GF Surface Research Articles

Interface construction of Ni(OH)2/Fe3O4 heterostructure decorating in-situ defected graphite felt for enhanced overall water splitting

There is a persistent need to design efficient and cheap electrode materials for water electrolysis. Herein, a hierarchical Ni(OH)2/Fe3O4/graphite felt (GF) (NFGF) heterostructure bifunctional electrocatalyst is tailor-designed to accelerate the water splitting process via boosting the heterostructure interfaces. A facile electrochemical method is probed to synthesize NFGF heterostructure with in-situ GF surface functionalization. Various analyses are used to demonstrate the GF in-situ surface functionalization and interface engineering. Remarkably, NFGF displays boosted hydrogen and oxygen evolution reactions by presenting a low overpotential of −50 mV and 281 mV at a current density of 10 mA cm−2 and 30 mA cm−2, respectively. Thus, NFGF is tested as a bifunctional electrocatalyst in the two-electrode cell and demonstrates a low cell voltage of 1.55 V at a current density of 10 mA cm−2 with outstanding performance over a long time of electrolysis up to 24 h.

Study of the Effect of NaOH Treatment on the Properties of GF/VER Composites Using AE Technique.

The purpose of this study is to use acoustic emission (AE) technology to explore the changes in the interface and mechanical properties of GF/VER composite materials after being treated with NaOH and to analyze the optimal modification conditions and damage propagation process. The results showed that the GF surface became rougher, and the number of reactive groups increased after treating the GF with a NaOH solution. This treatment enhanced the interfacial adhesion between the GF and VER, which increased the interfacial shear strength by 25.31% for monofilament draw specimens and 27.48% for fiber bundle draw specimens compared to those before the GF was modified. When the modification conditions were a NaOH solution concentration of 2 mol/L and a treatment time of 48 h, the flexural strength of the GF/VER composites reached a peak value of 346.72 MPa, which was enhanced by 20.96% compared with before the GF was modified. The process of damage fracture can be classified into six types: matrix cracking, interface debonding, fiber pullout, fiber relaxation, matrix delamination, and fiber breakage, and the frequency ranges of these failure mechanisms are 0~100 kHz, 100~250 kHz, 250~380 kHz, 380~450 kHz, 450~600 kHz, and 600 kHz and above, respectively. This paper elucidates the fracture process of GF/VER composites in three-point bending. It establishes the relationship between the AE signal and the interfacial and force properties of GF/VER composites, realizing the classification of the damage process and characterizing the mechanism. The frequency ranges of damage types and failure mechanisms found in this study offer important guidance for the design and improvement of composite materials. These results are of great significance for enhancing the interfacial properties of composites, assessing the damage and fracture behaviors, and implementing health monitoring.

Interfacial engineering of glass fiber‐reinforced vinyl ester resin composites: Using polydopamine‐SiO2 for property enhancement

AbstractTo enhance the flexural properties of glass fiber‐reinforced vinyl ester resin (GF‐VER) composites, this study focused on the influence of the duration of surface treatment on the flexural properties using polydopamine (PDA) and nanosilicon dioxide (nano‐SiO2). The GF‐VER composites were prepared via hot pressing. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized to characterize the microstructural and chemical attributes of the GF and GF‐VER composites. The mechanical properties of the GF‐VER composites were characterized using the flexural strength test. Furthermore, thermogravimetry was employed to investigate the thermal stability of the GF and the content of PDA nanoparticles on the GF. The results demonstrated that upon extending the treatment period, a greater quantity of PDA‐SiO2 nanoparticles adhered to the surface of the GF. The analysis of these results established that the optimal treatment duration is 12 h. This duration facilitated an enhanced adhesion between GF and VER owing to PDA‐SiO2, resulting in an optimal flexural strength of 562.8 MPa and signifying a 8.86% increase compared with the flexural strength of the untreated GF‐VER composites. Overall, the findings indicate that PDA‐SiO2 treatment greatly improves the flexural strength of GF‐VER composites.Highlights The method for modifying the GF surface was simple and mild. Silica nanoparticles were grafted onto GFs using dopamine as a reaction platform. The effect of the duration of PDA‐SiO2 treatment on the flexural strength of GF‐VER composites was examined. SEM revealed an improved GF‐VER interface. The flexural strength of the GF‐VER composites improved by 8.86%.

