Fe-Cu bimetal metal-organic framework for efficient decontamination via Fenton-like process: Synthesis, performance and mechanism.

Constructing Fe-Cu bimetal catalysts is an efficient strategy to promote Fe(III)/Fe(II) cycle, whereas there is still a long way to go before fully understanding the role of the Cu in the catalysts. Herein, a new Fe-MOF namely BUC-96(Fe) was fabricated from FeSO4·7H2O, 4,4'-bipyridine (bpy) and 2,5-dihydroxyterephthalic acid (H4dhtp) by both hydrothermal reaction and microwave-assisted method. Also, bimetal BUC-96(FeCu-x) were obtained when the CuSO4 was added into the system identical to the synthesis process of BUC-96(Fe). Series BUC-96 MOFs showed good organics elimination performance via Fenton-like process, where 88.1% (k = 0.0672 min-1) of chloroquine phosphate (CQ, 20 mg/L) was decomposed over pristine BUC-96(Fe) within 30 min. Interestingly, nearly 100% CQ was degraded over BUC-96(FeCu-5) as catalyst under the identical conditions within 5 min, whose reaction rate (1.3527 min-1) was 20.1-fold higher than that of BUC-96. Additionally, BUC-96(FeCu-5) exhibited excellent Fenton-like oxidation degradation performance for 10 selected emerging organic pollutants. The reaction mechanism was studied in detail by experiments, and density functional theory (DFT) calculation. The results revealed that the introduced Cu not only accelerated Fe(III)/Fe(II) cycles, hydroxyl radical (·OH) generation, electron transfer, but also lowered H2O2 dissociated energy barrier. This work advanced the bimetal MOFs construction and application in wastewater treatment via Fenton-like process.

FeMo@porous carbon derived from MIL-53(Fe)@MoO3 as excellent heterogeneous electro-Fenton catalyst: Co-catalysis of Mo.

An ultra-efficient electro-Fenton catalyst with porous carbon coated Fe-Mo metal (FeMo@PC), was prepared by calcining MIL-53(Fe)@MoO3. This FeMo@PC-2 exhibited impressive catalytic performance for sulfamethazine (SMT) degradation with a high turnover frequency value (7.89 L/(g·min)), much better than most of reported catalysts. The mineralization current efficiency and electric energy consumption were 83.2% and 0.03 kWh/gTOC, respectively, at low current (5 mA) and small dosage of catalyst (25.0 mg/L). The removal rate of heterogeneous electro-Fenton (Hetero-EF) process catalyzed by FeMo@PC-2 was 4.58 times that of Fe@PC/Hetero-EF process. Because the internal-micro-electrolysis occurred between PC and Fe0, while the co-catalysis of Mo accelerated the rate-limiting step of the Fe3+/Fe2+ cycle and greatly improved the H2O2 utilization efficiency. The results of radical scavenger experiments and electron paramagnetic resonance confirmed the main role of surface-bound hydroxyl radical oxidation. This process was feasible to remove diverse organic contaminants such as phenol, 2,4-dichlorophenoxyacetic acid, carbamazepine and SMT. This paper enlightened the importance of the doped Mo, which could greatly improve the activity of the iron-carbon heterogeneous catalyst derived from metal-organic frameworks in EF process for efficient removal of organic contaminants.

Degradation of carbamazepine over MOFs derived FeMn@C bimetallic heterogeneous electro-Fenton catalyst.

A highly efficient heterogeneous electro-Fenton (Hetero-EF) catalyst with core-shell structure was successfully prepared by calcination of Mn-doped Mil-53 (Fe) precursor at high temperature. FeMn@C-800/2 prepared at pyrolysis temperature of 800 °C and Fe:Mn molar doping ratio of 2:1 showed the best catalytic performance for the degradation of carbamazepine (CBZ). The characterization, properties and stability of FeMn@C-800/2 were systematically investigated, obtaining the apparent first-order reaction rate of Hetero-EF was 8.9 and 17.8 times higher than that on Fe@C-800 and Mn@C-800 at the optimized conditions of current density 10 mA cm-2, catalyst dosage of 50 mg L-1 and initial pH 4.0, respectively. The incorporation of Mn promoted the generation of more Fe0 and Fe3C during the pyrolysis process, and enhanced the internal micro-electrolysis between Fe0 and carbon shell. At the same time, the presence of Mn0 also promoted the regeneration of Fe2+, and improved the activity of iron-carbon heterogeneous catalysis in the EF process, so as to degrade organic pollutants more effectively. This work would help to gain insight into the design of MOFs derived Fe-Mn bimetal catalyst and its mechanism for enhanced heterogeneous electro-Fenton.

