Dual Positive Effects of Pre-Dechlorine and Low-Temperature Deep Reduction-Keeping on the PCDD/F Removal of Incineration Fly Ash

IF 7.4 Q1 ENGINEERING, ENVIRONMENTAL ACS ES&T engineering Pub Date : 2024-07-23 DOI:10.1021/acsestengg.4c00239

Chenqi Gao, Yang Yue, Wenying Li, Qing Zhang, Lingen Zhang, Guangren Qian

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Abstract

Low-temperature thermal degradation of PCDD/Fs in incineration fly ash (IFA) has attracted widespread attention with the advantages of low energy consumption and high efficiency. However, in the process of industrialization, the inevitable O₂ leakage in the system has always been a technical bottleneck. Based on the characteristics of IFA and the mechanism of PCDD/F regeneration, this study first proposes a dual-strategy LTTD of predechlorination and reduction atmosphere-keeping. Predechlorination removes soluble chlorine and soluble metals while hydrolyzing CaClOH in IFA into Ca(OH)₂ to accelerate the detoxication of PCDD/Fs, and deep reduction atmosphere-keeping is created by introducing activated carbon to inhibit the possible PCDD/F regeneration. Compared with typical LTTD, synergistic application of dual-strategy LTTD can obtain 99.4 and 97.4% detoxification efficiencies of PCDD/Fs in the presence of 1 and 2% O₂, respectively. Based on the identification of congener distribution and density functional theory calculations, the dechlorination mechanism of acid chloride group-containing PCDD/F intermediates with the participation of CO and Ca(OH)₂ was proposed. Finally, the reproducibility of dual-strategy LTTD after optimization of working parameters was well verified and the proposed dual strategies are expected to provide a new direction for the industrialization of LTTD.

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预脱氯法和低温深度还原法对焚烧飞灰去除多氯二苯并对二恶英和多氯二苯并呋喃的双重积极影响

低温热降解焚烧飞灰（IFA）中的多氯二苯并对二恶英和多氯二苯并呋喃（PCDD/Fs）具有能耗低、效率高等优点，已引起广泛关注。然而，在产业化过程中，系统中不可避免的 O2 泄漏一直是技术瓶颈。根据 IFA 的特点和 PCDD/F 的再生机理，本研究首先提出了预脱氯和还原气氛保持的双策略 LTTD。预脱氯法在去除可溶性氯和可溶性金属的同时，将 IFA 中的 CaClOH 水解为 Ca(OH)2 以加速多氯二苯并对二恶英和多氯二苯并呋喃的解毒；而深度还原气氛保持法则是通过引入活性炭来抑制多氯二苯并对二恶英和多氯二苯并呋喃可能的再生。与典型的 LTTD 相比，双策略 LTTD 的协同应用可在 1% 和 2%O2 存在下分别获得 99.4% 和 97.4% 的多氯二苯并对二恶英/多氯二苯并呋喃解毒效率。在同系物分布鉴定和密度泛函理论计算的基础上，提出了CO和Ca(OH)2参与的含酸氯基PCDD/F中间体的脱氯机理。最后，在优化工作参数后，双策略 LTTD 的重现性得到了很好的验证，所提出的双策略有望为 LTTD 的产业化提供一个新的方向。

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ACS ES&T engineering ENGINEERING, ENVIRONMENTAL-

CiteScore

8.50

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0.00%

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期刊介绍： ACS ES&T Engineering publishes impactful research and review articles across all realms of environmental technology and engineering, employing a rigorous peer-review process. As a specialized journal, it aims to provide an international platform for research and innovation, inviting contributions on materials technologies, processes, data analytics, and engineering systems that can effectively manage, protect, and remediate air, water, and soil quality, as well as treat wastes and recover resources. The journal encourages research that supports informed decision-making within complex engineered systems and is grounded in mechanistic science and analytics, describing intricate environmental engineering systems. It considers papers presenting novel advancements, spanning from laboratory discovery to field-based application. However, case or demonstration studies lacking significant scientific advancements and technological innovations are not within its scope. Contributions containing experimental and/or theoretical methods, rooted in engineering principles and integrated with knowledge from other disciplines, are welcomed.