Difference In Reduction Potential Research Articles

Fabrication of silver nanosheets on quartz glass substrates through electroless plating approach

Silver nanosheets (NSs) have been synthesized by an electroless plating approach using a complexation mechanism of triethanolamine (TEA) and Ag+ to reduce the oxidation–reduction potential difference and slow down the deposition speed of Ag on quartz glass substrates. The synthesized Ag NSs with 500 nm in edge length and 30 nm in thickness stand on the substrates and are dispersed uniformly. The formation mechanism of Ag NSs is proposed. The formation of Ag NSs is attributed to the molar ratio of AgNO3 to TEA, the concentration of AgNO3 and the influence of reaction temperature. This study is important in vertical immobilization Ag NSs on solid substrates, which could provide substrates for catalysis or surface-enhanced Raman scattering.

Heterometallic [AgFe(3)S (4)] ferredoxin variants: synthesis, characterization, and the first crystal structure of an engineered heterometallic iron-sulfur protein.

Heterometallic [AgFe(3)S(4)] iron-sulfur clusters assembled in wild-type Pyrococcus furiosus ferredoxin and two variants, D14C and D14H, are characterized. The crystal structure of the [AgFe(3)S(4)] D14C variant shows that the silver(I) ion is indeed part of the cluster and is coordinated to the thiolate group of residue 14. Cyclic voltammetry shows one redox pair with a reduction potential of +220 mV versus the standard hydrogen electrode which is assigned to the [AgFe(3)S(4)](2+/+) couple. The oxidized form of the [AgFe(3)S(4)] D14C variant is stable in the presence of dioxygen, whereas the oxidized forms of the [AgFe(3)S(4)] wild type and D14H variants convert to the [Fe(3)S(4)] ferredoxin form. The monovalent d (10) silver(I) ion stabilizes the [Fe(3)S(4)](+/0) cluster fragment, as opposed to divalent d (10) metal ions, resulting in more than 0.4 V difference in reduction potentials between the silver(I) and, e.g., zinc(II) heterometallic [MFe(3)S(4)] ferredoxins. The trend in reduction potentials for the variants containing the [AgFe(3)S(4)] cluster is wild type ≤ D14C < D14H and shows the same trend as reported for the variants containing the [Fe(3)S(4)] cluster, but is different from the D14C < D14H < wild type trend reported for the [Fe(4)S(4)] ferredoxin. The similarity in the reduction potential trend for the variants containing the heterometallic [AgFe(3)S(4)] cluster and the [Fe(3)S(4)] cluster can be rationalized in terms of the electrostatic influence of the residue 14 side chains, rather than the dissociation constant of this residue, as is the case for [Fe(4)S(4)] ferredoxins. The trends in reduction potentials are in line with there being no electronic coupling between the silver(I) ion and the Fe(3)S(4) fragment.

Preparation of alumina-supported intermetallic compounds

A series of alumina-supported intermetallic compounds, Pt3Co/Al2O3, PtCu/Al2O3, Pt3Sn/Al2O3 and Pd3Pb/Al2O3, being promising materials as catalysts, were prepared by reduction of two metal precursors co-impregnated on γ-Al2O3. As a Pt precursor, [Pt(NH3)4]2+ or PtCl62− was used coupled with the second metal precursors. Two different reduction procedures, gaseous H2 and LiBH4 in liquid phase, were also employed and compared. Using PtCl62− which possesses a more negative reduction potential than [Pt(NH3)4]2+ strongly enhanced formation of the desired Pt-based intermetallic nanoparticles regardless of the reduction procedure. A similar trend was observed in preparation of Pd3Pb/Al2O3 with PdCl42− compared to Pd2+. A strong reduction agent LiBH4 gave higher contents of the corresponding intermetallic phases than H2 in all cases. Single-phase intermetallic compounds supported on alumina were synthesized by employing the chloro-complexes and LiBH4 reduction. A systematic investigation indicates that the degree of intermetallic formation intrinsically depends on the difference in reduction potentials (ΔE) of the two metal precursors. Bimetallic combinations with small ΔE such as PdCl42−/Bi3+, Co2+/SnCl62− and Ni2+/SnCl62− also allow syntheses of PdBi/Al2O3, Co3Sn2/Al2O3, Ni3Sn/Al2O3 and Ni3Sn2/Al2O3 by H2 reduction, respectively. An appropriate choice of the metal precursor to reduce ΔE is an effective strategy to synthesize an alumina-supported intermetallic compound.