Glass fiber/epoxy composites with improved interfacial adhesion by using cross‐linking sizing agent

AbstractGlass fibers (GFs) are frequently employed as reinforcement fibers for polymer resins such as epoxy and polyester. The mechanical behaviors of GFs polymer composites are nevertheless constrained by weak interfacial adhesion between polymer matrix and GFs. Herein, we invented a cross‐linking modified sizing agent using polyethyleneimine and bisphenol A epoxy emulsion, and studied the effect of cross‐linking extent on GF surface characteristics and GF/epoxy interfacial adhesion. The treatment of GFs with cross‐linking modified sizing agent facilitated the formation of interpenetrating polymer networks in composites for strengthening interface interaction. The results show that the modified GFs have a rough surface and improved interfacial adhesion with epoxy matrix. When sizing agents with cross‐linking extent of the 23.0%, the GF/epoxy composites show advanced interfacial shear strength (IFSS) and transverse fiber bundle tension (TFBT) strength. This work demonstrates that the cross‐linking extent of sizing agent could regulate interfacial adhesion, which is a facile and promising strategy in reinforcing glass fiber polymer composites.Highlights Crosslink the sizing agent to enhance GF mechanical properties was reported. GF surface energy was enhanced and thickness of GF/epoxy interphase increased. IFSS and TFBT strength of the GF/resin composites increased by 23.65% and 30.54%, respectively.

Development of cashew nut shell lignin-acrylonitrile butadiene styrene 3D printed core and industrial hemp/aluminized glass fiber epoxy biocomposite for morphing wing and unmanned aerial vehicle applications

The aim of this study was to develop a lightweight epoxy based biocomposite for morphing wing and unmanned aerial vehicle (UAV) applications. The proposed composite was developed using a 3D printed high stiffness lignin-Acrylonitrile Butadiene Styrene (ABS) core and industrial hemp with aluminized glass fiber epoxy skin. The ABS was reinforced using lignin macromolecule derived from cashew nut shells via twin screw extruder and the core was printed using an industrial grade 3D printer. Furthermore, the composites were prepared by compression moulding with an ABS-lignin core and hemp/aluminized GF surface and characterized according to respective American society of testing and materials (ASTM) standards. The findings indicate that the addition of 30 vol% Al-glass and hemp fiber with lignin strengthened ABS core improved the mechanical properties. The composite material designated as “E2” exhibits the maximum mechanical properties, providing tensile strength, flexural strength, Izod impact, interlaminar shear strength (ILSS), and compression values of, 136 MPa, 168 MPa, 4.82 kJ/m2, 21 MPa, and 155 MPa respectively. The maximal energy absorbed by composite designation “E2,” during drop load impact test is 20.6 J. Similarly, the composite designation “E2”gives fatigue life cycles of 33,709, 25,781 and 19,633 for 50 %, 70 % and 90 % of ultimate tensile strength (UTS) and 32.5 (K1c) MPa⋅m and 0.76 (G1c) MJ/m2 in fracture toughness and energy release rate respectively.

Wrapping massive MnO2 around in-situ defective carbon felt with strong interaction for superb supercapacitive performance

