WATER RESEARCH
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2023
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IF 12.8
Tao Yang,Linqian An,Ge Zeng,Maoju Jiang,Juan Li,Changyu Liu,Jianbo Jia,Jun Ma
The widespread occurrence of p -arsanilic acid ( p -ASA) in natural environments poses big threats to the biosphere due to the generation of toxic inorganic arsenic (i.e., As(III) and As(V), especially As(III) with higher toxicity and mobility). Oxidation of p -ASA or As(III) to As(V) followed by precipitation of total arsenic using Fe-based advanced oxidation processes demonstrated to be a promising approach for the treatment of arsenic contamination. This study for the first time investigated the efficiency and inherent mechanism of p -ASA and As(III) oxidation by Fe(II)/peracetic acid (Fe(II)/PAA) and PAA processes. p -ASA was rapidly degraded by the Fe(II)/PAA process within 20 s at neutral to acidic pHs under different conditions, while it was insignificantly degraded by PAA oxidation alone. Lines of evidence suggested that hydroxyl radicals and organic radicals generated from the homolytic O O bond cleavage of PAA contributed to the degradation of p -ASA in the Fe(II)/PAA process. p -ASA was mainly oxidized to As (V), NH 4 + , and p -aminophenol by the Fe(II)/PAA process, wherein the aniline group and its para position were the most vulnerable sites. As(III) of concern was likely generated as an intermediate during p -ASA oxidation and it could be readily oxidized to As(V) by the Fe(II)/PAA process as well as PAA alone. The in-depth investigation demonstrated that PAA alone was effective in the oxidation of As(III) under varied conditions with a stoichiometric molar ratio of 1:1. Efficient removal (> 80%) of total arsenic during p -ASA oxidation by Fe(II)/PAA process or during As(III) oxidation by PAA process with additional Fe(III) in synthetic or real waters were observed, mainly due to the adsorptive interactions of amorphous ferric (oxy)hydroxide precipitates. This study systematically investigates the oxidation of p -ASA and As(III) by the Fe(II)/PAA and PAA processes, which is instructive for the future development of arsenic remediation technology.
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JOURNAL OF HAZARDOUS MATERIALS
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2023
·
IF 13.6
Xin Zhang,Qingling Fu,Hongqing Hu,Jun Zhu,Yonghong Liu
The co-oxidation of Fe(II) and As(III) occurs under aerobic conditions , and Fe(II) may largely determine the fate of As(III), but the effect of Fe(II) on the As(III) oxidation is barely explored. In this research, the limiting and driving roles of Fe(II) in As(III) oxidation were systematically studied through batch kinetic studies in combination with X-ray photoelectron spectroscopy (XPS) depth profiling, scanning electron microscopy and energy dispersive X-ray spectrometry (SEM-EDS), and quenching experiments. The results showed that As(III) oxidation efficiency increased with the increase of Fe/As molar ratio (from 63.1% to 98.3%), but decreased with the increase of pH (from 96.0% to 44.2%) and the increase of air flow rate (from 88.1% to 75.1%). The Fe(II) oxidation rate increased with the increase of pH and air flow rate. When Fe(II) was oxidized rapidly, As(III) was more likely to be immobilized in the “inner sphere” of formed Fe (hydr)oxides, limiting As(III) oxidation. On the other hand, Fe(II) was oxidized to produce Fe (hydr)oxides to adsorb or fix As(III); meanwhile, the ROS generated by Fenton-like reaction of Fe(II) promoted As(III) oxidation, especially, •O 2 − and H 2 O 2 were important ROS that drove the As(III) oxidation. These findings might provide a new insight for Fe(II) and As(III) geochemistry cycling in naturally occurring environment.
