Magnetically attracted iron scrap anode based electrocoagulation for phosphate removal.

This study shows the effectiveness of a novel electrocoagulation process using magnetically attracted iron scrap anodes for phosphate removal from aqueous solution. The effect of contact time, reaction temperature, dose of iron scrap, initial phosphate concentration, applied voltage, pH, magnetic force, and the species of competing anions on the efficiency of phosphate removal and the reaction products has been investigated. The techniques of XRD, XPS, and VSM were used to characterize the elemental composition and the types of the reaction products in order to clarify the interaction between novel anode and phosphate ions. The removal of phosphate was fitted by a pseudo first-order reaction kinetic model. The results showed that magnetically attracted iron scrap anodes were electrodissoluted under an applied potential and reacted with phosphate into Fe-hydroxo-phosphate complexes. The work suggested that electrocoagulation using magnetically attracted iron scrap anodes had the potential to become a promising technique for phosphate precipitation.

A flexible wearable self-supporting hybrid supercapacitor device based on hierarchical nickel cobalt sulfide@C electrode.

A flexible wearable electrode consisting of nickel-cobalt sulfide (NCS) nanowires was fabricated in this study. Self-supporting NCS was grown in situ on porous carbon nanofibers without a binder as a novel material for supercapacitor electrodes. The NCS nanowires were grown using cyclic voltammetry electrodeposition, which proved to be a fast and environmentally friendly method with good controllability of the material structure. One-dimensional carbon nanofibers (C) have high surface-area-to-volume ratios, short ion transmission distances, excellent mechanical strengths, and remarkable flexibilities. Moreover, the NCS@C flexible electrode exhibited a synergetic effect with the active compounds, and the dense active sites were uniformly distributed across the entire surface of the carbon fibers, enabling rapid electron transport and enhancing the electrochemical properties of the NCS@C nanowires. The NCS@C achieved specific capacitances of 334.7 and 242.0 mAh g-1 at a current density of 2 A g-1 and high current densities (up to 40 A g-1), respectively, corresponding to a 72.3% retention rate. An NCS@C-nanofilm-based cathode and an activated-carbon-based anode were used to fabricate a flexible asymmetric supercapacitor. The device exhibited high energy and power densities of 12.91 Wh kg-1 and 358 W kg-1, respectively.

Electroreduction of H2O2 by Co3O4 and NiCo2O4 nanowires and beta-Ni(OH)2 nanoplates grown on Ni foam.

Nanowires (Co3O4 and NiCo2O4) and nanoplates (beta-Ni(OH)2) grown on Ni foam are successfully prepared by a template-free method and used as cathode electrodes for the electroreduction of H2O2, in an alkaline medium. Catalytic performance is investigated via cyclic voltammetry and chronoamperometry. The Co3O4 and NiCo2O4 nanowire electrodes exhibit much better catalytic activity, stability, and mass transfer properties for H2O2 electroreduction than pressed Co3O4 and NiCo2O4 nanoparticle/carbon/PTFE electrodes. A current density of 101.8 mA cm(-2) and 122.7 mA cm(-2) are respectively achieved on Co3O4 and NiCo2O4 nanowire electrodes at -0.4 V in 0.4 mol/L H2O2, and 3.0 mol/L NaOH solution at room temperature.

Synthesis of Co3O4 nanowire arrays supported on Ni foam for removal of volatile organic compounds.

Crystalline Co3O4 nanowire arrays freely supported on Ni foam are successfully synthesized using a template-free method. The effects of reaction time, concentration of reactants, and temperature on the morphology of the nanowires are studied. The results indicate that uniform Co3O4 nanowires could be synthesized at 90 degrees C, and a transformation of the samples' morphology from nanoparticles to nanowires to microrods is observed by controlling the concentration of the reactants. The well-ordered nanowires synthesized under the selected reaction conditions are composed of spinel Co3O4 with diameters of 500-580 nm and lengths of 6-8 microm. These nanowires show good catalytic activity for the ozone catalytic oxidation of toluene.

