Rapid and efficient removal of Pb(II) from aqueous solutions using biomass-derived activated carbon with humic acid in-situ modification

•Humic acid (HA) was used as a modifying agent for activated carbon preparation.•Oxygen-containing functional groups on the surfaces of the prepared activated carbon was enhanced.•The prepared activated carbon was exhibited rapid and efficient performance of Pb(II) removal from aqueous solutions.•The adsorption mechanisms of Pb(II) were investigated by XPS study.

This study developed an humic acid (HA) in-situ modified activated carbon adsorbent (AC-HA) for the rapid and efficient removal of Pb(II) from aqueous media, and adsorption mechanisms are discussed. The physicochemical characteristics of activated carbons (AC) were investigated via N2 adsorption/desorption, scanning electron microscopy (SEM), Boehm's titration method and Fourier transform infrared spectroscopy (FTIR). AC-HA exhibited richer oxygen-containing functional groups than the original AC. In addition, the removal performance of AC-HA (250.0 mg/g) toward Pb(II) was greatly improved compared with the original AC (166.7 mg/g). The batch adsorption study results revealed that the Pb(II) adsorption data were best fit by the pseudo-second-order model of kinetics and Langmuir isotherm of isothermals, and therefore, the effect of the solution pH was studied. The superior performance of AC-HA was attributed to the HA modification, which contains numbers of groups and has a strong π-π interaction binding energy with AC and Pb(II) species. The adsorption mechanisms were confirmed via the XPS study. More importantly, the modified method is simple and has a low cost of production.

Graphic abstractDownload high-res image (383KB)Download full-size image