of alkaline lignin with ClCH 2 COOH and CS 2 . The main objective of the present was to prepare a biomass-based adsorbent that is suitable for scavenging heavy metals from wastewater. The DML was characterized using Fourier transform-infrared Spectroscopy (FT-IR), Elemental Analysis, Conductivity titration , Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The results show that carboxyl and ‒CSS‒ components are introduced into the DML, and the corresponding concentrations were 1.3 mmol/g and 30.5 %, yielding an adsorbent with a specific surface area of 3.13 m 2 /g. The rough aggregated porous structure of the DML enhances the adsorption of Pb 2+ . An adsorption experiments reveal that the Pb 2+ adsorption by the DML is adequately represented by a pseudo - second-order kinetic equation, and these produced a maximum Pb 2+ adsorption capacity of 208.3 mg/g. XPS (X-ray photoelectron spectroscopy) results demonstrates that complexation and electrostatic attraction constitute the Pb 2+ adsorption mechanisms associated with the DML. The adsorbent produced in the present study is valuable for protecting water quality and the environment, and provides another avenue for the utilization of lignin.