Adsorption of lead (Pb) from aqueous solution with Typha angustifolia biomass modified by SOCl2 activated EDTA

A chemically modified Typha angustifolia biomass (CMTAB) material with abundant carboxyl groups was prepared using thionyl chloride (SOCl2) activated ethylenediaminetetraacetic acid (EDTA) as a modification reagent. The CMTAB was characterized by back titration, elemental analysis, FTIR and SEM. The results show that EDTA is effectively grafted to the biomass matrix and the carboxyl group content of the biomass sharply increases almost 3 times after chemical modification. A series of adsorption experiments were carried out using CMTAB as an adsorbent. The adsorption equilibrium can be reached within 20 min and the kinetic data are fitted well to the pseudo-second-order model with a correlation coefficient (R2) of 0.998. The CMTAB exhibits a favorable performance for Pb adsorption and its maximum adsorption capacity calculated by Langmuir model is 263.9 mg g−1. The chemical states of the elements involved in the adsorption were analyzed by X-ray photoelectron spectroscopy (XPS). The results demonstrate that the adsorption mechanism of CMTAB involves NaPb ion-exchange and carboxyl group dominated surface complexation.