查找使用阿拉丁产品的科研文献

Enhanced molecular dipole moment driven charge separation accelerates Fe(II)/Fe(III) cycle in oxygen doped g-C3N4 microrods for scavenger-free photocatalysis-self-fenton degradation

Yibing Feng,Kun Qiao,Xiaohan Jiang,Huiling Ji,Jiang Meng,Jigang Wang

A photocatalysis–self-Fenton system (PSFs) offers a viable solution to the continuous hydrogen peroxide (H 2 O 2 ) dosing and insufficient Fe 2 + regeneration challenges in conventional Fenton chemistry. An oxygen-doped g-C 3 N 4 microrod (OCNT)-based PSFs was synthesized via a facile oxalic acid-mediated supramolecular self-assembly route, enabling efficient pollutant degradation. In situ H 2 O 2 production was achieved through a two-electron oxygen reduction reaction (2e − -ORR), with photogenerated electrons accelerating Fe 2+ /Fe 3+ cycling and enhancing H 2 O 2 utilization. The system exhibited an apparent rate constant of 0.071 min −1 for tetracycline (TC) removal, 12.2- and 4.2-fold higher than pristine g-C 3 N 4 and a photo-Fenton system, respectively. Density functional theory (DFT) calculations and experimental results indicated that oxygen heteroatom doping increased the molecular dipole moment and optimized the band structure, while the one-dimensional microrod morphology exposed abundant active sites. These synergistic effects facilitated charge-carrier separation, improved interfacial mass transfer, and promoted the two-electron oxygen-reduction pathway, thereby accelerating Fe 2+ /Fe 3+ cycling and hole oxidation. The platform demonstrated broad pH adaptability, strong anti-interference capability, and long-term operational stability. This work provides an effective strategy for on-site H 2 O 2 generation and utilization in photocatalytic–Fenton systems for the degradation of organic contaminants.

Synergistic effects and mechanisms of hydroxyl radical-mediated oxidative degradation of sulfamethoxazole by Fe(II)-EDTA catalyzed calcium peroxide: Implications for remediation of antibiotic-contaminated water

Amina,Xiongyuan Si,Kang Wu,Youbin Si,Balal Yousaf

In this study, a modified Fenton system using calcium peroxide (CaO 2 ) powder, as an effective source of hydrogen peroxide (H 2 O 2 ), for the degradation of sulfamethoxazole (SMX) in aqueous solution was investigated. Our results indicated that degradation of SMX in Fe(II)-EDTA catalyzed CaO 2 system was readily more efficient than in Fe(II) catalyzed CaO 2 system. The SMX degradation efficiency was found maximum at pH 6.0 and SMX degradation was suppressed as the initial solution pH was increased. Nevertheless overall removal efficiency in this system was favorable near to neutral pH. In addition, it was observed that the higher bicarbonates (HCO 3 − ) contents had a considerable scavenging ability to SMX degradation while low concentration exhibited auspicious role. The presence of chlorides (Cl − ), nitrates (NO 3 − ), sulfates (SO 4 2− ), and humic acid (HA) could improve SMX removal in this Fenton-like system. Furthermore, chemical probe and radical scavenging activity confirmed the formation of hydroxyl (HO ) and superoxide (O 2 − ) radicals, and also described that the SMX degradation was predominantly due to the HO -induced oxidative destruction. Electron paramagnetic resonance (EPR) studies for different systems, different pH values and different reaction times were carried out to determine the HO radical intensities. EPR results showed that HO intensities were higher in Fe(II)-EDTA catalyzed CaO 2 system, at pH 6.0 and at 90 s reaction time, respectively. Intermediate products of SMX were identified and possible mechanism of SMX degradation was suggested. In conclusion, this work provided comprehensive knowledge for the use of Fe(II)-EDTA catalyzed CaO 2 system for remediation of SMX contaminated sites.

