Jieli Guo,Shanmei Tu,Limin Li,Xiujing Xing,Wei Xiong,Hao Li
Combining two metal–organic frameworks (MOFs) with different compositions and structures is an effective way to grow MOF-on-MOF materials. MOF-on-MOF-derived Fe2O3/CoFe2O4 nanocomposites were constructed by epitaxial growth method and high-temperature heat treatment. The morphology and structure of Fe2O3/CoFe2O4 were modulated by varying different organic ligands, and their effects on the detection properties of Pb2+, Cu2+, Hg2+, and Cd2+ were explored. Co3O4 microspheres acted as stabilizing seeds, and typical samples of Fe2O3/CoFe2O4-2 nanocomposites showed spherical nanoparticles of the core–shell type with an average diameter of about 55–60 nm. Meanwhile, compared with individual MOF derivatives, the surface of MOF-on-MOF derivative materials had higher electrical conductivity and active surface area by high-temperature heat treatment, thus promoting efficient adsorption of a wide range of heavy metal ions (HMIs). Furthermore, Fe2O3/CoFe2O4-2/GCE exhibited excellent electrochemical detection performance for the simultaneous detection of Pb2+, Cu2+, Hg2+, and Cd2+ with low limit of detection (LOD) of 2.98, 8.56, 4.44, and 5.40 nM, respectively. By two-by-two and three-by-three assays, promoting and inhibiting effects of different HMIs were observed on the target ions. This work is significant for the development of high-performance MOF-on-MOF-derived Fe2O3/CoFe2O4 nanocomposites for real-time environmental monitoring.
Fanyue Meng,Chenbin Lin,Bing Song,Lei Yu,Yan Zhao,Zejian Zhi,Min Song
This study employed a self-designed underwater arc discharge (UAD) plasma reactor, which combined advanced oxidation process (Fe 2 O 3 -CoFe 2 O 4 /PMS) and low-temperature plasma technology to efficiently degrade refractory organic pollutants (i.e. phenol, p-chlorophenol, p-nitrochlorobenzene). The results illustrated that the plasma/PMS/Fe 2 O 3 -CoFe 2 O 4 system possessed high degradation efficiency and TOC removal rate towards three target pollutants (phenol: 99.8%, 96.12%; 4-CP: 98.4%, 86.48%; p-NCB: 99.9%, 88.31%). With the help of in-situ variable temperature EPR and Indigo colorimetry method, ·OH, SO 4 ·- , O 2 ·- , 1 O 2 and O 3 were identified as the main reactive oxygen species (ROS) for the degradation of target pollutants, revealing the synergistic catalytic mechanism between plasma and Fe 2 O 3 -CoFe 2 O 4 for PMS activation and inferring the degradation pathways of target pollutants. The results confirmed that the plasma/PMS/Fe 2 O 3 -CoFe 2 O 4 system was feasible for the degradation of refractory organic pollutants, has the advantages of high efficiency and low energy consumption, and could provide an effective strategy for the treatment of refractory organic pollutants in groundwater/soil.
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