Dissolution of iron in sodium chloride solution during alternating current polarization

Iron compounds are widely used in many industries and engineering, and even in medicine. The existing methods of obtaining iron compounds are multi-stage and complex. The purpose of this work is to obtain iron (II) hydroxide and oxide from metal waste under alternating current action using one and two half-cycles. For the first time, the electrochemical behavior of iron electrode was studied by electrolysis method during alternating current polarization of industrial frequency in sodium chloride solutions. The iron polarization was carried out in pair with titanium, while the current density on the iron electrode varied in the range of 200-1200 A/m2, and on the titanium is in the range of 20-100 kA/m2. It is established that in the anode half-cycle of alternating current, iron is oxidized to form divalent ions. At this moment, the titanium electrode is in the cathode half-cycle, hydrogen is released on it, hydroxyl ions are formed in the cathode space. In the solution, ions interact with iron (II) ions to produce iron hydroxide. At temperatures above 600C, iron (II) hydroxide is dehydrated with the production of iron (II) oxide. The electrolysis was carried out in two electrolyzers connected to each other in parallel with the immersion of pair of “titanium-iron” electrodes into each electrolyzer. The iron dissolution occurs simultaneously in two half-cycles of alternating current and this approach is proposed for the first time. The process productivity increases by more than 1.5 times.

Hydrogen peroxide assisted electrocoagulation treatment of rice gain based biodigester effluent: mechanism, performance, and cost analysis

In the current scenario treatment of industrial waste water is big challenge especially waste water that contain high organic load. Hydrogen peroxide assisted electrocoagulation (EC) process provides better result to treat highly polluted wastewater as compared to EC alone. However, hydrogen peroxide is well known as a strong oxidant, which cast a potential threat to human health. To overcome this problem hydrogen peroxide has been used here for treatment of wastewater in small quantity, and that consume during the process. Therefore the harmful effect of hydrogen peroxide in human and aquatic life could be minimized. This work is an attempt to treat biodigester effluent (BDE) using H2O2 assisted EC processes with respect to chemical oxygen demand (COD) and color reductions. To perform this experiment both iron and aluminum electrodes are used as an electrode material in the presence of H2O2. In case of iron electrode the maximum COD and color reduction efficiency of 98.3 and 83.6% was achieved at the cost of 1.5 Wh/dm3 energy consumption while maximum COD and color removal efficiency of 96.8 and 77.1% with 1.7 Wh/dm3 of energy consumption was observed in the aluminum electrode based EC process. A part from this conventional biological process (i.e., activated sludge treatment, ponds, and lagoon etc.) and physiochemical treatment process (i.e., coagulation, adsorption) provided treatment efficiency of 40–80% hence hydrogen peroxide assisted EC process should a better choice to treat distillery effluent. Furthermore, hybrid EC process was also performed with iron used as anode and aluminum as cathode in the presence of H2O2. Iron electrode based peroxi-EC process provided better result at optimum operating conditions; current density of 114 A/m2, initial COD concentration of 12,000 mg/dm3, initial pH of 7.3, H2O2 concentration of 120 mg/dm3, stirring speed of 120 rpm and electrolysis time of 90 min. The cost estimated for operation is 1.56 US $/m3. Finally, sludge analysis and cost optimization are also incorporated in this article.

Waste tea residue adsorption coupled with electrocoagulation for improvement of copper and nickel ions removal from simulated wastewater

