bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Corrosion and Hydrogen Permeation into Carbon Steel in the Chloride Media Containing H2s and CO2
Authors: Tsygankova Liudmila , Vigdorovich Vladimir , Shel Natalia , Esina Marina
Published: February 2020

Inhibiting action of compositions on base of the technological mixture of the polyaminoamides and polyaminoimidazolines dissolved in the specific organic protonic solvent (IC-1) and aprotonic one (IC-2) has been studied against steel corrosion and hydrogen diffusion through the steel membrane. Investigations were conducted in the HCl solutions (pH = 2 – 6) containing 0.25 – 25 g/l NaCl and saturated by CO2 (P = 1 – 2 atm) and H2S (5 – 1000 mg/L) separately and together by the methods of gravimetrical corrosion tests, potentiodinamic polarization measurements, electrochemical impedance spectroscopy. Electrochemical diffusion method has been used too.

Protective efficiency (Z, %) of the inhibitors increases with decreasing pH value and at the insertion of hydrogen sulfide. Its value reaches 96 % in the solutions with pH=2 containing 500 mg/L H2S and 200 mg/L of IC-1 or IC-2. At the inhibitor concentration equal to 50 mg/L, efficiencies of first and second inhibitors are near 93% and 85% respectively. Z increases with increasing CH2S up to 500 mg/l, further growth of the H2S concentration does not practically influence on the protective action.

The inhibitors slow down both partial electrode reactions of the corrosion process simultaneously. Their adsorption proceeds according to the Temkin isotherm in the wide range of the cathodic and anodic potentials. Both inhibitors decrease the hydrogen permeation into the steel membrane at the corrosion potential and under the anodic and cathodic polarization too in the presence of CO2 and H2S separately and together.
Characterization of Kaolinite (Al2Si2O5 (OH)4) and Lansoprazole (C16H14N3F3O2S) for Developing a Structured Coating
Authors: Sarmiento Bustos Estela , Concha Guzman Lizeth , Uruchurtu Jorge , Menchaca Carmina , Dominguez Perez Oscar
Published: February 2020

The phenomenon of corrosion is impaired and the different materials. Industrially it has worked in the protection of these, however, efforts can increase costs if the methods and mechanisms are not adequate and therefore inefficient. Currently, several studies focus on the development of new coatings that act as corrosion inhibitors from natural sources with no toxic properties. Kaolinite (Al2Si2O5 (OH) 4) is considered a "green" low cost material and promotes it to be used as a container of polymeric materials because of their porous characteristics. Moreover, some drugs such as omeprazole (C17H19N3O3S), pantoprazole (C16H15N3F2O4S) for their inhibitory properties in acidic environments are ideal candidates for use as corrosion inhibitors to replace those that are typically toxic as chromate lithium (Li2CrO4).

In this paper the development of a structured coating consisting of kaolinite (Al2Si2O5 (OH) 4) doped with lansoprazole (C16H14N3F3O2S) and a polymer film with the purpose of protecting metallic materials such as steel is presented. The objective of this work is to characterize kaolinite (Al2Si2O5 (OH) 4) in the raw natural state and heat treated at 350, 400, 450 and 560 ° C by Scanning Electron Microscopy (SEM). Lansoprazole ((C16H14N3F3O2S)) was characterized by electrochemical techniques: polarization curves and electrochemical impedance spectroscopy (EIS).

The results show that the kaolinite in its natural state has amorphous and crystalline particles with impurities. When the heating process mesoporous particles were obtained. Lansoprazole effectiveness at different concentrations (50, 75, 100, 125, 150 and 200 ppm) was evaluated in an aqueous solution of ammonium sulfate ((NH)4 SO4) with sodium chloride (NaCl) at pH 7 and 25 ° C using mild steel.

The results suggest that at 500 °C mesoporous kaolinite particles which may be applied as inhibitory container obtained lansoprazole, gave the better electrochemical response. Moreover lansoprazole has the highest efficiency as a corrosion inhibitor at 125 ppm.
Efficient Corrosion Inhibition of API 5L X52 STEEL in HCl By NN-Functionalized 1,2,3-Triazoles
Authors: Espinoza Araceli , Palomar Manuel , Romero Mario Alberto , Negrón Guillermo , Mendoza Daniel
Published: February 2020

The corrosion inhibition efficiency (IE) of a series of NN-functionalized 1,2,3-Triazoles was measured in the system: pipeline steel grade API 5L X52 / 1M HCl, using electrochemical impedance spectroscopy (EIS). The influence of the inhibitor concentration on the IE of all these compounds was determined. The results showed that in all cases the IE increased with increasing inhibitor concentration, and the best inhibitor of the series resulted the p-fluorinatedbenzyl triazole (TDF) with 96% of EI at 15 ppm.

Overall, it was found that the inhibitors follow a physisorption mechanism, which can be adequately described by the Langmuir isotherm. Moreover, it is shown that these compounds can affect both the anodic and cathodic processes, thus it can be classified as a mixed-type inhibitor that may block both anodic and cathodic sites in the API 5L X52 steel surface immersed in HCl.
Stress Corrosion Cracking of API 5lX52 in Ethanolic Environment
Authors: Pedraza Basulto Gabriela Karina , Miramontes Jose Angel Cabral , Chacon Jose , Achem Calahorra Jamnie Yazmin
Published: February 2020

The human interest on renewable energy it is due environmental preservation. In substitution of Methyl-therbutyl-ether (MTBE), ethanol it is being used as replacement of the oxidant agent in gasoline, because not only increases the fuel octane number and represents the best option for the increasing demand for fossil fuel observed over the last few years. However, one of the most common failures on mild steel found in ethanolic environments is stress corrosion cracking (SCC) and pitting corrosion. Based on the report of American Petroleum Institute (API), the safer way for transporting the blend is by the existing pipeline.

