Zheng Cheng,Can Chen,Jieyang Huang,Teng Chen,Yang Liu,Xiangyang Liu
The nondestructive functionalization of aramid fiber is an important research direction. In this study, a kind of benzimidazole-contained aramid fiber, Poly- p -phenylene-benzimidazole-terephthalamide (PBIA) fiber, was modified by the coordination of benzimidazole unit in fiber structure with Fe 3+ . Further, the coordinatively unsaturated sites of Fe 3+ endow the modified fiber with active sites for the grafting of PEI. Model compound of PBIA unit, PBA, was utilized to confirm the whole process of modification. In comparison with that of the untreated fiber, the IFSS value of fiber with PEI grafted has an increase by 47%, owing to the chemical bond formed on the fiber/epoxy interface and the better wettability of resin to fiber. In all, the study presents a nondestructive functionalization of aramid fiber and can be employed in the modification of other benzimidazole-contained substrates.
Traditional homogeneous Fenton systems face limitations, including a narrow pH range, potential secondary pollution, and poor repeatability. In this study, these bottlenecks in tetracycline wastewater treatment were addressed with using carbonized porous polyethyleneimine-grafted lignin microspheres (PLMs) supported Fe-loading catalysts (PLMs/Fe-C). An optimized PLMs/Fe-C catalyst under specific conditions (carbonization temperature: 350 °C, PLMs: Fe = 1:1, and alkali lignin: PEI = 1:4) was developed, which proved to be an efficient Fenton-like catalyst for tetracycline (TC) degradation. TC degradation results showed that the PLMs/Fe-C + H 2 O 2 system achieved a high removal efficiency of 100 % within 150 min (50 mL TC with an initial concentration of 50 mg/L, 0.015 g catalyst, 0.5 mL H 2 O 2 ), demonstrating its applicability over a wide pH range (3−10) and the capability to remove multiple pollutants (2,4-D, BPA, Lev, etc.). This efficiency was attributed to the stronger electron-donating ability and mass transfer properties derived from the porous structure and functional groups. Arrhenius fitting analysis revealed a lower activation energy (E = 52.98 kJ/mol) for the PLMs/Fe-C, indicating a more accessible reaction. Additionally, the removal efficiency marginally decreased from 100 % to 98.32 % after five cycles, demonstrating excellent reusability. Mechanistic investigations indicated that the PLMs/Fe-C can activate H 2 O 2 to produce reactive oxygen species •OH, 1 O 2 , effectively degrading TC.
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