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Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Zhengheng Yang,Xiaoming Ma,Hongbo Zhou,Jinxing Ma,Yuxin Ding,Di He
For more than a century, coagulation-precipitation using Fe(II) and Fe(III) are ubiquitous in wastewater treatment , however, a systematic understanding of the underlying mechanism and their performance toward chelated heavy metals (e.g. Cu II -EDTA) is still lacking. In this study, we therefore investigate the efficiency of Fe(II) and Fe(III) salts coagulation-precipitation, the properties (coagulation and crystallization behavior) of in-situ formed iron (oxy)hydroxides and explore the reaction mechanism using a suite of characterization techniques. Our results reveal that no matter Fe(II) and Fe(III) exhibited an exceptional removal performance for Cu(II) in terms of kinetics and iron dosage along with pH. Impressively, under optimal condition, over 95 % of chelated Cu(II) was removed within 10 min from Fe(II) while about 85 % from Fe(III) dosing. The highly reductive structural Fe(II) existing on mixed-valent iron bearing mineral results in reductive decomplexation of Cu II -EDTA in the Fe(II) coagulation-precipitation process in compare with replacement decomplexation in the Fe(III) coagulation-precipitation process, and then released free metal ions (Cu(I) and Cu(II)) can be removed by adsorption and coprecipitation . In addition, the in-situ formed Fe(III) (oxy)hydroxides were amorphous 2-line ferrihydrite with stable flocs and better sedimentation behavior than crystalline lepidocrocite from Fe(II) dosing, and these factors are crucial to the subsequent retention of heavy metals. The elucidation of this study has highlighted the great potential of using in-situ formed iron (oxy)hydroxides for cost-effective treatment of chelated heavy metal-bearing industrial wastewaters .
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Environmental Science-Nano
·
2023
·Vol. 10
·期 10
·2744-2753
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IF 7.3
Jiaxin Lv,Ruixin Chen,Zhen Wu,Yang Bai,Han Song,Chen Tian,Mengye Wang,Zhang Lin
The enrichment of microplastics in polar ice is a typical phenomenon discovered in recent years. Thus, it is worthwhile to explore the degradation behavior of microplastics in frozen environments, which is crucial to evaluate their impact on polar ecosystems. Here, taking polystyrene (PS) as an example, the degradation behaviors of MPs in frozen anoxic Fe(II)-containing solutions were investigated. The results revealed that PS degradation rate in frozen solution was 14.6-fold higher than that in water. Mechanism study showed that freezing-induced aggregation and extrusion of PS enhanced the generation of environmentally persistent free radicals (EPFRs), which in turn contributed to the formation of H2O2. Moreover, freezing-induced enrichment of Fe(II) further interreacted with H2O2 to form Fe(IV) and OH free radicals at a pH of ∼6.5, and thus accelerated the degradation of PS. Such reaction was accompanied by the formation of Fe(III)-containing products, which would further react with aged PS to produce new EPFRs and Fe(II). Such cycles of aged PS/EPFRs and Fe(III)/Fe(II) continued to accelerate the degradation of PS in the frozen solution. This study provides an overlooked pathway for microplastic degradation in frozen Fe(II)-containing solutions, which would be of key importance to understand the degradation behaviors of microplastics in frozen environments.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2023
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IF 22.1
Hongyan Zhang,Tao Yang,Hao Zhou,Yikai Wang,Xuehan Yang,Wenjie Liang,Dan Wu,Pan Yuan,Tingting Yu,Maoshuai He,Wenxian Wei
Ni phosphides have recently attracted considerable attention as promising catalysts for the oxygen evolution reaction (OER) and are generally promoted by Fe incorporation. However, the catalytic performance of nickel phosphide still does not meet the desired expectations. Additionally, the catalytic activity of iron (Fe) is insignificant and can be disregarded. In this study, we used C 3 N 4 as a carbon substrate to modulate the 3 d electron configurations and adsorption properties of Ni and Fe. Density functional theory (DFT) analysis reveals that the catalytic performance of Ni sites can be enhanced by utilizing the C 3 N 4 substrate. Surprisingly, the Fe sites can also be activated to catalyze OER through a direct O 2 mechanism and the catalytic activity of Fe is found to surpass that of Ni. As a result, the FeNi-C 3 N 4 -P catalyst demonstrated remarkable catalytic performance for OER. It exhibited a Tafel slope of 40.4 mV dec −1 , an overpotential of 235 mV at 100 mA cm −2 , and exhibited exceptional stability. This study highlights the activation of Fe and the enhancement of Ni by utilizing nitrogen-containing carbon substrates. This strategy offers promising prospects for the development of efficient Ni/Fe-based OER catalysts.