Thus, the aim of the present study is to investigate the effect of water content (0.5%, 5%, 10% ) in E95 blends on the stress corrosion cracking susceptibility of API 5L X-52 steel. In order to assess the steel mechanical and electrochemical response, slow strain rate tests (SSRT) of 1 X 10-6 s-1, coupled with electrochemical noise measurements (ECN) were carried out. In addition, the material response immersed into the various solutions was analyzed by using linear polarization resistance (LPR) measurements and weight loss measurements. Furthermore, fracture surface observations by scanning electron microscopy (SEM) on samples exposed to the various solutions were done. In general, a ductile behavior was observed. However, secondary cracking was only observed for specimens exposed to solution containing up to 2%V water. ECN gave indication of a likely localized corrosion process occurring at low water concentrations, whereas for water content above 2%V, a uniform corrosion process seems more likely to occur. the LPR results indicated that specimens exposed to water content up to 2%V disclosed the lower corrosion rates. Further, the results of weight loss measurements supported the behavior found.
Use of the Scanning Vibrating Probe for in-Situ Monitoring of SCC Via the Coupling Current in 5000 Series Al Alloys
Authors: Williams Krystaufeux , Bayles Robert , Macdonald Digby
Published: February 2020

When as-received or sensitized AA5083 are immersed in an electrolyte, a growing crack creates a galvanic couple with the external surfaces according to the differential aeration hypothesis. Monitoring the resulting “coupling current” yielded “real-time” information about the status of a stress corrosion crack. As a result of this study, we have determined that the scanning vibrating electrode technique (SVET) can be used to monitor the coupling current flowing through the solution from the crack to the external surfaces. Preliminary feasibility studies were performed to map the current/potential in larger galvanic couples designed to simulate Cu-rich intermetallics dispersed in an aluminum matrix. A novel horizontal fracture mechanics apparatus, designed to apply a known stress intensity, was employed to reveal the onset of subcritical crack growth. In addition to the preliminary studies, we successfully designed a setup to allow the typical fracture mechanics testing to occur with the SVET. We report on the progress that was made in designing a customized four-point bend, fracture mechanics device that allows for simultaneous loading and electrochemical mapping. Spatially resolved coupling current/potential maps indicate that both the notch and the crack-tip become and remain anodic for a considerable duration of the crack growth process. Furthermore, there are peaks in the coupling current associated with the onset of subcritical crack growth.
Electrochemical Study of the Corrosion of Steel Embedded in Concrete Added with Composite Substituting Cement
Authors: Vásquez-Zacarias Leticia , Poisot Martha , Velazquez-Manzanares Miguel , Pérez-López Tezozomoc
Published: February 2020

In this work, an electrochemical study of the corrosion of steel embedded in concrete was conducted. This five test samples with cement, sand, water are produced; adding composite of hydrophobic cellulose and sugar cane bagasse ash (SCBA) previously treated, both substances are agroindustrial wastes from: Bioppapel and the sugar mill in this city of San Juan Bautista Tuxtepec. After 24 hours of drying, the samples are subjected to curing in saturated solution of calcium hydroxide and electrochemical measurements were started and continued for a period of 28 days. Then a solution of sodium chloride 3% was added according to electrochemical measurements. This study was conducted in order to observe the potential for inhibiting the steel corrosion by adding this new composite to traditional concrete . The electrochemical techniques applyed are: Electrochemical Impedance Spectroscopy and linear polarization resistance using a potentiostat/galvanostat ACM Instruments serial 914 with a calomel reference electrode. The results of these tests will be explained in the poster presentation.
Study of the Stability of the Steel Embedded in Mortars Added with Pozzolans
Authors: Martínez-Rosales Roxana Isabel , Miranda Juana María , Narváez Lilia , Lomeli Martha Alejandra
Published: February 2020

The present study explores the behavior of structural steel embedded in Portland cement mortars and 15, 20 y 25 % natural pozzolan added in partial substitution of the cement, in the presence and absence of 2% Cl- as contaminant. Furthermore was evaluated the influence of the content of pozzolan in the mechanical properties the mortars. Variations were determined in the corrosion potential (Ecorr), linear polarization resistance (Rp) and corrosion current density (icorr) under ≈ 95% relativity humidity conditions during 12 month of exposure. In the absence of Cl-, the pozzolan added in the mortars were able to passivate the steel reinforcement. Steel corrosion in the presence of 2% Cl- and different contents of puzzolan was observed to be similar to corrosion reported for the material in Portland cement mortars.
Behavior Electrochemical of Carbon Steel in a Synthetic Medium and Hydrocarbon on a System with Continuous Flow Rate
Authors: Lopez Luis Daimir , Olguin Francisco Javier , veloz Rodriguez Maria aurora , Almeraya Facundo Mauricio , Marquez Casasola Miguel
Published: February 2020