This study focuses on the dual-functional one-step preparation method and characterization of the high-mass loading electrode with outstanding capacitive performance. Three electrodes, MnO2/GF-100, MnO2/GF-300, and MnO2/GF-600, are prepared using anodic polarization from a solution containing various concentrations of MnSO4, 100 mM, 300 mM, and 600 mM, respectively. The anodic electrodeposition of massive MnO2 in conjunction with in-situ functionalization of GF is done via sweeping anodic potential from 2.5 to 0.5 V alongside a sweep rate of 5 mV s−1. At a high potential region, the GF surface is modified via oxygenated functional groups that assist in the regular deposition of MnO2. In the low potential region, the degree of MnO2 deposition is heightened. Additionally, by raising the salt concentration in the deposition bath, the extent of GF's functionalization is greatly enhanced, leading to heavy deposition of MnO2 with a cinnamon stick-like structure and rolling GF. Wrapping MnO2 over defective GF is addressed using characterization tools, SEM, Mapping EDX, XPS, XRD, contact angle measurements, and Raman analysis. Advantageously, the amorphous and massive MnO2/GF-600 electrode (3.82 mg cm−2), with a cinnamon stick-like structure, displays the best performance by exhibiting a maximum specific capacitance of 627.9 mF cm−2 (166.9 F g−1) over a wide potential window up to 2.4 V. Interestingly, MnO2/GF-600 shows superb capacitance retention of 129% for 5000 cycles. The remarked capacitive execution is assigned to enhanced conductivity, an amorphous structure, and strong contact between the electrode and MnO2 active material.

Mediating Triple Ions Migration Behavior via a Fluorinated Separator Interface toward Highly Reversible Aqueous Zn Batteries.

Rampant dendrite growth, electrode passivation and severe corrosion originate from the uncontrolled ions migration behavior of Zn2+ , SO4 2- , and H+ , which are largely compromising the aqueous zinc ion batteries (AZIBs) performance. Exploring the ultimate strategy to eliminate all the Zn anode issues is challenging but urgent at present. Herein, a fluorinated separator interface (PVDF@GF) is constructed simply by grafting the polyvinylidene difluoride (PVDF) on the GF surface to realize high-performance AZIBs. Experimental and theoretical studies reveal that the strong interaction between C─F bonds in the PVDF and Zn2+ ions enables evenly redistributed Zn2+ ions concentration at the electrode interface and accelerates the Zn transportation kinetics, leading to homogeneous and fast Zn deposition. Furthermore, the electronegative separator interface can spontaneously repel the SO4 2- and anchor H+ ions to alleviate the passivation and corrosion. Accordingly, the Zn|Zn symmetric cell with PVDF@GF harvests a superior cycling stability of 500h at 10 mAh cm-2 , and the Zn|VOX full cell delivers 76.8% capacity retention after 1000 cycles at 2 A g-1 . This work offers an all-round solution and provides new insights for the design of advanced separators with ionic sieve function toward stable and reversible Zn metal anode chemistry.

Modification of the interfacial glass fiber surface through graphene oxide-chitosan interactions for excellent dye removal as an adsorptive membrane

In the present study, the interfacial surface of glass fiber, i.e., GF-like inorganic membrane, was modified using the functional groups of graphene oxide (GO)/chitosan (CTS) hybrid network for the first time. It is considered as a successful incorporation to fabricate the GO/CTS-GF-GO/CTS (GC-GF-GC) composite membrane for wastewater treatment applications, using a very simple and low-cost casting process, which can become a promising adsorptive membrane (AM). More obviously, the adsorption performance of the AM in removing cationic and anionic dyes was excellent, and it exhibited superb recycling performance compared to other existing types of AM. In addition, the adsorption performance was shown to be consistent with the pseudo-second-order and Langmuir models, regard with a chemical adsorption and a monolayer approach, respectively. Due to the additional linking bond formations and interactions between the GF surface and the active GC hybrid network through their functional groups, the dye adsorption and desorption capacities were significantly enhanced. The interfacial GF surface was formed by its interfacial linking bridges, as well as it sustained the composite membrane and provided an outstanding performance in the recycling approach. Thus, the GC-GF-GC membrane is a superb adsorbent for wastewater treatment that may contribute to build an eco-friendly AM in this field, i.e., the organic dye removal in textile industries wastewater.

