Sum Of CO Research Articles

Colorimetric Oxygen Sensing by Analyzing Chromaticity Points for Polymer Cobalt Schiff Base in CIELAB

AbstractPolymer membranes of a copolymer ligand (L) coordinated to tetra‐coordinated N,N'‐ethylene bis(salicylideneiminato) cobalt(II) at the fifth coordinating site of the center cobalt(II), Co(II)S‐L, are prepared to measure colorimetrically the color changes in response to rapid reversible oxygen binding simultaneously with slow oxidation under moist conditions to yield Co(III)S‐L. The chromaticity point observed in CIELAB is the endpoint of the vector sum of the unit vectors for Co(II)S‐L, O2‐Co(II)S‐L, and Co(III)S‐L, scaled by their respective abundance ratios: (1 − m)(1 − n), m(1 − n), and n, where m is the ratio of O2‐Co(II)S‐L to the sum of Co(II)S‐L and O2‐Co(II)S‐L and n is the ratio of Co(III)S‐L to the total of the three cobalt complexes. The observed limited area in CIELAB as a stoichiometric Euclidean space is supported by the following two different reaction processes of the polymer membranes: an oxygen‐binding reaction under several different partial pressures of oxygen supplied to the membranes in a short period, during which oxidation of the cobalt(II) complexes is negligible, and an oxidation reaction over a long period at a constant partial pressure of oxygen. The chromaticity points in both processes progress linearly in three different two‐dimensional coordinates: a*b*, a*L*, and b*L*.

CeO2-conjugated CoFe layered double oxides as efficient non-noble metal catalysts for NH3-decomposition enabling carbon-free hydrogen production

CeO2-conjugated Co1.5Fe1.5 LDOs were synthesized through a one-pot co-precipitation method of Ce-introduced Co1.5Fe1.5 LDHs and their thermal treatment. By manipulating the stoichiometric molar ratio of Ce/(Co + Fe), a series of Cex-Co1.5Fe1.5 LDOs (x = 0.05, 0.1. 0.2, 0.5, and 1, corresponding to the molar ratio for the sum of Co and Fe) was comprehensively characterized to investigate the intricate interplay among factors such as spinel mixed metal oxides, LDH-derived LDOs, and the introduced Ce to achieve high catalytic performance in NH3 decomposition. Notably, Ce0.2-Co1.5Fe1.5 LDOs exhibited remarkable activity, achieving an NH3 conversion of 81.9 % at 450 °C and a WHSV of 6,000 mLNH3 gcat-1h−1, and maintained excellent NH3-conversion with a negligible decrease over 80 h of continuous operation at 550 °C and high WHSV of 30,000 mLNH3 gcat-1h−1. The synergistic interaction between the incorporated CeO2 and Co1.5Fe1.5 LDOs induced modifications of structural properties including the distribution of Co and Fe within the spinel crystal structure, as well as affecting the lattice parameters and electronic properties. These modifications play a pivotal role in ultimately altering metal-N binding energy, which facilitates the efficient activation of absorbed NH3 at the lowest temperature and minimizes the delay in recombinative N2-desorption. Hence, this study aims to highlight a new concept and demonstrate its feasibility for fabricating cost-effective and high-performing catalysts at mild temperatures to meet the growing demand for NH3 as a hydrogen carrier.

Manganese metallogenesis in the Hellenic arc: Case studies from a Triassic rift-related volcaniclastic succession of the Cycladic Blueschist Unit, Greece