In this work the study of the behavior electrochemical of system continuous flow rate over a system of carbon steel immersed in a synthetic corrosive medium (brine type born 1D196), in the absence and presence of hydrocarbon. Electrochemical techniques used were curves of polarization and electrochemical impedance spectroscopy. In the polarization curves, shows that the immersion time affects both the Anodic part and the cathodic, .showing that currents obtained are higher as the exposure time increases for systems in study (in the absence and presence of hydrocarbon), it is worth mentioning that the presence of hydrocarbon in the system increases currents in comparison to the system in the absence of hydrocarbon. Electrochemical impedance spectroscopy technique, shows that steel has great activity in the systems studied to be most noticeable at low frequencies and in the presence of hydrocarbon, since the spectrum shows a flattened semi-circle, with low values of impedance and an inductive loop in the presence of hydrocarbon. This establishes the interaction of ions present in the solution with metal, favored by presence of hydrocarbon; the adsorption stage governing the corrosion process, are also favored.
Protection and Failure Mechanism Analysis of Zinc Coatings for Galvanic Protection
Authors: Wijesinghe Sudesh Lakshitha , Tan Zixi
Published: February 2020

Zinc coatings have been used for many decades for various applications to protect against corrosion. These coatings provide a very effective and an economical way of protecting steel against corrosion. Both substrate-coating interface and the bulk of coating play important roles in terms of galvanic protection capability, thus the transformation process of zinc particles and their interactions were analysed together with corrosion resistant properties. It is imperative to study the protection and failure mechanisms of these coatings related to corrosion.

Two zinc coatings; namely hot dip galvanised (HDG) together with a special commercial zinc rich paint coated on AISI 1020 mild steel substrates were selected for a detailed study of their protection/failure mechanism. High resolution cross sectional analysis of samples at different exposure stages together with other corrosion and electrochemical data will help to unveil the story.

Samples were exposed in an advanced cyclic corrosion test chamber according to ISO 14993 and were withdrawn at the end of each cycle for respective evaluation. Electrochemical evaluations were conducted using corrosion potential measurements and electrochemical impedance spectroscopy (EIS).

Localised electrochemical details and anodic and cathodic activities were investigated by high scanning vibrating electrode technique (SVET).

Cross sectional analysis of samples at different stages of exposure were done by high resolution scanning electron microscope with and without backscattering techniques to scrutinise the protection and failure mechanisms of the coatings.

Corrosion rates were calculated by chemical pickling followed by mass loss measurements whilst visual examinations were performed according to ISO 10289 whilst corrosion products were analysed by scanning electron microscope, Fourier Transformation infrared spectroscopy (FTIR) together with micro Raman spectroscopy.

Results will be discussed in detail in the presentation
Surface Modification and Electrochemical Metallization of Advanced Polymers for Energy Application
Authors: Oriani Andrea Vittorio , Spreafico Marco Alberto , Cojocaru Paula , Triulzi Francesco , Magagnin Luca , Apostolo Marco
Published: February 2020

For some demanding applications the peculiar properties of polymers, as lightweight, flexibility and chemical resistance, need to be enriched with additional characteristics that are traditionally associated with metals, such as thermal and electrical conductivity, barrier to fluids, high hardness, tribological resistance and reflectivity. Applications, requiring this coupling of different properties, include flexible electronics, barrier layers and alternative energy1–3. In these applications a thin layer of metal, on top of the polymeric substrate, is sufficient to assure the required properties. The main issue of these composites is the adhesion between the two materials and is related to the low surface energy of polymers4. To overcome adhesion issues between the polymeric and metallic layer, several dry and wet processes have been proposed5–7 that imply the utilization of expensive tools or aggressive chemicals. We propose an alternative method to perform metallization of partially fluorinated polymers based on a two-step process: a) chemical functionalization of the substrate surface, for increased adhesion and b) activation and electroless metallization with Cu or Ni-P. After this process we have a continuous, adherent and conductive metallic layer that allows for surface finishing by electrodeposition. We produced continuous metallic thin layers of Cu and Ni-P on different partially fluorinated polymers achieving a 5B adhesion in the ASTM D3359 cross cut test. Considering the application of metallized polymeric films for solar thermodynamic, the electrodeposition of Al from air and water stable ionic liquids is being investigated.

References:

1. G. Garnier et al., Polym. Adv. Technol., 22, 847–856 (2011).

2. Y. Su et al., Int. J. Solids Struct., 49, 3416–3421 (2012).

3. J. Vanfleteren et al., MRS Bull., 37, 254–260 (2012).

4. J. M. Burkstrand, J. Appl. Phys., 52, 4795 (1981).

5. K. L. Mittal, J. Vac. Sci. Technol., 13, 19 (1976).

6. K.-W. Lee and A. Viehbeck, IBM J. Res. Dev., 38, 457–474 (1994).

7. P. Bertrand, P. Lambert, and Y. Travaly, Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms, 131, 71–78 (1997).
Electrodeposition of Selective Absorber Coatings Based on Black Nickel for Solar - Thermal Energy Conversion
Authors: Estrella-Gutierrez Manuel Alejandro , Lizama-Tzec Francisco Ivan , Arés-Muzio Oscar , Oskam Gerko
Published: February 2020

Solar energy is the most abundant, renewable and clean energy source, and several systems exist to convert solar energy into a useful form for specific applications. One of them is the development of solar collectors based on selective coatings, with a high absorptivity in the visible and low emissivity in the near to mid infrared regions of the solar spectrum. The use of selective coatings has been widely established as an industrial practice to improve the efficiency in solar energy collection. For practical applications, a solar absorber coating with selective optical properties should be easily applicable with easy scale-up, low cost and short time of synthesis. These coatings can be applied to the collector substrate by various techniques including vacuum deposition, spray methods, sol-gel chemistry, and electrodeposition.