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CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Xiaomeng Zhang,Yang Zong,Longqian Xu,Yunfeng Mao,Deli Wu
Abiotic humification can be facilitated by iron-containing minerals or oxides, but most studies have focused on well-crystallized and stable iron phases, the catalytic effect of which is generally unremarkable. In the present study, we report an enhanced abiotic integrated polyphenol-Maillard humification reaction catalysed by Mg/Fe-layered double hydroxide (Mg/Fe-LDH) with high surface reactivity. The results demonstrated that Mg/Fe-LDH could effectively promote the humification reaction at a lower dosage compared with Fe 2 O 3 . As an iron-chelating ligand, catechol rapidly induced iron dissolution from Mg/Fe-LDH through the formation of an Fe(III)-catechol complex, which strengthened the catalytic effect of Fe(III). The photochemical behaviour of Fe(III)-catechol complex and its impact on the Fe(III)-catalysed humification process were investigated. Under light irradiation, environmentally persistent free radicals (EPFRs) originated from the Fe(III)-catechol complex were formed and stabilized in the presence of Mg/Fe-LDH particles, which inhibited the oxidation of catechol and the humification process. Hence, the formation of humic substances (HS) catalysed by Mg/Fe-LDH was more efficient under darkness. Iron redox cycling and generation of reactive oxygen species (ROS), HO• and O 2 •- , were also involved. According to transformation products (TPs) analysis, ortho -aminophenol was proposed to be a key product in the humification reaction. Self-coupling of catechol radical and ortho -aminophenol radical, ring cleavage were likely to occur in the Fe(III)-catalysed humification process. Higher relative abundance of CHO products was observed in the presence of Mg/Fe-LDH by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), suggesting that iron is effective on promoting C–C bonds formation. The above results provide more comprehensive insights into Fe(III)-catalysed humification and a guidance to improve the efficiency of HS formation and carbon sequestration in organic wastes utilization.
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CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Usman Farooq,Jingguo Zhuang,Xinhai Wang,Shuguang Lyu
The removal of chlorinated hydrocarbons through heterogeneous catalysts from groundwater has become a valuable approach. However, the synthesis of a highly efficient and persistent material especially for trichloroethane (TCA) removal is still immature . In this study, we prepared polydopamine (PDA) embedded Fe/rGO nanocomposite via pH-induced polymerization of dopamine for the degradation of TCA in sodium percarbonate (SPC) system. The experimental outcomes revealed that PDA decorated Fe/rGO not only enhanced the TCA degradation (98%) more economically but also strengthened the stability and recyclability of catalyst compared to bare Fe/rGO. The TEM, XRD, FTIR, XPS and VSM analyses declared the successful preparation of magnetically separable PDA@Fe/rGO nanocomposite. Furthermore, a higher degradation rate of probe compounds in PDA@Fe/rGO/SPC system indicated that PDA decoration improved the formation of active species due to autoxidation of dopamine and reducing capability of PDA. The impact of solution matrix on PDA@Fe/rGO performance elucidated the effect of various species on degradation. The GCMS, TOC analysis and dechlorination experiments validated the formation of non-toxic products and reasonable TOC and chloride ions removal. The PDA@Fe/rGO catalyst can be recycled for six consecutive cycles retaining a 76% along with abundant availability of Fe 2+ and Fe 3+ species validated using XRD and XPS analysis. The enhanced remediation capacity and improved recyclability of PDA@Fe/rGO nanocomposite can serve as a shining star for the practical application of TCA removal in groundwater.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2020