The Triassic volcaniclastic sequence in the Cycladic Blueschist Unit (CBU) of Greece is known to contain several occurrences of metamorphosed Mn mineralization. Despite previous literature reports, a comprehensive and holistic review of the origin of these occurrences is hitherto lacking. Here we revisit the Mn metallogenic system of the CBU through a comprehensive study of Mn mineralisation at Varnavas area, Northern Attica, and its correlation with a similar occurrence at Mparades Hill, Andros island. Manganese mineralogy at both localities is manifested in a typical high-P metamorphic silicate assemblage dominated by piemontite, spessartine garnet, and minor pyroxmangite (rhodonite). Whereas at Andros Mn-rich subdomains contain brecciated braunite micronodules, preservation of tetravalent Mn oxides in a similar nodular form is documented from Varnavas, comprising dominant todorokite along with lesser hollandite, pyrolusite, and minor Mn-bearing hematite. The contrasting Mn oxide mineralogy and comparable textural characteristics at the two sites are tentatively interpreted as the result of locally incomplete reduction of precursor Mn(IV) phases during metamorphism. Bulk Mn concentrations of the studied materials generally do not exceed the value of 10 wt% Mn, unless small-scale subsampling of Mn-rich domains is undertaken. Key geochemical characteristics of the Mn-rich rocks include low transition metal concentrations (sum of Co + Ni + Cu + Zn between 0.02 and 0.06 wt%); positive-sloping, PAAS-normalised REE spidergrams at a maximum Ndsn/Ybsn ratio of 0.3; positive Ce anomalies, albeit of variable magnitude across individual samples; and high As (up to 1930 ppm) and Ba (up to 2767 ppm) contents. A combination of structural, geochemical and mineralogical evidence from the two localities along with published results from similar occurrences elsewhere (e.g., Kythnos) suggest that Mn-oxide accumulation in the CBU is genetically linked to hydrothermal venting in a back-arc rift setting during the Triassic. The geochemical variability recorded is attributed primarily to the variable mixing of a hydrothermal-sourced, hydrogenous metalliferous component that precipitated broadly contemporaneously with the deposition of the host tuffs. Low transition metal contents coupled with substantial enrichments in elements such as Ba, As, Pb and REY, attest to the felsic/intermediate character of back-arc magmatism/volcanism and associated hydrothermal activity. Primary Mn precipitates are thought to have been in the form of tetravalent Mn assemblages, which may locally be partially preserved through metamorphism, as appears to be the case in the Varnavas occurrence. The fully oxic and hydrogenous character of the precursor Mn(IV) oxy-hydroxides is supported by the consistently positive Ce anomalies observed in practically all samples from both sites. Although the Mn concentrations and distribution of the studied assemblages are sub-economic at best, we consider possible that their geographically widespread occurrence may still hold untapped potential for future discovery of commercially viable Mn ores sensu stricto, both in the Hellenic arc and in other regions of similar geotectonic and metallogenic activity.

Conditional moment closure method with tabulated chemistry in adiabatic turbulent nonpremixed jet flames

The conditional moment closure (CMC) method with tabulated chemistry is proposed to reduce the computational load for integration of stiff reaction steps in the conventional CMC methods. It is based on the assumption that temperature and all species except CO and CO2 adjust fast enough so that they can be uniquely determined by the single reaction progress variable given as the sum of CO and CO2 mass fractions. The CMC equations are solved for the conditional reaction progress variable, Qpv, whereas the other species mass fractions and the reaction rates including that for Qpv are retrieved from lookup tables. A steady homogeneous form of the conditional variance and covariance equations are solved to construct the second-order closure table to be consistent with Steady Laminar Flamelet Model (SLFM)-based first-order closure. Good agreement is shown between the results by integrated and tabulated chemistry in both the first-order and the second-order CMC for Sandia Flames D, E and F. The overall computational time is reduced to about 0.5% of that by the conventional CMC method involving integration of the detailed reaction mechanism for all species and temperature.

Modelling, simulation and optimization of a solid residues downdraft gasifier: Application to the co-gasification of municipal solid waste and sugarcane bagasse

This work modelled a downdraft gasifier with air in the co-gasification of municipal solid waste (MSW) and sugarcane bagasse using a kinetic, one-dimensional and steady state approach. A central composite design was carried out to assess the impact of the co-gasification ratio (CGR), defined as the MSW mass fraction in the feeding biomass, the biomass moisture content and the equivalence ratio. As a result, polynomial models were obtained for syngas composition, lower heating value (LHV), energy efficiency and sum of CO and H2 molar fractions on wet basis. The models were considered robust since the coefficient of determination R2 ranged from 0.96082 to 0.99345. The impact of each chosen factor was investigated to maximize the energy efficiency and the sum of CO and H2 molar fractions. The optimal case, with CGR 50%, a biomass moisture of 5.0% and an equivalence ratio of 0.18, resulted in a syngas molar fraction of 3.63, 30.51, 7.53, 19.76 and 0.77% for H2O, CO, CO2, H2 and CH4, respectively, corresponding to a LHV of 6.74 MJ/Nm3 and an energy efficiency of 39.93%. By the end, the process showed great potential to produce a syngas rich in CO and H2.