In this work, bright and black nickel coatings were electrodeposited onto copper and stainless steel substrates with an area of 16 cm2. The experiments were performed at room temperature using electrolytes from nickel sulfate and nickel chloride salts. For the characterization of the coatings, several techniques were used, as profilometry, scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The optical properties of the coatings were measured by reflectance spectroscopy. For the evaluation of the energy conversion efficiency, the electrodeposited coatings were irradiated at 1 sun and the heating of an aqueous was measured as a function of film properties.
Underpotential Deposition of Copper onto 3D Gold Nanostructures
Authors: Aldana-González Jorge , Olvera Juan Carlos , Montes de Oca Maria Guadalupe , Romero-Romo Mario Alberto , Ramirez-Silva Maria Teresa , Palomar-Pardavé Manuel
Published: February 2020

The electrochemical formation of atomic adlayers introduces significant changes in the electrocatalytic properties of electrode surfaces. In the present contribution, we study the surface properties of Au nanoparticles analysing the electrochemical responses associated to the copper underpotential deposition (upd) in acid pH. The Au nanoparticles were synthesised by the chemical method, using HAuCl4 and trisodium citrate with an average diameter of 19.2 ± 1.2 nm. Three-dimensional networks of Au nanoparticles were assembled via electrostatic layer-by-layer adsorption employing poly-L-Lysine (PLL) on In-doped SnO2 electrodes (ITO). The electrochemical studies in sulfuric acid (Figure 1A) show the voltammetry behavior, while (Figure 1B) in copper sulfate (CuSO4) show the potentiostatic current transients of Cu onto Au nanoparticles. Detailed electrochemical analysis of the responses showed that the average Cu coverage on a single Au nanoparticle is close to those observed at extended Au surfaces. These results demonstrate that each individual nanoparticle in the assembly participate in the electrochemical copper deposition.
Fabrication and Characterization of CdS Nanoparticles Obtained via Microwave-Assisted Synthesis
Authors: Tamasauskaite-Tamasiunaite Loreta , Grinciene Giedre , Selskis Algirdas , Norkus Eugenijus
Published: February 2020

Cadmium sulfide (CdS) is an important II-IV semiconductor with a direct band gap of 2.42 eV at room temperature for various applications in optoelectronic, electronic devices and solar cells. Size, structure and morphology of CdS nanoparticles play a major role on the physical and optical properties of CdS thin films.

In the present study a rapid microwave heating method was used to prepare CdS nanoparticles. The reaction mixture consisted of cadmium chloride, cadmium acetate, cadmium nitrate and thiourea precursors. The influence of reaction mixture medium and power on the size and structure of synthesized CdS was investigated. The morphology, structure and composition of the prepared CdS were examined by means of Field-Emission Scanning Electron Microscopy and Energy Dispersive X-ray analysis. The optical properties of the CdS thin films deposited onto glass substrates were investigated by means of UV/Vis spectrophotometric measurements.

It has been found that the size and structure of CdS particles synthesized by rapid heating irradiation depend on the alkalinity of reaction mixture and microwave power. The synthesized CdS nanoparticles have a band gap of 2.5 – 2.7 eV.

Acknowledgement

The work was carried out within the project VP1-3.1-ŠMM-08-K-01-009 that is partly supported by the National Programme “An improvement of the skills of researchers” launched by the Lithuanian Ministry of Education and Science.
Keynote: Successful Electrochemical Energy Storage: A Battery Is More Than the Sum of Its Parts
Authors: Takeuchi Esther S , Takeuchi Kenneth J , Marschilok Amy C
Published: February 2020

Advances in electrochemical energy storage have taken on expanded significance due to the needed ability to store electricity for many applications including aerospace, transportation, portable electronics, and biomedical devices. Recently, large scale electrochemical energy storage is also being contemplated for storage related to the generation and distribution of electricity by the electrical grid.

The specific needs of each application vary widely where a single solution can not meet the demands of all applications. This results in the tethering of the energy storage solution with the need where the energy storage system should be viewed synergistically with the application. The application is often enabled by the power source and conversely, without an application the power source has little value.

The design of next generation power sources is successful taken in the context of systems level function. Expertise spanning the range from molecular analysis to mesoscale interrogation to systems level observation is required. An example based on the deployment of a successful battery, lithium/silver vanadium oxide, for implantable medical applications will be considered. Recent results in the quantification of the life limiting process based on anode – cathode – electrolyte interactions will be presented. Further, the investigation of a new class of materials for extending battery life will be discussed.
A Portable Oxygen Concentrator for Wound Healing Applications
Authors: Scherson Daniel , Cali Larry , Sarangapani Sarang
Published: February 2020

Wound healing is a complex biological process that involves an organized cell assembly leading to tissue regeneration and repair, a process that requires oxygen. As has been reported in many studies, hypoxia delays wound healing; oxygen modulates the inflammatory response of the tissues and it serves as an infection control agent by enhancing the ability of leukocytes to kill bacteria when supplied in adequate amounts. In addition, it promotes collagen synthesis and stimulates angiogenesis. Most importantly, continuous oxygen application leads to wound closure, as has been shown in a number of clinical studies where closure rates as high as 80% have been observed for non-healing recalcitrant wounds.

