Electrode Consumption Research Articles

Variation of Coulombic Efficiency Versus Upper Cutoff Potential of Li-Ion Cells with Different Electrolyte Solvents

Introduction One of the easiest ways to increase the energy density of Li-ion cells is to increase the operating voltage range. However, the instability of state-of-the-art electrolyte towards high voltage is a great challenge [1, 2]. Electrolyte oxidation reactions can cause gas generation and impedance growth, result in swelling, capacity loss and cell failure. Accurate measurements of the coulombic efficiency (CE) of Li-ion cells are valuable to characterize these parasitic reaction rates occurring between the electrodes and the electrolyte. In this presentation, the impact of the various solvent blends on CE, charge endpoint capacity slippage, cell impedance and gas evolution during ultra high precision coulometry (UHPC) cycling tests were measured at 4.2, 4.4 and 4.5 V. Careful analysis of CE was made to determine the effect of different electrolyte solvents separately on the positive electrode and negative electrode as the upper cut-off voltage increases. Symmetric cells were made to distinguish the effect of the electrolyte solvents on the impedance at the positive or negative electrode. Experimental The pouch cells employed in this study were LaPO4-coated Li[Ni0.4Mn0.4Co0.2]O2 (NMC442)/graphite cells with a capacity of 180 mAh balanced for 4.7 V operation. Three electrolyte systems including 2 wt.% PES + 1 wt.% DTD + 1 wt.% TTSPi (PES 211) in 1M LiPF6 ethylene carbonate (EC):ethyl methyl carbonate (EMC) 3:7, 2 wt.% PES in 1M LiPF6 fluoroethylene carbonate (FEC) and bis(2,2,2-trifluoroethyl) carbonate (TFEC) 1:1 and 2 wt.%VC + 2 wt.% TAP in 1M LiPF6 sulfolane (SL):EMC 3:7 were chosen for this study. The cells then underwent a formation protocol during which they were opened and re-vacuum sealed at 3.5 V and 4.5 V to remove any gas generated during the first charge. After formation, cells were moved to Ultra High Precision Charger (UHPC) and cycled 15 times using “barn-charge” protocols [3]. After UHPC cycling, these cells were opened in the glovebox where symmetric cells were made. The detailed procedure for making symmetric cells has been described by Petibon et al.[4]. Some cells were studied using battery isothermal calorimetry as outlined by Downie et al. [5] Results and discussion Figure 1a shows the fractional charge endpoint capacity slippage per hour and the fractional capacity fade per hour plotted versus upper cutoff potential for cells containing EC:EMC, FEC:TFEC as well as SL:EMC electrolytes. Figure 1a allows one to determine which parasitic reactions, electrolyte oxidation at the positive electrode or Li consumption in the SEI at the negative electrode, play the dominant role in reducing the coulombic efficiency (CE) or increasing 1-CE when the upper cutoff potential increases [3]. Figure 1a shows that the fractional slippage per hour (positive electrode) increases dramatically when the upper cut-off potential increases from 4.2 V to 4.5 V, while, by contrast, the fractional fade per cycle (negative electrode) does not change dramatically with potential. Figure 1a shows the FEC:TFEC electrolyte has smaller slippage but higher capacity fade rate compared to SL:EMC or EC:EMC electrolyte at high voltages. This means the FEC:TFEC electrolyte partially fixes the positive side (small fractional slippage per hour) but has problems at the negative electrode side (larger fractional fade per hour). Figures 1b, 1c and 1d show the area-specific Nyquist plots of negative and positive electrode symmetric cells as well as full coin cells constructed from electrodes after UHPC cycling tests. Figures 1b to 1d show that cells containing FEC:TFEC electrolyte have much smaller positive impedance but higher negative electrode impedance, compared to cells containing SL:EMC and EC:EMC electrolytes after UHPC cycling. Figures 1b to 1d further prove that the benefit of using FEC:TFEC electrolyte is mainly on the positive side by hindering the electrolyte oxidation at the positive electrode/electrolyte interface. Microcalorimetry results which support this interpretation will also be shown. References L. Ma, J. Xia and J. R. Dahn, J. Electrochem. Soc., 161, A2250 (2014).K.J. Nelson, J. Xia and J.R. Dahn, J. Electrochem. Soc., 161, A1884 (2014).J. Xia, M. Nie, L. Ma and J. R. Dahn, J. Power Sources, 306, (2016) 233.R. Petibon, C. P. Aiken, N. N. Sinha, J. C. Burns, H. Ye, C. M. VanElzen, G. Jain, S. Trussler, and J. R. Dahn J. Electrochem. Soc., 160, A117 (2013).L.E. Downie and J. R. Dahn, J. Electrochem. Soc. 161, A1782 (2014). Figure captions Figure 1 a) Fractional charge endpoint capacity per hour and fractional fade per hour plotted versus the upper cutoff potential for the NMC442/graphite pouch cells with different electrolytes. The area-specific Nyquist plot of b) negative electrode symmetric cells, c) positive electrode symmetric cells and d) full coin cells made from the NMC442 pouch cells after the UHPC cycling to 4.5 V. Figure 1