Theoretical study of chloro-α,β,γ,δ-tetraphenylporphyrinato cobalt(III) dimer reaction: A reaction path to form π cation radicals

Chloro-α,β,γ,δ-tetraphenylporphyrinato-cobalt(III) (Co(III)TPPCl) is a five-coordinate Co complex ([Co(III)(N)4Cl]) having square-pyramidal structure with chlorine atom at the apex. The compound is diamagnetic. Its 1H NMR spectra in inert solvents show unusual signal broadening at higher temperatures. This was attributed to the partial transformation of the complex to paramagnetic species. To elucidate this specific phenomenon, we proposed a dimer reaction mechanism based on density functional theory calculations with M06-2X/segmented all-electron Gaussian (for Co atom) and 6-31G(d, p) (for C, H, N, Cl atoms) basis sets. The porphyrin dimer, [Co(III)TPPCl]2 (S = 0), is assumed as the important reaction intermediate. The optimized geometry of the dimer is stable compared to two optimized monomers (S = 0) by 22.27 kcal mol−1, but is unstable compared to one Co(III)TPPCl2 (S = 1/2) and one Co(II)TPP (S = 1/2) by 0.95 kcal mol−1. Using the vibrational frequencies from the geometry optimization, the sum of Co(III)TPPCl2 and Co(II)TPP species, the so-called π cation radicals, is the overwhelming majority in the theoretical product distribution at 298.15 K and 1 atm. The dimer reaction can produce the paramagnetic species with a potential energy barrier of 1.65 kcal mol−1.

Role of Zn2+ Substitution on the Magnetic, Hyperthermic, and Relaxometric Properties of Cobalt Ferrite Nanoparticles

Zinc substitution is often proposed as an efficient strategy to improve the performances of spinel ferrite nanoparticles, particularly related to their application as theranostic agents. In this work, a series of 8 nm spinel ferrite nanoparticles of formula CoxZnyFe3–(x+y)O4 is synthesized by thermal decomposition with the purpose of investigating the role of Zn2+ ions in modifying the structural and magnetic properties. Contrary to most of the literature on this subject, where the sum of Co and Zn is kept constant (x + y = 1), here, the amount of Co is maintained at ca. x = 0.6, corresponding to the maximum of magnetic anisotropy of the Zn-undoped system, whereas the amount of Zn is progressively varied along the series from y = 0.05 to 0.4. This approach allows enlightening the effect of the Zn introduction on the magnetic and crystal structures and, particularly, on magnetic anisotropy, which is deeply investigated by several complementary techniques. A significant increase of the saturation magnetizat...

GAS PRODUCTS OF ARGON PLASMA INTERACTION WITH POLYARAMID AND POLY(ETHYLENE TEREPHTHALATE)

