Hierarchical Porous Bimetallic FeMn Metal-Organic Framework Gel for Efficient Activation of Peracetic Acid in Antibiotic Degradation.

Effective techniques for eliminating antibiotics from water environments are in high demand. The peracetic acid (PAA)-based advanced oxidation process has recently drawn increasing attention for its effective antibiotic degrading capability. However, current applications of PAA-based techniques are limited and tend to have unsatisfactory performance. An additional catalyst for PAA activation could provide a promising solution to improve the performance of PAA. Bulky metal-organic framework gels (MOGs) stand out as ideal catalysts for PAA activation owing to their multiple advantages, including large surface areas, high porosity, and hierarchical pore systems. Herein, a bimetallic hierarchical porous structure, i.e., FeMn13BTC, was synthesized through a facile one-pot synthesis method and employed for PAA activation in ofloxacin (OFX) degradation. The optimized FeMn MOG/PAA system exhibited efficient catalytic performance, characterized by 81.85% OFX degradation achieved within 1 h owing to the specific hierarchical structure and synergistic effect between Fe and Mn ions, which greatly exceeded the performance of the only PAA-catalyzed system. Furthermore, the FeMn MOG/PAA system maintained >80% OFX degradation in natural water. Quenching experiments, electron spin resonance spectra, and model molecular degradation revealed that the primary reactive oxygen species responsible for the catalytic effect was R-O•, especially CH3C(=O)OO•, with minor contributions of •OH and 1O2. Overall, introduction of the MOG catalyst strategy for PAA activation achieved high antibiotic degradation performance, establishing a paradigm for the design of heterogeneous hierarchical systems to broaden the scope of catalyzed water treatment applications.

Combined conditioning of inorganic coagulant and polyamine to improve the dewaterability of municipal sludge, minimize dosage and reduce the influence of filtrate.

Efficient dewatering of sludge is necessary for its cost-effective transportation and final disposal. However, the common method of using polyferric sulfate (PFS) and polyacrylamide (PAM) requires a large amount of dosage and produces high iron ion content in the filtrate. This study examined a solution of applying polyamine (PA) coupled with inorganic coagulant PFS. The results demonstrated that using PFS + PA together could achieve the same or similar filtering rates as using PFS + PAM. The capillary suction time (CST) of PFS + PA (89.0 s) was equivalent to that of PFS (75.1 s) and better than that of PA (117.1 s) and raw sludge (RS, 403.8 s). Compared with PFS + PAM, the combination of PFS and PA efficiently removed Fe ions and chemical oxygen demand (COD) in sludge water content, with Fe ions in the sludge filtrate reduced by 97.8% and COD reduced by 78.9%, respectively. By analyzing the basic physicochemical properties of the sludge system, including the synergistic effect of coagulation and flocculation, sludge hydrolysis and flocculation, it indicated that PA + PFS could reduce bound water. These results demonstrated that combining PFS and PA to improve sludge dewatering performance is more beneficial than utilizing a coagulant or flocculant alone, even PFS + PAM.

Hierarchical porous melamine sponge@MIL-101-Fe-NH2 composite as Fenton-like catalyst for efficient and rapid tetracycline hydrochloride removal.

Metal-organic frameworks have been investigated in Fenton-like catalysis for tetracycline hydrochloride degradation, a widely used antibiotic which threatens the growth and health of creatures. However, powder phase and absence of large pores limit the materials' degradation performance and application. In this work, a hierarchical macro-meso-microporous composite melamine sponge@MIL-101-Fe-NH2 was firstly designed and constructed. While the micropores provided plenty of active sites to generate reactive oxygen species, the macropores and mesopores accelerated mass transfer. Besides, MIL-101-Fe-NH2 particles dispersed on melamine sponge individually, exposing more catalytic sites and avoiding inactivation caused by aggregation compared to powder catalysts. Its catalysis performance for tetracycline hydrochloride degradation was evaluated through changing various influence factors like H2O2 concentration, catalyst amount, pH and coexisting ions. Different from the preference of homogenous Fenton catalysts for pH 2-4, the composite displayed the most effective degradation at a subacid environment closer to nature with 77.24% in 30 min. Owing to the synergistic effect of hierarchical porous structure and monodispersed nanoparticles, the composite exhibited faster reaction rate and longer persistence compared to powder MIL-101-Fe-NH2. Easy recycling and less ion leaching made it advantages for practical application. •OH, •O2- and 1O2 active species contributed together to the degradation and two main possible degradation pathways were put forward based on 35 detected intermediates.

Facile Synthesis of Indium Sulfide/Flexible Electrospun Carbon Nanofiber for Enhanced Photocatalytic Efficiency and Its Application.

Heterojunction system has been proved as one of the best architectures for photocatalyst owing to extending specific surface area, expanding spectral response range, and increasing photoinduced charges generation, separation, and transmission, which can provide better light absorption range and higher reaction site. In this paper, Indium Sulfide/Flexible Electrospun Carbon Nanofiber (In2S3/CNF) heterogeneous systems were synthesized by a facile one-pot hydrothermal method. The results from characterizations of SEM, TEM, XRD, Raman, and UV-visible diffuse reflectance spectroscopy displayed that flower-like In2S3 was deposited on the hair-like CNF template, forming a one-dimensional nanofibrous network heterojunction photocatalyst. And the newly prepared In2S3/CNF photocatalysts exhibit greatly enhanced photocatalytic activity compared to pure In2S3. In addition, the formation mechanism of the one-dimensional heterojunction In2S3/CNF photocatalyst is discussed and a promising approach to degrade Rhodamine B (RB) in the photocatalytic process is processed.