Well-designed protein amyloid nanofibrils composites as versatile and sustainable materials for aquatic environment remediation: A review.

Amyloid nanofibrils (ANFs) are supramolecular polymers originally classified as pathological markers in various human degenerative diseases. However, in recent years, ANFs have garnered greater interest and are regarded as nature-based sustainable biomaterials in environmental science, material engineering, and nanotechnology. On a laboratory scale, ANFs can be produced from food proteins via protein unfolding, misfolding, and hydrolysis. Furthermore, ANFs have specific structural characteristics such as a high aspect ratio, good rigidity, chemical stability, and a controllable sequence. These properties make them a promising functional material in water decontamination research. As a result, the fabrication and application of ANFs and their composites in water purification have recently gained considerable attention. Despite the large amount of literature in this field, there is a lack of systematic review to assess the gap in using ANFs and their composites to remove contaminants from water. This review discusses significant advancements in design techniques as well as the physicochemical properties of ANFs-based composites. We also emphasize the current progress in using ANFs-based composites to remove inorganic, organic, and biological contaminants. The interaction mechanisms between ANFs-based composites and contaminants are also highlighted. Finally, we illustrate the challenges and opportunities associated with the future preparation and application of ANFs-based composites. We anticipate that this review will shed new light on the future design and use of ANFs-based composites.

Efficient visible-light-driven degradation of tetracycline by a 2D/2D rGO-Bi2WO6 heterostructure.

Constructing heterostructures has been a simple yet effective strategy for improving the photocatalytic performance of individual semiconductor photocatalysts. However, the poor quality of the contacted interface coupled with the narrow and overlapping light absorption scope between heterocomponents limits potential improvement. Herein, a 2D/2D rGO-Bi2WO6 heterostructure with face-to-face compact contact interface and UV to NIR light absorption ability was synthesized to overcome the aforementioned limitations. The as-prepared 2 wt%-rGO-Bi2WO6 with a high contact interface quality exhibits the highest kinetic rate of (5.53 ± 0.75) × 10-2 L mg-1 min-1 toward tetracycline (TC) degradation, which is 2.4 times higher than that of pristine Bi2WO6 and 2.1 times higher than that of the 2 wt%-rGO-Bi2WO6 composite with a poor interface quality. Moreover, approximately 30% of TC can be mineralized with a 2 wt%-rGO-Bi2WO6 presented system after 120 min. The subsequent Escherichia coli culture and liquid chromatography-mass spectrometry were employed to detect the biotoxicity variation of degradation intermediates and the possible transformation pathways of TC, respectively. Finally, the reactive species trapping results indicate that photogenerated holes and superoxide radical anions play dominant roles during the TC degradation process. This work provides a facile and effective method to fabricate an efficient heterojunction photocatalyst for pollutant degradation.

Development and evaluation of cancer differentiation analysis technology: a novel biophysics-based cancer screening method.