In Situ Characterization for Boosting Electrocatalytic Carbon Dioxide Reduction.

The electrocatalytic reduction of carbon dioxide into organic fuels and feedstocks is a fascinating method to implement the sustainable carbon cycle. Thus, a rational design of advanced electrocatalysts and a deep understanding of reaction mechanisms are crucial for the complex reactions of carbon dioxide reduction with multiple electron transfer. In situ and operando techniques with real-time monitoring are important to obtain deep insight into the electrocatalytic reaction to reveal the dynamic evolution of electrocatalysts' structure and composition under experimental conditions. In this paper, the reaction pathways for the CO2 reduction reaction (CO2 RR) in the generation of various products (e.g., C1 and C2 ) via the proposed mechanisms are introduced. Moreover, recent advances in the development and applications of in situ and operando characterization techniques, from the basic working principles and in situ cell structure to detailed applications are discussed. Suggestions and future directions of in situ/operando analysis are also addressed.

Mechanistic insights into NO‒H2 reaction over Pt/boron-doped graphene catalyst.

This work presents a systematical experimental and density functional theory (DFT) studies to reveal the mechanism of NO reduction by H2 reaction over platinum nanoparticles (NPs) deposited on boron-doped graphene (denoted as Pt/BG) catalyst. Both characterizations and DFT calculations identified boron (in Pt/BG) as an additional NO adsorption site other than the widely recognized Pt NPs. Moreover, BG led to a decrease of Pt NPs size in Pt/BG, which facilitated hydrogen spillover. The mathematical and physical criteria of the Langmuir-Hinshelwood dual-site kinetic model over the Pt/BG were satisfied, indicating that adsorbed NO on boron (in Pt/BG) was further activated by H-spillover. On the other hand, Pt/graphene (Pt/Gr) demonstrated a typical Langmuir-Hinshelwood single-site mechanism where Pt NPs solely served as active sites for NO adsorption. This work helps understand NO-H2 reaction over Pt/BG and Pt/Gr catalysts in a closely mechanistic view and provides new insights into roles of active sites for improving the design of catalysts for NO abatement.

Simultaneous removal of ammonia and phosphate by electro-oxidation and electrocoagulation using RuO2-IrO2/Ti and microscale zero-valent iron composite electrode.

Electro-oxidation using RuO2-IrO2/Ti plate anode and electrocoagulation using iron plate anode were widely applied to remove ammonia and phosphate in an aquatic environment, respectively. In this work, we designed magnetically bound ZVI microparticles on RuO2-IrO2/Ti plate as a composite electrode for the simultaneous removal of ammonia and phosphate from aqueous solution via combined EO and EC (EO/EC) processes. We present a series of experiments to study such simultaneous removal under an electric field via the EO/EC process. In the electrochemical unit, mZVI-RuO2-IrO2/Ti, mZVI-graphite, and RuO2-IrO2/Ti electrodes were used as anodes. The influence of applied voltage, initial pH, zero-valent iron dosage, reaction temperature, and organic compounds on the EO/EC process was also examined. Ammonia and phosphate could be completely removed at an applied voltage of 10 V, pH of 7, zero-valent iron dosage of 0.1 g, and reaction temperature of 35 °C using mZVI-RuO2-IrO2/Ti anode when influent ammonia and phosphate concentrations is 200 and 100 mg L-1. Ammonia degradation was consistent with pseudo-zero-order kinetic model. The characterization was analyzed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Hence, the mZVI-RuO2-IrO2/Ti electrode can be used for efficient simultaneous removal of ammonia and phosphate.

Supercapacitor performance of porous nickel cobaltite nanosheets.