EPIFLO® (Ogenix, Beachwood, OH). (Figure 1) is a commercially available device that can deliver Transdermal Continuous Oxygen therapy and represents an inexpensive alternative to systemic hyperbaric oxygen therapy without the side effects of vasoconstriction, toxicity, and tissue destruction associated with the latter. EPIFLO is a light-weight (~100 g) electrochemical oxygen concentrator with no moving parts and silent operation. It generates continuously 3 mL/hour oxygen (98+% purity) and delivers to the wound site through a cannula tubing. It employs leading-edge oxygen ‘fuel cell’ concentration technology to stimulate tissue regenerative processes driving closure of delayed-healing acute or chronic wounds. This product is US FDA approved for a broad range of indications as a Class II Medical Device; prescribed on order of a physician. It is also CE, ISO 13485:2003 and CMDCAS (Canadian Medical Devices Conformity Assessment Scheme) Health Canada Certified

The heart of the device is a Membrane Electrode Assembly (MEA) consisting of a perfluorosulfonic acid cation exchange membrane, such as NafionR, interposed between two high area electrodes made of finely divided Pt based metal catalysts (Figure 2). Atmospheric air composed mostly of ~ 21 % oxygen, 78 % nitrogen is exposed to the device through the slots in the seam formed between the lid and the bottom part of the enclosure, where when activated using a small battery, it promotes the reduction of dioxygen at the cathode and the oxidation of water at the anode to produce oxygen delivered through a suitable tubing to the wound. Since the cation exchange membrane has overall very low gas permeability, gases cannot permeate through the membrane, thus ensuring a higher than 98% purity of the product oxygen.

This presentation will describe the critical steps involved in the bench-to-shelf process, invention to product, as well as the highly promising results found from its use in recalcitrant patients.
Solution Equilibria and Electroless Copper Deposition in Alkaline Formaldehyde-Containing Solutions
Authors: Norkus Eugenijus
Published: February 2020

The industrial electroless copper plating solutions containing formaldehyde as reducing agent are known from the middle of this century and are widespread in the practice up to now. However, the investigation of this system remains actual because of its complexity, e. g.alkaline medium, hydrated form of formaldehyde (methanediol), Cu(II) complex compounds with different ligands, additives which improve the properties of the coatings obtained and/or protect from the reduction of copper(II) in the solution bulk. Moreover, various equilibria are possible including deprotonation of methanediol, Cu(II) complex formation, additional interactions between components of the solution.

The aims and tasksof this work were to investigate or define more precisely equilibria in conventional alkaline solutions of electroless copper deposition as well as influence of the nature of Cu(II) ligands on the copper deposition process.

This research report deals with the results obtained by means of dc-polarography, vis-spectrophotometry, voltammetry, potentiometry, pH-metry, 1H and 13C NMR spectroscopy, scanning electron microscopy, X-ray diffractometry and gravimetry.

The composition, stability and the values of the diffusion coefficient of Cu(II) complex compounds with ligands (EDTA, DTPA, pyridine-2,6-dicarboxylic acid and 4-hydroxypyridine-2,6-dicarboxylic acid, Quadrol, L(+)-, D(–)- and DL()-tartrate, glycerol, saccharose and OH- ions) which are used or usable in alkaline electroless copper deposition solutions were established. The formation of mixed complex compounds between Cu(II) complexonates and K4Fe(CN)6, as well as between Cu(II) tartrate complexes and methanediol was investigated. The interaction of methanediol with L(+)-tartrate alongside with the influence of the ionic strength and cation nature on the deprotonation of methanediol in alkaline solutions were studied.

The kinetic data on electroless copper deposition from solutions containing above-mentioned ligands is presented and the influence of the ligand nature on the process of electroless copper deposition is discussed.
Reaction Mechanism of Thiourea as Suppressor in Electroless Cu Deposition Process
Authors: Kunimoto Masahiro , Naito Takehiro , Nakai Hiromi , Homma Takayuki
Published: February 2020

For more precise control of the electroless deposition process, reaction mechanisms of additives should be elucidated well. Particularly, in the case of the electroless deposition of Cu, behavior of thiourea (TU), which is one of the most widely used suppressor, molecular level understanding is significant. Although analyses of TU have been reported by numbers of researchers [1,2], its suppression mechanism has not been systematically understood. In this study we attempted to elucidate suppression mechanism of TU in electroless Cu deposition with formaldehyde as a reducing agent.

Since the electroless Cu deposition reaction involves both oxidation of formaldehyde and reduction of Cu2+ ion, the effect of TU on each reaction should be evaluated separately. For this, we employed “separated bath” system [3]; the bath without Cu2+ ion (oxidation bath), in which the only oxidation of formaldehyde proceeds, and the bath without formaldehyde (reduction bath), in which the only reduction of Cu2+proceeds, are connected with copper wire as shown in Fig. 1. The conditions of each bath are listed in Table 1.