An Active Series Reactor for an Electric Arc Furnace: A Flexible Alternative for Power-Flow Control

Series reactors are used in electric arc furnaces (EAFs) to provide furnace operation with longer arcs, lower currents, and lower electrode consumption. Such reactors are very useful in the first melting period. Along with the molten scrap, the absence of the series reactor allows a higher power transfer to the EAF, reducing the tap-to-tap cycle and thus increasing productivity. This article proposes an active series reactor (ASR) based on static power converters that has the flexibility to dynamically change its impedance value during steel production. A plant simulation will demonstrate the effectiveness of this proposition.

Treatment of oilfield produced water with electrocoagulation: improving the process performance by using pulse current

The main aim of this study is to investigate the technical and economic feasibility of the pulse electrocoagulation (PE) process on the treatment of oilfield alkali/surfactant/polymer flooding produced water. By using an Fe electrode, the performance of the PE process was analyzed in terms of operating parameters such as pulse duty cycle, current density, pulse frequency, electrode distance, and reaction time with removal efficiencies, some of which are presented in figures and others are given in tables due to the numbers of parameters. Under the optimal conditions of a pulse duty cycle of 0.3, current density of 35 mA/cm2, pulse frequency of 3.0 kHz, electrode distance of 1.0 cm, and reaction time of 40 min, the removal efficiencies of chemical oxygen demand (COD), oils and greases, turbidity, total suspended solids, and polyacrylamide reach 98.3, 99.0, 98.8, 98.1 and 94.3%, respectively, with an energy consumption of 0.19 kWh/kg CODremoved and an electrode consumption of 3.1 kg Fe/kg CODremoved. The quality of the final effluent could satisfy the requirement of the national discharge standard. Compared with the traditional direct current method, the PE process could save 76% of the energy. Moreover, the treatment performance of PE is much better than traditional chemical coagulation treatment using polymeric ferric sulfate.

Remove of phosphorous and turbidity of swine wastewater using electrocoagulation under continuous flow

Abstract Electrocoagulation (EC) is a process of hydroxides generating by passing electric current through electrodes of aluminum and/or iron, to remove impurities in some effluent. Thus, this study investigated the EC process for turbidity and total phosphorus (TP) removal of swine wastewater. For this purpose, two central composite rotatable design (CCRD) 2 2 were applied aiming at investigating the effects of current density (CD) (16.3–57.5 mA/cm 2 ) and the hydraulic retention time (HRT), where different times were evaluated for the aluminum electrode (31.8–88.2 mL/min) and for iron electrode (61.8–118.2 mL/min). The removals of turbidity using aluminum and iron electrodes were of 91%. For aluminum electrode the removals of TP were 93% and for iron were 96%. The central composite rotatable design showed that the current density (DC) is the most important process variable for both electrode materials (Al and Fe) evaluated, since the removal efficiency was enhanced with increasing CD. The hydraulic retention time (HRT) had no significant effect. For aluminum electrode the energy and electrode consumption was of 2.2–15.3 kW h/L and of 0.56–2.01 g, respectively. For iron electrode the energy and electrode consumption was of 2.1–17.2 kW h/L and of 0.74–2.77 g. EC could be considered a promisor post-treatment effluent of the anaerobic digestion for the simultaneous removal of turbidity and TP. In the conditions of HRT and CD of this study, the iron electrode presented best removals efficiencies in relation to aluminum electrode.