BACKGROUND: Routine health checkup is an essential strategy for monitoring population health and maintaining healthy workforces. However, there was a lack of cancer screening tests among routine health checkups due to high costs and unreliable methods. METHODS: We conducted a two-stage study to evaluate the value of a blood test, Cancer Differentiation Analysis (CDATM), which is developed to differentiate the blood samples of healthy individuals from those of cancer patients through measuring and analyzing multiple biophysical properties. RESULTS: The first stage of a cross-sectional study included 75,942 healthy individuals in routine health checkup, and the second stage of a prospective population-based cohort included 1,957 healthy community members. Forty-eight and ten cancer cases were identified among cross-sectional study and prospective population-based cohort, respectively. Using a pre-determined cutoff, we found that the CDA™ test could differentiate blood samples between healthy and cancer individuals with >93% specificity and >55% sensitivity in both studies. CONCLUSIONS: With high specificity and moderate sensitivity of CDA™ test, our study indicates that we can analyze biophysical properties in the blood to rapidly and reliably screen healthy individuals from cancer patients in a health checkup setting where most individuals are healthy or with average risk of cancer.

A novel electro-Fenton process coupled with sulfite: Enhanced Fe3+ reduction and TOC removal.

To promote the reduction of Fe3+ and improve the mineralization of organic pollutants, a novel electro-Fenton coupled with sulfite (Fe3+-EF/sulfite) process was constructed, which was superior to Fe3+-EF process in terms of carbamazepine (CBZ) degradation and mineralization with 5.99 times enhancement in degradation rate constant and 15.7 times enhancement on TOC removal. The complexation of Fe3+ and sulfite prevented the precipitation of Fe3+, reduced Fe3+ to Fe2+, and accelerated the iron cycle, so that H2O2 utilization efficiency (0.051 mgTOC mgH2O2-1) was greatly improved and electric energy consumption was greatly reduced (0.081 kWh g-1 TOC). The quenching experiments and EPR test confirmed that the reactive species, such as SO3•-, SO4•-, •OH, O2•- and 1O2 were responsible for the degradation of CBZ. This process also expanded the pH application range from 3 to 9 with satisfactory CBZ removal efficiency. This work verified the suitability of the Fe3+-EF/sulfite process for different sulfites (sulfite and bisulfite), typical pollutants (atrazine, sulfamethazine, rhodamine B) and real wastewater with 2.1-18.7 folds enhancement in degradation rate. The Fe3+-EF/sulfite process can achieve deep mineralization with low cost and simple operation, which has a broad and cost-effective application prospect in removal of refractory organic pollutants.

S-doped MIL-53 as efficient heterogeneous electro-Fenton catalyst for degradation of sulfamethazine at circumneutral pH.

The reduced S-modified MIL-53(Fe) was prepared by sulfurizing MIL-53(Fe) at low temperature, which was an efficient electro-Fenton catalyst at wide pH range (3-9) for sulfamethazine (SMT) degradation. The best temperature and MIL-53(Fe)/S ratio were 350 °C and 1:2, at which the BET surface area was much enlarged. The MIL-53(Fe) surface was etched by S to many 2D nanosheets with the thickness of ~50 nm, while S2-2 replaced OH- to coordinate with Fe2+ and increased the Fe2+ content, which improved the catalytic performance. Even at initial pH of 7.0, the SMT removal was 95.8%, and the rate constant (k) in the Hetero-EF process was 16-folds of that in the Homo-EF process. The turnover frequency (TOFd) value of MIL-53(Fe)/S(1:2)-350 was 0.48 L g-1 min-1, which was 6.8 times that of commercial FeS2. The S2-2in catalyst adjusted the pH superfast, and promoted the generation of Fe2+ and thus efficiently activating H2O2 to form surface ·OH, which was verified to be the main radical by EPR and radical scavenger experiments. This catalyst showed promising prospect for environmental application and could be regenerated by sulfidation method. S-doped MIL-53(Fe) was an excellent pH regulator, thus promoting promising application in Hetero-EF processes.

Derivatives of metal-organic frameworks for heterogeneous Fenton-like processes: From preparation to performance and mechanisms in wastewater purification - A mini review.

Organic pollution is an ever-growing issue in aquatic environment, Fenton-like processes have gained widespread acceptance due to their high oxidative potential and environmental compatibility. Derivatives of metal-organic frameworks (MOFs) are emerging heterogeneous Fenton-like catalysts, which have advantages of large surface area, diversity of structures, and abundant active sites. This work focuses on the recent advances in MOFs derivatives including metal compounds and metal incorporated carbons for Fenton-like processes. First, preparation strategies, structures and compositions are introduced. And then, the removal of organic pollutant in Fenton, electro-Fenton, and photo-Fenton process catalyzed by MOFs derivative is summarized, respectively. The contents particularly devote efforts to build connections among preparation, structures, compositions, and performance. Furthermore, the mechanisms of improving performance are discussed in detail. Finally, the perspectives of MOFs derivatives toward Fenton-like applications are proposed.