When TU is added only to the oxidation bath, current density steeply decreased as shown in Fig. 2 (a), indicating that TU inhibits the oxidation of formaldehyde. On the other hand, when TU is added only to the reduction bath, current density slightly increased as shown in Fig. 2 (b), indicating that TU accelerates the reduction of Cu2+, probably due to the capturing effect of TU on Cu2+around the interface [4]. Overall, TU suppresses the Cu deposition reaction by inhibiting the oxidation reaction of reducing agent.

To elucidate the inhibition effect of TU on the reaction of formaldehyde, the adsorption states of TU and formaldehyde are calculated by DFT. Comparing these results, it is indicated that the adsorption energy of TU is much higher than that of formaldehyde. This shows that the adsorption of TU is much favorable on Cu substrate rather than that of formaldehyde. Hence, TU should inhibit the adsorption of formaldehyde by occupying the adsorption sites. Furthermore, from the DFT analysis, combined with SERS measurement, monomeric TU was indicated to adsorb on Cu surface via its NH2group because of the solvent effect.

Acknowledgements

This work was financially supported in part by Grant-in-Aid for Scientific Research (A) and “Development of Systems and Technology for Advanced Measurement and Analysis” program of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

References

[1] D. Papapanayiotou, R. N. Nuzzo, R. C. Alkire, J. Electrochem. Soc., 145 (10), 3366 (1998).

[2] G. M. Brown, G. A. Hope, D. P. Schweinsberg, P. M. Fredericks, J. Electroanal.
Chem., 380, 161 (1995).

[3] M. Kunimoto, K. Endo, H. Nakai, T. Homma, Electrochim.
Acta, 100, 311 (2013).

[4] J. S. Sallo, J. Kivel, F. C. Albers, J. Electrochem. Soc., 110, 890 (1963).
Kinetic Monte Carlo Studies of Enhanced Chemical Reactions on Nanoporous Electrodes
Authors: Sato Shutaro , Kaneko Yutaka
Published: February 2020

Kinetic Monte Carlo studies of enhanced chemical reactions on nanoporous electrodes

Nanoporous electrodes have the effect of enhancing kinetically-limited electrochemical reactions due to the enlargement of electrode surface area. It has recently been reported that the confinement effect of reactants in the pores plays an important role for the enhancement of the reactions[1, 2]. By using these catalytic effect of nanoporous electrodes, the application to nonenzymic sensor (ex. glucose) has been explored[3]. The purpose of the present work is to study the effects of nanoporous electrodes on the enhanced chemical reactions on an atomic length scale by the kinetic Monte Carlo (KMC) simulation. We focus our attention on the confinement effect of reactants as well as the enlargement of the electrode area. We have developed a combination of KMC and grand canonical Monte Carlo (GCMC) for the multiscale simulation of the reactions and the mass transport in solution.

We have performed a series of KMC-GCMC simulations to study the correlation between the porous structures (cylindrical, random) and the enhancement of the reactions. The simulation system is a three-dimensional square lattice consisting of electrode, solution and replenishing region. Figure-1 is a schematic diagram of this system. Reactant particles are distributed in solution and their diffusion is simulated by random walk. The upper part of the solution is a replenishing layer to supply the reactant particles when the concentration becomes low as a result of the surface reactions. We consider a simple electrode reaction. It is assumed that reactants are removed on the electrode with a given rate constant. We consider two types of pore structures; cylindrical pore and random pore. The diffusion and reaction of the particles are simulated by KMC method. The replenishing layer is simulated by GCMC method.

We first confirmed that nanoporous electrodes enhance slow reactions compared to flat electrodes. The influence of the pore structures on the reaction mechanism is studied in detail. We also study the reaction of the mixture of slow and fast reactant particles as an application to the sensors.

References

[1] J.-H. Han, E. Lee, S. Park, R. Chang and T. D. Chung, J. Phys. Chem. C, 114, 9546-9553 (2010)

[2] S. Park, H. C. Kim and T. D. Chung, Analyst, 137, 3891-3093 (2012)

[3] S. Park, T. D. Chung and H. C. Kim, Anal. Chem., 75, 3046-3049 (2003)
Magnetic Bit Patterned Media Fabrication Using Block Copolymer Directed Assembly
Authors: Ruiz Ricardo
Published: February 2020

Perpendicular magnetic recording media in excess of 1Tbit/in2 faces thermal stability and/or writeability challenges that are currently driving intense research in alternative technologies. Bit patterned media (BPM), in which magnetic bits are lithographically patterned as individual islands, stands as a promising technology for thermally stable, writable media. One of the main challenges of BPM lies in its lithographic specifications which push dimensions beyond those established for the conventional semiconductor industry roadmap. The most promising solution to the lithographic challenge can be found in directed self assembly of block copolymer films which has recently evolved as a viable technique to achieve sub-20nm lithography in time for BPM technology.