Non-equilibrium plasma is widely used for surface modification of polymer materials. Reactions of plasma active species with polymers lead not only to the surface modification, but to the formation of gaseous products, which change the plasma composition and internal plasma parameters. It results in the dependence of surface etching and modification kinetics on the quantity of material been treated (on sample sizes in a reactor). These phenomena are known as so called “loading effect” and have been studied for the treatment of polypropylene and polyimide films, poly(ethylene terephthalate) films and fabrics in oxygen and air plasma. It can be expected that gas products of noble gas plasma action on polymers will change strongly plasma parameters and modification results. In this paper, experimental data are represented on composition of gas products and their evolution rates at the treatment of polyaramid films, fibers and poly(ethylene terephthalate) fabric in low-pressure argon plasma. Poly(ethylene terephthalate) textile fabric (PET) made of monofilament yarns (SAATI, S.p.A., Italy) and polyaramide (PA) films and complex yarns “Rusar®” (Termotex, Russia) were used in experiments. Direct current discharge was excited in a flow of argon (technical grade) in a glass tube reactor with 3 cm inner diameter. Fabric samples were placed as cylinders on the reactor wall in the discharge positive column. Square of PET samples was varied from 18 to 111 cm2. The PA yarns with the total length of 550 or 1020 cm were placed in the reactor on special holder with the length of 20 cm. Total gas pressure in reactor was varied from 30 to 300 Pa at discharge current of 20 – 110 mA. Gas flow rate in the reactor was kept constant and equal to 30 cm´s-1. Gas phase analysis was carried out by the methods of plasma emission spectroscopy and mass-spectrometry. Plasma emission spectra and mass-spectra show evolution of H2, CO and H2O molecules at the treatment of PA and PET in argon plasma. Evolution rates for different gas products and their mole fractions have been obtained as functions of total gas pressure. Increase in polymer sample square has been shown to result in changing the ratios between evolution rates for different gas products. Sum of CO, H2 and H2O mole fractions increases with polymer sample square and decreases with gas pressure. Dissociation of molecular gas products results in the changing plasma active species. Oxygen and hydrogen atom lines and OH emission bands are observed in plasma emission spectra. Alteration of intensity ratio for О(3p3P ® 3s3S0) and Ar (4p3D3 ® 4s3P2) lines (IO/IAr) versus time after discharge starting shows the possible participation of oxygen atoms in heterogeneous reactions with polymers. Evolution of molecular gas products of heterogeneous reactions influences plasma properties and rates of plasma chemical reactions. The data obtained will be used for the further analysis of mechanisms of heterogeneous reactions of plasma active species with polymers.

Photocatalytic Reduction of CO2 with a Cobalt Chlorin Complex in Water

Photoctalytic reduction of CO2 and H2O to CO and H2 has merited increasing attention, because synthesis gas (a fuel gas mixture consisting primarily of CO and H2) can be converted to liquid hydrocarbon fuels by Fischer-Tropsch processes.[1-3] Because the CO2 reduction to CO competes with the proton reduction to H2 as well as CO2 reduction to HCOOH, selective CO production in the photocatalytic reduction of CO2in water has been a challenging issue. We report herein photoelectrochemical reduction of CO2 to CO with high Faradaic efficiency using a cobalt chlorin complex (CoII(Ch)) adsorbed on multi-walled carbon nanotubes (MWCNTs) as a cathode and a surface-modified BiVO4 photoanode with iron(III) oxide(hydroxide) (FeO(OH)) for oxidation of water in a CO2-saturated aqueous solution (pH 4.6). The photoelectrochemical reduction of CO2 was performed in a two-compartment cell composed of an FeO(OH)/BiVO4/FTO photoanode and a CoII(Ch)/MECNTs cathode, where the two electrodes were connected with conducting wire as an external circuit and separated by a Nafion membrane (Figure 1). Electrocatalytic reduction of CO2 occurred efficiently using the CoII(Ch)/MECNTs electrode at an applied potential of –1.1 V vs. NHE to yield CO with a Faradaic efficiency of 89% with hydrogen production accounting for the remaining 11% at pH 4.6.[4] CO was produced with 83% Faradaic efficiency at an applied potential of –1.3 V vs the potential of the photoanode under visible light irradiation in a CO2-saturated aqueous solution (pH 4.6). The amount of O2 produced in the photoelectrochemical oxidation of water is one-half of the amounts of the sum of CO and H2 produced in the electrochemical reduction of CO2 and H2O on the cathode. The difference in the oxidation potential of the FeO(OH)/BiVO4/FTO electrode under dark and that under light illumination was ca. 1.5 V, indicating that the FeO(OH)/BiVO4/FTO photoanode lowered the total bias that enabled simultaneous water oxidation and CO2 reduction. Faradaic efficiency for CO production was much improved by adsorption of CoII(Ch) on MWCNTs, because two [CoI(Ch)]– are located close to each other when the two-electron reduction of CO2to CO occurs.[4,5] Photocatalytic reduction of CO2 and H2O with triethylamine also occurred efficiently using CoII(Ch) adsorbed on MWCNTs as a CO2 reduction catalyst and [RuII(Me2phen)3]2+ (Me2phen = 4,7-dimethyl-1,10-phenanthroline) as a photocatalyst to yield CO and H2with a ratio of 2.4:1 and the high turnover number of 710.[5] The present study provides a unique strategy for selective photoelectrocatalytic reduction of CO2 to CO over proton reduction to H2using an earth-abundant metal cathode.

