<br>热解碳质促进 2,4-二硝基苯甲醚 (DNAN) 水解的实验和计算研究,Environmental Science & Technology

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热解碳质促进 2,4-二硝基苯甲醚 (DNAN) 水解的实验和计算研究
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2024-05-13 , DOI: 10.1021/acs.est.4c01069
Nourin I Seenthia ₁ , Eric J Bylaska ₂ , Joseph J Pignatello ₃ , Paul G Tratnyek ₄ , Samuel A Beal ₅ , Wenqing Xu ₁

Affiliation

本研究研究了 2,4-二硝基苯甲醚 (DNAN) 在热解碳质物质 (PCM) 上的反应途径，以评估 PCM 促进的表面水解的范围和机制。使用模型 PCM（石墨）在 pH 11.5 和 25 °C 下观察到 DNAN 降解，而没有石墨则没有发生明显的降解。实验在 pH 11.5 下进行，因为 pH 值低于 11.0 时 DNAN 没有衰减，这与之前的研究一致。通过将 DNAN 水解的活化能降低 54.3 ± 3.9%，石墨在 65 °C 和 pH 11.5 条件下相对于均质溶液表现出 1.78 倍的 DNAN 分解增强。我们使用从头算分子动力学/分子力学 (AIMD/MM) 进行的 Car-Parrinello 模拟和 DFT 自由能模拟进行的计算建模结果支持了这一点，这表明 PCM 有效地将反应势垒降低了约 8 kcal mol ^–1与均质溶液相比。季铵 (QA) 改性活性炭在多种 PCM 中表现最好，在 pH 11.5 和 25 °C 下将 DNAN 半衰期从 185 天缩短至 2.5 天，同时在连续 10 次添加 DNAN 后仍保持其反应性。我们认为，PCM 可以通过将反应物质限制在 PCM 表面附近来影响水解反应的热力学和动力学，从而使溶剂分子不易接近它们，并创造一个介电常数较弱、有利于亲核取代反应的环境。 DNAN 衰变过程中亚硝酸盐的形成证实了脱硝途径，而去甲基化是均质溶液中的首选途径，会产生 2,4-二硝基苯酚 (DNP)。 PCM催化的脱硝有利于去甲基化，因为亚硝酸盐的毒性比DNAN和DNP小。这些发现为反应性吸附剂设计提供了重要的见解，对催化剂设计和污染物减排具有广泛的影响。

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Experimental and Computational Study of Pyrogenic Carbonaceous Matter Facilitated Hydrolysis of 2,4-Dinitroanisole (DNAN)

This study investigated the reaction pathway of 2,4-dinitroanisole (DNAN) on the pyrogenic carbonaceous matter (PCM) to assess the scope and mechanism of PCM-facilitated surface hydrolysis. DNAN degradation was observed at pH 11.5 and 25 °C with a model PCM, graphite, whereas no significant decay occurred without graphite. Experiments were performed at pH 11.5 due to the lack of DNAN decay at pH below 11.0, which was consistent with previous studies. Graphite exhibited a 1.78-fold enhancement toward DNAN decay at 65 °C and pH 11.5 relative to homogeneous solution by lowering the activation energy for DNAN hydrolysis by 54.3 ± 3.9%. This is supported by our results from the computational modeling using Car–Parrinello simulations by ab initio molecular dynamics/molecular mechanics (AIMD/MM) and DFT free energy simulations, which suggest that PCM effectively lowered the reaction barriers by approximately 8 kcal mol^–1 compared to a homogeneous solution. Quaternary ammonium (QA)-modified activated carbon performed the best among several PCMs by reducing DNAN half-life from 185 to 2.5 days at pH 11.5 and 25 °C while maintaining its reactivity over 10 consecutive additions of DNAN. We propose that PCM can affect the thermodynamics and kinetics of hydrolysis reactions by confining the reaction species near PCM surfaces, thus making them less accessible to solvent molecules and creating an environment with a weaker dielectric constant that favors nucleophilic substitution reactions. Nitrite formation during DNAN decay confirmed a denitration pathway, whereas demethylation, the preferred pathway in homogeneous solution, produces 2,4-dinitrophenol (DNP). Denitration catalyzed by PCM is advantageous to demethylation because nitrite is less toxic than DNAN and DNP. These findings provide critical insights for reactive adsorbent design that has broad implications for catalyst design and pollutant abatement.

更新日期：2024-05-13

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