In this work, nickel cobaltite (NiCo2O4) nanosheets with a porous structure were fabricated on nickel foam as a working electrode for supercapacitor applications. The nanosheets were fabricated by electrochemical deposition of nickel-cobalt hydroxide on the nickel foam substrate at ambient temperature in a three-electrode cell followed by annealing at 300 °C to transform the coating into a porous NiCo2O4 nanosheet. Field emission scanning electron microscopy and transmission electron microscopy revealed a three-dimensional mesoporous structure, which facilitates ion transport and electronic conduction for fast redox reactions. For one cycle, the NiCo2O4 electrodeposited nickel foam has a high specific capacitance (1734.9 F g-1) at a current density (CD) of 2 A g-1. The electrode capacitance decreased by only approximately 12.7% after 3500 cycles at a CD of 30 A g-1. Moreover, a solid-state asymmetric supercapacitor (ASC) was built utilising the NiCo2O4 nanosheets, carbon nanotubes, and a polyvinyl alcohol-potassium hydroxide gel as the anode, cathode, and solid-state electrolyte, respectively. The ASC displayed great electrochemical properties with a 42.25 W h kg-1 energy density at a power density of 298.79 W kg-1.

Treatment of landfill leachate using magnetically attracted zero-valent iron powder electrode in an electric field.

This study combined electro-oxidation (EO) and electrocoagulation (EC) process (EO/EC) to treat landfill leachate by using RuO2-IrO2/Ti plate and microscale zero-valent iron powder composite anode. EO was achieved by direct oxidation and indirect oxidation on RuO2-IrO2/Ti plate, whereas EC was achieved using iron powder to lose electrons and produce coagulants in situ. The influences of variables including type of anode material, applied voltage, zero-valent iron dosage, interelectrode gap, and reaction temperature on EO/EC were evaluated. Results showed that at an applied voltage of 10 V, zero-valent iron dosage of 0.2 g, interelectrode gap of 1 cm, and non-temperature-controlled mode, the removal efficiencies were 72.5 % for total organic carbon (TOC), 98.5 % for ammonia, and 98.6 % for total phosphorus (TP). Some heavy metals and hardness were also removed. Further analysis indicated that the removal of TOC, ammonia, and TP followed pseudo-first order, pseudo-zero order, and pseudo-second order kinetic models, respectively. Other characteristics were examined by scanning electron microscopy-energy dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Overall, our results showed that EO/EC can be used to efficiently remove organic matter, ammonia, TP, and heavy metals from landfill leachate.

Synthesis and Characterization of a NiCo2O4@NiCo2O4 Hierarchical Mesoporous Nanoflake Electrode for Supercapacitor Applications.

In this study, we synthesized binder-free NiCo2O4@NiCo2O4 nanostructured materials on nickel foam (NF) by combined hydrothermal and cyclic voltammetry deposition techniques followed by calcination at 350 °C to attain high-performance supercapacitors. The hierarchical porous NiCo2O4@NiCo2O4 structure, facilitating faster mass transport, exhibited good cycling stability of 83.6% after 5000 cycles and outstanding specific capacitance of 1398.73 F g-1 at the current density of 2 A·g-1, signifying its potential for energy storage applications. A solid-state supercapacitor was fabricated with the NiCo2O4@NiCo2O4 on NF as the positive electrode and the active carbon (AC) was deposited on NF as the negative electrode, delivering a high energy density of 46.46 Wh kg-1 at the power density of 269.77 W kg-1. This outstanding performance was attributed to its layered morphological characteristics. This study explored the potential application of cyclic voltammetry depositions in preparing binder-free NiCo2O4@NiCo2O4 materials with more uniform architecture for energy storage, in contrast to the traditional galvanostatic deposition methods.

3D heterostructured cobalt oxide@layered double hydroxide core-shell networks on nickel foam for high-performance hybrid supercapacitor.