MoO3침출공정 폐액으로부터 치환반응 시스템을 이용한 구리 분말 회수에 대한 연구

Recovery of copper powder from copper chloride solution used in <TEX>$MoO_3$</TEX> leaching process was carried out using a cementation method. Cementation is a simple and economical process, necessitating less energy compared with other recovery methods. Cementation utilizes significant difference in standard reduction potential between copper and iron under standard condition. In the present research, Cementation process variables of temperature, time, and added amount of iron scraps were optimized by using design of experiment method and individual effects on yield and efficiency of copper powder recovery were investigated using bench-scale cementation reaction system. Copper powders thus obtained from cementation process were further characterized using various analytical tools such as XRF, SEM-EDS and laser diffraction and scattering methods. Cementation process necessitated further purification of recovered copper powders and centrifugal separation method was employed, which successfully yielded copper powders of more than 99.65% purity and average <TEX>$1{\mu}m$</TEX> in size.

Development of an electroanalytical sensor for γ-hexachlorocyclohexane based on a cellulose acetate modified glassy carbon electrode

A simple, reproducible, environmentally friendly cellulose acetate modified glassy carbon electrode was prepared and used for the direct reduction of lindane in aqueous alcoholic medium. This modified electrode offers a high sensing current with a lower reduction potential for lindane. The lowest adsorption of pesticide molecules was observed on the cellulose acetate modified electrode when compared with a bare glassy carbon electrode which enhances the sensitivity of the sensor. This modified electrode is highly stable with respect to time, so that the single electrode can be used for the multiple analysis of the lindane sample. Cyclic voltammetry, differential pulse voltammetry and amperometry were used as the sensing techniques. The reduction potential of lindane on this modified electrode is −1.5 V whereas the reduction potential of nitropesticides is around −0.600 V. This wide difference in reduction potential can be used to estimate lindane even in the presence of nitropesticides by cyclic voltammetry and differential pulse voltammetry. The analytical utility of the proposed method was checked with a commercial lindane lotion and drinking water samples. An amperometric instrument, interfaced with the cellulose acetate modified glassy carbon electrode was designed and tested for the sensing of lindane. The performance of this instrument was assessed.

Investigation on electrochemical removal of CaCl 2 from LiCl–KCl melts

In order to investigate the possibility of electroseparation of CaCl 2 from CaCl 2–LiCl–KCl melts prior to Li + reduction, Ca 2+ and Li + ions reduction potentials in the melts were investigated by cyclic voltammetry (CV) and chronopotentiometry (CP) on both a tungsten and a tin electrodes. The potential difference between the two ions in CaCl 2 (0.5 wt%)–LiCl–KCl melts was 0.2 V at 953 K analyzed by CV. About 0.4 V reduction potential difference between Ca 2+ and Li + ions was observed on chronopotentiograms recorded on a tungsten electrode in CaCl 2 (2.0 wt%)–LiCl–KCl melts either at 723 K or 953 K, which can meet the requirements of total electroseparation. Tin electrode can shift the reduction potentials of Ca 2+ and Li + to more positive ones and also can improve Ca deposition rate and removal efficiency. After 3.0 h electrolysis on solid tungsten at −3.4 V vs. Cl 2/Cl − and liquid tin cathode at −3.0 V vs. Cl 2/Cl −, the Ca/Li (weight ratio) in the melts changed from 3/25 before electrolysis to 2.6/25 and 0.76/25 respectively, analyzed by ICP. Under stirring, even higher removal rates of 83.65 wt% and 94.66 wt%, corresponding to 0.54/25 and 0.16/25 of Ca/Li have been obtained for 3.0 h and 6.0 h electrolysis at −3.0 V vs. Cl 2/Cl − on a tin electrode. Clearly, stirring availably increases the Ca 2+ ions diffusion rate and its electrochemical reaction rate.