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IF 6.551
Xia Ruan,Hong Liu,Xiaoyong Ning,Dongye Zhao,Xianyuan Fan
Zero-valent iron (ZVI), Fe 2+ and H 2 are possible electron donors in the reduction of Cr(VI) by nanoscale ZVI (n-ZVI). However, it is often ambiguous about the roles of these electron donors in the reductive removal of Cr(VI) from groundwater and wastewater. This study investigated the action mechanisms of Fe and Ni in Cr(VI) reduction by Fe/Ni nanoparticles (n-Fe/Ni). Among the three possible reduction mechanisms of ZVI, direct electron transfer from ZVI and its corrosion product, Fe 2+ , were confirmed to be responsible for the reduction removal of Cr(VI). H 2 , another product of ZVI corrosion, was found incapable of reducing Cr(VI). In addition, the secondary metal Ni in n-Fe/Ni was found to facilitate the direct electron transfer from ZVI owing to its ability to inhibit the passivation of ZVI and to enhance the production of Fe 2+ due to the formation of Fe Ni galvanic cells . The results of characterizations on n-Fe/Ni before and after the reaction with Cr(VI) demonstrated that Cr(VI) was reduced to Cr(III), which existed as FeCr 2 O 4 precipitates on the surface of n-Fe/Ni, resulting in effective sequestration of Cr(VI). These findings are important for understanding the main mechanisms of bimetallic nanoparticles or nanomaterials for reductive immobilization of Cr(VI), and may guide further ZVI-based technology development for remediation of contaminated water or soil with redox-active contaminants.
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Sustainable Energy & Fuels
·
2019
·Vol. 3
·期 12
·3455-3461
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IF 4.912
Bomin Feng,Xiuju Wu,Yanli Niu,Wei Li,Yunxi Yao,Weihua Hu,Chang Ming Li
Fe/N–C catalysts show great potential for the oxygen reduction reaction (ORR) but their catalytic activity should be further improved for practical application. Here, we report a high performance Fe/N–C hollow sphere with excellent ORR activity in both alkaline and acidic solutions. It is synthesized via pyrolysis of a melamine/Fe-incorporated polydopamine nanosphere precursor at 800 °C in an argon atmosphere. The N-rich melamine in the precursor affords abundant N dopants to form dense Fe–Nx active sites and also facilitates the formation of micropores in the catalyst via the gasification effect, together improving the ORR activity. The as-reported Fe/N–C catalyst outperforms the Pt/C catalyst in basic media (45 mV more positive half wave potential), approaches the Pt/C catalyst in acidic media (55 mV lower half wave potential), and exhibits impressive performance in Zn–air primary batteries.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2019
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IF 2.683
Zigui Luo,Xi'an Fan,Wentao Hu,Fan Luo,Jian Wang,Zhaoyang Wu,Xin Liu,Guangqiang Li,Yawei Li
In this work, Fe 2 SiO 4 /SiO 2 coated Fe-Si soft magnetic composites (SMCs) have been prepared successfully via ball milling Fe-6.5wt%Si/Fe 3 O 4 composite particles combined with subsequent spark plasma sintering (SPS) process. The formation mechanism of Fe 2 SiO 4 /SiO 2 insulating layer and effect of Fe 3 O 4 coating content on the microstructure and properties for the Fe-Si SMCs were investigated in detail. It is interesting that high temperature SPS process would lead to the occurrence of redox reactions between Fe 3 O 4 and Si from Fe-Si alloy cores, and resulted in the transformation from Fe 3 O 4 coating layer to Fe 2 SiO 4 /SiO 2 insulating layer. As a consequence, the novel Fe-Si SMCs exhibited superior performances including high saturation magnetization (190.4 emu/g) and low core loss (9.02 mW/cm 3 at 10 kHz) decreased by 89.1% compared to that of the uncoated Fe-Si SMCs (83.08 mW/cm 3 at 10 kHz). The results indicated that the method of preparing insulating layer by the redox reactions is a simple and effective way to synthesize new SMCs with high performance for electro-magnetic energy conversion equipments.