High performance of an electrode relies largely on scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. Here, a 3D heterostructured core-shell architecture was fabricated as a supercapacitor electrode, in which Co3O4 nanowire cores were grown on nickel foam prior to the in situ deposition of layered double hydroxide (LDH) nanosheet shells. Owing to the unique configuration and hybridization, the as-fabricated Co3O4@LDH core-shell electrode exhibited high capacities of 818.6 C g-1 at 2 A g-1 and 479.3 C g-1 at 40 A g-1 (3.2 C cm-2 at 7.8 mA cm-2 and 1.87 C cm-2 at 156 mA cm-2), which were much higher than those of the individual components, namely, Co3O4 and LDH. A hybrid supercapacitor with Co3O4@LDH as the positive electrode and graphene nanosheets as the negative electrode yielded an energy density of 53.2 W h kg-1 and a power density of 16.4 kW kg-1, which outperformed devices reported in the literature; the device also exhibited long-term cycling stability and retained 71% of its initial capacity even after 10 000 cycles at 6 A g-1. The rational design of the core-shell architecture may lead to the development of new strategies for fabricating promising electrode materials for electrochemical energy storage.

Potential use of a combined ozone and zeolite system for gaseous toluene elimination.

This study investigated the performance of a combined ozone and zeolite system in eliminating gaseous toluene which is a major contaminant in many industrial and indoor environments. The hypothesis that the removal of toluene by ozone can be substantially affected by confining the oxidation reaction in a zeolite structure was evaluated. The degradation of toluene seemed to be contributed by the active oxygen atom generated from the decomposition of ozone at the Lewis acid sites in the zeolite 13X. Air containing toluene levels at 1.5, 2 and 3 ppm was injected with ozone in the range of 0-6 ppm before being vented into a fixed amount of 3600 g zeolite 13X with 90 mm bed-length. The experimental results showed that the elimination rate of toluene was significantly enhanced when compared to using zeolite or ozone alone. In particular, over 90% of the 1.5 ppm toluene was removed when 6 ppm ozone was used at 40% relative humidity level. Deactivation of the zeolite 13X after a few hours of reactions under the current experimental conditions was probably due to the adsorbed water, carbon dioxide and the reaction by-products. The residue species left in the zeolite and the intermediate species in the exhaust gas stream were characterized by FT-IR, GC-MS and HP-LC methods, respectively. A distinctive peak of O atom attached to the Lewis acid site at 1380 cm(-1) was found in the FT-IR spectrum and trace amount of aldehydes was found to be the reaction by-products.

Synthesis of MCM-41 from coal fly ash by a green approach: influence of synthesis pH.

The present study reports a green synthesis method for preparing pure (free of fly ash) and ordered MCM-41 materials from coal fly ash at room temperature (25 degrees C) during 24 h of reaction. It was shown that the impurities in the coal fly ash were not detrimental to the formation of MCM-41 at the tested conditions. The influence of initial synthesis pH on material properties of calcined MCM-41 samples was investigated by various techniques such as XRF, XPS, XRD, FTIR, DR-UV-vis, solid state NMR, N2 physisorption, TG-DTA, SEM and TEM. The experimental results showed that the amount of trace elements such as Al, Na, Ti and Fe incorporated into the sample increased with synthesis pH value. More aluminum species were incorporated with tetrahedral coordination in the framework under a high pH value. The particle size of the sample decreased with the synthesis pH value. Samples synthesized at high pH values had a larger pore size and were more hydrothermally stable than those at low pH values. From thermal analysis, it was observed that the synthesized MCM-41 samples showed a high thermal stability. These properties made the synthesized MCM-41 suitable for further processing into more useful materials in a wide range of applications.

Pure, single phase, high crystalline, chamfered-edge zeolite 4A synthesized from coal fly ash for use as a builder in detergents.

