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

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.