Reinforcing urea‐formaldehyde based composite foam by formation of tailored chemical/mechanical interlocking structure

AbstractUrea‐formaldehyde (UF) foam is considered to be a potential alternative for commercial polymeric foams due to its intrinsic flame retardancy and inexpensiveness, but it showed high brittleness and low strength, which restricts its wide applications. In this work, glass fiber powder (GF) was selected as the reinforcing filler, and by formation of tailored chemical/mechanical interlocking structure for the composite system, UF foam was highly reinforced. The surface of GF was coated with granular polydopamine (PDA) layer through self‐polymerization of dopamine, and then, carbon nanotubes (CNTs) were further grafted onto GF surface with high grafting ratio via the bridge effect of PDA to construct a network like entanglement structure. The active groups of PDA layer on GF surface generated chemical/hydrogen bonding interactions with UF matrix, while rough CNTs network structure promoted the mechanical interlocking between GF and UF resin. Such multiple interfacial enhancement improved the stress transmission ability of the interface, exhibiting “supporting” on the cell wall and “cracks bridging” effect of GF. Compared with neat UF foam, the composite foam exhibited smaller cell size, narrower cell size distribution, higher cell density, more complete closed cell structure, while compressive strength and modulus of the composite foam increased by 78.7% and 90.08%, respectively. Moreover, the composite foam showed improved thermal stability and excellent flame retardancy with V‐0 rating of UL‐94 tests.

Uniform polypyrrole electrodeposition triggered by phytic acid-guided interface engineering for high energy density flexible supercapacitor

Unevenly distributed polypyrrole (PPy) films/coatings with extensive “dead volumes” via electrodeposition have emerged as a main challenge for high energy density flexible supercapacitor. In this work, we have fabricated a phytic acid-guided graphite carbon felt/polypyrrole (GF@PA@PPy) 3D porous composite with less “dead volumes” via electrodeposition. After the activation of phytic acid (PA), the quantity and content of defects and oxygen-containing groups on the surface of carbon felt (GF) have increased. First, these functional groups improve the hydrophilicity of the surface of GF, resulting in the preferential uniform distribution of pyrrole monomer (Py). While significantly, the synergistic effects between the defects and oxygen-containing groups boost the attraction of pyrrole ring, and thus promotes the formation of perfect PPy films with less “dead volume” on GF. Finally, the supercapacitor assembled from the GF@PA@PPy-40 displays a high areal energy density of 0.0732 mWh cm−2, exceeding the previously reported PPy-based electrodes values. The deeper understanding of the role for the defects and oxygen-containing groups in the synthesis of PPy/carbon materials offers a new strategy to construct advanced PPy-based supercapacitors.

A Finite Element Investigation into the Cohesive Properties of Glass-Fiber-Reinforced Polymers with Nanostructured Interphases.

Glass-fiber-reinforced polymer (GFRP) composites represent one of the most exploited composites due to their outstanding mechanical properties, light weight and ease of manufacture. However, one of the main limitations of GFRP composites is their weak inter-laminar properties. This leads to resin delamination and loss of mechanical properties. Here, a model based on finite element analysis (FEA) is introduced to predict the collective advantage that a GF surface modification has on the inter-laminar properties in GFRP composites. The developed model is validated with experimental pull-out tests performed on different samples. As such, modifications were introduced using different surface coatings. Interfacial shear stress (IFSS) for each sample as a function of the GF to polymer interphase was evaluated. Adhesion energy was found by assimilating the collected data into the model. The FE model reported here is a time-efficient and low-cost tool for the precise design of novel filler interphases in GFRP composites. This enables the further development of novel composites addressing delamination issues and the extension of their use in novel applications.

Improved properties of PTFE composites filled with glass fiber modified by sol–gel method

PTFE/GF(glass fiber) composites are widely applied in high-frequency printed circuit board (PCB) substrate materials due to the excellent dielectric properties of PTFE and the low thermal expansion coefficient of GF. However, the poor interface compatibility between PTFE and GF affects the performance of the composite substrates. In this study, tetraethyl orthosilicate (TEOS) was used as the silicon source, and polydimethylsiloxane (PDMS) was the organic precursor to modify the surface of GF through the sol–gel method to promote the interface compatibility of GF and PTFE. The modified GF noted T-GF was filled in PTFE to prepare PTFE/T-GF composites. SEM, FTIR, XPS, and contact angle confirmed that organic–inorganic hybrids were successfully loaded on GF's surface. Moreover, compared with PTFE/GF and the conventional coupling agent modified GF filled PTFE composites, the PTFE/T-GF exhibited improved dielectric constant (2.305), decreased dielectric loss (9.08E−4), higher bending strength (21.45 MPa) and bending modulus (522 MPa), better thermal conductivity (0.268 W/m*K) and lower CTE (70 ppm/°C), making it has promising application as the substrate materials for high frequency PCB.