Evaluation of Green House Gases (GHGs) Reduction Plan in Combination with Air Pollutants Reduction in Busan Metropolitan City in Korea

Since most Green House Gases (GHGs) and air pollutants are generated from the same sources, it will be cost-effective to develop a GHGs reduction plan in combination with simultaneous removal of air pollutants. However, effects on air pollutants reduction according to implementing any GHG abatement plans have been rarely studied. Reflecting simultaneous removal of air pollutants along with the GHGs emission reduction, this study investigated relative cost effectiveness among GHGs reduction action plans in Busan Metropolitan City. We employed the Data Envelopment Analysis (DEA), a methodology that evaluates relative efficiency of decision-making units (DMUs) producing multiple outputs with multiple inputs, for the investigation. Assigning each GHGs reduction action plan to a DMU, implementation cost of each GHGs reduction action plan to an input, and reduction potential of GHGs and air pollutants by each GHGs reduction action plan to an output, we calculated efficiency scores for each GHGs reduction action plan. When the simultaneous removal of air pollutants with the GHGs reduction were considered, green house supply-insulation improvement and intelligent transportation system (ITS) projects had high efficiency scores for cost-positive action plans. For cost-negative action plans, green start network formation and running, and daily car use control program had high efficiency scores. When only the GHGs reduction was considered, project priority orders based on efficiency scores were somewhat different from those when both the removal of air pollutants and GHGs reduction were considered at the same time. The expected action plan priority difference is attributed to great difference of air pollutants reduction potential according to types of energy sources to be reduced.

Columnar Benzoperylene‐Hexa‐ and Tetracarboxylic Imides and Esters: Synthesis, Mesophase Stabilisation and Observation of Charge‐Transfer Interactions between Electron‐Donating Esters and Electron‐Accepting Imides

Benzo[ghi]perylene 1,2,4,5,10,11-hexacarboxylic trialkylimide and dialkylimido-dialkyl ester derivatives, displaying a thermodynamically stable hexagonal columnar liquid-crystalline phase at room temperature, have been obtained by the use of previously unexplored chiral racemic α-branched alkylimide functions. One of the trialkylimides described here is the first room temperature columnar solely oligo-alkylimide-substituted arene, and thus constitutes a prototype case of self-assembling organic acceptor materials. As the related hexacarboxylic hexaesters are found to exhibit only a weak tendency to form columnar mesophases, benzo[ghi]perylene 1,2,5,10-tetracarboxylic tetraalkyl esters have been synthesized by regioselective oxidative Diels-Alder addition of maleic anhydride to 3,10-dicyanoperylene, and a room temperature hexagonal columnar mesophase was obtained with branched alkyl chains. The acceptor-type electronic properties of the tri- and diimides have been found to be considerably more pronounced than those of the hexa- and tetracarboxylic esters, and to approach those of the prototype acceptor material C(60). The formation of bathochromically absorbing donor-acceptor complexes was observed with a di- or triimide as acceptor and a tetraester as donor, but not with a hexaester as donor. Exploiting the non-negligible differences in reduction and oxidation potentials between all four types of materials, the minimum HOMO energy difference necessary for charge-transfer-complex formation has been determined to lie between 0.29 and 0.35 eV.

Thermal Conversion of Electronic and Electrical Properties of AuCl3-Doped Single-Walled Carbon Nanotubes

By using carbon-free inorganic atomic layer involving heat treatment from 150 to 300 °C, environmentally stable and permanent modulation of the electronic and electrical properties of single-walled carbon nanotubes (SWCNTs) from p-type to ambi-polar and possibly to n-type has been demonstrated. At low heat treatment temperature, a strong p-doping effect from Au(3+) ions to CNTs due to a large difference in reduction potential between them is dominant. However at higher temperature, the gold species are thermally reduced, and thermally induced CNT-Cl finally occurs by the decomposition reaction of AuCl(3). Thus, in the AuCl(3)-doped SWCNTs treated at higher temperature, the p-type doping effect is suppressed and an n-type property from CNT-Cl is thermally induced. Thermal conversion of the majority carrier type of AuCl(3)-doped SWNTs is systematically investigated by combining various optical and electrical tools.

Surfactant Effects on Microemulsion-Based Nanoparticle Synthesis.

The effect of the surfactant on the size, polydispersity, type of size distribution and structure of nanoparticles synthesized in microemulsions has been studied by computer simulation. The model simulates the surfactant by means of two parameters: the intermicellar exchange parameter, kex, related to dimer life time, and film flexibility parameter, f, related to interdroplet channel size. One can conclude that an increase in surfactant flexibility leads to bigger and polydisperse nanoparticle sizes. In addition, at high concentrations, the same reaction gives rise to a unimodal distribution using a flexible surfactant, and a bimodal distribution using a rigid one. In relation to bimetallic nanoparticles, if the nanoparticle is composed of two metals with a moderate difference in reduction potentials, increasing the surfactant flexibility modifies the nanoparticle structure, giving rise to a transition from a nanoalloy (using a rigid film) to a core-shell structure (using a flexible one).

