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首页> 外文期刊>RSC Advances >Model system study of environmentally persistent free radicals formation in a semiconducting polymer modified copper clay system at ambient temperature
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Model system study of environmentally persistent free radicals formation in a semiconducting polymer modified copper clay system at ambient temperature

机译：环境温度下半导体聚合物改性铜粘土系统环境持久自由基形成的模型系统研究

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This paper systematically investigates how environmentally persistent free radicals (EPFRs) are formed in a phenol contaminated model soil. Poly-p-phenylene (PPP) modified and copper-loaded montmorillonite (MMT) clays were developed and used as models of soil organic matter and the clay mineral component, respectively, with phenol being employed as a precursor pollutant. The polymer modification of the clays was carried out via surface-confined Kumada catalyst-transfer chain-growth polymerization. The presence and location of the polymer were confirmed by a combination of thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray diffraction data. EPFRs were formed by the Cu(II)-clay (Cu(II) CaMMT) and poly-p-phenylene-Cu(II) clay (PPP-Cu(II) CaMMT) composite systems under environmentally relevant conditions. The g-factor and concentration of EPFRs formed by the Cu(II) CaMMT and PPP-Cu(II) CaMMT systems were found to be 2.0034 and 1.22 x 10(17) spins per g and 2.0033 and 1.58 x 10(17) spins per g, respectively. These g-factors are consistent with the formation of phenoxyl radicals. Extended X-ray absorption fine structure (EXAFS) analysis shows that there are distinct differences in the local structures of the phenoxyl radicals associated with only the Cu(II) redox centers and those formed in the presence of the PPP polymer. X-ray absorption near edge spectroscopy (XANES) results provided evidence for the reduction of Cu(II) to Cu(I) in the EPFR forming process. The 1/e lifetimes of the formed EPFRs revealed a decay time of similar to 20 h for the Cu(II) CaMMT system and a two-step decay pattern for the PPP-Cu(II) CaMMT system with decay times of similar to 13.5 h and similar to 55.6 h. Finally, the generation of reactive oxygen species (hydroxyl radical; (OH)-O-center dot) by these clay systems was also investigated, with higher concentrations of (OH)-O-center dot detected for the phenol-dosed Cu(II) CaMMT and PPP-Cu(II) CaMMT systems, compared to the non-EPFR containing undosed PPP-Cu(II) CaMMT system.
机译：本文系统地研究了酚污染的模型土中的环境持久自由基（EPFRS）。经过聚-P-亚苯基（PPP）改性和铜负载的蒙脱石（MMT）粘土，并分别用作土壤有机物质和粘土矿物组分的模型，用苯酚作为前体污染物。粘土的聚合物改性通过表面限制的熊猫催化剂转移链 - 生长聚合进行。通过热重分析（TGA），拉曼光谱和X射线衍射数据的组合来确认聚合物的存在和位置。通过Cu（II）-Clay（Cu（II）CAMMT）和聚-P-苯基-CU（II）粘土（PPP-CU（II）CAMMT）复合体系在环境相关条件下，通过EPFRS形成。 Cu（II）CAMMT和PPP-CU（II）CAMMT系统形成的G-FACTIO和浓度为2.0034和1.22×10（17）旋转，每G和2.0033和1.58 x 10（17）旋转每G分别。这些G族因子与苯氧基自由基的形成一致。扩展的X射线吸收细结构（EXAFS）分析表明，与仅在PPP聚合物存在下形成的Cu（II）氧化还原中心相关的苯氧基自由基的局部结构存在明显差异。边缘光谱（XANES）附近的X射线吸收结果提供了在EPFR成型过程中减少Cu（II）至Cu（I）的证据。所形成的EPFR的1 / E寿命揭示了用于Cu（II）CAMMT系统的20小时的衰减时间，以及用于PPP-Cu（II）CAMMT系统的两步衰减模式，衰减时间与13.5相似h和55.6小时。最后，还研究了这些粘土系统的反应性氧物质（羟基--O-中心点），对酚诱导的Cu检测（OH）-O-中心点浓度较高（OH）-O-中心点（II ）CAMMT和PPP-CU（II）CAMMT系统与包含未定的PPP-CU（II）CAMMT系统的非EPFR相比。

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