Characteristics of Graphite Felt Electrodes Treated by Atmospheric Pressure Plasma Jets for an All-Vanadium Redox Flow Battery.

In an all-vanadium redox flow battery (VRFB), redox reaction occurs on the fiber surface of the graphite felts. Therefore, the VRFB performance highly depends on the characteristics of the graphite felts. Although atmospheric pressure plasma jets (APPJs) have been applied for surface modification of graphite felt electrode in VRFBs for the enhancement of electrochemical reactivity, the influence of APPJ plasma reactivity and working temperature (by changing the flow rate) on the VRFB performance is still unknown. In this work, the performance of the graphite felts with different APPJ plasma reactivity and working temperatures, changed by varying the flow rates (the conditions are denoted as APPJ temperatures hereafter), was analyzed and compared with those treated with sulfuric acid. X-ray photoelectron spectroscopy (XPS) indicated that the APPJ treatment led to an increase in O-/N-containing functional groups on the GF surface to ~21.0% as compared to ~15.0% for untreated GF and 18.0% for H2SO4-treated GF. Scanning electron microscopy (SEM) indicated that the surface morphology of graphite felt electrodes was still smooth, and no visible changes were detected after oxidation in the sulfuric acid or after APPJ treatment. The polarization measurements indicated that the APPJ treatment increased the limiting current densities from 0.56 A·cm−2 for the GFs treated by H2SO4 to 0.64, 0.68, and 0.64 A·cm−2, respectively, for the GFs APPJ-treated at 450, 550, and 650 °C, as well as reduced the activation overpotential when compared with the H2SO4-treated electrode. The electrochemical charge/discharge measurements showed that the APPJ treatment temperature of 550 °C gave the highest energy efficiency of 83.5% as compared to 72.0% with the H2SO4 treatment.

Tailoring the microstructure of an oriented graphite flake/Al composite produced by powder metallurgy for achieving high thermal conductivity

An Al matrix composite reinforced with 40 vol% graphite flake (Gf) was developed by powder metallurgy as a promising candidate for thermal management applications. Thermal conductivity (TC) along the orientation direction of the composite sintered at 640 °C was measured to be 452 W/m K, which is approximate to the highest TC value theoretically predicted by effective medium approximation model. The three underlying mechanisms responsible for such TC enhancement were clarified in terms of microstructure characterization. First, heat treatment of as-received Gf under Ar + H2 atmosphere resulted in reduction of defects on the edge contributing to improvement of interface thermal exchange efficiency between Al and Gf. Second, image analysis quantitatively confirmed that a step-by-step die filling process using the spherical powder ensures the perfect orientation of Gf in the Al matrix. Third, it was found that the TC of the composite increases with the sintering temperature from 580 to 640 °C. The formation of a small amount of fine platelet-like Al4C3 at the interface between the side surface of Gf and Al matrix indicates the desirable bonding state for minimizing interfacial thermal resistance, beneficial for the overall TC enhancement. Besides, the relevant coefficient of thermal expansion and bending strength were discussed.