Airborne Laser-Spark for Ambient Desorption/Ionisation

A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die Desorption als auch die Ionisation erfolgen hierbei durch ein laserbetriebenes Luftplasma. Die Abwesenheit fester oder flüssiger Elektroden hat zur Folge, dass die Methode weder unter chemischen Interferenzen noch unter Verschleiß durch Korrosionsbrand oder abgetragenes Elektrodenmaterial leidet. Insgesamt betrachtet herrscht in dem Plasma Elektroneutralität, wodurch Aufladungseffekte minimiert werden, die andernfalls zu einer langfristigenÄderung der Flugbahnen von Ionen während der Experimente führen kann. In dem Ansatz eine freischwebende Luftentladung bei Atmosphärendruck zu verwenden agiert die Luft nicht nur als Plasmamedium sondert dient zusätzlich als Badgas für die stoßinduzierte Kühlung der entstehenden Ionen. Die Ionisierung der Analytmoleküle erfolgt nicht unmittelbar im Plasma sondern in dessen direkter Umgebung durch Wechselwirkung mit freigesetzten ionischen Luftspezies, freien Elektronen oder Photonen im kurzwelligen ultravioletten Bereich. Jede Laserentladung erzeugt eine hörbare Stoßwelle, in welcher neu produzierte reaktive Spezies freigesetzt werden, welche sich konzentrisch ausbreiten, so dass eine Diffusion der Analytmoleküle ins heiße Innere des Plasmas verhindert wird. Daraus folgt, dass im Interaktionsvolumen zwischen Plasma und Analyt der Temperaturgrenzwert für eine thermische Dissoziation oder Fragmentierung der Moleküle nicht überschritten wird. Experimentell konnte belegt werden, dass das vorgestellte Ionisierungsschema sehr unselektiv bezüglich der chemischen Analytklasse ist und kaum Fragmentierungsprodukte beobachtet werden können. Messungen einer breitgefächerten Auswahl unterschiedlicher Testsubstanzen, wie beispielsweise polarer und unpolarer Kohlenwasserstoffe, Zuckern, niedermolekularer pharmazeutischer Wirkstoffe, sowie natürlicher Biomoleküle in Lebensmittelproben unmittelbar aus ihren komplexen Matrizes, führten zu aussagekräftigen Massenspektren. Zumal das Lasermedium feuchte Luft ist, scheint der Reaktionsmechanismus dem anderer Atmosphärendruckionisierungsmethoden zuähneln.

Electrocoagulation using a rotated anode: A novel reactor design for textile wastewater treatment

This paper investigates the optimum operational conditions of a novel rotated bed electrocoagulation (EC) reactor for the treatment of textile wastewater. The effect of various operational parameters such as rotational speed, current density (CD), operational time (RT), pH, temperature, and inter-electrode distance (IED) on the pollutant removal efficiency were examined. In addition, the consumption of aluminum (Al) and electrical energy, as well as operating costs at optimum conditions were also calculated. The results indicated that the optimum conditions for the treatment of textile wastewater were achieved at CD = 4 mA/cm2, RT = 10 min, rotational speed = 150 rpm, pH = 4.57, temperature = 25 °C, and IED = 1 cm. The electrode consumption, energy consumption, and operating costs were 0.038 kg/m3, 4.66 kWh/m3 and 0.44 US$/m3, respectively. The removal efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solid (TSS), turbidity and color were 97.10%, 95.55%, 98%, 96% and 98.50%, respectively, at the first 10 min of reaction time, while the phenol compound of the wastewater was almost entirely removed (99.99%). The experimental results confirm that the new reactor design with rotated anode impellers and cathode rings provided high treatment efficiency at a reduced reaction time and with lower energy consumption.