The periodic features naturally formed in block copolymer films display superior size uniformity at ultra-high densities, making them ideal lithographic masks to define the highly periodic data bits in the data sectors of hard disk drives for bit patterned media (BPM) technology at densities beyond 1Tbit/in2. Nanofabrication challenges towards bit patterned media, however, reach far beyond pattern formation at small length scales. The challenges faced in the fabrication of templates for BPM have spurred a set of important innovations in nanofabrication techniques such as the formation of geometries that deviate from the typical shapes naturally formed by block copolymers, as well as advances in high-fidelity pattern transfer and progress in scalability towards higher feature densities. In this presentation, we discuss some of these innovations. We demonstrate a process that combines directed self assembly with nanoimprint lithography to achieve rectangular patterns mounted on circular tracks. We will also discuss the impact of the nanofabrication process on the magnetic performance of the magnetic islands and the outlook for BPM technology. We will also explore additional innovations in nanofabrication techniques made possible by block copolymer lithography including opportunities in electroplating using self assembled masks.
Magnetic Alloy Plating with Hydroxymethyl-P-Tolylsulfone (HPT) Organic Additive
Authors: Sun Ming , Medina Jose , Sam Sopheak , Jiang Ming
Published: February 2020

Additives play an important role in thin magnetic alloy electrodeposition since they impact the film grain boundary, the nucleation and growth mechanism. Consequently, they significantly determine the film properties.

In this study, we have evaluated a α-hydroxy sulfone compound as plating additive (Hydroxymethyl-P-Tolylsulfone or HPT was used as a case study) in CoNiFe and CoFe electrodeposition processes. From the chemical nature of HPT, the major drawback of this compound is its poor stability in aqueous medium in the presence of air. Analytical (HPLC) and electrochemical methods have been utilized to identify the compound decay mechanism and behavior. The HPLC spectrum of HPT and its decay by-products are compared to those of pure known compounds in Fig 1. With HPT added into CoNiFe and CoFe electrolytes, a strong grain refining effect was noticed in the deposits and the related film properties (magnetic, morphology and corrosion properties, etc.) have been characterized accordingly.
Nanoparticle Electrocatalysts for the Oxidation of Waste Lignin
Authors: Movil-Cabrera Omar , Garlock Michael , Staser John A
Published: February 2020

Lignin is a large organic molecule and a primary waste from the pulping industry and biorefineries [1, 2]. Currently, lignin has little value other than as a fuel to generate heat. Lignin can, however, be used as a renewable raw material for a variety of value-added chemicals. Unfortunately, catalytic processes are difficult to implement for the degradation of waste lignin because selective oxidation is difficult and these processes produce an unacceptable amount of solid residue like char [2, 3].

Electrochemical processes, on the other hand, have several advantages over catalytic processes, including the use of mildly basic solvents as electrolytes, and control over the rate of reaction and the products. Thus, the electrochemical oxidation of waste lignin would be an ideal process to utilize this renewable raw material.

While there have been efforts related to the electrochemical oxidation of lignin, most work has focused either on expensive platinum electrodes or on low surface area, large metal electrodes. However, nanoparticle electrocatalysts can be developed that enhance the rate of electrochemical reaction through enhancement of electrocatalyst surface area and porosity.

We will report on our efforts to develop nanoparticle electrocatalysts with specific compositions and architectures for the electrochemical oxidation of lignin in weak alkaline solution. For example, Ni-Cu alloy nanoparticle electrocatalysts are suitable for the electro-oxidation of lignin in basic solution, as shown in Figure 1.

Figure 1. Electrochemical oxidation of lignin on Ni-Cu alloy nanoparticle electrocatalysts. Baseline is 1 M NaOH in the absence of lignin.

As shown in Figure 1, oxidation peaks in the presence of lignin occur around 0.03 V and 0.45 V vs. NHE that do not occur in the absence of lignin. Figure 1 indicates that lignin may undergo a complicated, multi-step oxidation process. For example, lignin may oxidize to one product at a lower potential, and that product may in turn oxidize to yet another product at higher potential. The oxidation potential and oxidation time (i.e., charge passed) affects the product distribution.

One of the most important aspects of the electrochemical oxidation of lignin in alkaline solution is the identification of the oxidation products. We will present GC/MS data that identify lignin oxidation products. This process could provide an economic way of reducing the organic waste from the pulping and biorefinery industries.

References.

1. A. French, “’Lignin’ May Be the Magic Word,” Innovation: America’s Journal of Technology Commercialization, June/July 2011.

2. C. Grestini, “Conversion of Lignin: Chemical Technologies and Biotechnologies,” EuroBioRef Summer School, Universita Degli Studi di Roma, Castro Marina, Lecce, Italy, September 21, 2011.

3. M. P. Pandey and C. S. Kim, “Lignin Depolymerization and Conversion: A Review of Thermochemical Methods,” Chemical Engineering and Technology, 34, 327-331 (1999)
Electrooxidation Treatment for Wastewater Sludge
Authors: De Leon Condes Cristina , Barrios Jose A , Becerril Elias , Barrera-Díaz Carlos , Roa-Morales G.
Published: February 2020

Sludge produced during wastewater treatment, contain pathogens that increases the risks to human health. In particular, the density of bacteria and helminth eggs in sludge generated in Mexico significantly exceeds the levels reported in developed countries (Jimenez , et al. 2002 ; Jimenez, 2007). These microorganisms enter into the sewage system and due to its physicochemical properties tend to accumulate in the sludge during the wastewater treatment (Diaz Cruz, et al. 2009 ) .