Glass fiber reinforced PET modified by few‐layer black phosphorus

AbstractGlass fiber reinforced polyethylene terephthalate (PET/GF) with enhanced flame retardancy was prepared with few‐layer black phosphorus (BPs) for the first time. The performance of red phosphorus (RP) modified PET/GF was also investigated for comparison. Results show that PET/GF with 0.9 wt% BPs (PET/GF@BP‐0.9) can eliminate the ignition of cotton by dripping. The addition of 2.7 wt% of BPs can make the PET/GF sample pass UL 94 V‐0 classification, while a much higher of 6.3 wt% RP was needed to pass the same classification. Compared with neat PET/GF, the peak heat release rate (PHRR) and total heat release (THR) rate of PET/GF@BP‐2.7 decreases ca. 52.5% and 34.8%, respectively. The studies of char residues reveal that BPs could act as a catalyst for char formation and the formed char could roughen the surface of GF and thus restrain the “wick effect.” Thermogravimetric analysis/infrared spectrometry shows that the addition of BPs significantly inhibited the release of gas‐phase products. The attractive abilities of BPs as flame retardant provide a novel and effective way of PET/GF modification.

Room temperature xylene sensor based on Co3O4/GF hybrid

Sensitive Xylene solid-state gas sensor based graphene foam decorated with cobalt oxide has been successfully fabricated via a simple impregnation method. The structure and surface morphological analysis carried out using multiple techniques including XRD, SEM, Raman, TGA, BET, and BJH. The morphological examination using SEM confirmed that spherical CO3O4 particles fully covered both the outer surface and interior pores of GF. Raman analysis confirmed that both characteristic bands for carbon nanomaterials are absent. The specific surface area was estimated using the BET method to be 543.254 m²/g which is a relatively high value. The prepared sensors showed a good response towards xylene. Moreover, we examine the sensitivity of the CO3O4/GF sensor to detect other volatile organic compounds, such as methanol, ethanol, toluene, and heptane, demonstrating that the CO3O4/GF sensor exhibits excellent sensitivity to xylene (detection limit = 0.5 ppm) at room temperature.

Simultaneously Providing Iron Source toward Electro-Fenton Process and Enhancing Hydrogen Peroxide Production via a Fe3O4 Nanoparticles Embedded Graphite Felt Electrode.

Electro-reduction of O2 to generate H2O2 is an attractive alternative to the current anthraquinone process and quite necessary for chemical industries and environmental remediation. In general, sufficient porous structure contributes to expose more catalytic active sites and shorten diffusion paths for the heterogeneous catalysis of O2. In this work, initially the Fe3O4 nanoparticles embedded graphite felt (Fe3O4@GF) is prepared through a mild hydrothermal following with thermal reduction method. This special combination not only provides iron source for the electro-Fenton reaction but also supplies rich active sites from the Fe3O4 embedded structure with abundant cracks, which are beneficial to increase the reaction rate. Compared with raw graphite felt (RGF), fresh Fe3O4@GF exhibits superior pollutant degradation kinetics with more than 400% increase and approximately 37.8% improvement to the removal of total organic carbon. A 98% decolorization of rhodamine B (RhB) can be achieved in just 5 min and quickly completes 100% removal of RhB in the next few seconds. As the electro-Fenton reaction progresses, Fe3O4 dissolves in the electrolyte, leaving a porous structure on the surface of the GF to form a porous GF (PGF), and the rapid radical reaction activates the GF surface. Both the chemical etching of Fe3O4 and the electro-Fenton process can further increase the specific surface area, defects, and actives sites of the electrode. As expected, the active PGF exhibits favorable performance of H2O2 production in electrolytes of different pHs: 1 (320.0 ± 36.5 mg L-1), 3 (301.9 ± 13.2 mg L-1), and 7 (320.4 ± 21.2 mg L-1). The degradation performance of PGF does not significantly decay even after 20 cycles of repeated use, indicating the good structural stability and long-term durability. The superiority of the in situ Fe source and fast reaction kinetics for electro-Fenton of Fe3O4@GF is confirmed, and this holey engineered strategy also provides the possibility to achieve swift water purification and open up a new way for developing efficient carbon-based electrodes.