Synthesis of Bimetallic Au@Pt Nanoparticles with Au Core and Nanostructured Pt Shell toward Highly Active Electrocatalysts

Au@Pt nanocolloids with nanostructured dendritic Pt shells are successfully synthesized by chemically reducing both H2PtCl6 and HAuCl4 species in the presence of a low-concentration surfactant solution. By applying an ultrasonic treatment, the particle size of the Au@Pt nanocolloids is dramatically decreased and their size distribution becomes very narrow. The difference in reduction potentials of the two soluble metal salts (Au(III) and Pt(IV) species) plays a key role in the one-step synthesis of the core−shell structure. Because of the different reduction potentials, the reduction of Au ions preferentially occurs over a short time to form the Au seeds. It is followed by overgrowth of Pt nanodendritic nanowires on the Au seeds, which is confirmed by ultraviolet−visible light absorption spectroscopy and transmission electron microscopy. Interestingly, the Pt shell thicknesses on Au cores can be easily tuned by controlling the Pt/Au molar ratios in the starting precursor solutions. Through the optimization of the Pt shell thicknesses, the Au@Pt nanocolloids can exhibit enhanced activity as an electrocatalyst for a methanol oxidation reaction, which will be important to improve the utilization efficiency of Pt catalysts in the future.

Effects of Electronic Mixing in Ruthenium(II) Complexes with Two Equivalent Acceptor Ligands. Spectroscopic, Electrochemical, and Computational Studies

The lowest energy metal to ligand charge transfer (MLCT) absorption bands found in ambient solutions of [Ru(NH(3))(4)(Y-py)(2)](2+) and [Ru(L)(2)(bpy)(2)](+) complexes (Y-py a pyridine ligand and (L)(n) a substituted acetonylacetonate, halide, am(m)ine, etc.) consist of two partly resolved absorption envelopes, MLCT(lo) and MLCT(hi). The lower energy absorption envelope, MLCT(lo), in these spectra has the larger amplitude for the bis-(Y-py) complexes, but the smaller amplitude for the bis-bpy the complexes. Time-dependent density functional theory (TD-DFT) approaches have been used to model 14 bis-bpy, three bis-(Y-py), and three mono-bpy complexes. The modeling indicates that the lowest unoccupied molecular orbital (LUMO) of each bis-(Y-py) complex corresponds to the antisymmetric combination of individual Y-py acceptor orbitals and that the transition involving the highest occupied molecular orbital (HOMO) and LUMO (HOMO-->LUMO) is the dominant contribution to MLCT(lo) in this class of complexes. The LUMO of each bis-bpy complex that contains a C(2) symmetry axis also corresponds largely to the antisymmetric combination of individual ligand acceptor orbitals, while the LUMOs are more complex when there is no C(2) axis; furthermore, the energy difference between the HOMO-->LUMO and HOMO-->LUMO+1 transitions is too small (<1000 cm(-1)) to resolve in the spectra of the bis-bpy complexes in ambient solutions. Relatively weak MLCT(lo) absorption contributions are found for all of the [Ru(L)(2)(bpy)(2)](m+) complexes examined, but they are experimentally best defined in the spectra of the (L)(2) = X-acac complexes. TD-DFT modeling of the HOMO-->LUMO transition of [Ru(L)(4)bpy](m+) complexes indicates that it is too weak to be detected and occurs at significantly lower energy (about 3000-5000 cm(-1)) than the observed MLCT absorptions. Since the chemical properties of MLCT excited states are generally correlated with the HOMO and/or LUMO properties of the complexes, such very weak HOMO-->LUMO transitions can complicate the use of spectroscopic information in their assessment. As an example, it is observed that the correlation lines between the absorption energy maxima and the differences in ground state oxidation and reduction potentials (DeltaE(1/2)) have much smaller slopes for the bis-bpy than the mono-bpy complexes. However, the observed MLCT(lo) and the calculated HOMO-->LUMO transitions of bis-bpy complexes correlate very similarly with DeltaE(1/2) and this indicates that it is the low energy and small amplitude component of the lowest energy MLCT absorption band that is most appropriately correlated with excited state chemistry, not the absorption maximum as is often assumed.