Single phase chamfered-edge zeolite 4A samples in pure form with a high crystallinity were synthesized by applying step-change of synthesis temperature during hydrothermal treatment of coal fly ash. The calcium binding capacity of these zeolite 4A samples (prepared from coal fly ash) and the commercial detergent grade zeolite 4A were tested for usage as a detergent builder. The results show that these zeolite 4A samples behaved similarly as the commercial one in removing calcium ions during the washing cycle. Moreover, from the leaching tests (evaluation of toxicological safety), the results show that these zeolite 4A samples leached the same elements (Sb, As, Se and Tl) as the commercial one with the concentrations in the same order of magnitude. This shows that the toxicological effect of the coal fly ash converted zeolite 4A was not worse than that of the commercial sample. Finally, economic and environmental aspects of converting coal fly ash to useful products were discussed.

Flower-like Copper Cobaltite Nanosheets on Graphite Paper as High-Performance Supercapacitor Electrodes and Enzymeless Glucose Sensors.

Flower-like copper cobaltite (CuCo2O4) nanosheets anchored on graphite paper have been synthesized using a facile hydrothermal method followed by a postannealing treatment. Supercapacitor electrodes employing CuCo2O4 nanosheets exhibit an enhanced capacitance of 1131 F g(-1) at a current density of 1 A g(-1) compared with previously reported supercapacitor electrodes. The CuCo2O4 electrode delivers a specific capacitance of up to 409 F g(-1) at a current density of as high as 50 A g(-1), and a good long-term cycling stability, with 79.7% of its specific capacitance retained after 5000 cycles at 10 A g(-1). Furthermore, the as-prepared CuCo2O4 nanosheets on graphite paper can be fabricated as electrodes and used as enzymeless glucose sensors, which exhibit good sensitivity (3.625 µA µM(-1) cm(-2)) and an extraordinary linear response ranging up to 320 µM with a low detection limit (5 µM).

Chloride ion-driven transformation from Ag3PO4 to AgCl on the hydroxyapatite support and its dual antibacterial effect against Escherichia coli under visible light irradiation.

Visible light-driven photocatalytic inactivation of Escherichia coli was performed using hydroxyapatite-supported Ag3PO4 nanocomposites (Ag3PO4/HA). The antibacterial performance was evaluated by the methods of zone of inhibition plates and minimum inhibitory concentration test. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to investigate the instability and transformation of the nanocomposite by comparing the crystalline, phase, and the morphology before and after exposure to Luria-Bertani culture medium under visible light irradiation. Ag3PO4 nanoparticles on the support were found to be shortly transformed into AgCl due to high chloride concentration of Luria-Bertani culture medium. The AgCl/HA nanocomposite showed both excellent intrinsic antibacterial performance contributed by the released silver ions and visible light-induced photocatalytic disinfection toward E. coli cells. This dual antibacterial function mechanism was validated by trapping the hydroxyl free radical and detecting the silver ions during the photocatalytic antibacterial process. The morphological change of E. coli cells in different reaction intervals was obtained by scanning electron microscopy (SEM) to complementally verify photocatalytic inactivation of E. coli. This work suggests that an essential comparison study is required for the antibacterial materials before and after the photocatalytic inactivation of bacterial cells using Ag3PO4 nanoparticles or Ag3PO4-related nanocomposites in mediums containing high-concentration chloride ions.

Removal of mixed heavy metal ions in wastewater by zeolite 4A and residual products from recycled coal fly ash.

The removal performance and the selectivity sequence of mixed metal ions (Co(2+), Cr(3+), Cu(2+), Zn(2+) and Ni(2+)) in aqueous solution were investigated by adsorption process on pure and chamfered-edge zeolite 4A prepared from coal fly ash (CFA), commercial grade zeolite 4A and the residual products recycled from CFA. The pure zeolite 4A (prepared from CFA) was synthesized under a novel temperature step-change method with reduced synthesis time. Batch method was employed to study the influential parameters such as initial metal ions concentration, adsorbent dose, contact time and initial pH of the solution on the adsorption process. The experimental data were well fitted by the pseudo-second-order kinetics model (for Co(2+), Cr(3+), Cu(2+) and Zn(2+) ions) and the pseudo-first-order kinetics model (for Ni(2+) ions). The equilibrium data were well fitted by the Langmuir model and showed the affinity order: Cu(2+) > Cr(3+) > Zn(2+) > Co(2+) > Ni(2+) (CFA prepared and commercial grade zeolite 4A). The adsorption process was found to be pH and concentration dependent. The sorption rate and sorption capacity of metal ions could be significantly improved by increasing pH value. The removal mechanism of metal ions was by adsorption and ion exchange processes. Compared to commercial grade zeolite 4A, the CFA prepared adsorbents could be alternative materials for the treatment of wastewater.

