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Mechanism and Prediction of Cr and Zn Immobilization from Industrial Residues by Glass-Ceramics
ACS ES&T Engineering ( IF 7.4 ) Pub Date : 2021-07-14 , DOI: 10.1021/acsestengg.1c00152
Lina Liu 1 , Jing Dai 1 , Zhikun Zhang 2 , Shiyun Liu 3 , Yifei Sun 4
Affiliation  

Controllable preparation of a waste-derived glass-ceramics provides a promising and environmentally safe strategy for industrial residue recycling by immobilizing hazardous heavy metals in its amorphous-crystal multiphase structure. A modified two-step method was developed for treatment of Zn- and Cr-containing wastes to enhance the economic feasibility and reduce the risk of heavy metal evaporation. ZnO and Cr2O3 with various Zn or Cr contents (1, 5, and 10 wt %) were added after vitrifying the CaO(25 wt %)-Al2O3(20 wt %)-SiO2(55 wt %) system, followed by crystallization at 1000 and 1100 °C, respectively. Various qualitative and quantitative characterizations including TG-DSC, XRD, Rietveld refinement analysis of XRD patterns, XPS, and HRTEM were performed to demonstrate the immobilization mechanism of Zn and Cr species. Meanwhile, an artificial neural network (ANN) model was trained and optimized for simulation and prediction of heavy metal immobilization in glass-ceramics. The results demonstrated that the predicted results obtained from the well-trained ANN model fitted well with the experimental results. Both Zn and Cr were immobilized in glass-ceramics efficiently with immobilization efficiencies of 86.5–97.6% for Zn and 99.3–99.9% for Cr. Zn preferred to be immobilized in glass-ceramics by chemical stabilization. Around 50 wt % of Zn was incorporated in Ca2ZnSi2O7 crystals, while the rest was present in the glass matrix as dissolved Zn2+ ions. However, the most dominant immobilization mechanism of Cr was physical encapsulation, with 82 wt % of Cr embedded in the glass matrix of glass-ceramics as Cr2O3 crystals. The sensitive analysis suggests that the heavy metal content played the most important role, while crystallization temperature contributed the least for heavy metal immobilization. Among various inherent natures of heavy metals, the atomic radius was the most critical in determining immobilization efficiency of heavy metals. The results provide a comprehensive guidance for the preparation of heavy-metal-incorporated glass-ceramics and further enhancement of heavy metal immobilization effects.

中文翻译:

微晶玻璃固定工业废渣中铬锌的机理及预测

废物衍生微晶玻璃的可控制备通过将有害重金属固定在其非晶晶体多相结构中,为工业残留物回收提供了一种有前景且环境安全的策略。开发了一种改进的两步法处理含锌和铬的废物,以提高经济可行性并降低重金属蒸发的风险。在将 CaO(25 wt%)-Al 2 O 3 (20 wt%)-SiO 2玻璃化后加入具有不同 Zn 或 Cr 含量(1、5 和 10 wt%)的ZnO 和 Cr 2 O 3(55 wt %) 体系,然后分别在 1000 和 1100 °C 下结晶。进行了各种定性和定量表征,包括 TG-DSC、XRD、XRD 图案的 Rietveld 精修分析、XPS 和 HRTEM,以证明 Zn 和 Cr 物质的固定机制。同时,对人工神经网络(ANN)模型进行了训练和优化,以模拟和预测微晶玻璃中重金属的固定化。结果表明,从训练有素的人工神经网络模型获得的预测结果与实验结果非常吻合。Zn 和 Cr 都被有效地固定在微晶玻璃中,Zn 的固定效率为 86.5-97.6%,Cr 的固定效率为 99.3-99.9%。Zn 更倾向于通过化学稳定性固定在微晶玻璃中。大约 50 wt% 的 Zn 被掺入到 Ca 中2 ZnSi 2 O 7晶体,而其余的作为溶解的Zn 2+离子存在于玻璃基质中。然而,Cr最主要的固定机制是物理包封,82wt%的Cr以Cr 2 O 3 的形式嵌入微晶玻璃的玻璃基质中。晶体。敏感性分析表明,重金属含量起最重要的作用,而结晶温度对重金属的固定作用最小。在重金属的各种固有性质中,原子半径是决定重金属固定效率的最关键因素。研究结果为制备掺重金属微晶玻璃和进一步提高重金属固定化效果提供了综合指导。
更新日期:2021-09-10
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