ABSTRACT
Magnetic phosphorous biochar ï¼MPBCï¼ was prepared from Camellia oleifera shells using phosphoric acid activation and iron co-deposition. The materials were characterized and analyzed through scanning electron microscopy ï¼SEMï¼ï¼ X-ray diffractometry ï¼XRDï¼ï¼ specific surface area and pore size analysis ï¼BETï¼ï¼ Fourier infrared spectroscopy ï¼FT-IRï¼ï¼ and X-ray photoelectron spectroscopy ï¼XPSï¼. MPBC had a high surface area ï¼1 139.28 m2·g-1ï¼ and abundant surface functional groupsï¼ and it could achieve fast solid-liquid separation under the action of an external magnetic field. The adsorption behavior and influencing factors of sulfamethoxazole ï¼SMXï¼ in water were investigated. The adsorbent showed excellent adsorption properties for SMX under acidic and neutral conditionsï¼ and alkaline conditions and the presence of CO32- had obvious inhibition on adsorption. The adsorption process conformed to the quasi-second-order kinetics and Langmuir model. The adsorption rate was fastï¼ and the maximum adsorption capacity reached 356.49 mg·g-1. The adsorption process was a spontaneous exothermic reactionï¼ and low temperature was beneficial to the adsorption. The adsorption mechanism was mainly the chemisorption of pyrophosphate surface functional groups ï¼C-O-P bondï¼ between the SMX molecule and MPBC and also included hydrogen bondingï¼ π-π electron donor-acceptor ï¼π-πEDAï¼ interactionï¼ and a pore filling effect. The development of MPBC adsorbent provides an effective way for resource utilization of waste Camellia oleifera shells and treatment of sulfamethoxazole wastewater.
Subject(s)
Sulfamethoxazole , Water Pollutants, Chemical , Sulfamethoxazole/chemistry , Adsorption , Spectroscopy, Fourier Transform Infrared , Water , Water Pollutants, Chemical/analysis , Charcoal/chemistry , Phosphorus , Kinetics , Magnetic PhenomenaABSTRACT
This study reported a novel application of Mn0.67Fe0.33-MOF-74 with two-dimensional (2D) morphology grown on carbon felt as a cathode for efficiently removing antibiotic sulfamethoxazole in the heterogeneous electro-Fenton system. Characterization demonstrated the successful synthesis of bimetallic MOF-74 by a simple one-step method. Electrochemical detection showed that the second metal addition and morphological change improved the electrochemical activity of the electrode and contributed to pollutant degradation. At pH 3 and 30 mA of current, the degradation efficiency of SMX reached 96% with 12.09 mg L-1 H2O2 and 0.21 mM ·OH detected in the system after 90 min. During the reaction, electron transfer between ≡FeII/III and ≡MnII/III promoted divalent metal ions regeneration, which ensured the continuation of the Fenton reaction. Two-dimensional structures exposed more active sites favoring ·OH production. The pathway of sulfamethoxazole degradation and the reaction mechanisms were proposed based on the intermediates identification by LC-MS and radical capture results. High degradation rates were still observed in tap and river water, revealing the potential of Mn0.67Fe0.33-MOF-74@CF for practical applications. This study provides a simple MOF-based cathode synthesis method, which enhances our understanding of constructing efficient electrocatalytic cathodes based on morphological design and multi-metal strategies.
Subject(s)
Sulfamethoxazole , Water Pollutants, Chemical , Manganese , Iron/chemistry , Hydrogen Peroxide/chemistry , Oxidation-Reduction , Electrodes , Water Pollutants, Chemical/analysisABSTRACT
Advanced oxidation processes (AOPs) have demonstrated an effective wastewater treatment method. But the application of AOPs using nanomaterials as catalysts is challenged with a series of problems, including limited mass transfer, surface fouling, poor stability, and difficult recycling. Recently, metal-organic frameworks (MOFs) with high tunability and ultrahigh porosity are emerging as excellent precursors for the delicate design of the structure/composition of catalysts and many MOF-derived catalysts with distinct physicochemical characteristics have shown optimized performance in various AOPs. Herein, to elucidate the structure-composition-performance relationship, a review on the performance optimization of MOF-derived catalysts to overcome the existing problems in AOPs by micro/macrostructure and multicomponent design is given. Impressively, MOF-derived strategy for the design of catalyst materials from the aspects of microstructure, macrostructure, and multicomponent (polymetallic, heteroatom doping, M/C hybrids, etc.) is firstly presented. Moreover, important advances of MOF-derived catalysts in the application of various AOPs (Fenton, persulfate-based AOPs, photocatalysis, electrochemical processes, hybrid AOPs) are summarized. The relationship between the unique micro/macrostructure and/or multicomponent features and performance optimization in mass transfer, catalytic efficiency, stability, and recyclability is clarified. Furthermore, the challenges and future work directions for the practical application of MOF-derived catalysts in AOPs for wastewater treatment are provided.