3D hierarchical porous graphene aerogel with tunable meso-pores on graphene nanosheets for high-performance energy storage.

New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53 nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the individual GNS were uniform and could be tuned by controlling the sizes of the Co3O4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100 mAh/g at a current density of 0.1 A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20 A/g, the reversible capacity was retained at 300 mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields.

Changes in puromycin-sensitive aminopeptidases in postmortem schizophrenic brain regions.

We studied the distribution of puromycin-sensitive aminopeptidase (PSA) in well-defined human brain ares by Western immunoblot in an attempt to examine its possible role in schizophrenia. The schizophrenic brains were from suicide victims (n = 13) of either sex, with an age range of 30-60 yr (average 45). The controls were mostly victims of myocardial infarction (n = 12), of either sex and between 32 and 56 yr old (average 44). The brain regions were obtained within 48 h after death. After ultracentrifugation the PSA was quantified by Western blot analysis using a PSA antiserum. The distribution of the two most abundant antigens, MW 100 kDa (PSA-100) and 170 kDA (PSA-170), were compared. PSA-100 had peptidase activity, PSA-170 did not. PSA-100 was found in all of the region studied. In the control brain areas prefrontal cingulate and frontal cortices, thalamus, hippocampus, hypothalamus and outer globus pallidus contained significantly more PSA-100 than the corresponding areas from schizophrenic brain. PSA-170 was mostly found only in areas of schizophrenic brains. In three control brains, in one area of each, it could be detected, but the level in each of these regions was less than 30% of that in the corresponding schizophrenic area. PSA-170 was found in all the schizophrenic brains, in 20 of the 35 regions we studied, with parahippocampal cortex the highest (134 ng/g wet tissue) and frontal inferior cortex the lowest (9.3 ng/g wet tissue). It was not detectable in cerebral or cerebellar white matter. Our data show that the amounts and distribution of PSA-170, a protein of unknown function, is restricted mostly to schizophrenic brain areas. The difference is not due either to neuroleptic treatment of the patient or to the postmortem proteolysis of the brain samples.

Two cytosolic puromycin-sensitive aminopeptidase isozymes in chicken brain: molecular homology to brain-specific 14-3-3 protein.

Two puromycin-sensitive aminopeptidase isozymes (PSA-I and PSA-II) were isolated from chicken brain cytosol by ammonium sulfate fractionation followed by column chromatography on Cellex D and AH-Sepharose 4B and separated on Bio-Gel HTP. Each was purified to homogeneity on Sephadex G-200, Arg-Tyr-AH-Sepharose, Bio-Gel HTP, and preparative gel electrophoresis. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, PSA-I appeared to be a monomer with a molecular mass of 105 kDa, and PSA-II to be composed of two subunits of 25 kDa and 100 kDa. The tryptic maps of 100 kDa and 105 kDa protein in HPLC are different in peak frequency, height, and composition. The internal peptide sequence of PSA-I has a considerable homology to PSA-II. Both isozymes have repeated copies of common peptide segments and have no significant sequence homology to other peptidases and proteinases. These thio and Co(2+)-activated isozymes have a neutral pH optimum and are inhibited by puromycin and bestatin. PSA-II is more sensitive to trypsin and heat treatment, has a lower Km to Met-enkephalin, and is more active on Arg BNA and Pro BNA. Our results suggest that PSA-I and PSA-II derive from translation of two RNAs of a new gene family related to the brain-specific 14-3-3 protein.