2-Ketoglutarate-Generated In Vitro Enzymatic Biosystem Facilitates Fe(II)/2-Ketoglutarate-Dependent Dioxygenase-Mediated C–H Bond Oxidation for (2s,3r,4s)-4-Hydroxyisoleucine Synthesis

Xiao-Ran Jing,Huan Liu,Yao Nie,Yan Xu

Fe(II)/2-ketoglutarate-dependent dioxygenase (Fe(II)/2-KG DO)-mediated hydroxylation is a critical type of C–H bond functionalization for synthesizing hydroxy amino acids used as pharmaceutical raw materials and precursors. However, DO activity requires 2-ketoglutarate (2-KG), lack of which reduces the efficiency of Fe(II)/2-KG DO-mediated hydroxylation. Here, we conducted multi-enzymatic syntheses of hydroxy amino acids. Using (2s,3r,4s)-4-hydroxyisoleucine (4-HIL) as a model product, we coupled regio- and stereo-selective hydroxylation ofl-Ile by the dioxygenase IDO with 2-KG generation from readily availablel-Glu byl-glutamate oxidase (LGOX) and catalase (CAT). In the one-pot system, H2O2significantly inhibited IDO activity and elevated Fe2+concentrations of severely repressed LGOX. A sequential cascade reaction was preferable to a single-step process as CAT in the former system hydrolyzed H2O2. We obtained 465 mM 4-HIL at 93% yield in the two-step system. Moreover, this process facilitated C–H hydroxylation of several hydrophobic aliphatic amino acids to produce hydroxy amino acids, and C–H sulfoxidation of sulfur-containingl-amino acids to yieldl-amino acid sulfoxides. Thus, we constructed an efficient cascade reaction to produce 4-HIL by providing prerequisite 2-KG from cheap and plentifull-Glu and developed a strategy for creating enzymatic systems catalyzing 2-KG-dependent reactions in sustainable bioprocesses that synthesize other functional compounds.Keywords:Fe(II)/2-ketoglutarate-dependent dioxygenase;2-ketoglutarate generation;regio- and stereo-selective synthesis;hydroxy amino acids;sequential cascade reaction

Study on NO Removal Characteristics of the Fe(II)EDTA and Fe(II)PBTCA Composite System

Liwei Ma,Guoqiang Li,Youqian Wang,Siqi Chai,Guojie Zhang

Fe2+ complexation wet denitrification technology has become a research hotspot. It is very important to achieve efficient regeneration of the absorbent and increase NO absorption in the Fe2+ complexation system. They are the key to the industrial application of the Fe2+ complexation absorption process. In this paper, 2-phosphonate-butane-1,2,4-tricarboxylic acid and ethylenediamine tetraacetic acid were used as ligands to prepare a composite system for the first time. The characteristics of NO removal were investigated under different temperatures, pHs, Fe2+ concentrations, O2 contents, NO concentrations, CO2 contents, and SO2 concentrations. Compared with the single ligand, the results show that the denitrification performance of the solution with a complex ligand is significantly improved. In this system, pH 9, 40 °C temperature, and 20 mmol/L Fe2+ concentration are the economic ideal conditions for NO removal. The system can realize simultaneous removal of NO and SO2, but SO2 in flue gas has a dual effect on the NO removal reaction.

Comparative study of Fe(II)/sulfite, Fe(II)/PDS and Fe(II)/PMS for p-arsanilic acid treatment: Efficient organic arsenic degradation and contrasting total arsenic removal

Yuan Gao,Yun Luo,Zhao Pan,Zhu Zeng,Wenxia Fan,Jingyu Hu,Zhong Zhang,Jinxing Ma,Yang Zhou,Jun Ma

