Application Of Electrochemical Processes Research Articles

Layer-by-Layer Materials for the Fabrication of Devices with Electrochemical Applications

The construction of nanostructured materials for their application in electrochemical processes, e.g., energy storage and conversion, or sensing, has undergone a spectacular development over the last decades as a consequence of their unique properties in comparison to those of their bulk counterparts, e.g., large surface area and facilitated charge/mass transport pathways. This has driven strong research on the optimization of nanostructured materials for the fabrication of electrochemical devices, which demands techniques allowing the assembly of hybrid materials with well-controlled structures and properties. The Layer-by-Layer (LbL) method is well suited for fulfilling the requirements associated with the fabrication of devices for electrochemical applications, enabling the fabrication of nanomaterials with tunable properties that can be exploited as candidates for their application in fuel cells, batteries, electrochromic devices, solar cells, and sensors. This review provides an updated discussion of some of the most recent advances on the application of the LbL method for the fabrication of nanomaterials that can be exploited in the design of novel electrochemical devices.

The application of electrochemical processes in oily wastewater treatment: a review

Oily wastewater is becoming a concern worldwide due to its quantities and the presence of contaminants and its sustainable treatment should be cost-effective and meet all requirements so the contaminants are not transferred to the environment. The paper reviews the state-of-the-art in the oily wastewater treatment by electrochemical processes such as electrochemical advanced oxidation processes and electrocoagulation. Efficiency of oily wastewater treatment has been thoroughly investigated with its expression as a function of the main technological (process) parameters. Fe and Al electrodes, as well as their combination have proven to be very effective in oily wastewater treatment with slightly better performance of Al electrodes. Higher current densities and longer reaction times result with higher COD, TOC, turbidity, phenol and oil and grease removal efficiencies, but with resulting increase in wastewater temperature and energy consumption, so there is a strong need for the process optimization. There is a need for further research on the treatment efficiencies of different contaminants (heavy metals, total hydrocarbons, organic halogens, cyanides, etc.). A lack of research is presented on the treatment efficiency with electrodes of different materials as well as the analyses of the sludge production and its further treatment and use or disposal.

Graphdiyne based catalysts for energy applications

This review has comprehensively reviewed the graphdiyne-based catalysts for broad applications in electrochemical processes and energy storage devices, which will supply significant references for future research in this field.

Physicochemical and electrochemical characterization of Ce/carbonaceous matrices-based composites

Ce/carbonaceous matrices-based composites with potential application in electrochemical processes were successfully produced. Ce-based MOF-76 (Metal Organic-Framework-76 family, formed by lanthanide ions coordinated to 1,3,5-benzenetricarboxylic acid ligand - H3BTC or simply BTC) was prepared with different percentages of graphene oxide (GO) in situ (named Ce-BTC-GOX%), then calcined to CeO2-rGOX%. All obtained materials were characterized by physicochemical techniques. The presence of carbonaceous matrices in the composites improves their thermal stability, alters particles shape, and decreases their size. All materials underwent Cyclic Voltammetry tests and selected composites were evaluated by Electrochemical Impedance Spectroscopy, Hydrogen Evolution Reaction and Oxygen Evolution Reaction. The electron transfer between Ce3+/Ce4+ redox pairs is observed around 1.3 and 1.2 V vs. Ag/AgCl(sat.KCl) for oxidation and reduction, respectively. Among all produced materials, the Ce-BTC-GO30% presented the best electrochemical response, reaching 0.506 A g−1 of anodic current and 19.92 C g−1 of charge density. Its capacitance reaches 3340.8 μF cm−2, while its resistance to charge transfer decreases (2.4 Ω cm2) and Tafel equation slopes are 84.3 mV dec−1 for HER and 60.5/127.9 mV dec−1 for OER.

Recent Advances in the Understanding of Nickel-Based Catalysts for the Oxidation of Hydrogen-Containing Fuels in Alkaline Media

Nickel is a very abundant transition metal in the Earth’s crust, and it finds numerous applications in electrochemical processes where metallic Ni or its oxides are thermodynamically stable, partic...

