作者机构：
[Fengjiao Quan; Pengfei Xu; Xiaolan Chen; Wenjuan Shen; Yun He; Jianfen Li] College of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023, China;[Falong Jia] College of Chemistry, Central China Normal University, Wuhan 430079, China;[Guangming Zhan] School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
通讯机构：
[Falong Jia] C;College of Chemistry, Central China Normal University, Wuhan 430079, China
摘要：
Nitrate (NO3–) is a widespread pollutant in high-salt wastewater and causes serious harm to human health. Although electrochemical removal of nitrate has been demonstrated to be a promising treatment method, the development of low-cost electro-catalysts is still challenging. In this work, a phosphate modified iron (P-Fe) cathode was prepared for electrochemical removal of nitrate in high-salt wastewater. The phosphate modification greatly improved the activity of iron, and the removal rate of nitrate on P-Fe was three times higher than that on Fe electrode. Further experiments and density functional theory (DFT) calculations demonstrated that the modification of phosphoric acid improved the stability and the activity of the zero-valent iron electrode effectively for NO3– removal. The nitrate was firstly electrochemically reduced to ammonium, and then reacted with the anodic generated hypochlorite to N2. In this study, a strategy was developed to improve the activity and stability of metal electrode for NO3– removal, which opened up a new field for the efficient reduction of NO3– removal by metal electrode materials.
期刊：
Journal of Hazardous Materials,2024年465:133009 ISSN：0304-3894
通讯作者：
Jia, FL
作者机构：
[Zhang, Lizhi; Jia, Falong; Guo, Furong; Li, Donglei; Zhang, Yuhang; She, Liang; Ai, Zhihui; Liu, Xiao] Cent China Normal Univ, Coll Chem, Wuhan 430079, Peoples R China.
通讯机构：
[Jia, FL ] C;Cent China Normal Univ, Coll Chem, Wuhan 430079, Peoples R China.
关键词：
Cu(II)-EDTA;Decomplexation;Ferrous formate shell;Oxidative degradation;Zero-valent iron
摘要：
Heavy metal complexes in industrial wastewater are challenging to be removed by conventional methods arising from their stable chelating structure. In this study, zero-valent iron (ZVI) was ball-milled with tiny formic acid (FA), and the as-prepared sample (FA-ZVI(bm)) was attempted to eliminate a model heavy metal complex of Cu(II)-ethylenediaminetetraacetic acid (Cu(II)-EDTA). The addition of FA to ball-milling could dramatically enhance the performance of ball-milled ZVI (ZVI(bm)) towards Cu(II)-EDTA removal and increase the removal rate constant by 80 times. This conspicuous improvement of Cu(II)-EDTA elimination was attributed to the ferrous formate (Fe(HCOO)(2)) shell formed on the surface of FA-ZVI(bm). Results revealed that the Fe(HCOO)(2) shell facilitated the activation of O(2) to reactive oxygen species (ROS) and the leaching of Fe(3+). Cu(II)-EDTA was decomplexed through both oxidative destruction and Fe(3+) replacement, and the released Cu(2+) was reduced by FA-ZVI(bm) and immobilized synchronously. Meanwhile, the ligands underwent oxidative degradation by ROS, thus avoiding the re-chelation ecological risk. Impressively, FA-ZVI(bm) could achieve cyclic treatment of actual copper complex wastewater and possessed promising advantage in treatment cost. This study would offer a promising approach for eliminating Cu(II)-EDTA through EDTA ligands degradation and synchronous Cu(II) removal, moreover to shed light on the decomplexation mechanism.
摘要：
The comprehensive understanding of contaminant interfacial behavior strongly depends on the in situ characterization technique, which is still a great challenge. In this study, we constructed a device integrated with open-circuit potentialand attenuated total reflectance Fourier transform infrared (OCP-ATR-FTIR) spectroscopy to simultaneously monitor the electrochemical and infrared spectral information on the interfacial reaction for the process analysis, taking the competitive adsorption of hexavalent chromium (Cr(VI)) and oxalate on hematite nanocubes (HNC) as an example. The synchronous OCP and infrared results revealed that Cr(VI) interacted with HNC via bidentate binuclear inner-sphere coordination, accompanied by electron transfer from HNC to Cr(VI), while oxalate was adsorbed on HNC through bidentate mononuclear side-on inner-sphere coordination with electron transfer from HNC to oxalate, and also outer-sphere coordination with negative charge accumulation. When oxalate was added to HNC with preadsorbed Cr(VI), oxalate would occupy the inner-sphere adsorption sites and thus cause the detaching of preadsorbed Cr(VI) from HNC. This study provides a promising in situ characterization technique for real-time interfacial reaction monitoring and also sheds light on the competitive adsorption mechanism of oxalate and Cr(VI) on the mineral surface.