The present research deals with the removal of copper and nickel ions from synthesized wastewater by using simple, cheap, cost-effective and sustainable activated green waste tea residue (AGWTR) adsorption coupled with electrocoagulation (ADS/EC) process in presence of iron electrode. Considering previous studies, their adsorbents used for treating their wastewaters firstly activate them by applying either chemicals or activating agents. Our adsorbent was prepared without applying neither chemicals nor any activating agents. The operating parameters of both metals were optimized: pH (4.0), hydraulic retention time (HRT = 30 min), adsorbent dose (1 mg.L− 1), initial concentration (20 mg.L− 1) and Fe-Fe electrode was found to be better with compared to the other electrodes with a current density of 1.19 mA/cm2. In the process of ADS/EC, The removal efficiency was obtained as 100% for copper and 99.99% for nickel ions. After the ADS/EC process, Fourier transform infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and EDS analysis were used to characterize the adsorbent green waste tea residue. The results showed seven clear peaks of functional groups that were detected in the range of 1000–4000 cm− 1, the rough-stone-like with various larger holes and higher amounts of carbon containing traces of different elements, respectively. The adsorption isotherm and kinetic model results showed that the Langmuir and the pseudo-second-order were well-fitted to the adsorption experimental data better than the Freundlich and pseudo-first-order models for both Cu2+ and Ni2+ with their maximum adsorption capacity of 15.6 and 15.9 mg.g− 1, respectively. These indicate that the dominant adsorption occurs in a monolayer of homogeneous adsorbent surfaces on AGWTR and its kinetic mechanism belongs to chemical adsorption. Based on the above results, it is well understood that the use of the ADS coupled with EC technique is the cheapest compared with single ADS and EC technique for heavy metal removal due to remarkable low adsorption dose, energy consumption and also it is a suitable technique for developind countries. Therefore, the AGWTR shows the greatest potential to improve the quality of water contaminated with different heavy metals in the environment.

The Iron-Age of Storage Batteries: Techno-Economic Promises and Challenges

In this article, we explore the techno-economic promises and challenges related to iron electrode systems, specifically in the iron-air system. We study the discharge-charge products of an iron-air system in an aqueous electrolyte using an iron-water Pourbaix diagram. Using the discharge-charge products from the Pourbaix analysis, we construct a proposed baseline iron-air cell to estimate the basic voltage and capacity of the cell. This cell is then assembled into a battery pack to analyze the unit cost of a 150-hour iron-air system using a process-based cost model developed from the BatPaC model. With the appropriate choice of materials for an iron-air system, we estimate the total battery pack system cost for iron-air to be about US$25/kWh where the cell material costs are around US$5/kWh. The pack hardware costs, air delivery system, and manufacturing costs together account for over US$20/kWh. Through further engineering improvements, better catalysts, and cell chemistry improvements, the battery pack costs may be reduced further, which is promising for long-duration storage applications.

Synthesis of Fe2O3 nanomaterials for a rechargeable battery anode

Iron electrode plays an important role in iron-air batteries. Mastering the fabrication technology of this electrode material is a key step in improving capacity, cycling efficiency, and lowering the cost of commercial batteries. The sol-gel method is known to be simple and easy to implement for producing nanomaterials. In this study, α-Fe2O3 nanoparticles with various shapes were synthesised by the sol-gel method for iron-air battery anodes. Electrochemical characteristic measurements performed on Fe2O3/AB electrodes using synthesised Fe2O3nanomaterials showed that the size and morphology of iron particles strongly affect their cycleability. Optimisation of the fabrication process to obtain the suitable Fe2O3 particle size and shape for the best electrochemical properties was performed. Additionally, the effect of the K2S additive in electrolyte solution on the electrochemical properties of the Fe2O3/AB electrode was also studied.

Etude des paramètres opératoires d’électrocoagulation pour le traitement d’un effluent de textile : Exemple du bleu de méthylène