Cover Feature: Application of Electrochemical Processes to Classical Iodocyclisation: Utility for Selectivity and Mechanistic Insight (ChemElectroChem 23/2019)

Cover Feature: Application of Electrochemical Processes to Classical Iodocyclisation: Utility for Selectivity and Mechanistic Insight (ChemElectroChem 23/2019)

Electrochemical monitoring of Acidithiobacillus thiooxidans biofilm formation on graphite surface with elemental sulfur

Inorganic wastewaters and sediments from the mining industry and mineral bioleaching processes have not been fully explored in bioelectrochemical systems (BES). Knowledge of interfacial changes due to biofilm evolution under acidic conditions may improve applications in electrochemical processes, specifically those related to sulfur compounds. Biofilm evolution of Acidithiobacillus thiooxidans on a graphite plate was monitored by electrochemical techniques, using the graphite plate as biofilm support and elemental sulfur as the only energy source. Even though the elemental sulfur was in suspension, S0 particles adhered to the graphite surface favoring biofilm development. The biofilms grown at different incubation times (without electric perturbation) were characterized in a classical three electrode electrochemical cell (sulfur and bacteria free culture medium) by non-invasive electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The biofilm structure was confirmed by Environmental Scanning Electrode Microscopy, while the relative fractions of exopolysaccharides and extracellular hydrophobic compounds at different incubation times were evaluated by Confocal Laser Scanning Microscopy. The experimental conditions chosen in this work allowed the EIS monitoring of the biofilm growth as well as the modification of Extracellular Polymeric Substances (EPS) composition (hydrophobic/ exopolysaccharides EPS ratio). This strategy could be useful to control biofilms for BES operation under acidic conditions.

Electrochemical Energy Conversion and Storage with Zeolitic Imidazolate Framework Derived Materials: A Perspective

AbstractThe development of transition‐metal‐based materials for electrochemical energy conversion and storage has received immense interest throughout the last two decades. In this respect, zeolitic imidazolate framework (ZIF)‐derived materials are particularly important for accessing various morphologies, sizes, exposed facets, variations in the electronic structure, high surface area, and large numbers of available active sites. The properties of the ZIF‐derived materials can be tuned by applying different synthetic protocols, introducing a heteroatom in the ZIF structure or by accessing core‐shell or hollow structures. Many studies have described the beneficial effects of ZIF‐derived materials, but no critical review is available in the growing field of electrochemical energy conversion and storage. Herein, we have described the basic principles of material synthesis from ZIFs, their applications in electrochemical processes, difficulties with the synthesis, and their future development.

Application of Electrochemical Process as Inner Holes Cleaner

Application of Electrochemical Process as Inner Holes Cleaner

<b>Electro-flocculation associated with the extract of <i>Moringa oleifera</i> Lam as natural coagulant for the removal of reactive blue 5G dye

Although an important significant sector in world economy, the textile industry is known for its large volumes of wastewater generated in production processes. In the search for cleaner technologies, the application of electrochemical processes, such as electro-flocculation, or natural coagulants, such as Moringa oleifera Lam extract, have become recurrent in literature. Since the required operating conditions for alternative technologies are such that they hamper effective application, current paper presents results obtained with the use of a hybrid system of treatment which combines electro-flocculation and the aqueous extract of Moringa oleifera lam to evaluate the removal of reactive blue 5G dye from aqueous solutions. Milder conditions of electric current intensity (0.10 – 1.50 A) and natural coagulant concentration (250-2000 mg L -1 ) were tested. Through a Central Composite Rotatable Design, it was possible to obtain a quadratic model which subsidized the optimization of operating conditions. Applying an electric current of 0.97 A to sacrificial electrodes of iron and a concentration of 2000 mg L -1 for the extract of Moringa oleifera Lam , an average 86.79% color removal was obtained, considered a satisfactory rate.

Electrochemical Disintegration of Activated Sludge Using Ti/RuO<sub>2</sub> Anode

Electrochemical process is one of the most effective methods to enhance sludge disintegration. In this study, Ti/RuO2 anodes were prepared by Pechini’s method and the electrode surface morphology was characterized by FESEM and EDAX. The effects of various operating conditions were investigated including initial pH value of sludge, sludge concentration, electrolysis time and current density. The study showed that the removal efficiencies of TS, VS, TSS and VSS increased with the increase of pH in the alkaline range, electrolysis time and current density but decreased with the increase of initial sludge concentration. The application of electrochemical process using Ti/RuO2 electrodes enhanced the sludge disintegration for possible subsequent biological treatment.