Some studies have reported on the BDD electrooxidation for removal of emerging pollutants in secondary effluents (Frontistis, 2011), however, with respect to sludge, this process has been applied only for stabilization and conditioning (Drogui et al. 2013) but not for the removal of pathogens. This work presents the results obtained when electrooxidation with BDD electrodes was applied to sludge under laboratory conditions.

A batch cylindrical electrochemical reactor containing a pair of BDD electrodes (BDD film supported on a niobium substrate) was used for electrooxidation tests. Each electrode was 20.0 cm by 2.5 cm with a surface area of 50 cm2. Batch volumes of 0.3 L were treated in a 1.0 L glass reactor. A direct-current power source supplied the system with 0.5, 1.0 and 2.0 amperes, corresponding to current densities of 10, 20, and 30 mA/cm2. Sludge samples were mixed using a magnetic stirrer to reduce liquid-solid phase separation.

Figure 1 shows the COD removal as a function of the pH. Note that the best conditions are reached under acid pH.

References

Díaz-Cruz, M.J. García-Galán, P. Guerra, A. Jelic, C. Postigo, E. Eljarrat, M. Farré, M.J. López d Alda, M. Petrovic, D. Barceló. 2009. Analysis of selected emerging contaminants in sewage sludge. TrAC Trends in Analytical Chemistry Volume 28, Issue 11, Pages 1263–1275.

Jiménez, B. (2007). Helminth ova control in sludge: a review. Water
Science & Technology, Vol. 56, No. 9, pp. 147–155.

Jiménez, B., Maya, C., Sánchez, E., Romero, A., Lira, L. and Barrios, J.A. (2002) Comparison of the quantity and quality of the microbiological content of sludge in countries with low and high content of pathogens. Water Science & Technology, Vol. 46, No. 10, pp. 17–24.
Comparison of Rectangular and Cylindrical-Flux Reactors in Electrochemical Remediation of Mercury Polluted Soil
Authors: Robles Irma , Bustos Erika
Published: February 2020

Mercury removal from soil is one of the most important approaches in the environmental field. In this way, electroremediation have shown a good alternative to remove it from soil. Electrochemical remediation is based on the generation of an electric field from the imposition of a direct current or potential using electrodes (anode and cathode), which are placed in pit excavated soil.

Two configuration reactors laboratory scale were tested in order to analyze the effect of current, flux, soil type, pH and conductivity. Both reactors include two titanium electrodes, separated 7 cm, and placed face to face in a 1D configuration. First reactor is a rectangular cell, and second reactor is a cylindrical-flux cell. In both cases same amount of soil was placed. Different potential values (5, 10, 15, 20 and 25 V) were tested in order to obtain the better conditions of electroremediation. All the experiments were done at room temperature and EDTA [0.1 M] was used as a complexing agent to improve electrochemical treatment.

Results indicated that in the rectangular reactor without flux, mercury moves toward the anode (+), by the presence of EDTA that forms a strong complex in a negative charge that promotes the movement of the complex ([EDTA-Hg]2-) to the electrode by the current application; pH and conductivity vary slightly in this experiments. The best condition is to apply a potential of 20 V, for a period of 1 h. At the end of the treatment passivation was observed in the electrodes at 20 and 25 V applied.

In the case of cylindrical reactor, flux of 2.5 and 6.5 mL·min were tested, this flux was imposed in a cathode-anode direction because of previous results. In this way, for the case of soil 1, a potential of 1 V shows same effectiveness as 25 V; but in the case of soil 2, 20 V are needed to remove most mercury amount. It depends on soil composition as organic matter content. Lower flux improves the current distribution. In this analysis pH and conductivity does not vary as in the case of rectangular cell.

Cylindrical-flux configuration improves the distribution of current and the efficiency of mercury removal. In this case no damage was observed in the electrodes, and pH and conductivity follows as initial values.
Analysis of Tertiary Current Distribution Modeling in a Turbulent Flow inside Parallel-Plate Electrochemical Reactor Used for Copper Recovery
Authors: Rivero Eligio Pastor , Cruz-Díaz Martín R , Almazán-Ruiz Francisco J , González Ignacio
Published: February 2020

The effect of hydrodynamics and electrical field on the performance of electrochemical cells is a central issue in electrochemical reactor engineering. This work presents an approach for such issue by modeling the effect of hydrodynamics on the mass transport and tertiary current and potential distribution in a parallel-plate electrochemical reactor used to study the copper recovery process. The operating conditions of the reactor were in turbulent regime and under charge and mass transfer mixed control. For hydrodynamics, the Reynolds averaged Navier–Stokes (RANS) equations, the standard k–ε turbulence model and wall functions were used. The mass transfer model was a combination of the convection–diffusion equation and a wall function adapted for mass transfer. The Butler-Volmer kinetics for copper reduction and simplified Tafel equations for water oxidation were also included in the model. The electrical continuity equation was used for evaluating the ohmic potential drop. An important part of the proposed numerical modeling is the concentration wall function that allows linking the transport equations with Cu2+ concentration at the interface in order to obtain, along with interfacial potential, the electrode kinetics. Using this approach it was possible to model a very complex interrelation between physical phenomena and the electrochemical reaction taking place in a reactor under a turbulent flow regime using moderate computer resources. The numerical results obtained are in agreement with experimental data of mass transfer coefficient and current-potential behavior. Fig 1 illustrate the effect of the velocity field on the overpotential distribution over the cathode.