Improved methanol oxidation activity and stability of well-mixed PtRu catalysts synthesized by electroless plating method with addition of chelate ligands

A new synthetic scheme of PtRu catalysts for methanol oxidation reaction is reported. P containing PtRu nanoparticles 2 nm in size were synthesized by electroless plating method using phosphinic acid as a reducing agent as well as the source of P. Chelate ligands were added in the synthetic system to decrease the difference of effective reduction potentials between Pt 4+ and Ru 3+ cations in their chloride precursors. Coordination ability of the chelate ligands with the cations was evaluated using UV–vis spectroscopy. It was found that dl-tartaric acid has the highest coordination ability with the cations and that the difference decreases from 0.4 to 0.19 V with addition of dl-tartaric acid. Microstructure, bulk and surface compositions of the PtRu catalysts were analyzed by means of XRD, XRF and Cu stripping voltammetry techniques, respectively. Results revealed that Pt and Ru atoms are well mixed and that both bulk and surface compositions are close to Pt 50Ru 50 in PtRu catalyst synthesized with dl-tartaric acid. The well-mixed PtRu catalyst synthesized with dl-tartaric acid showed higher methanol oxidation reaction activity and stability values relative to those of PtRu catalyst synthesized without dl-tartaric acid.

Acid–base and electrochemical properties of manganese meso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria

The difference in electrostatics and reduction potentials between manganese ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP) and manganese meta-tetrakis(N-ethylpyridinium-3-yl)porphyrin (MnTE-3-PyP) is a challenging topic, particularly because of the high likelihood for their clinical development. Hence, a detailed study of the protolytic and electrochemical speciation of Mn(II-IV)TE-2-PyP and Mn(II-IV)TE-3-PyP in a broad pH range has been performed using the combined spectrophotometric and potentiometric methods. The results reveal that in aqueous solutions within the pH range ∼2-13 the following species exist: (H(2)O)Mn(II)TE-m-PyP(4+), (HO)Mn(II)TE-m-PyP(3+), (H(2)O)(2)Mn(III)TE-m-PyP(5+), (HO)(H(2)O)Mn(III)TE-m-PyP(4+), (O)(H(2)O)Mn(III)TE-m-PyP(3+), (O)(H(2)O)Mn(IV)TE-m-PyP(4+) and (O)(HO)Mn(IV)TE-m-PyP(3+) (m = 2, 3). All the protolytic equilibrium constants that include the accessible species as well as the thermodynamic parameters for each particular protolytic equilibrium have been determined. The corresponding formal reduction potentials related to the reduction of the above species and the thermodynamic parameters describing the accessible reduction couples were calculated as well.

Synthesis of Ag-Mn&lt;SUB&gt;3&lt;/SUB&gt;O&lt;SUB&gt;4&lt;/SUB&gt; Core–Shell Nanorods and Mn&lt;SUB&gt;3&lt;/SUB&gt;O&lt;SUB&gt;4&lt;/SUB&gt; Nanotubes from Sacrificial Ag Nanorod Templates

Our research focuses on the preparation of Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes which have various engineering applications. Hausmannite manganese oxide (Mn3O4) nanotubes were synthesized via a galvanic replacement reaction at mild reaction conditions. The Mn3O4 nanotubes were prepared by solidification of manganese ions on a sacrificial silver nanorod due to the standard reduction potential difference between solid silver and manganese ions. The Mn ions were reduced to solid while the solid Ag rod was oxidized to ions. Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes were simply prepared by changing the amount of manganese ions. The Mn3O4 layer in the nanorods and nanotubes had a Hausmannite crystalline structure and showed weak hysteresis of magnetism. This weak magnetism is likely due to the diamagnetic property of silver and multiple magnetic domain of Mn3O4. This simple replacement reaction could be applied to various oxide nanotube fabrications with exact shape control.

