Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Zhejiang Ecological Civilization Academy, Anji, Zhejiang 313300, China; The Key Laboratory of Organic Pollution Process and Control, Zhejiang Province, Hangzhou, Zhejiang 310058, China.
Sci Total Environ. 2022 Apr 10;816:151502. doi: 10.1016/j.scitotenv.2021.151502. Epub 2021 Nov 6.
To scrutinize the crucial role of carbon configuration and nitrogen speciation in peroxymonsulfate (PMS) activation, nitrogen-doped biochars (NBCs) were prepared at different pyrolysis temperatures (700, 800 and 900 °C) and named NBC700, NBC800 and NBC900, respectively. Nitrogen doping introduced many nitrogen-containing groups into NBCs and the carbon configuration and nitrogen speciation of NBCs were regularly changed by the pyrolysis temperature. Compared to the phenol (PN) removal in the pristine biochar (BC)/PMS system that mainly depended on adsorption, NBCs showed excellent PMS activation activity for efficient PN degradation and the PMS activation activity was highly dependent on the carbon configuration and nitrogen speciation of NBCs. Furthermore, the PMS activation pathways of NBCs were unveiled to convert O to electron transfer with increasing pyrolysis temperature, which was ascribed to the variation of active sites on NBCs caused by the regular changes in carbon configuration and nitrogen speciation. Pyridinic N and oxygen groups (CO, CO and O-C=O) were proposed as potential active sites on NBC700 and NBC800 for O generation via PMS activation. Differently, the highly sp-hybridized carbon skeleton and graphitic N of NBC900 played an important role in the electron transfer pathway by acting as a carbon bridge to accelerate electron transfer from PN to PMS. This study provides new insight into the effects of carbon configuration and nitrogen speciation on PMS activation mechanism of NBCs and identifies opportunities for the subsequent catalyst design in a specific degradation pathway.
为了深入研究碳构型和氮形态在过一硫酸盐（PMS）活化中的关键作用，我们在不同的热解温度（700、800 和 900°C）下制备了氮掺杂生物炭（NBC），并分别将其命名为 NBC700、NBC800 和 NBC900。氮掺杂使 NBC 中引入了许多含氮基团，并且 NBC 的碳构型和氮形态随热解温度而发生规律性变化。与原始生物炭（BC）/PMS 体系中主要依靠吸附作用去除苯酚（PN）相比，NBC 对 PMS 具有优异的活化活性，可实现高效 PN 降解，且 PMS 的活化活性高度依赖于 NBC 的碳构型和氮形态。此外，我们揭示了 NBC 的 PMS 活化途径，即随热解温度升高，O 向电子转移的转化，这归因于 NBC 上活性位点因碳构型和氮形态的规律性变化而发生变化。吡啶 N 和含氧基团（CO、CO 和 O-C=O）被认为是 NBC700 和 NBC800 通过 PMS 活化生成 O 的潜在活性位点。相比之下，NBC900 中高度 sp 杂化的碳骨架和石墨 N 通过充当碳桥来加速 PN 向 PMS 的电子转移，在电子转移途径中起着重要作用。本研究深入了解了碳构型和氮形态对 NBC 活化机制的影响，并为特定降解途径中后续催化剂设计提供了新的思路。
