Xing Cao,Qiushi Zhang,Weichen Yang,Lin Fang,Shiwei Liu,Rui Ma,Kai Guo,Ning Ma
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 Pb 5 (PO 4 ) 3 Cl in MKPC. In-situ X-ray diffraction (XRD) tests showed that Pb 3 (PO 4 ) 2 was gradually transformed to Pb 5 (PO 4 ) 3 Cl through a dissolution-precipitation process. The formation energy, Bader charge, charge density difference and density of states (DOS) of Pb 5 (PO 4 ) 3 Cl were analyzed by first-principles calculations, confirming that Pb 5 (PO 4 ) 3 Cl was more thermodynamically stable than Pb 3 (PO 4 ) 2 and PbCl 2 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.
This study presented the synthesis of phosphorus (P) and chlorine (Cl) co-doped carbon quantum dots (P/Cl-CQDs) derived from Epimedium brevicornu Maxim. and established a simple and effective chemiluminescence (CL) system for detecting Sulfacetamide (STM) and Sulfadimethoxine Sodium Salt (STX). Employing traditional Chinese medicine Epimedium brevicornu Maxim. as a green precursor material, (NH 4 ) 2 HPO 4 and NH 4 Cl were utilized as dopants for P and Cl, respectively. The P/Cl-CQDs was synthesized through a one-step hydrothermal method exhibited excellent CL properties, effectively catalyzing the luminol system and markedly amplifying its CL intensity. Both STM and STX were observed to inhibit the CL intensity of the luminol-(P/Cl-CQDs) system. Based on this, a novel CL method combining flow injection technique was established for the detection of STM and STX. Under optimal conditions, the method demonstrated the capability to detect STM in the range of 1–400 × 10 −6 mol/L, with a limit of detection (LOD) of 0.34 × 10 −6 mol/L and a relative standard deviation (RSD) of 1.29 %, and STX within the range of 5–280 × 10 −6 mol/L, with a LOD of 0.16 × 10 −6 mol/L and an RSD of 1.23 %. This method successfully determined the content of STM and STX in pork, with spike recoveries ranging from 100.0 % to 103.8 % for STM and from 98.0 % to 102.3 % for STX.
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