Aminated biochar for efficient co-removal of Cd(II) and 2,4-dichlorophenol: Performance, mechanisms, and application in water-soil systems

Composite pollution arising from the coexistence of heavy metals and organic compounds in environmental systems is becoming increasingly prevalent. However, the marked differences in physicochemical properties between these two categories of pollutants render conventional materials inadequate for their simultaneous and efficient removal. In this study, a novel aminated biochar (NBC) was synthesized using water hyacinth as feedstock and triethylenetetramine as the modifying agent to achieve concurrent removal of Cd(II) and 2,4-dichlorophenol (2,4-DCP). The results demonstrate that NBC achieves removal efficiencies of 94.6% for Cd(II) and 92.8% for 2,4-DCP. Compared with pristine biochar, NBC exhibits a rougher surface, an enlarged specific surface area, and abundant –NH 2 and –CH 2 – functional groups. Mechanistic investigations reveal that the –NH 2 groups are capable of forming coordination bonds with Cd(II), while simultaneously engaging in N–H···O hydrogen bonding with the phenolic hydroxyl groups of 2,4-DCP. The –CH 2 – crosslinked framework confers excellent structural stability, as evidenced by sustained removal efficiencies of 80.34% and 75.67% for the two pollutants after eight regeneration cycles. Moreover, the 2,4-DCP adsorbed on the material surface can act as a π-electron donor, establishing cation–π interactions with free Cd(II) in solution, which further enhances the overall removal performance. This study offers a viable strategy for the simultaneous remediation of heavy metals and organic pollutants in complex environmental matrices. Download: Download high-res image (202KB) Download: Download full-size image