As a widely used feed additives, p-arsanilic acid (p-AsA) frequently detected in the environment poses serious threats to aquatic ecology and water security due to its potential in releasing more toxic inorganic arsenic. In this work, the efficiency of Fe(II)/sulfite, Fe(II)/PDS and Fe(II)/PMS systems in p-AsA degradation and simultaneous arsenic removal was comparatively investigated for the first time. Efficient p-AsA abatement was achieved in theses Fe-based systems, while notable discrepancy in total arsenic removal was observed under identical acidic condition. By using chemical probing method, quenching experiments, isotopically labeled water experiments, p-AsA degradation was ascribed to the combined contribution of high-valent Fe(IV) and SO 4 •− in these Fe(II)-based system. In particular, the relative contribution of Fe(IV) and SO 4 •− in the Fe(II)/sulfite system was highly dependent on the molar ratio of [Fe(II)] and [sulfite]. Negligible arsenic removal was observed in the Fe(II)/sulfite and Fe(II)/PDS systems, while ∼80% arsenic was removed in the Fe(II)/PMS system under identical acidic condition. This interesting phenomenon was due to that ferric precipitation only occurred in the Fe(II)/PMS system. As(V) was further removed via adsorption onto the iron precipitate or the formation of ferric arsenate-sulfate compounds, which was confirmed by particle diameter measurements, fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Through tuning solution pH, complete removal of total arsenic could achieve in all three systems. Among these three Fe-based technologies, the hybrid oxidation-coagulation Fe(II)/PMS system demonstrated potential superiority for arsenic immobilization by not requiring pH adjustment for coagulation and facilitating the in-situ generation of ferric arsenate-sulfate compounds with comparably low solubility levels like scorodite. These findings would deepen the understanding of these three Fe-based Fenton-like technologies for decontamination in water treatment.

Extreme chromium transformation and immobilization via ferrous coupling surfactant-enhanced nanofiltration process

Bin Liu,Junlong Cai,Xin Mao,Fazhi Xie,Xuewu Zhu

The efficient reduction and immobilization of highly toxic and migratory Cr(VI) present significant challenges in chromium-containing wastewater. This research demonstrates that the Fe(II)-coupled micelle-enhanced nanofiltration (MENF) system facilitated the rapid conversion and removal of Cr(VI). The co-complexation of cetyltrimethylammonium chloride (CTAC) and Fe(II) improved the molecular-level coordination and reduction capacity of Cr(VI), leading to its effective transformation to Cr(III) and a 41 % removal rate of Cr. The interaction between CTAC, Cr, and Fe generated larger aggregates, such as CTAC-Cr, (Fe x , Cr 1 − x )(OH) 3 , and CTAC-Cr-Fe, which enhanced Cr immobilization. Moreover, during the Fe(II)-coupled MENF process, a large amount of CTAC-Cr(III)-Fe(II, III) precipitates were removed during the complexation phase, while a small portion of the complexes adhered to the membrane surface, forming a porous cake layer. Due to the increased hydrodynamic diameter of the aforementioned Cr complexes, they could be easily retained by the nanofiltration membrane. Even under interference from high concentrations of anions and humic acids, the Fe(II)-coupled MENF system could still completely remove Cr(VI). This investigation contributes to a holistic understanding of the utilization of Fe(II)-coupled MENF systems and proposes effective sustainable strategies for Cr(VI) removal.

Visible light induced photocatalytic reduction of Cr(VI) by self-assembled and amorphous Fe-2MI