摘要：
Catalytic oxidation technology is currently considered as a feasible approach to degrade and mineralize volatile organic compounds (VOCs). However, it is still challenging to realize efficient removal of VOCs through catalytic oxidation at room temperature. In our study, a novel flow-through electrocatalytic reactor was designed, composed of porous solid-electrolyte, gas-permeable titanium sub-oxides/titanium-foam (TiSO/Ti-foam) as anode and platinum coated titanium foam (Pt/Ti-foam) as cathode. This device could oxidize nearly 100% of benzene (10 ppm) to carbon dioxide at a current density of 1.2 mA/cm2 under room temperature. More importantly, the device maintained excellent stability over 1000 h. Mechanism of benzene mineralization was discussed. Hydroxyl radicals generated on the TiSO/Ti-foam anode played a crucial role in the oxidation of benzene. This study provides a promising prototype of the electrochemical air purifier, and may find its application in domestic and industrial air pollution control.
通讯机构：
[Hongwei Sun; Zhihui Ai] K;Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental Chemistry, Central China Normal University, Wuhan 430079, PR China
关键词：
Heterogeneous fenton reaction;Oxalic acid;Proton transfer;Thiamphenicol;Zero-valent iron
摘要：
Heterogeneous Fenton reactions of zero-valent iron (ZVI) requires the sufficient release of Fe(II) to catalyze the H(2)O(2) decomposition. However, the rate-limiting step of proton transfer through the passivation layer of ZVI restricted the Fe(II) release via Fe(0) core corrosion. Herein we modified the shell of ZVI with highly proton-conductive FeC(2)O(4)·2H(2)O by ball-milling (OA-ZVI(bm)), and demonstrated its high heterogeneous Fenton performance of thiamphenicol (TAP) removal, with 500 times enhancement of the rate constant. More importantly, the OA-ZVI(bm)/H(2)O(2) showed little attenuation of the Fenton activity during 13 successive cycles, and was applicable across a wide pH range of 3.5-9.5. Interestingly, the OA-ZVI(bm)/H(2)O(2) reaction showed pH self-adapting ability, which initially reduced and then sustained the solution pH in the range of 3.5-5.2. The abundant intrinsic surface Fe(II) of OA-ZVI(bm) (45.54% vs. 27.52% in ZVI(bm), according to Fe 2p XPS profiles) was oxidized by H(2)O(2) and hydrolyzed to generate protons, and the FeC(2)O(4)·2H(2)O shell favored the fast transfer of protons to inner Fe(0), therefore, the consumption-regeneration cycle of protons were accelerated to drove the production of Fe(II) for Fenton reactions, demonstrated by the more prominent H(2) evolution and nearly 100% H(2)O(2) decomposition by OA-ZVI(bm). Furthermore, the FeC(2)O(4)·2H(2)O shell was stable and slightly decreased from 1.9% to 1.7% after the Fenton reaction. This study clarified the significance of proton transfer on the reactivity of ZVI, and provided an efficient strategy to achieve the highly efficient and robust heterogeneous Fenton reaction of ZVI for pollution control.
摘要：
Oxygen vacancies (O(V)), as the sites of molecular oxygen adsorption and activation, play an important role in the catalytic combustion process of volatile organic compounds (VOCs). Revealing the relationship between O(V) concentration and molecular oxygen activation behavior is of significance to construct the efficient catalysts. Herein, α-MnO(2) with different O(V) concentrations was prepared to investigate the molecular oxygen activation for C(3)H(8) combustion. It is disclosed that the enhanced O(V) concentration in α-MnO(2) induced the reconfiguration of surface metal atoms, resulting in the transformation of oxygen activation configuration from end-on mode to side-on mode. Oxygen molecules in side-on mode possessed more localized electron density and weaker coordination bond strength with surrounding Mn atoms, which were more favorable to adsorb C(3)H(8) molecules and activate C-H bond for the improved combustion performance. This work provides a new understanding to reveal that the increased O(V) concentration contributes to more efficient VOCs combustion.
通讯机构：
[Yancai Yao] S;School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
关键词：
Electrocatalytic nitrogen fixation;Single-layerMoS2;Adjacent Mo sites;Spin-delocalized electrons
摘要：
Electrocatalytic nitrogen fixation is crucial for sustainable NH3 production, however it still suffers from sluggish kinetics. Here, we report that single-layer MoS2 with adjacent Mo sites (A-Mo-MoS2) prepared by preciously controlling the oriented topological conversion could exhibit an exceptional NH3 yield rate of 48.8 mu g h-1 mg-1 and Faradic efficiency (FE) of 27.3 % at-0.20 V vs. RHE, far beyond MoS2 with isolated sulfur vacancies (I-SV-MoS2) with a 18.8 mu g h-1 mg-1 rate and 8.4 % FE. Theoretical analysis reveal that A-Mo-MoS2 could induce their unpaired spin-polarized electrons to share along the outermost Mo edge, thereby forming a grand spin-delocalized electrons reservoir. Compared to limited spin-localized electrons on I-SV-MoS2, these spin-delocalized electrons could significantly facilitate nitrogen activation and switched the rate-determining step from energy-demanding *N2 hydrogenation to surmountable *HNNH hydrogenation. Our work offers a new strategy to promote nitrogen fixation by spin-delocalized electrons effect.
