The removal of low-concentration antibiotics from water to alleviate the potential threat of antibiotic-resistant bacteria and genes calls for the development of advanced treatment technologies with high efficiency. In this study, a novel graphene modified electro-Fenton (e-Fenton) catalytic membrane (EFCM) was fabricated for in situ degradation of low-concentration antibiotic florfenicol. The removal efficiency was 90%, much higher than that of electrochemical filtration (50%) and single filtration process (27%). This demonstrated that EFCM acted not only as a cathode for e-Fenton oxidation process in a continuous mode but also as a membrane barrier to concentrate and enhance the mass transfer of florfenicol, which increased its oxidation chances. The removal rate of florfenicol by EFCM was much higher (10.2 ± 0.1 mg m h) than single filtration (2.5 ± 0.1 mg m h) or batch e-Fenton processes (4.3 ± 0.05 mg m h). Long-term operation and fouling experiment further demonstrated the durability and antifouling property of EFCM. Four main degradation pathways of florfenicol were proposed by tracking the degradation byproducts. The above results highlighted the feasibility of this integrated membrane catalysis process for advanced water purification.
This study was undertaken to design a stable easy-recoverable Fe 3 O 4 @EDTA-Ag hybrid with rich catalytic sites via wet-chemical method for the catalytic reduction of multiple dyes in wastewater. The amorphous ethylenediaminetetraacetic acid (EDTA) layer plays an important role by strongly pinning the Ag nanoparticle (NP) catalytic sites on the surface of the Fe 3 O 4 core with a very high ratio of 10.8%. In addition, an improved surface area from 42 to 72 and 81 m 2 g −1 was achieved after the decoration of Fe 3 O 4 by EDTA and EDTA-Ag NPs, respectively. Finally, catalytic tests showed that Fe 3 O 4 @EDTA-Ag hybrid exhibits an ultrafast catalytic reduction of azo, heterocyclic, and cationic dyes with a reduction rate of about 0.05 mM/150 s. Moreover, the catalyst demonstrated a high efficiency for the simultaneous reduction of mixed dyes (N.R+MB+AY and MB+Rh−B+AY). Recycling tests showed that Fe 3 O 4 @EDTA-Ag has an excellent stability wherein the catalyst was recycled 10 times with a slight decrease in the reduction rate of only ∼4.5%. The dissolution of Fe from Fe 3 O 4 @EDTA-Ag was very small compared to bare Fe 3 O 4 due to protective EDTA coating. The high catalytic activity, the magnetic recoverability, along with the excellent stability of Fe 3 O 4 @EDTA-Ag make it a potential candidate for the reduction of multiple dyes in real textile wastewaters.
Microbial electrochemical technologies provide sustainable wastewater treatment and energy production. Despite significant improvements in the power output of microbial fuel cells (MFCs), this technology is still far from practical applications. Extracting electrical energy and harvesting valuable products by electroactive bacteria (EAB) in bioelectrochemical systems (BESs) has emerged as an innovative approach to address energy and environmental challenges. Thus, maximizing power output and resource recovery is highly desirable for sustainable systems. Insights into the electrode-microbe interactions may help to optimize the performance of BESs for envisioned applications, and further validation by bioelectrochemical techniques is a prerequisite to completely understand the electro-microbiology. This review summarizes various extracellular electron transfer mechanisms involved in BESs. The significant role of characterization techniques in the advancement of the electro-microbiology field is discussed. Finally, diverse applications of BESs, such as resource recovery, and contributions to the pursuit of a more sustainable society are also highlighted.
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