Effect of Active Gas on Weld Shape and Microstructure of Advanced A-TIG-Welded Stainless Steel

Advanced A-TIG method was conducted to increase the weld penetration and compared with the conventional TIG welding process. A two-pipeline setup was designed to apply Ar + CO2 mixed gas as the outer layer, while pure argon was applied as the inner layer to prevent any consumption of the tungsten electrode. The results indicate that the presence of active gas in the molten pool led to the change in the temperature coefficient of surface tension so that the Marangoni convection turns inward and forms a deep weld zone. The increase in gas flow rate causes a decrease in the weld efficiency which is attributed to the increase in oxygen content in the weld pool and the formation of a thicker oxide layer on the weld surface. Moreover, the stir and the temperature fluctuation, led by double shielding gas, create more homogeneous nucleation sites in the molten pool so that a fine grain microstructure was obtained.

Experimental Design Approach with Response Surface Methodology for Removal of Indigo Dye by Electrocoagulation

Treatment of Indigo dye (leuco form), reduced in the industrial conditions of the SITEX (Textile Industrial Company), by a batch electrocoagulation using aluminum electrodes. Response Surface Methodology (RSM) and Box-Behnken design were used to optimize for Color Removal (CR(%)). Our results showed that the quadratic second order equation provided the best correlation for the decolorization of Indigo dye (CR(%)). On the other hand, the ANOVA analysis proved the large interaction between the current intensity and the initial concentration of the dye. Experiments were conducted to find the desired conditions for removal of particular concentration of the dye and lower Operation Cost. The results showed that CR(%) = 88.3% (R2) of color removal for initial dye concentration of 12.31 mg/l, with a current density of 2.81 A/m2, solution concentration of NaCl of 2.67 g/l. Under these conditions, Electrical Energy Consumption (EEC) and Electrode Consumption (EMC) and Operation Cost were 0.01999 kWh/m3 (R2 = 93.1%), 0.00142768 Kg/m3 (R2 = 79.4%) and 0.000558 US$/m3, respectively.

Impact of Substrate Outgassing on the Growth of Carbon Nanotubes Using the Single-Pulse Discharge Method

Carbon nanotubes (CNTs) were fabricated in air using the electrical discharge machining method. The main parameters for this process were substrate temperature, peak current (Ip), and pulse duration (τ). The substrate was baked at 50°C and this temperature was maintained for 12 h under vacuum chamber; it was then cooled to room temperature and stored in vacuum for outgassing. During single-pulse discharge in air, the substrate was heated from room temperature to the test temperatures (50 and 70°C). The results indicated that the length, density, and purity of CNTs grown on outgassed substrates were better than those of CNTs grown without outgassing. Additionally, CNTs grown withIp= 3 A andτ= 1200 μs were of better quality than those grown with other combinations of parameters. The size of the discharge pit was effectively reduced by 30% (80 μm). This finding may help in controlling the amount of peak current used during the process, thereby reducing the problems of heat-affected zones and electrode consumption. Consequently, there was substantial improvement in the zonal selectivity and reticular density of the CNTs grown using the single-pulse discharge method.

Efficiency of aluminum and iron electrodes in removal of colour, turbidity and total suspended solid from biologically treated municipal wastewater

The present investigation was undertaken to observe the effect of different combinations of aluminium and iron (Al-Al, Al-Fe, Fe-Fe and Fe-Al) electrodes on the removal of colour, turbidity (TD) and total suspended solids (TSS) of biologically treated municipal wastewater ( BTMW) using applied potential (V), operating time (OT) and initial pH. The maximum removal of colour (98.7 %) and TSS (96.89 %) was found with the use of Al-Al combination with optimum operating conditions (Voltage: 40 V; OT: 40 mins.; IED: 1.0 cm; EA: 160 cm2; initial pH: 7.5 and ST: 30 mins). It was interesting to note that TD of BTMW was completely removed at these optimal operating conditions. The economic evaluation of electrode combinations was observed to be in the order of Fe-Al (1.17 US $/m3)> Al-Fe (1.11 US $/m3)> Fe-Fe (1.08 US $/m3) >Al-Al (1.01 US $/m3) in terms of energy and electrode consumption. Thus, the BTMW can be effectively treated with the Al-Al electrode combination in comparison to other electrode combinations (Al-Fe , Fe-Fe and Fe-Al).

