Geopolymers have been widely applied to pretreat Pb-containing solid wastes due to low carbon footprint and superior stabilization/solidification (S/S) performance. However, the wastes may be exposed to rainwater or water flow during long-term landfill, leading to the decalcification of internal geopolymer structure. Here, the influence of decalcification on the S/S performance of Pb-containing geopolymers was investigated through combined inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD), differential Thermogravimetry (DTG), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and mercury intrusion porosimeter (MIP) tests. Results show that decalcification can increase the cumulative leaching concentration of Pb and degrade the S/S performance of geopolymers due to the release of [Pb(OH)₄]^2- ions from the end-of-chain silicates of calcium aluminosilicate hydrates and the dissolution of Pb(OH)₂ precipitates. A leaching model further indicates that surface wash off, i.e., the dissolution of Pb(OH)₂ precipitates from the surface, is the main factor controlling degradation. In addition, for evaluating potential hazards of Pb leakage, electrochemical impedance spectroscopy (EIS) test was proposed to precisely predict the cumulative leaching concentration of Pb. Overall, this study is an innovative attempt to reveal the changes of the S/S characteristics of geopolymers under decalcification and track the leaching behaviors of Pb in landfill sites.

由于低碳足迹和出色的稳定化/固化（S / S）性能，地质聚合物已被广泛应用于含铅固体废物的预处理。但是，在长期填埋过程中，废物可能会暴露在雨水或水流中，从而导致内部地质聚合物结构脱钙。在这里，通过组合电感耦合等离子体质谱法（ICP-MS），X射线衍射（XRD），差示热重分析（DTG），X射线光电子，研究了脱钙对含铅地质聚合物S / S性能的影响。光谱（XPS），核磁共振（NMR）和压汞法（MIP）测试。结果表明，由于[Pb（OH）的释放，脱钙会增加Pb的累积浸出浓度并降低地聚合物的S / S性能。₄ ] ^2-离子来自铝硅酸钙水合物的链端硅酸盐，Pb（OH）₂的溶解沉淀。浸出模型进一步表明表面冲刷，即Pb（OH）₂从表面沉淀出来的溶解，是控制降解的主要因素。此外，为了评估铅泄漏的潜在危害，提出了电化学阻抗谱（EIS）测试来精确预测铅的累积浸出浓度。总体而言，这项研究是一项创新性的尝试，旨在揭示脱钙作用下地聚合物的S / S特性的变化，并跟踪填埋场中Pb的浸出行为。