Aiming to improve the flame retardancy efficiency and rheological properties of hydroxides commonly used in asphalt, a combined flame retardant was fabricated using aluminium hydroxide (ATH), halloysite nanotube (HNT) and ferrocene. The optimal loading of flame retardant and process parameters for asphalt preparation were determined through an orthogonal experimental design. Through microscopic observation, the combined flame retardant was evenly dispersed within the asphalt matrix, with minimal agglomeration and segregation. Asphalt containing the combined flame retardant achieved an improved limiting oxygen index (LOI) value of 28.1 %, accompanied by a 30.9 % and 41.2 % reduction in peak of heat release rate (PHRR) and peak of smoke production rate (PSPR) compared to conventional Styrene-Butadiene-Styrene (SBS) modified asphalt used in asphalt pavement. In-depth mechanism analysis revealed that the formation of high-quality charring layers was facilitated by the catalytic reaction of ferrocene and catalytic oxidation of gases produced during asphalt combustion. Moreover, the improved network crosslinking function in asphalt significantly enhanced the rheological properties observed in the dynamic shear rheometer (DSR) and multiple stress creep recovery (MSCR) tests. Prospectively, this study provides an effective approach for simultaneously achieving prominent fire safety and enhanced rheological properties of asphalt through a simple preparation method.
Two colorimetric and fluorescent probes based on ferrocene derivatives have been designed and synthesized. Among studied anions (F − , AcO − , H 2 PO 4 − , Cl − , Br − and I − ), probe 1 with p -nitrophenyl hydrazine structure has the strongest binding ability for F − , as well as probe 2 for H 2 PO 4 − . It had strong binding ability and was not affected by other anions. The determination limit of 1 toward F − was 5.0×10 −6 mol⋅L −1 which can be used for the trace detection of F − . The interacted process of host–guest accompanied by colorimetric changes and increment in fluorescent intensity of the probes. A 1 H-NMR titration experiment and theoretical investigation indicated that −NH in hydrazine participated in the interaction, and the hydrogen-bonding formed between the probes and anions. These results provided an essential clue to the developing the colorimetric probe based on hydrazine participation.
Rongxiu Tu,Yujun Wang,Jinyun Peng,Chuantao Hou,Zonghua Wang
The application of porphyrin metal–organic frameworks (MOFs) as a ratiometric electrochemical sensing platform is still unexplored. In this paper, we report a ratiometric electrochemical sensor by the integration of multiple redox centers into porphyrin MOFs for the detection of dissolved oxygen (DO). Specifically, the ferrocene (Fc) group was integrated into the nanosized PCN-222(Fe) (PCN = porous coordination networks) via acid–base reaction to synthesize the Fc@PCN-222(Fe) composite with two redox centers of the Fc group and Fe-porphyrin. The Fc group that is insensitive to DO serves as an internal reference, and the Fe-porphyrin in PCN-222(Fe) is a DO indicator. The ratios of the cathodic currents for the two redox centers exhibit a linear relationship with DO concentrations from 2.8 to 28.9 mg mL–1 and a limit of detection of 0.3 mg mL–1. In addition, the ratiometric electrochemical sensor has high selectivity and stability for DO sensing results from the Fc@PCN-222(Fe) composite. Because there are numerous redox centers, such as methylene blue and thionine, which can be integrated into MOFs, many MOF-based ratiometric electrochemical sensors can be simply developed for high-performance biosensing.
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