Treatment of multicomponent aqueous solution of purified terephthalic acid wastewater by electrocoagulation process: Optimization of process and analysis of sludge

The present research work is based on degradation of major pollutants of purified terephthalic acid (PTA) wastewater by electrocoagulation (EC) process. Terephthalic acid (TPA), benzoic acid (BA) and para-toluic acid (p-TA) are the major pollutants of PTA wastewater. A central composite design (CCD) has been developed for maximum removal of TPA, BA, p-TA, COD and minimum consumption of energy. Effects of various process parameters viz. pH: (5–13), current density: (49.5–255.5 A/m2), supporting electrolyte concentration, NaCl: (0.25–2.25 g/L) and electrolysis time: (15–95 min) are studied on removal efficiencies of responses. Aluminium (Al) and iron (Fe) were selected as electrode materials. Maximum percentage removal of TPA: 56.21, 54.10; BA: 59.52, 53.84; p-TA: 45.71, 39.91, and COD: 49.91, 42.95 are achieved at optimum operating conditions by Al and Fe electrodes respectively. Operating cost of the process was calculated based on energy consumption, electrode consumption, sludge disposable, and transportation costs and found $13.64 and $14.46 per kg of COD removed by Al and Fe electrodes respectively. Sludge residues obtained after EC treatment at optimum operating conditions are analyzed by settling, sludge volume index (SVI), XRD, SEM/EDX, point of zero charge (PZC), FTIR and DGA/TGA.

Development of Box Behnken design for treatment of terephthalic acid wastewater by electrocoagulation process: Optimization of process and analysis of sludge

Present research work deals with the treatment of terephthalic acid (TPA) wastewater by electrocoagulation (EC) process. TPA is counted in the major toxic pollutants of purified terephthalic acid (PTA) wastewater and contributes high COD. Box Behnken Design (BBD) in Response Surface Methodology (RSM) tool of Design Expert Software (8.0.7.1, 2010, Stat-Ease Inc., Minnepolis) has been developed for this study. Effect of various operating parameters viz. pH: (7 to 11), current density (A/m2): (38.40 to 105), electrolysis time (min): (15.0 to 60.0) and NaCl dosages (g/L): (0.50 to 1.25) on percentage removal of TPA, chemical oxygen demand (COD) and energy consumption (kWh/kgCODremoved) are presented. Maximum percentage removal of TPA: 89.75, 73.86; COD: 83.88, 67.63 and minimum energy consumption (kWh/kgCODremoved): 57.25, 70.84 are found at optimum operating conditions using Al and Fe electrodes respectively. Properties of sludge were analyzed by point of zero charge, settling, XRD, SEM/EDX, FTIR and TGA/DTA. Process operating costs ($) (Al: 8.59, Fe: 9.82) are determined based on electrical energy, electrode consumption and electrode maintenance cost for per kg of COD removal at optimum operating conditions.

Effect of machining area on material removal rate in strip EDM

Strip EDM is similar to wire EDM, except that the electrode is a roll of brass strip. In this study, investigated is the effect of machining area on material removal rate (MRR) in strip EDM, The MRR was measured according to different machining areas and different electrical discharge conditions. For a given discharge condition, optimal machining area for maximum MRR was identified. The optimal machining area was larger under higher discharge energy condition. It is shown that strip EDM is much more efficient than wire EDM because material removal rate is much higher and the electrode consumption is much less.

Characterization of Tungsten Inert Gas (TIG) Welding Fume Generated by Apprentice Welders.