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Small
·
2019
·Vol. 16
·期 6
·1906057
·
IF 10.856
Xueping Sun,Peng Wei,Songqi Gu,Jinxu Zhang,Zheng Jiang,Jing Wan,Zhaoyang Chen,Li Huang,Yue Xu,Chun Fang,Qing Li,Jiantao Han,Yunhui Huang
Highly active and durable bifunctional oxygen electrocatalysts are of pivotal importance for clean and renewable energy conversion devices, but the lack of earth-abundant electrocatalysts to improve the intrinsic sluggish kinetic process of oxygen reduction/evolution reactions (ORR/OER) is still a challenge. Fe-N-C catalysts with abundant natural merits are considered as promising alternatives to noble-based catalysts, yet further improvements are urgently needed because of their poor stability and unclear catalytic mechanism. Here, an atomic-level Fe-N-C electrocatalyst coupled with low crystalline Fe 3 C-Fe nanocomposite in 3D carbon matrix (Fe-SAs/Fe 3 C-Fe@NC) is fabricated by a facile and scalable method. Versus atomically FeN x species and crystallized Fe 3 C-Fe nanoparticles, Fe-SAs/Fe 3 C-Fe@NC catalyst, abundant in vertical branched carbon nanotubes decorated on intertwined carbon nanofibers, exhibits high electrocatalytic activities and excellent stabilities both in ORR ( E 1/2 , 0.927 V) and OER ( E J=10 , 1.57 V). This performance benefits from the strong synergistic effects of multicomponents and the unique structural advantages. In-depth X-ray absorption fine structure analysis and density functional theory calculation further demonstrate that more extra charges derived from modified Fe clusters decisively promote the ORR/OER performance for atomically FeN 4 configurations by enhanced oxygen adsorption energy. These insightful findings inspire new perspectives for the rational design and synthesis of economical–practical bifunctional oxygen electrocatalysts.
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ACS Applied Materials & Interfaces
·
2018
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IF 8.097
Yanan Wei,Bingfeng Wang,Xinfang Cui,Yaseen Muhammad,Yanjuan Zhang,Zuqiang Huang,Xuesheng Li,Zhenxia Zhao,Zhongxing Zhao
MIL(Fe)/Fe-doped nanospongy porous biocarbon (Fe-SPC) composite was fabricated from MIL-100(Fe) via in situ growth on a unique Fe-doped nanospongy porous biocarbon (Fe-SPC) and was used as Fenton-like catalyst for advanced degradation of thiamethoxam (THIA). Fe was loaded on silkworm excrement and calcined to Fe-SPC with nanospongy and high sp2 C structure. The in situ growth strategy embedded the Fe-SPC into MIL-100(Fe) crystals and formed conductive heterojunctions with an intensified interface by Fe-bridging effect, which was confirmed by negative shift of Fe3+ binding energy in X-ray photoelectron spectroscopy. MIL(Fe)/Fe-SPC composites exhibited high degree of crystallinity and surface area (Brunauer–Emmett–Teller: 1730 m2/g). Liquid chromatography–mass spectrometry and density functional theory simulations demonstrated that THIA was converted to a relatively stable compound (C4H5N2SCl), which could be captured by MIL-100(Fe) with strong chemical bonding energy (Fe–N, −587 kJ/mol), followed by a significant geometric distortion, resulting in a thorough degradation. Efficient charge separation and synergistic chemisorption-catalysis strategy resulted in the high catalytic activity of MIL(Fe)/Fe-SPC. The composite catalyst concurrently exhibited high mineralization ratio with 95.4% total organic carbon removal (at 25 °C and 180 min) and good recycling ability under wider neutral/alkaline conditions. Endorsing to these intriguing properties, MIL(Fe)/Fe-SPC can be deemed an efficient contender for removal of hard-degradable pesticides and other environmental pollutants in practical applications.
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