Co-production of Biochar, Bio-oil, and Syngas from Tamarix chinensis Biomass under Three Different Pyrolysis Temperatures

Pyrolysis of Tamarix chinensis feedstock was performed at 300, 500, and 700 °C to investigate the characteristics of biochar, bio-oil, and syngas. Biochar yield decreased and syngas yield increased as the pyrolysis temperature increased. The biochar was characterized for elemental composition, surface, and adsorption properties. Values of pH, electrical conductivity (EC), ash, C, K, Na, and basic functional group contents all increased as the pyrolysis temperature increased, whereas P, Ca, Mg, and acidic functional groups decreased. The methylene blue adsorption capacity values were 1.78, 2.08, and 1.96 (mg g-1) and iodine 256.48, 255.51 and 76.42 (mg g-1) for the biochars produced at 300, 500, and 700 °C, respectively. The C and H contents in bio-oil ranged from 66 to 62% and 8 to 7%, while O changed from 25 to 29% when temperature was increased from 300 to 700 °C. The concentration of hydrocarbon gases, such as ethane, ethylene, propane, and acetylene, increased as the pyrolysis temperature increased. The sum of CO and CO2 occupied great percentage of the total gas, while the H2 concentration increased markedly to a maximum of 16% at 500 °C. Thus, T. chinensis is a potential feedstock for biochar and bioenergy production.

Growth Pattern and Its Indication of Spheroidal Nano-Micro Crystal Aggregates of Pyrite in the Baiyunpu Pb-Zn Polymetallic Deposit, Central Hunan

The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas (A–E). The results of electron probe micro analysis (EPMA) show that from the zone A1 to B, Co/Ni <1, the sum of Co and Ni is 0.08%−0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction (XRD) analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the (111) and (220) crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the (111) plane is the most prominent Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes: nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallow-water carbonate platform edge. The variations in the S/Fe ratio and crystallisation characteristics indicate that during pyrite crystal growth, the sulphur fugacity was high locally and rose constantly, the degree of supersaturation decreased locally and the growth environment was stable relatively.

Kinetic study on CO2 photoreduction by Re complexes

The photoreduction of CO2 using Re(btp)(CO)3Cl (btp: bathophenanthroline) was investigated in a CO2-saturated DMF-triethanolamine solution. CO formation was observed during irradiation with 365-nm light. Meanwhile, UV-vis spectral changes suggested that Re(btp)(CO)3Cl was degraded and its amount decreased during irradiation. The degradation of Re(btp)(CO)3Cl could cause CO formation, and the observed CO amount was the sum of CO produced by CO2 reduction and Re(btp)(CO)3Cl degradation. Thus, in the present paper, we discuss how the net amount of CO produced by CO2 reduction could be determined via a kinetic study during UV irradiation which considers the CO production originating from the Re(btp)(CO)3Cl degradation process.

Open air mineral treatment operations and ambient air quality: assessment and source apportionment

We present a methodology for evaluating and quantifying the impact of inhalable mineral dust resuspension close to a potentially important industrial point source, in this case an open air plant producing sand, flux and kaolin in the Capuchinos district of Alcañiz (Teruel, NE Spain). PM(10) levels at Capuchinos were initially high (42 μg m(-3) as the annual average with 91 exceedances of the EU daily limit value during 2007) but subsequently decreased (26 μg m(-3) with 16 exceedances in 2010) due to a reduced demand for minerals from the ceramic industry and construction sector during the first stages of the economic crisis. Back trajectory and local wind pattern analyses revealed only limited contribution from exotic PM sources such as African dust intrusions whereas there was clearly a strong link with the mineral stockpiles of the local industry. This link was reinforced by chemical and mineral speciation and source apportionment analysis which showed a dominance of mineral matter (sum of CO(3)(2-), SiO(2), Al(2)O(3), Ca, Fe, K, Mg, P, and Ti: mostly aluminosilicates) which in 2007 contributed 76% of the PM(10) mass (44 μg m(-3) on average). The contribution from Secondary Inorganic Aerosols (SIA, sum of SO(4)(2-), NO(3)(-) and NH(4)(+)) reached 8.4 μg m(-3), accounting for 14% of the PM(10) mass, similar to the amount of calcareous road dust estimated to be present (8 μg m(-3); 13%). Organic matter and elemental carbon contributed 5.3 μg m(-3) (9%) whereas marine aerosol (Na + Cl) levels were minor with an average concentration of 0.4 μg m(-3) (1% of the PM(10) mass). Finally, chemical and mineralogical analysis of stockpile samples and comparison with filter samples confirmed the local industry to be the major source of ambient PM(10) in the area.

