Adsorption behavior and mechanism of Pb(II) and complex Cu(II) species by biowaste-derived char with amino functionalization.

This work aimed to develop a feasible technology to reuse dead pig biowaste for heavy metals removal, which was first carbonized into pig bone char (PBC) after pyrolysis and further functionalized with amino (NH2) to improve its affinity with heavy metals. The application of PBC after NH2-functionalization for aqueous heavy metals removal was explored, including Pb2+, Cu2+, and different complex Cu(II) species. PBC@SiO2-NH2 showed comparable performance with AC@SiO2-NH2. The adsorption capacity of Pb2+ and Cu2+ by PBC@SiO2-NH2 was 120 and 30 mg g-1, respectively. The NH2 functionalization enhanced the adsorption of complex Cu(II) species, and PBC@SiO2-NH2 exhibited good performance under a wide pH range and coexisting ions. The adsorption of Cu(II)EDTA species with an EDTA/Cu(II) molar ratio of 1.0 by PBC would be enhanced ~3 times and ~6 times after NH2 functionalization and further addition of Fe3+, respectively. The results of EDX, elemental mapping, and XPS confirmed the adsorption of Cu(II) species. The adsorption kinetics, isotherm, and thermodynamics of different Cu(II) species by PBC@SiO2-NH2 were investigated. The regeneration of PBC@SiO2-NH2 was easily performed via acidic wash. These results suggested the application potential of the reuse of biowaste, which could be a promising adsorbent for aqueous heavy metals after specific functionalization.