A carboxyl group abundant Typha angustifolia biomass material was prepared using SOCl2 activated EDTA as a modification reagent and employed as an adsorbent for Pb removal from aqueous solution. The following conclusions can be drawn:
(1) The EDTA can be effectively grafted to the biomass matrix using SOCl2 as an activating reagent in moderate conditions, and the carboxyl group content of the biomass sharply increases from 0.297 to 0.833 mmol g−1 after modification.
(2) The CMTAB shows an excellent performance for Pb adsorption and its maximum adsorption capacity calculated from Langmuir model is 263.9 mg g−1.
(3) The Pb adsorption by CMTAB can reach the equilibrium within 20 min, and the kinetic data are well described by pseudosecond-order model with the correlation coefficient (R2) more than 0.99, confirming that the chemical sorption is the ratelimiting step in the adsorption process.
(4) The adsorption is a highly pH dependant process and pH 5.0 is the optimum pH for Pb adsorption onto CMTAB. According to the XPS analysis, the adsorption mechanism of CMTAB involves Na Pb ion-exchange and carboxyl group dominated surface complexation.