Kinetics of carbon degradation and PCDD/PCDF formation on MSWI fly ash

The native carbon oxidation and PolyChloroDibenzo- p-Dioxins and PolyChloroDibenzoFurans, PCDD/F, formation were simultaneously studied at different temperatures (230–350 °C) and times (0–1440 min) in order to establish a direct correlation between the disappearance of the reagent and the formation of the products. The kinetic runs were conducted in an experimental set up where conditions were chosen to gain information on the role of fly ash deposits in cold zones of municipal solid waste incinerators in PCDD/F formation reaction. The carbon oxidation measured as the decrease of total organic carbon of fly ash was in agreement with the carbon evolved as sum of CO and CO 2. The carbon mass balance indicated an increase in the efficiency of carbon conversion in CO and CO 2 with temperature. The CO and CO 2 formation was the result of two parallel pseudo first order reactions thus giving significant information about the reaction mechanism. PCDD/F formation as a function of temperature showed that the maximum formation was achieved in a narrow range around 280 °C; the time effect at 280 °C was a progressive formation increase at least up to 900 min. The PCDF:PCDD molar ratio increased with temperature and time, and the most abundant homologues were HxCDD, HpCDD, OCDD for PCDD, and HxCDF, HpCDF within PCDF. These experimental results supported the hypothesis that the formation mechanism was the de novo synthesis.

Water vapor release from biomass combustion

Abstract. We report on the emission of water vapor from biomass combustion. Concurrent measurements of carbon monoxide and carbon dioxide are used to scale the concentrations of water vapor found, and are referenced to carbon in the biomass. The investigated fuel types include hardwood (oak and African musasa), softwood (pine and spruce, partly with green needles), and African savanna grass. The session-averaged ratio of H2O to the sum of CO and CO2 in the emissions from 16 combustion experiments ranged from 1.2 to 3.7, indicating the presence of water that is not chemically bound. This non-bound biomass moisture content ranged from 33% in the dry African hardwood, musasa, to 220% in fresh pine branches with needles. The moisture content from fresh biomass contributes significantly to the water vapor in biomass burning emissions, and its influence on the behavior of fire plumes and pyro-cumulus clouds needs to be evaluated.

Influence of addition of cobalt oxide on microstructure and electrochemical capacitive performance of nickel oxide

Ni–Co oxide nanocomposite was prepared by thermal decomposition of the precursor obtained via a new method—coordination homogeneous coprecipitation method. The synthesized sample was characterized physically by X-ray diffraction, scanning electron microcopy, energy dispersive spectrum, transmission electron microscope, and Brunauer–Emmett–Teller surface area measurement, respectively. Electrochemical characterization of Ni–Co oxide electrode was examined by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance measurements in 6-mol L−1 KOH aqueous solution electrolyte. The results indicated that the addition of cobalt oxide not only changed the morphology of NiO but also enhance its electrochemical capacitance value. A specific capacitance value of 306 F g−1 of Ni–Co oxide nanocomposite with n Co = 0.5 (n Co is the mole fraction of Co with respect to the sum of Co and Ni) was measured at the current density of 0.2 A g−1, nearly 1.5 times greater than that of pure NiO electrode. Lower resistance and better rate capability can also be observed.