The Cage and Metal Effect: Spectroscopy and Electrochemical Survey of a Series of Sm-Containing High Metallofullerenes

A series of Sm-containing high metallofullerenes, namely, Sm@C82 (I, II, III, IV), Sm@C84 (I, II, III), Sm@C86, Sm@C88 (I, II, III), Sm@C90 (I, II, III), Sm@C92 (I, II), Sm@C94 (I, II, III), and Sm@C96, is successfully synthesized and characterized by UV/Vis/NIR absorption spectroscopy, and cyclic and differential pulse voltammetry. Sm-containing high metallofullerenes have a relatively larger number of isomers compared with other divalent ones. The highest boiling point of Sm among Group II metals may be responsible for this phenomenon. Comparing the spectroscopic and electrochemical behaviors of Sm-containing metallofullerenes with those of other divalent ones, it is seen that when the size of the carbon cage enlarges, different structures form stable molecules with different metals. Furthermore, there are also some important differences in the electrochemistry properties. The cage effect on the electronic structures of high metallofullerenes is also estimated from the differences in reduction potentials between metallofullerenes and their corresponding fullerenes. It is believed that the influence of transferred electrons from the metal to the carbon cage becomes much weaker for high fullerenes. The redox property of high metallofullerene is more dependent on the carbon-cage structure than the effect of electron transfer.

CO2 reduction potentials by utilizing waste plastics in steel works

Feedstock recycling has received attention as an effective method to recycle waste plastics. However, estimating the reduction potential by life cycle assessment using coke oven and blast furnace in steel works has been a challenging task due to the complex structure of energy flow in steel works. Municipal waste plastics consist of several plastic resins. Previous studies have generally disregarded the composition of waste plastics, which varies significantly depending on the geographical area. If the reduction potentials by using each plastic resin in steel works can be quantified, the potential of municipal waste plastics (mixtures of plastic resins) can be estimated by summing up the potential of each resin multiplied by the composition of each resin in municipal waste plastics. Therefore, the goal of this study is to investigate the reduction potentials of CO2 emissions by using individual plastic resins (polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET)) and those for municipal waste plastics in the coke oven and blast furnace. A model was developed to clarify the energy flow in steel works. In order to estimate the changes in energy and material balance in coke ovens when waste plastics are charged, the equations to calculate the coke product yield, gas product yield, and oil product yields of each plastic resin were derived from previous studies. The Rist model was adopted to quantify the changes in the inputs and outputs when plastics were fed into a blast furnace. Then, a matrix calculation method was used to calculate the change in energy balance before and after plastics are fed into a coke oven. It was confirmed that product yields of municipal waste plastics (mixtures of plastic resins) could be estimated by summing up the product yield of each plastic resin multiplied by the composition of each resin in municipal waste plastics. In both cases of coke oven and blast furnace feedstock recycling, the reduction potential of CO2 emissions varies significantly depending on the plastic resins. For example, in the case of coke oven chemical feedstock recycling, the reduction potential of PS and PP is larger than that of PE. On the other hand, in the case of blast furnace feedstock recycling, PE has the largest CO2 emissions reduction potential, whereas the CO2 emission reduction potential of PP is smaller than those of PE and PS. In both cases, PET has negative CO2 emission reduction potentials, i.e., there is an increase of CO2 emissions. In addition, the reduction potentials of CO2 emissions are slightly different in each city. The differences in the reduction potentials of CO2 emissions by coke oven chemical feedstock recycling of each plastic resin is attributable to the differences in calorific values and coke product yields of each plastic resin. On the other hand, the difference in the CO2 emission reduction potential for each plastic resin in blast furnace feedstock recycling is attributable to the difference in calorific values and the carbon and hydrogen content of each plastic resin, which leads to a difference in the coke substitution effect by each plastic resin. In both cases, the difference in those of municipal waste plastics is mostly attributable to the amount of impurities (e.g., ash, water) in the municipal waste plastics. It was found that the reduction potential of CO2 emissions by coke oven and blast furnace feedstock recycling of municipal waste plastics (mixtures of plastic resins) could be estimated by summing up the potential of each resin multiplied by the composition of each resin in municipal waste plastics. It was also clarified that feedstock recycling of waste plastic in steel works is effective for avoiding the increase in CO2 emissions by incinerating waste plastics, such as those from household mixtures of different resins. With the results obtained in this study, reduction potentials of CO2 emissions can be calculated for any waste plastics because differences in composition are taken into account.