Synergistic Effect of Co(III) and Co(II) in a 3D Structured Co3O4/Carbon Felt Electrode for Enhanced Electrochemical Nitrate Reduction Reaction.

As nitrate contamination causes serious environmental problems, it is necessary to develop stable and efficient electrocatalysts for efficient electrochemical nitrate reduction reaction (ENRR). Here, a nonprecious Co3O4/carbon felt (CF) electrode with a 3D structure was prepared by integrating electrodeposition with calcination methods. This 3D structured Co3O4/CF electrode exhibits a high-rate constant of 1.18 × 10-4 s-1 cm-2 for the ENRR, surpassing other Co3O4 electrodes in previous literature. Moreover, it also has an excellent stability with a decrease of 6.4% after 10 cycles. Density functional theory calculations, electron spin resonance analysis, and cyclic voltammetry were performed to study the mechanism of the ENRR on the Co3O4/CF electrode, proving that atomic H* (indirect pathway) plays a prominent role in NO3- reduction and clarifying the synergistic effect of Co(III) and Co(II) in the Co(II)-Co(III)-Co(II) redox cycle for the ENRR: Co(III) prefers the adsorption of NO3- and Co(II) favors the production of H*. Based on this synergy, a relatively large amounts of Co(II) on the surface of the Co3O4/CF electrode (1.3 Co(II)/Co(III) ratio) was maintained by controlling the temperature of calcination to 200 °C with a lower energy barrier of H* formation of 0.46 eV than other ratios, which is beneficial for forming H* and enhancing the performance of the ENRR. Thus, this study suggests that building 3D structure and optimizing Co(II)/Co(III) ratio are important for designing efficient Co3O4 electrocatalyst for ENRR.

Efficient H2O2 generation and spontaneous OH conversion for in-situ phenol degradation on nitrogen-doped graphene: Pyrolysis temperature regulation and catalyst regeneration mechanism.

H2O2 is a green and valuable chemical that can be electrochemically synthesis from oxygen reduction, offering in-situ application for organic pollutants removal in environmental remediation. However, how to improve activity and further convert into powerful radicals is a still challenge. Herein, we show a facile and general approach to fabricate nitrogen-doped graphene (N-GE) catalyst via pyrolysis temperature regulation. The optimal N-GE at 400 °C exhibited the highest active N content (12.2 wt.%) and H2O2 selectivity (85.45 %) and spontaneous OH production (19.42 µM), achieving a high phenol degradation (93.58 %) at 180 min in neutral pH condition. Importantly, a simple catalyst regeneration method and mechanism was disclosed. It is proposed that the conversion of graphite N and pyridinic N in N-GE plays an important role in oxygen reduction reaction (ORR) and OH conversion, while the conversion of pyridinic N-oxide to pyridinic N is critical to catalyst stability and sustainability. This study provides a new insight into structure design of electro-catalyst about stability of nitrogen-doped carbon materials for efficient H2O2 generation and cost-effective pollutants removal.

Highly efficient electrosynthesis of hydrogen peroxide on a superhydrophobic three-phase interface by natural air diffusion.

Hydrogen peroxide (H2O2) synthesis by electrochemical oxygen reduction reaction has attracted great attention as a green substitute for anthraquinone process. However, low oxygen utilization efficiency (<1%) and high energy consumption remain obstacles. Herein we propose a superhydrophobic natural air diffusion electrode (NADE) to greatly improve the oxygen diffusion coefficient at the cathode about 5.7 times as compared to the normal gas diffusion electrode (GDE) system. NADE allows the oxygen to be naturally diffused to the reaction interface, eliminating the need to pump oxygen/air to overcome the resistance of the gas diffusion layer, resulting in fast H2O2 production (101.67 mg h-1 cm-2) with a high oxygen utilization efficiency (44.5%-64.9%). Long-term operation stability of NADE and its high current efficiency under high current density indicate great potential to replace normal GDE for H2O2 electrosynthesis and environmental remediation on an industrial scale.