Recent Developments in Ion-Exchange Membranes and Their Applications in Electrochemical Processes for in situ Ion Substitutions, Separation and Water Splitting

Membrane-based separation processes are achieving a remarkable attention both in academics and industrial research due to the versatility and economic considerations. Ongoing challenges in water and wastewater treatment, food and biotechnology industries accelerating applications of electro-membrane processes. Intensified research on ion-exchange membranes (IEMs) based electro-membrane processes has been accomplished during recent years to produce potable water and downstream processes for biomolecules separation and recovery. The choice of proper membrane, design and operational optimization of the process are highly essential for successful commercialization of any process. Thus, the development of cost effective membranes by eco-friendly route is highly required for researchers working in the field of membrane development by electro-membrane-based processes. This review provides a brief summary of different preparative procedures for IEMs, transport phenomenon and their applications in electro-membrane separation processes. The most relevant studies have been discussed.

ChemInform Abstract: X‐Ray Probes for in situ Studies of Interfaces

AbstractReview: 96 refs.

X-Ray Probes for In Situ Studies of Interfaces

AbstractSurfaces and buried interfaces play critical roles in many environmental, catalytic, and tribological processes and in a wide variety of applications, including microelectronics and optoelectronics. Interfacial structure and composition are closely coupled to their surroundings, and probes that yield information about materials in situ are essential to obtain a thorough understanding of interface functions and properties. The highly brilliant, hard x-rays available from synchrotron light sources can easily penetrate through gas or liquid environments, or even solid thin-film overlayers, and enable real-time monitoring of the evolving chemistry and structure of the interface with atomic-scale resolution. Here we review the in situ study of interfaces by a variety of synchrotron x-ray scattering techniques and provide several examples of their application in electrochemical processes and thin-film island growth. We also discuss recent advances in analytical techniques and x-ray optics that are facilitating the in situ study of surfaces and buried interfaces with direct imaging.

The Chalkboard: An Electroanalytical Approach for Investigating the Reaction Pathway of Molecules at Surfaces

The study of electrochemical reactions involves knowledge of various domains in chemistry and physics: thermodynamics, kinetics, electricity, transport phenomena, hydrodynamics, and so on. Therefore the fields of application of electrochemical processes are equally vast: production of electric energy from chemical reactions, production of chemical reaction from electric energy, determination of kinetics and reactions mechanisms, conception of electrical and electrochemical devices, etc.

Application of electrochemical process for landfill leachate treatment with emphasis on heavy metal and organic removal

This study was conducted to investigate the mechanisms of electrochemical treatment of a landfill leachate with emphasis on lead and organic removal. Laboratory electrochemical experiments were conducted using both synthetic wastewater and landfill leachate samples. From the synthetic wastewater experiments, the lead removal efficiencies were found to be more than 99%. The lead removal was observed to be dependent on: the electrical current, ratio between reacting surface area and volume of reactor and operation time, and following a first‐order reaction. Similar results on lead removal were obtained when the landfill leachate samples were treated in the electrochemical reactor; the percent removal of soluble biological oxygen demand and soluble chemical oxygen demand concentrations from the landfill leachate during the electrochemical treatment were 30–60%, while the color removal was 70%. The sludge generated from the electrochemical reactions using the synthetic lead wastewater, analyzed by X‐ray diffractometry, was found to be composed mainly of maghemite, magnetite, and laurionite. Based on the X‐ray fluorescence spectrometry analysis, the percent contents of iron and lead were 68.6% as maghemite and 10.1% as lead oxide, respectively. The sludge generated from the landfill leachate treatment containing lead, analyzed by X‐ray diffractometry, was found to be composed mainly of maghemite. Based on the X‐ray fluorescence spectrometry analysis, the percent contents of iron and lead in the sludge were 69.49% as maghemite and 0.63% as lead oxide, respectively. The sludge volume index, capillary suction time and teachability values of the sludge were in suitable range for settling, dewatering and disposal.

Electrochemical performance of carbon materials derived from paper mill sludge

A pure, high surface area and cost-effective carbon-based material with possible application in electrochemical processes was synthesized from industrial sludge. Surface characterization included N 2-adsorption isotherm data and mathematical models such as the DR equation, and BJH methods. The extent of the purity was assessed from thermogravimetric analysis (TGA). The electrochemical properties, i.e. the potential use as electrode in Li ion batteries, were evaluated using conventional electrochemical testing such as charge/discharge cycling and impedance spectroscopy. The results of the data analysis were promising and indicated that paper mill sludge can be successfully used to produce a pure carbon for potential use in electrochemical applications.