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Lead-chlorine synergistic immobilization mechanism in municipal solid waste incineration fly ash (MSWIFA)-based magnesium potassium phosphate cement
Journal of Hazardous Materials ( IF 12.2 ) Pub Date : 2022-09-20 , DOI: 10.1016/j.jhazmat.2022.130038
Xing Cao 1 , Qiushi Zhang 1 , Weichen Yang 1 , Lin Fang 1 , Shiwei Liu 1 , Rui Ma 1 , Kai Guo 1 , Ning Ma 2
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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.



中文翻译:

生活垃圾焚烧飞灰(MSWIFA)基磷酸镁钾水泥的铅-氯协同固定机理

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。

更新日期:2022-09-24
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