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In this study, biochars with different structures were prepared through HNO3 oxidation and secondary pyrolysis to study the relationship between the structure of biochar and its selectivity for the adsorption of light and heavy aromatics in bio‐oil. The results showed that the adsorption rates of biochar with different structures ranged from 2.90 to 4.00 g bio‐oil per g biochar. The influence of pore structure was dominant, followed by the influence of O‐containing functional groups and the degree of graphitization. The higher the adsorption capacity of biochar for bio‐oil, the smaller the concentrations of the light aromatic model compounds in the absorbed bio‐oil (ABO). Among the five light aromatics, biochar has the best adsorption selectivity for dihydroxybiphenyl and the worst for eugenol and propyl phenol. This is attributed to the diphenyl ring structure of dihydroxybiphenyl, which makes it more susceptible to adsorption, and other light model compounds only have one benzene ring. In summary, biochar demonstrates better adsorption selectivity for heavy aromatics than light aromatics. The more developed the pore structure is, the more enriched O‐containing functional groups are, and the higher the graphitization degree of biochar is, the better the selective adsorption of aromatic compounds in bio‐oil. [ABSTRACT FROM AUTHOR]

In this study, composites obtained through low-temperature carbonization of elastomeric matrix highly filled with graphite, carbon black and short carbon fibers were studied for the purpose of determining residual stresses at different scales using a combination of several complementary methods. The state-of-the-art techniques included X-ray stress analysis using the sin2 ψ method, the micro-ringcore technique via Focused Ion Beam milling and Digital Image Correlation (FIB-DIC), the contour method, the strain gauge method, and the hole drilling technique with digital laser speckle pattern interferometry (DLSPI). It was found that the contour method could not be used implemented for residual stress evaluation due to the low electrical conductivity of composite. Moreover, the DLSPI hole drilling method did not reveal any fringes indicating significant residual stress level exceeding a few MPa. The strain gauge method also revealed a narrow residual stress distribution with an average value of approximately zero. In contrast, the X-ray sin2 ψ method as well as FIB-DIC technique both returned values of about 150-250 MPa. A hierarchical model of the composite is proposed based on the Davidenkov Type I-II-III stress classification that provides an explanation of these observations. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene has been regarded as one of the most promising materials for nonradical peroxymonosulfate (PMS) activation. However, facile construction of nitrogen-doped graphene and systematic investigation of its nonradical PMS activation in a practical environment still far lag behind. Herein, graphitic N-rich graphene was prepared by one-step pyrolysis of urea. The obtained urea-derived graphitic N-rich graphene (UGNG) possessed a high N content of 12.12 at. % and a graphitic N proportion of 41.12%, giving a high graphitic N content of 4.98 at. %. We confirmed that PMS donated electrons to the graphitic N in UGNG, resulting in the cleavage of PMS to singlet oxygen for nonradical oxidation. The turnover frequency for the oxidation reached the highest value of 10.5 min–1. Also, the reaction could be conducted in a wide temperature (5–45 °C) range, even with the existence of common matrix species and different natural water matrixes. This work presented the direct conversion of N-rich organic urea to UGNG and systematically investigated its nonradical PMS activation, which is believed to be helpful to its further practical use. [ABSTRACT FROM AUTHOR]

Increasing the N-doping concentration has been recognized as one of the most effective strategies to improve the potential properties of carbonaceous materials in energy, the environment, and other fields. However, the instability of N dopants at high temperatures makes the N-doping concentration far from the theoretical upper limit. Herein, we prepared bamboo-like carbon nanotubes (BCNTs) with a theoretically upper-limited N-doping concentration via one-step pyrolysis of zinc cyanamide in the presence of Ni ions. The N-doping concentration of optimized BCNT-5 reached 12.45 atom %, approximate to the theoretical upper limit of 12.50 atom % at a carbonization temperature of 1000 °C. By using peroxymonosulfate-based advanced oxidation processes as an example, BCNT-5 exhibited excellent catalytic performance for nonradical tetracycline degradation with good versatility and adaptability. Graphitic N was demonstrated to be the active site for nonradical peroxymonosulfate activation. Our work provided a facile and effective strategy for ultrahigh N-doping and morphology regulation in carbonaceous materials toward different applications. [ABSTRACT FROM AUTHOR]