Hydrazone-linked COFs with N/O synergistic sites achieving ultrahigh and fast Pd(II) capture under acidic conditions.

作者：Yumei Luo, Kaiyu Xia, Yuancheng Qin, Cailing Ni, Chao Liu, Hewei Yan, Renjie Song, Jian-Ping Zou · 发表于：Journal of Hazardous Materials · 年份：2026 · DOI：10.1016/j.jhazmat.2026.141362 · 被引用次数：16 · 研究领域：Medicine

The selective adsorption of palladium (Pd) from acidic wastewater is of great importance for sustainable resource utilization and environmental remediation. Herein, covalent organic frameworks (COFs) employing hydrazide-containing amine monomers as linkage units are successfully synthesized. At pH= 1, the pyridyl-functionalized COF (BTHN) exhibited a record-high Pd(II) adsorption capacity of 898.09 mg g-1, achieving 96.3 % removal of Pd(II) ions within 30 min at an initial concentration of 100 mg L-1. Meanwhile, both COFs (BTHN and BTHO) demonstrated remarkable recyclability and selectivity, maintaining over 94 % removal efficiency after five adsorption-desorption cycles and achieving nearly 100 % Pd(Ⅱ) removal even in the presence of 16 coexisting competitive ions. Notably, BTHN showed a high dynamic adsorption capacity (443.69 mg g-1) under continuous-flow conditions and enabled efficient Pd(II) recovery from real spent catalyst leachates, highlighting its practical applicability. XPS and DFT analyses revealed that the outstanding performance originates from a coordination-enriched pore microenvironment, where locally concentrated and spatially proximate N/O donor sites enable synergistic coordination with Pd(II) ions, together with favorable electrostatic interactions. This study highlights the potential of hydrazone-linked COFs as efficient and regenerable adsorbents for noble metal recovery under strongly acidic conditions.