Tungsten inert gas welding (TIG) represents one of the most widely used metal joining processes in industry. Its propensity to generate a greater portion of welding fume particles at the nanoscale poses a potential occupational health hazard for workers. However, current literature lacks comprehensive characterization of TIG welding fume particles. Even less is known about welding fumes generated by welding apprentices with little experience in welding. We characterized TIG welding fume generated by apprentice welders (N = 20) in a ventilated exposure cabin. Exposure assessment was conducted for each apprentice welder at the breathing zone (BZ) inside of the welding helmet and at a near-field (NF) location, 60cm away from the welding task. We characterized particulate matter (PM4), particle number concentration and particle size, particle morphology, chemical composition, reactive oxygen species (ROS) production potential, and gaseous components. The mean particle number concentration at the BZ was 1.69E+06 particles cm−3, with a mean geometric mean diameter of 45nm. On average across all subjects, 92% of the particle counts at the BZ were below 100nm. We observed elevated concentrations of tungsten, which was most likely due to electrode consumption. Mean ROS production potential of TIG welding fumes at the BZ exceeded average concentrations previously found in traffic-polluted air. Furthermore, ROS production potential was significantly higher for apprentices that burned their metal during their welding task. We recommend that future exposure assessments take into consideration welding performance as a potential exposure modifier for apprentice welders or welders with minimal training.

Vibroacustical Method for Measuring the Effect of Cavitation Erosion

One of the most harmful effects of cavitation, with strong influence on the life of the hydraulic machines is the destruction caused by erosion Since its discovery, over 150 years ago, evaluating the degradation is achieved by mass of material removed by erosion in a given time, which in the case of rotors and blades of hydraulic machines and marine propeller blades are equivalent by amount of electrode consumption for filling the voids left by the removal of material. Laboratory research on cavitation, from the beginning until now, evaluates the intensity of cavitation erosion rate, defined as a mass of material removed by erosion at a certain time of attack.The purpose of this paper is to develop and validate a technique based on vibroacoustic signal analysis of corroded samples, and that through their natural frequencies deviations to emphasize mass loss.The experimental measurement of the vibroacustic response of corroded specimens is carried out by using a condenser microphone. The vibration responses, in free-free conditions of the specimens, are analyzed using algorithm based on Fast Fourier Transform (FFT). The results are compared with other indicators of cavitation corrosion, such as lost mass and mass loss rate.

Evaluations of operating parameters on treatment of can manufacturing wastewater by electrocoagulation

In this study, treatment of can manufacturing wastewater (CMW) by electrocoagulation (EC) process using aluminium plate electrodes was investigated in a batch mode operation to obtain optimum operating conditions with minimum operating cost. Effects of operating parameters such as current density, operating time and electrode connection modes (monopolar series (MP-S), monopolar parallel (MP-P) and bipolar series (BP-S)) on removal efficiencies of aluminium (125.1mg/L), zirconium (81.2mg/L), and phosphate (PO43−−P, 32.1mg/L), chemical oxygen demand (COD: 850mg/L) and total organic carbon (TOC: 300mg/L) from the CMW were evaluated. The results indicated that removal efficiencies of Al, Zr, and phosphate at the optimum conditions (20A/m2, 40min and MP-P electrode connection mode) were determined to be 99.41% for Al, 99.38% for Zr and 99.80% for phosphate, 72% for COD, and 37% for TOC in the wastewater, respectively. In addition, charge density, electrode and energy consumptions, amount of sludge and operating cost at the optimum operating conditions were calculated as 13.196F/m3 or 1270.59C/L, 0.1432kg/m3, 1.366kWh/m3, 1.674kg/m3 and 0.366€/m3. The results indicated that the EC process is very effective and efficient process for treatment of the CMW.