Use of regenerated ferric oxide for CO destruction and suppressing dioxin formation in flue gas in a pilot-scale incinerator

Catalytic destruction of chlorinated compounds is one of the key methods in reducing pollutant emissions. For the purpose of utilizing waste materials, a catalyst was regenerated from ferric ion sludge, obtained from the addition of iron salts to precipitate heavy metals. The sludge was dewatered, heated (800 °C for 4 h), and ground into smaller particles. The regenerated ferric oxide particles were then used as the oxidation catalyst to destroy CO formation during the combustion of three chlorinated solvents and to suppress dioxin formation in flue gas in a real waste solvent. In the presence of catalyst, the combustion efficiency (ratio of CO 2 to the sum of CO 2 and CO) for chlorobenzene was more than 98% at 850 °C in a pilot-scale incinerator. The destruction and removal efficiencies of chlorobenzene, 2,4-dichlorophenol and trichlorofluoroethane were more than three nines. In the absence of catalysts, the flue gas emission from a real waste could not meet the regulatory dioxin standard of 0.1 ng-TEQ/N m 3 even with the powdered activated carbon injection. The use of catalyst at either 100 or 300 g/h, however, was able to meet the emission standard.

Differentiating commitments world wide: global differentiation of GHG emissions reductions based on the Triptych approach—a preliminary assessment

In the context of global climate negotiations various approaches have been proposed to distribute commitments regarding greenhouse gas emissions mitigation over different countries. One of them is the Triptych approach, which is a sector approach that accounts for differences in national circumstances such as population size and growth, standard of living, economic structure and fuel mix in power generation. It was successfully applied in the negotiations on differentiation of commitments in the European Union in 1997. In this study we aim to see what problems we encounter when applying the approach in a wider geographical context. In order to reach this aim we establish a test differentiation of CO 2 emission reduction obligations for a selection of 48 countries. The criteria we apply comprise technical emission reduction options only. According to our Triptych criteria, including the choice for particular growth scenarios and a convergence of CO 2 emissions in the domestic sectors by the year 2030, the sum of CO 2 emissions in the 48 countries in 2015 is estimated to increase by 8% over 1990 levels. With the criteria used the average reduction objective for the OECD will be somewhere between −10% and −20%. For economies in transition to a market economy our calculations indicate on average a reduction between −30% and −50%. For the developing countries we established increases varying roughly from +40% to +200%. The choice for a particular growth scenario as well as the assumption for the period for the convergence of per capita emissions in the domestic sectors are crucial and may effect the outcome of the calculations to a large extent. If these problems can be sufficiently solved the Triptych approach can serve as a valuable tool to rank countries in a global differentiation scheme.

Efficient incomplete international climate agreements

We study the optimal design of a carbon tax when a group of countries seeks to maximize its net income minus its environmental costs, which depend on the sum of CO 2 emissions from all countries. When both production and consumption of internationally traded fossil fuels are taxed, a particular combination of producer and consumer taxes exists which is optimal. It is also shown that with this tax the sum of the consumer tax and producer tax should be equal across all fossil fuels per unit of carbon. On the other hand, when the cooperating countries use a tax on consumption (or production) of fossil fuels as the only policy instrument, the tax per unit of carbon should in general be differentiated across fossil fuels. We close the paper by giving an empirical illustration of the theoretical analysis, assuming that the cooperating countries are those of the OECD.

CARBON MINERALIZATION IN PRISTINE AND PHOSPHORUS-ENRICHED PEAT SOILS OF THE FLORIDA EVERGLADES

Differences in microbial mineralization of added organic carbon were assessed in pristine (0.231 g total P (TP) kg -1 ) and P-polluted (1.473 g total P kg -1 ) neutral peat soils from Everglades National Park, Florida. Kinetic parameters associated with CO 2 and CH 4 evolution from glucose added to the two soils were significantly different, and the extent of evolution of both gases was greater in the high TP soil over a range of 1 to 5 mol added glucose C kg -1 soil. Carbon mineralization, measured as the sum of CO 2 and CH 4 evolved from added acetate, glucose, cellulose, or sawgrass, was significantly more extensive in the high TP soil. The lag time before the onset of CH 4 evolution was shorter and the fraction of gases evolved composed of CH 4 higher in the high TP soil for all substrates tested. Addition of PO 4 stimulated C mineralization in low TP soil amended with acetate, glucose, or sawgrass, but either had no effect or depressed mineralization of these substrates in the high TP soil. No significant differences in rates of CH 4 oxidation were observed between the two soils. Our results indicate that soil P levels may mlay a significant role in determining the relative importance of aerobic and anareobic microbial metabolism in these soils