Comparison of the Sorption of Cu(II) and Pb(II) by Bleached and Activated Biochars: Insight into Complexation and Cation–π Interaction

Attention has been paid to the application of biochar in remediation heavy metal contamination soils. In this study, two modification methods, bleaching and activation, were used enhance sorption Cu(II) Pb(II). Multiple techniques, including XPS, FTIR 13C NMR, applied investigate properties bleached activated biochars. Combined with density functional theory (DFT) calculations, structural changes biochars main mechanism Pb(II) discussed after modification. The without non-condensed aromatic C possessed many oxygen-containing groups due oxidation. contrast, activation increased specific surface area (SSA) removed carboxyl groups. Both modifications had an excellent effect on by high-temperature biochars, especially treatment. exhibited superior compared larger electron cloud configuration significantly positive correlation Kd values COOH/C=O content indicated that responsible for sorption. DFT calculation demonstrated a higher energy cation–π interaction than complexation sorption, whereas opposite case was observed mechanisms This study provides important guidance modified metals environment.