Heterogeneous Electro-Fenton Process by MWCNT-Ce/WO3 Nanocomposite Modified GF Cathode for Catalytic Degradation of BTEX: Process Optimization Using Response Surface Methodology

This study investigates the degradation and mineralization of BTEX by heterogeneous electro-Fenton process using GO/MWCNT/Fe3O4 as a catalyst and MWCNT-Ce/WO3/GF as an electrode. The nanoscale MWCNT-Ce/WO3 composite catalyst was distributed more evenly on GF surface to form a catalyst layer with higher oxygen reduction reaction performance. After optimization of pH and time variables, the Box–Behnken experimental design (BBD) and response surface methodology (RSM) were used to design and optimize the performance of proposed system and energy consumption. Analysis of variance (ANOVA) revealed that the quadratic model was adequately fitted to the experimental data with R2 (0.98) and adj-R2 (0.97). The significance levels of linear and interaction effects of the reaction parameters on process efficiency were obtained. Then, the optimization of the working conditions for the design of a sustainable treatment system with optimum efficiency was carried out using a response surface methodology. The experiment carried out in the calculated optimal conditions for the electro-Fenton degradation process (current intensity 300 mA, catalyst dosage of 0.6 g, initial BTEX concentration of 100 ppm, and electrode distance of 1 cm) showed a BTEX removal of 73.2% and energy consumption of 12.3 (kWh/m3) close to the theoretical value predicted by the model 73. 2% and 11.8 (kWh/m3), respectively. Furthermore, the reusability test of GO/MWCNT/Fe3O4 nanocomposite after several cycles confirmed the high catalytic activities of adsorbent. Comparing the proposed system with conventional GF electrode and Fe2+ catalyst showed that modification of cathode and catalyst led to increasing COD removal efficiency by around 36.6 and 31.6%, respectively. The findings of present study revealed that the proposed heterogeneous electro-Fenton process can be utilized as pre-treatment technology to improve the biodegradability and reduce the organic load of wastewater by combine oxidation and coagulation.

Enhanced Bio-Electro-Fenton degradation of phenolic compounds based on a novel Fe–Mn/Graphite felt composite cathode

Phenolic compounds are problematic byproducts generated from lignocellulose pretreatment. In this study, the feasibility degradation of syringic acid (SA), vanillic acid (VA), and 4-hydroxybenzoic acid (HBA) by Bio-Electro-Fenton (BEF) system with a novel Fe–Mn/graphite felt (Fe–Mn/GF) composite cathode were investigated. The nano-scale Fe–Mn multivalent composite catalyst with core shell structure distributed more evenly on GF surface to form a catalyst layer with higher oxygen reduction reaction performance. Accordingly, the maximum power density generated with Fe–Mn/GF cathode was 48.1% and 238.9% higher than Fe/GF and GF respectively, which further enhanced the in situ generation of H2O2 due to the superiority of nano-scale core shell structure and synergistic effect of Fe and Mn species. The degradation efficiency of the three phenolic compounds in the BEF system could reached 100% after optimization of influencing parameters. Furthermore, a possible SA degradation pathway by BEF process in the present system was proposed based on the detected intermediates. These results demonstrated an efficient approach for the degradation of phenolic compounds derived from lignocellulose hydrolysates.

Simultaneous electrochemical determination of levodopa and uric acid based on ZnS nanoparticles/3D graphene foam electrode

Levodopa and uric acid are important neurotransmitters associated with many neurological diseases. Abnormal concentrations of levodopa and uric acid in biological fluids can be used for the evaluation of such diseases. In this work, three-dimensional graphene foam (3D GF) was prepared by chemical vapor deposition. ZnS nanoparticles were in-situ grown on the surface of 3D GF (ZnS NPs/3D GF) using a simple hydrothermal method, which was used to simultaneously determinate levodopa and uric acid. The results show that a porous mesh film made up of ZnS NPs with the diameter of 200 nm is evenly covered on the surface of 3D GF. The ZnS NPs/3D GF electrode exhibits a high sensitivity of 2.34 and 2.39 μA·μM−1·cm−2 for the detection of levodopa and uric acid, respectively. Also, it shows a low limit of detection, excellent selectivity, good anti-interference ability and stability. Moreover, the electrode was successfully used in human plasma samples.