Les effluents industriels issus des activités textiles présentent une grande charge polluante difficilement biodégradable et qui a des impacts non négligeables sur l’environnement et l’Homme. Leur décontamination par les procédés conventionnels biologiques ou physiques est souvent inefficace et nécessite par conséquent le recours à des procédés d’oxydation avancée dont l’électrocoagulation. Dans le présent travail, nous avons étudié l’élimination par électrocoagulation du bleu de méthylène, modèle de colorant synthétique textile, en utilisant des électrodes de fer et d’aluminium. L’étude des paramètres pouvant influencer l’élimination par électrocoagulation du bleu de méthylène tels que le pH, la durée de l’électrolyse, la densité de courant et la nature de l’anode a montré que les meilleurs traitements sont obtenus avec un effluent de pH égal à 7 pendant 4 heures d’électrolyse à une densité de courant de 3,75 A/cm2 en utilisant l’électrode de fer. Dans ces conditions, le pourcentage d’élimination du bleu de méthylène dans les eaux atteint 80,1%. Des électrodes en fer seraient donc plus intéressantes pour l’élimination du bleu de méthylène, comparativement à des électrodes en aluminium.Mots clés : Electrocoagulation, fer, aluminium, effluents industriels, bleu de méthylène. English Title: Study of operator parameters in electrocoagulation for the treatment of a synthetic textile effluent: example of methylene blueIndustrial effluents from textile activities have a large polluting load that is difficult to biodegrade and which has significant impacts on the environment and on humans. Their decontamination by conventional biological or physical processes is often ineffective and therefore requires the use of advanced oxidation processes including electrocoagulation. In the present work, we investigated the electrocoagulation removal of methylene blue, a synthetic textile dye model, using iron and aluminum electrodes. The study of the parameters of EC which can influence the elimination of methylene blue in wastewater, such as the pH, the duration of the electrolysis, the current density and the nature of the anode showed that the best treatment are obtained with a pH effluent equal to 7, for 4 hours of electrolysis with an iron electrode at a current density of 3.75 A / cm2. Under these conditions, the percentage of elimination of methylene blue in water reaches 80.1%. Iron electrodes would therefore be more advantageous for the removal of methylene blue, compared to aluminum electrodes.Keywords: Electrocoagulation, iron, aluminum, industrial effluents, methylene blue.

Analysis of EDM Performance, through a Thermal–Electrical Model with a Trunk-Conical Discharge Channel, Using a Steel Tool and an Aluminium Workpiece

In this article, a finite element (FE) thermal–electrical model with a trunk-conical discharge channel is employed to simulate individual EDM discharges with a time-on of 18 μs up to 320 μs, which are subsequently compared with the experimental results to validate the model. The discharge channel is a trunk-conical electrical conductor which dissipates heat by the Joule heating effect, being the correspondent factor equal to 1. Instead of the usual copper–iron electrode combination, steel (DIN CK45) and aluminium alloys (DIN 3.4365) are the implemented materials on both the tool and the workpiece, respectively. The numerical results were measured using the melting temperature of the materials as the boundary of material removal. The results obtained with the thermal–electrical model, namely the tool wear ratio, the tool wear rate, the material removal rate, and the surface roughness, are in good agreement with experimental results, showing that the new FE model is capable of predicting accurately with different materials for the electrodes.

Pollutant removal from mining processing wastewater by electrochemical method

<p>Discharging wastewater from industries without any treatment causes environmental pollution and endangers biotic life. In this study, pollutant removal by electrocoagulation (EC) process was investigated using wastewater of the ore processing plant (magnesite crushing and screening plant). In the EC process, iron-iron and copper-copper electrodes were used in parallel in the reactor. Chemical oxygen demand (COD), Sulphate, Chromium (VI), Nickel, Zinc, Magnesium, and Total Suspended Solids (TSS) removals were investigated in the EC process of mineral processing industry wastewater with the iron electrode. These pollutants were calculated as %97.6, %95.1, %98.2, %98.1, %97.8, %88.2, and %98.9, respectively. COD, Sulphate, Chromium (VI), Nickel, Zinc, Magnesium, and TSS removals in the EC process of mineral processing industry wastewater with the copper electrode are %92.8, %94.9, %99.5, %98.7, %96.1, %91.6, and %96.9 respectively. It has been observed that high removal efficiency can be achieved by using the electrocoagulation process in the treatment of ore washing wastewater resulting from the crushing and screening processes in the Chrome Magnesite processing plant.</p>