The high chlorine (Cl) and lead (Pb) content characteristics of municipal solid waste incineration fly ash (MSWIFA) pose environmental risks and hinder resource utilization. Herein, an MSWIFA-based magnesium potassium phosphate cement (MKPC) preparation strategy was developed, which allowed the MSWIFA recycling and the Pb-Cl synergistic immobilization without the washing pretreatment. The compressive strength of the resulting 10 wt% MSWIFA-based MKPC was 28.44 MPa, with over 99.2% reduction in leaching toxicity of Pb and Cl. The high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) and X-ray absorption spectroscopy (XAS) analyzes showed that Pb, phosphate and Cl^- formed Pb₅(PO₄)₃Cl in MKPC. In-situ X-ray diffraction (XRD) tests showed that Pb₃(PO₄)₂ was gradually transformed to Pb₅(PO₄)₃Cl through a dissolution-precipitation process. The formation energy, Bader charge, charge density difference and density of states (DOS) of Pb₅(PO₄)₃Cl were analyzed by first-principles calculations, confirming that Pb₅(PO₄)₃Cl was more thermodynamically stable than Pb₃(PO₄)₂ and PbCl₂ and that electronic interactions between Pb-p, O-p, P-p and Cl-p orbits were the origin of Pb-Cl synergistic immobilization. This work provides a new strategy for the resource utilization of MSWIFA without washing pretreatment, and provides an in-depth understanding of the Pb-Cl synergistic immobilization mechanism.

城市生活垃圾焚烧飞灰 (MSWIFA) 的高氯 (Cl) 和铅 (Pb) 含量特征带来环境风险并阻碍资源利用。在此，开发了一种基于 MSWIFA 的磷酸镁钾水泥 (MKPC) 制备策略，该策略无需洗涤预处理即可实现 MSWIFA 回收和 Pb-Cl 协同固定。所得 10 wt% 基于 MSWIFA 的 MKPC 的抗压强度为 28.44 MPa，Pb 和 Cl 的浸出毒性降低了 99.2% 以上。大角度环形暗场扫描透射电子显微镜（HAADF-STEM）和X射线吸收光谱（XAS）分析表明，Pb、磷酸盐和Cl-^形成Pb ₅ (PO ₄ ) ₃MKPC 中的 Cl。原位X射线衍射(XRD)测试表明，Pb ₃ (PO ₄ ) ₂通过溶解-沉淀过程逐渐转变为Pb ₅ (PO ₄ ) _{3 Cl。通过第一性原理计算分析了Pb 5} (PO ₄ ) ₃ Cl的形成能、Bader电荷、电荷密度差和态密度(DOS) ，证实了Pb ₅ (PO ₄ ) ₃ Cl的热力学稳定性高于Pb ₃ (PO ₄ ) ₂和 PbCl ₂Pb-p、Op、Pp 和 Cl-p 轨道之间的电子相互作用是 Pb-Cl 协同固定的起源。该工作为MSWIFA的资源化利用提供了一种无需洗涤预处理的新策略，并提供了对Pb-Cl协同固定化机制的深入理解。