Shi Jiaqi, Li Yan, Wei Qi, Zhu Xin, Cao Shaohua, Xie Wenyi, Guo Yang, Wei Jing, Li Zekai, Long Tao
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Nanjing 210042, China.
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Nanjing 210042, China; College of Agricultural Science and Engineering, Hohai University, Nanjing 210098, China.
Environ Int. 2025 Apr;198:109438. doi: 10.1016/j.envint.2025.109438. Epub 2025 Apr 4.
The widely used rubber antioxidant N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and its ozonated product, 6PPD-quinone (6PPD-Q), are highly toxic to aquatic life, yet understanding on their environmental behaviors is limited. This study comprehensively investigated their adsorption and transformation processes on natural Fe-Mn nodules (NFMN), which commonly exist in sediments and soils through a combination of diverse experimental and computational methods. The maximum adsorption capacity of 6PPD-Q (719.2 μg·g) is significantly higher than that of 6PPD (133.8 μg·g) at 293 K, and it is more difficult to desorb. They follow different kinetic and isothermal adsorption models, and environmental conditions (including temperature, pH, and anions) exert distinct influences on the adsorption of the two substances. Adsorption mechanisms involving electrostatic attraction, charge transfer, hydrogen bonding, and Lewis acid-base complexation were unveiled. For 6PPD, electrostatic adsorption and Lewis acid-base complexation contribute significantly to its adsorption. Conversely, for 6PPD-Q, the contribution of Lewis acid-base complexation outweighs that of hydrogen bonding, while the effect of electrostatic adsorption is relatively negligible. The stronger electrostatic attraction, more efficient charge transfer, and a greater number of binding sites for hydrogen bonding and Lewis acid-base complexation with NFMN results in more robust adsorption of 6PPD-Q. Furthermore, 6PPD can transform into 6PPD-Q on NFMN, facilitated by dissolved Mn(III). This study advances understanding of the adsorption behavior and mechanism of 6PPD and 6PPD-Q, and highlights a new pathway for 6PPD-Q formation, which provides valuable reference for assessing the water body exposure risks and formulating environmental remediation strategies for such pollutants. ENVIRONMENTAL IMPLICATION: This study offers the first comprehensive insight into the interactions between 6PPD/6PPD-Q and NFMN, illuminating their environmental behavior in water and soil systems. It reveals the adsorption discrepancy between 6PPD and 6PPD-Q, and elucidates the mechanisms underlying the difference in adsorption. Additionally, it uncovers a novel pathway for 6PPD-Q formation, offering valuable implications for risk assessment and environmental remediation strategies.
广泛使用的橡胶抗氧化剂N-(1,3-二甲基丁基)-N'-苯基对苯二胺(6PPD)及其臭氧化产物6PPD-醌(6PPD-Q)对水生生物具有高毒性，然而对它们环境行为的了解有限。本研究通过多种实验和计算方法相结合，全面研究了它们在天然铁锰结核(NFMN)上的吸附和转化过程，天然铁锰结核通常存在于沉积物和土壤中。在293K时，6PPD-Q的最大吸附容量(719.2μg·g)显著高于6PPD(133.8μg·g)，且更难解吸。它们遵循不同的动力学和等温吸附模型，环境条件(包括温度、pH值和阴离子)对这两种物质的吸附有不同影响。揭示了涉及静电吸引、电荷转移、氢键和路易斯酸碱络合的吸附机制。对于6PPD，静电吸附和路易斯酸碱络合对其吸附有显著贡献。相反，对于6PPD-Q，路易斯酸碱络合的贡献超过氢键，而静电吸附的影响相对可以忽略不计。更强的静电吸引、更有效的电荷转移以及与NFMN形成氢键和路易斯酸碱络合的更多结合位点导致6PPD-Q的吸附更强。此外，在溶解的Mn(III)的促进下，6PPD可以在NFMN上转化为6PPD-Q。本研究推进了对6PPD和6PPD-Q吸附行为及机制的理解，并突出了6PPD-Q形成的新途径，为评估水体暴露风险和制定此类污染物的环境修复策略提供了有价值的参考。环境意义：本研究首次全面深入了解了6PPD/6PPD-Q与NFMN之间的相互作用，阐明了它们在水和土壤系统中的环境行为。揭示了6PPD和6PPD-Q之间的吸附差异，并阐明了吸附差异背后的机制。此外，还发现了6PPD-Q形成的新途径，对风险评估和环境修复策略具有重要意义。