Exergy based efficiency indicators for the silicon furnace

The production of silicon requires input of carbon and electric power, both high in exergy, in addition to the silicon source (quartz). We report exergy efficiencies of a new furnace for two choices of carbon raw material mixtures and compare this to reported data. From the collected experience for this industry, we propose to evaluate the silicon furnace using a set of two exergy performance indicators: the overall exergy efficiency and the silicon yield exergy indicator, introduced in this work. The new indicator is a measure for the performance of furnace operation. The overall exergy efficiency was 0.30 for both cases of the present furnace. The new silicon yield exergy indicator, together with data from the specific power consumption, favoured the mixture without coal for the present furnace (0.41). Additional exergy introduced as volatiles and through the consumption of electrodes accounted for 8 and 11%, respectively, of the total exergy destruction in the furnace. At 800 °C, the off-gas contained a potential of roughly 25% of the exergy input. This documented the potential to increase the overall exergy efficiency beyond 0.30.

Removal of nitrate and sulphate from biologically treated municipal wastewater by electrocoagulation

The present investigation observed the effect of current density (j), electrocoagulation (EC) time, inter electrode distance, electrode area, initial pH and settling time on the removal of nitrate (NO3−) and sulphate (SO42−) from biologically treated municipal wastewater (BTMW), and optimization of the operating conditions of the EC process. A glass chamber of two-liter volume was used for the experiments with DC power supply using two electrode plates of aluminum (Al–Al). The maximum removal of NO3− (63.21 %) and SO42− (79.98 %) of BTMW was found with the optimum operating conditions: current density: 2.65 A/m2, EC time: 40 min, inter electrode distance: 0.5 cm, electrode area: 160 cm2, initial pH: 7.5 and settling time: 60 min. The EC brought down the concentration of NO3− within desirable limit of the Bureau of Indian Standard (BIS)/WHO for drinking water. Under optimal operating conditions, the operating cost was found to be 1.01$/m3 of water in terms of the electrode consumption (23.71 × 10−5 kg Al/m3) and energy consumption (101.76 kWh/m3).

Spark Parameter Monitoring Feedback System for Preparation of Nanosilver Colloid in EDM

This study developed a system monitoring the electric discharge machine's (EDM) discharge energy and success rate to replace conventional oscilloscope observation. By using logic circuit, the signals are transmitted to the PC monitoring platform in order to display the discharge success times, discharge success rate, and electrode's consumption energy. The advantage of the proposed system is the capability to observe real-time discharges and record the experimental conditions, as well as optimize the discharge parameter settings. The experimental results suggest that, in the preparation of nanosilver colloid, the cost-performance of Ton–Toff at 10–100 µs is the optimal setting. The monitoring system also can take advantage of the discharge success rate to control the energy consumption of the electrode to obtain the standardization of products. The results suggest that, while discharge success rate, electrode's weight loss and wavelength of the absorption peak are considerably accurate, but concentration accuracy is relatively poor. The discharge success rate monitoring system is an innovative method that can help to realize electric discharge processing, optimize product quality, and it may be a powerful processing tool in the future.

Evaluation of electrochemical peroxidation (ECP) process variables for removal of co-complex dye using a central composite design

In this study, electrochemical peroxidation was employed to remove color and total organic carbon (TOC) from co-complex (acid yellow 194) dye using iron electrodes in a batch-mode operation. The effects and relationships of the process variables were evaluated, and optimizations were carried out using response surface methodology to maximize removal efficiencies and minimize operating costs in relation to energy, electrode, and chemical (such as H2O2) consumptions. The initial pH (2.0–6.0 pHi), conductivity (500–2,500 μS/cm, k), initial dye concentration (100–800 mg/L, C0), current density (10–30 A/m2, j), operating time (4–20 min, t), and dosage of H2O2 (2–10 mM or 175–860 μL/L, MH2O2) were selected as independent variables. The proposed models fit very well with experimental data, evidenced by high R2 correlation coefficients (>90%). Maximum color removals were 98 and 80% when C0 was 275 and 625 mg/L, respectively. In contrast, maximum TOC removals were poor (52 and 40% when C0 was 275 and 625 mg/L, respectively). On the other hand, color and TOC removals were found to be 86 and 33.5%, respectively, at optimum conditions (C0, 275 mg/L; pHi 3; k, 1.010 μS/cm; MH2O2, 5.1 mM; j, 15 A/m; and t, 8.02 min). The calculated operating cost at optimized conditions was 0.647 €/m.