Qiaoyuan Gao,Dagang Lin,Yongjie Fan,Qin He,Qi Wang

Visible-light-active Fe-2MI assemblies were prepared at room temperature using 2-Methylimidazole (2MI) as organic ligand to form complex with Fe(II) or Fe(III). TGA and XRD characterizations indicated that Fe(II) can form more stable complex and higher coordinating percentage with 2MI relative to Fe(III). Besides, Fe(II)-2MI displayed amorphous state with larger BET surface area and higher photocurrent response. At very low catalyst dosage (0.1 g/L), highest activity for Cr(VI) reduction can be achieved using Fe(II)-2MI as photocatalyst. The estimated pseudo-first-order rate constant (0.021 min −1 ) was 1.4 and 2.1 times that on Fe(III)-2MI and Fe(II)-NaOH, respectively. The well-known ZIF-67 (Co-2MI), ZIF-7 (Zn-2MI) and Fe-MOFs with other organic ligands (H 2 BDC, NH 2 -H 2 BDC or FA) were also used as control samples. Optimal activity for photocatalytic reduction of Cr(VI) was achieved by Fe(II)-2MI. The operating factors was optimized at acidic pH (2.0), higher catalyst dosage (0.3 g/L) and appropriate concentration of coexisting organics (2.0 mM) within the tested range. The stability of Fe(II)-2MI was investigated at different pH values (2, 3 and 4.64), which all displayed good stability. Mechanism study indicated that Fe(II)-2MI has adequate conduction and valence band positions for Cr(VI) reduction and organics oxidation, respectively. Therefore, the as-prepared amorphous Fe(II)-2MI assemblies may be cheap, stable and easy available candidate for the photocatalytic disposal of Cr(VI)-containing wastewaters.

The photoactivity of complexation of DOM and Fe(Ⅱ)/Mn(Ⅱ) in aquatic system: Implication on the photodegradation of MCLR

Haishuo Wang,Xinke Tian,Zhichun Li,Jie Zhang,Shiyin Li,Heyong Huang

Lake eutrophication leads to the excessive proliferation of cyanobacteria in aquatic environments, resulting in microcystin-LR (MCLR) concentrations exceeding regulatory limits. The associated environmental risks and health concerns attract widespread attention. As one of the most active chemical substances in aquatic environments, dissolved organic matter (DOM) plays a critical role in the phototransformation of MCLR. In environments where Fe(II) and Mn(II) coexist, the phototransformation process of MCLR may be influenced. Among fulvic acid (FA), humic acid (HA), cyanobacteria-derived DOM (CDOM), and reed leaf-derived DOM (RDOM), FA has the highest apparent reaction rate constant for MCLR at 0.03567   h -1 . Using isopropanol, furfuryl alcohol, and sorbic acid as quenchers, the contributions of different photochemically produced reactive intermediates(PPRIs) to MCLR photodegradation follow the order: 3 DOM⁎ > ·OH > 1 O 2 . As pH increases, changes in the conformation and charge distribution of DOM and MCLR suppress MCLR photodegradation. The addition of Fe(II) or Mn(II) enhances the photodegradation of MCLR by DOM. Electron paramagnetic resonance tests and radical quenching experiments indicate that the introduction of Fe(II)/Mn(II) increases ·OH production. The enhanced ·OH promotes MCLR photodegradation more effectively than the suppression caused by Fe(II)/Mn(II) quenching of ³DOM⁎. Product analysis reveals that demethylation, hydroxylation, decarbonylation, decarboxylation, denitration, and bond cleavage are the main pathways of MCLR photodegradation. These findings provide valuable insights into the migration and transformation of MCLR in complex environments, contributing to a deeper understanding of the fate of pollutants in natural water systems, particularly in the presence of metal ions.

Oxidation of ferrous ions enhanced by CaMg(CO3)2 for their efficient separation from neodymium solution

Kaibo Hu,Yucheng Liu,Xiaowen Zhou,Fang Gao,Chuanqi Zhang,Tianci Chen,Ke Li,Jiuyang Lin,Xuewei Li