Stable boron and cobalt co-doped TiO2 nanotubes anode for efficient degradation of organic pollutants.

Anode materials are crucial to anodic oxidation for wastewater treatment. In this regard, stable boron and cobalt co-doped TiO2 nanotube (B, Co-TNT) was prepared for the first time, and its lifetime was found increased significantly while electrocatalytic activity decreased with the increase of Co(NO3)2 in preparation from 1 to 10 mM. Characterized by scanning electron microscope (SEM), X-Ray Diffraction (XRD) and X-ray Photo-electronic Spectroscopy (XPS), B and Co content were optimized and successfully doped on TNT, which was more smooth without ripple with Co content of 0.038 mg/cm2 in a valence of +2, and B atomic content of 2.17 at.% in form of Ti-B-O. This optimized anode enhanced electrode lifetime 122.8 times while the electrochemical activity decreased slightly when compared to the undoped TNT. The effects of current density, initial pH and initial 2,4-dichlorophenoxyacetic acid (2,4-D) concentration were investigated, and the mainly responsible radical for degradation was confirmed to be the surface OH on B, Co-TNT anode. This anode had better performance on the TOC removal, mineralization current density (MCE) and energy consumption (Ec) when compared with BDD, PbO2, DSA and Pt anodes, and it also presented a very stable degradation for 10 cycles oxidation of 20 mg/L 2,4-D with allowable Co leaching. Therefore, B, Co-TNT anode is a promising, stable, safety and cost-effective anode for application in electrochemical advanced oxidation processes (EAOPs).

Photoelectrochemical degradation of 2,4-dichlorophenoxyacetic acid using electrochemically self-doped Blue TiO2 nanotube arrays with formic acid as electrolyte.

Blue TiO2 nanotube arrays (Blue-TNTs) were fabricated via an electrochemical reduction method with formic acid as the electrolyte. The optimum reduction conditions were obtained as bias potential of -1.3 V, reduction time of 5 min and formic acid of 3 M. Blue-TNTs were remarkably corroded compared with the intact TNTs. Similar crystal structures of the two catalysts were observed using X-ray diffraction, while red-shift was observed for Blue-TNTs using Raman spectra. X-ray photoelectron spectroscopy indicated of the presence of Ti3+ in Blue-TNTs that resulted from the reduction of Ti4+ and reduced the resistance of the catalyst. Blue-TNTs exhibited much stronger light-absorption than intact TNTs over the entire ultraviolet-visible region, especially in the visible region. The catalyst was used toward the photoelectrochemical oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D) for the first time where the influencing factors were studied. Photoelectrocatalysis with Blue-TNTs presented a 2,4-D degradation rate constant (0.0295 min-1) more than twice the sum of that of electrocatalysis (0.0055 min-1) and photocatalysis (0.0089 min-1). Blue-TNTs fabricated in formic acid showed a better photoelectrocatalytic performance for 2,4-D removal compared with that prepared in ethylene glycol, Na2SO4 and NaNO3 solution. Blue-TNTs is considered to be a promising photoelectric anode for contaminant degradation.

Extensive and selective adsorption of ZIF-67 towards organic dyes: Performance and mechanism.

Zeolitic imidazolate frameworks-67 (ZIF-67) was prepared via electrochemical deposition, which was used to conduct adsorptive removal of various organic dyes. The results revealed that ZIF-67 displayed good adsorption performance towards some dyes due to its positive Zeta potential at wide pH range or some special functional groups like SO3 of dyes. Also, ZIF-67 could separate some dyes from the matrix subjected to its preferential uptake towards certain dyes. The possible adsorption mechanism including electrostatic interactions, coordination interactions and hydrogen bonding interactions was proposed and tested.