製鉄所での廃プラスチック利用によるCO&lt;sub&gt;2&lt;/sub&gt;削減ポテンシャル

Background, Aim and Scope. Feedstock recycling has received attention as an effective method to recycle waste plastics. However, estimating the reduction potential by LCA using coke oven and blast furnace in steel works has been a challenging task due to the complex structure of energy flow in steel works. Municipal waste plastics consist of several plastic resins. Previous studies have generally disregarded the composition of waste plastics, which varies significantly depending on the geographical area. If the reduction potentials by using each plastic resin in steel works can be quantified, the potential of municipal waste plastics (mixtures of plastic resins) can be estimated by summing up the potential of each resin multiplied by the composition of each resin in municipal waste plastics. Therefore, the goal of this study is to investigate the reduction potentials of CO2 emissions by using individual plastic resins (PE, PP, PS, PET) and those for municipal waste plastics in the coke oven and blast furnace.Materials and Methods. A model was developed to clarify the energy flow in steel works. In order to estimate the changes in energy and material balance in coke ovens when waste plastics are charged, the equations to calculate the coke product yield, gas product yield, and oil product yields of each plastic resin were derived from previous studies. The Rist model was adopted to quantify the changes in the inputs and outputs when plastics were fed into a blast furnace. Then, a matrix calculation method was used to calculate the change in energy balance before and after plastics are fed into a coke oven.Results. It was confirmed that product yields of municipal waste plastics (mixtures of plastic resins) could be estimated by summing up the product yield of each plastic resin multiplied by the composition of each resin in municipal waste plastics. In both cases of coke oven and blast furnace feedstock recycling, the reduction potential of CO2 emissions varies significantly depending on the plastic resins. For example, in the case of coke oven chemical feedstock recycling, the reduction potential of PS and PP is larger than that of PE. On the other hand, in the case of blast furnace feedstock recycling, PE has the largest CO2 emissions reduction potential, whereas, the CO2 emission reduction potential of PP is smaller than those of PE and PS. In both cases, PET has negative CO2 emission reduction potentials, i.e., there is an increase of CO2 emissions. In addition, the reduction potentials of CO2 emissions are slightly different in each city.Discussions. The differences in the reduction potentials of CO2 emissions by coke oven chemical feedstock recycling of each plastic resin is attributable to the differences in calorific values and coke product yields of each plastic resin. On the other hand, the difference in the CO2 emission reduction potential for each plastic resin in blast furnace feedstock recycling is attributable to the difference in calorific values and the carbon and hydrogen content of each plastic resin, which leads to a difference in the coke substitution effect by each plastic resin. In both cases, the difference in those of municipal waste plastics is mostly attributable to the amount of impurities (e.g., ash, water) in the municipal waste plastics.(View PDF for the rest of the abstract.)

Activity and Durability of PtRuP Catalysts and Their Atomic Structures

Carbon supported PtRuP catalyst 2 nm in size was synthesized by electroless plating method by using HPH2O2 as a reducing agent as well as a source of P. Chelate ligand of citric acid was added in synthetic solution to decease difference of reduction potentials between Pt and Ru ions. Electrochemical measurements showed that the addition of chelate ligand decreased the difference from 0.42 V to 0.31 V and that CO tolerance, methanol oxidation activity and durability were improved in PtRuP catalyst synthesized with the chelate ligand. XRD and EXAFS analyses revealed that mixing state of Pt and Ru atoms was promoted in the PtRuP catalyst. The improved CO tolerance, methanol oxidation activity and durability arise from the well-mixed Pt and Ru atoms in the PtRuP catalyst, which supported bi-functional mechanism.

Effects of stannous ions on the electrochemical performance of the alkaline zinc electrode

The effect of stannous ions as an electrolyte additive on the electrodeposition characteristics of Zn was investigated by chronoamperometry, the potential-step method and cyclic voltammetry. The chronoamperometry measurements showed that the addition of stannous ions inhibited the dendritic growth of Zn deposits. SEM observation also revealed that the Zn deposit was in the form of compact cylinders with rounded tops that consist of many small crystallites, rather than the classical dendrites with side branches. The inhibition effect of Sn2+ on the very initial electrocrystallization of Zn was not a substrate effect. The 0.17 V difference in reduction potential between Zn and Sn resulted in the codeposition of Sn and Zn. An interruption effect was proposed to illuminate the inhibition effect of Sn2+ on the formation of Zn dendrites. Furthermore, Sn2+ additive was found to suppress the corrosion reaction of Zn by 87% in the Sn2+-containing zincate electrolyte, comparing to that in the blank zincate electrolyte.