The waste products of NdFeB magnets are an attractive resource for the recovery of rare earth elements (REEs), especially for neodymium [Nd]. Conventional methods employed to remove ferric (Fe[II]) from Nd solutions involve high energy consumption and the extensive use of chemicals, including oxidants and pH regulators, leading to substantial wastewater generation. In this work, an environmentally friendly approach utilizing CaMg(CO3)2 was presented to remove Fe(II) from Nd solution. Under optimized conditions, including a reaction temperature of 70°C, a CO32-/Fe2+ ratio of 1.5/1, a reaction time of 240 min, and an initial concentration of 200 mg/L, the heterogeneous precipitation reaction on the surface of CaMg(CO3)2 exhibited an exceptional Fe(II) removal efficiency of 98.6%, with a negligible loss of Nd (only 0.8%). It was observed that the CaMg(CO3)2 not only provide a suitable alkaline environment for the selective precipitation of Fe(II), but also significantly enrich the concentration of dissolved oxygen at a high temperature. In fact, at a CaMg(CO3)2 concentration of 2 g/L, the dissolved oxygen concentration in the solution increased significantly to 15.5 mg/L at 70°C. Consequently, the usage of CaMg(CO3)2 facilitated the rapid conversion of Fe(II) to Fe(III) without the need for additional oxidants, which was perfect for the removal of Fe(II) rather than Nd.

Synergistic effect of ferrous ion and copper oxide on the oxidative degradation of aqueous acetaminophen at acid conditions: A mechanism investigation

Yunfei Zhang,Jinhong Fan,Bo Yang,Luming Ma

A synergistic effect of Fe(II) and copper oxide (CuO) was observed on the degradation of acetaminophen (ACT) in the presence of O 2 . The results showed that 89% of ACT (50   mg/L) was degraded within 6   h by 10   mM Fe 2+ with 5   g/L CuO powder at pH 3.0, among which about 30% of ACT was mineralized. The sorbed Fe(II) on the CuO surface which is more reactive than the dissolved Fe(II) was capable of reducing both Cu(II) and O 2 . The resulting Cu(I) significantly accelerated the destruction of ACT by serving as an electron-mediator between the sorbed Fe(II) and O 2 . In addition, the hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( OH) and superoxide anion radical ( O 2 − ) were identified as the main reactive oxygen species (ROSs) generated in Fe(II)/CuO suspension by Electron paramagnetic resonance (EPR) technique and quenching studies; however, only OH was found to have caused the decomposition and mineralization of ACT. First O 2 − was generated by reduction of O 2 through a one-electron transfer pathway. Then the generated O 2 − mediated the production of H 2 O 2 , which further decomposed into OH by Cu(I)- and Fe(II)-catalyzed Fenton reactions. The effects of Fe(II) concentration, CuO dose, solution pH and the degradation pathway were investigated, respectively.

Degradation of diclofenac by Fe(II)-activated peracetic acid

Zhenran Wang,Hongle Shi,Shixiang Wang,Yiqing Liu,Yongsheng Fu

Mechanochemical dolomite accurately modulating the activity of newly formed Fe-hydroxide for superior and stable arsenic removal

Zhenlei Wang,Yinxing Zhao,Tingting Zhang,Sizhe Lai,Qiwu Zhang,Yunliang Zhao

Arsenic (As) contamination in industrial wastewater on a large scale has posed a enormous threat to ecological security in recent decades. However, a key challenge at present is the efficient and cost-effective removal of As contamination, as Fe in the As removal process cannot quickly and stably form an active phase with high activity for arsenic removal. Here, we propose a strategy to use mechanical activation of dolomite to regulate the formation of newly formed Fe-hydroxide from Fe(II) with high arsenic-removal activity, while stably regulating the pH of water in the near-neutral range, thereby substantially improving the removal efficiency as well as the stability of Fe(II) for As. Activated dolomite can significantly enhance the oxidation rate of Fe(II) in water, and synergistically remove As contamination over 99.5 % of water with an initial concentration of 50 mg/L within 2 h, far superior to the performance of single Fe(II) or dolomite&Fe(II). The simulation and characterisation results reveal that in the presence of activated dolomite, the solution pH as well as the oxidation rate of Fe(II) are effectively regulated, which promotes the As in the solution to be significantly immobilised on the surface of activated dolomite as a ternary precipitate of Ca/Mg-Fe-As, conducive to the stability of the enhanced As removal precipitation. This study provides new insights into the role of carbonate mineral materials in As transformation, which is important for the efficient and cost-effective purification of As contamination in water.