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 1 O 2 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 (C O, C O and O-C=O) were proposed as potential active sites on NBC700 and NBC800 for 1 O 2 generation via PMS activation. Differently, the highly sp 2 -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.
Jialong Zhou,Zhelun Xu,Shanshan Zhong,Youli Yu,Zhongyi Xu,Daolin Du,Congyan Wang
The allelopathy of alien plants is critical to their successful invasion. In nature, two alien plants can co-invade the same habitat. Changes in the forms of nitrogen may have the potential to alter the invasion process of alien plants by causing alterations in their allelopathy. This study aimed to evaluate the individual and combined allelopathy of two alien plants from theAsteraceaefamily,Solidago canadensisL. andConyza canadensis(L.) Cronq. This study examined the effects of aqueous leaf extracts of the two alien plants with different nitrogen forms (NO3−N, NH4−N, and CO(NH2)2−N, and the mixed nitrogen forms at a 1:1:1 ratio) on the seed germination and seedling growth of the horticulturalAsteraceaespeciesLactuca sativaL. using a germination bioassay. The allelopathy of the two alien plants significantly reduced the seed germination and seedling growth ofL. sativa. Extracts fromS. canadensisproduced stronger allelopathy on the seed germination and seedling growth ofL. sativacompared with those fromC. canadensis. The mixture of extracts from the two alien plants produced an antagonistic effect when compared with the effects of extracts from each plant species. The addition of nitrogen intensified the allelopathy of the two alien plants on the seed germination and seedling growth ofL. sativa. The degree of influence of nitrogen on the individual and combined allelopathy of the two alien plants was similar. Thus, nitrogen deposition may facilitate the independent invasion and co-invasion of the two alien plants via intensified allelopathy.Keywords:alien plant;allelochemicals;aqueous leaf extracts;nitrogen deposition;Lactuca sativaL.
危险品化学品经营许可证（带存储）