通讯机构：
[Falong Jia; Lizhi Zhang] I;Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, China
关键词：
Ammonia nitrogen removal;Single-atom iron;Non-noble metal catalyst;Aquaculture wastewater
摘要：
Ammonia nitrogen (NH4+-N) is a ubiquitous environmental pollutant, especially in offshore aquaculture systems. Electrochemical oxidation is very promising to remove NH4+-N, but suffers from the use of precious metals anodes. In this work, a robust and cheap electrocatalyst, iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C), was developed for electrochemical removal of NH4+-N from in wastewater containing chloride. The Fe-SAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon (Fe-NPs/N-C), unmodified carbon and conventional Ti/IrO2-TiO2-RuO2 electrodes. And high removal efficiency (> 99%) could be achieved as well as high N-2 selectivity (99.5%) at low current density. Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH4+-N. This study provides promising inexpensive catalysts for NH4+-N removal in aquaculture wastewater. (C) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
关键词：
Ammonia recovery;Cl-modified Cu electrode;Flow-through coupled device;Membrane-free electrolyzer;Nitrate electroreduction
摘要：
Green ammonia production from wastewater via electrochemical nitrate reduction contributes substantially to the realization of carbon neutrality. Nonetheless, the current electrochemical technology is largely limited by the lack of suitable device for efficient and continuous electroreduction nitrate into ammonia and in-situ ammonia recovery. Here, we report a flow-through coupled device composed of a compact electrocatalytic cell for efficient nitrate reduction and a unit to separate the produced ammonia without any pH adjustment and additional energy-input from the circulating nitrate-containing wastewater. Using an efficient and selective Cl-modified Cu foam electrode, nearly 100% NO(3)(-) electroreduction efficiency and over 82.5% NH(3) Faradaic efficiency was realized for a wide range of nitrate-containing wastewater from 50 to 200 mg NO(3)(-)-N L(-1). Moreover, this flow-through coupled device can continuingly operate at a large current of 800 mA over 100 h with a sustained NH(3) yield rate of 420 μg h(-1) cm(-2) for nitrate-containing wastewater treatment (50 mg NO(3)(-)-N L(-1)). When driven by solar energy, the flow-through coupled device can also exhibit exceptional real wastewater treatment performance, delivering great potential for practical application. This work paves a new avenue for clean energy production and environmental sustainability as well as carbon neutrality.
通讯机构：
[Lizhi Zhang] S;[Xiao Liu] K;Key Laboratory of Pesticide & Chemical Biology of the Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China<&wdkj&>School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
关键词：
transition metal oxides;H2O;lattice oxygen activation;HCHO oxidation;oxygen vacancy
摘要：
A small amount of water can enhance the catalytic combustion activity of volatile organic compounds (VOCs) on transition metal oxides (TMOs), but its intrinsic mechanism is still controversial. Herein, we systematically demonstrate that water molecules can constantly activate lattice oxygen of transition metal oxides to form hydroxyl species theoretically and experimentally. The oxygen atoms of the generated hydroxyl species possess a weak bonding strength with circumjacent metal atoms to easily escape from the surface and attack electron-deficient carbon atoms of VOCs due to their comparatively stronger nucleophilicity, leaving abundant oxygen vacancies as the active sites for subsequent molecular oxygen activation. This work helps us deeply understand the role of water in lattice oxygen activation of transition metal oxides and provides direction for water-related catalysis, such as catalytic VOC combustion, water splitting, water-gas shift reactions, and corrosion.
通讯机构：
[Zhihui Ai; Lizhi Zhang] K;Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China<&wdkj&>School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China<&wdkj&>Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China
关键词：
Cu recovery;decomplexation;electro-Fenton;heavy metal−organic complexes;sodium tetrapolyphosphate electrolyte
通讯机构：
[Peng, X; Zhang, LZ] C;Cent China Normal Univ, Coll Chem, Inst Environm & Appl Chem, Key Lab Pesticide & Chem Biol,Minist Educ, Wuhan 430079, Peoples R China.
关键词：
Zero-valent iron;FeC2O4 center dot 2H(2)O shell;Cr(VI) removal;Proton transfer;Surface-bound Fe2+
摘要：
In this study, we coated a high proton conducive shell on the zero-valent iron (ZVI) surface by mechanically ball-milling ZVI with oxalic acid dihydrate (OX-ZVI), and demonstrated that the generated FeC2O4 center dot 2H(2)O shell dramatically improved the Cr(VI) removal rate of ZVI by about 15-80 times. Owing to a higher proton conductivity of FeC2O4 center dot 2H(2)O shell than that of Fe2O3 shell, proton could easily transfer through FeC2O4 center dot 2H(2)O shell into iron core and be reduced to center dot H, accompanying with fast surface-bound Fe2+ generation, resulting in high efficiency of Cr(VI) removal in a wide pH range. Meanwhile, the removed Cr(VI) was deposited on OX-ZVI surface in the formation of FexCr1-x(OH)(3) composites, accompanied by the appearance of typical hollow structure derived from iron core dissolution. This study clarifies the significance of proton transfer on the reactivity of zero-valent iron, and also provides a new strategy to prepare highly active zero-valent iron for Cr(VI) removal.
