Influence of current density and temperature in the zinc electroplating process at sulfate-based acid solution: study on process efficiency and coating morphology

Zinc as a metallic coating is a common strategy to protect the carbon steel against corrosion. The most common process of zinc deposition is known as electroplating. Because of the high toxicity of cyanide-based baths, the interest in acid baths has grown, but they present many challenges to be overcome. Several operational parameters and bath constitution – such as current density, pH, and zinc concentration – can impact the current efficiency, deposit quality, and coating morphology. In this work, the process efficiency and the coating morphology were evaluated on electroplated AISI 1008 carbon steel samples. The current density and temperature were individually varied on a range from 7.5 mA.cm-2 to 30.5 mA.cm-2, and from 40 °C to 60 °C, respectively. The process efficiency was evaluated by current efficiency (eC). The surface morphology was analyzed by both optical microscopy (OM) and scanning electron microscopy (SEM). Varying the bath temperature did not promote impacts in the current efficiency, which remained in all temperatures evaluated over 95%. On the other hand, increasing the current density, increased the current efficiency, starting from (85 ± 2)% at 7.5 mA.cm-2 to (92 ± 2)% at 19.0 mA.cm-2, and (95 ± 1)% at 30.5 mA.cm-2. Through OM and SEM analysis, the increase in the temperature tended to turn the coating rougher, and the sample was not completely covered at 7.5 mA.cm-2. Therefore, we recommend the use of a temperature between 40 °C and 50 °C associated with a current density of 30.5 mA.cm-2.

Download Full-text

INVESTIGATION OF ELECTROCHEMICAL COLOR REMOVAL FROM ORGANIZED INDUSTRIAL DISTRICT (OID) WASTEWATER TREATMENT PLANTS USING NEW GENERATION Sn/Sb/Ni-Ti ANODES

Global NEST Journal ◽

10.30955/gnj.002696 ◽

2018 ◽

Vol 21 (2) ◽

pp. 106-112

Keyword(s):

Energy Consumption ◽

Current Efficiency ◽

Current Density ◽

Wastewater Treatment Plants ◽

Salt Content ◽

Color Removal ◽

Ozone Production ◽

Ambient Conditions ◽

Operational Parameters ◽

Oxidation Efficiency

<p>In this study, the application of Sn/Sb/Ni-Ti electrodes for the treatment of waste streams were investigated which is promising for ozone production by electrolysis of water because of their stability and high potential for ozone evolution reaction. These series of anodes have a high electrochemical ozone generation potential at ambient conditions (approximately up to 40% current efficiency). But using and testing of these novel anodes for real wastewater are too limited in the literature. Titanium mesh substrate coated with Sn/Sb/Ni-Ti alloy was used as anode immersed in wastewater at room temperature with platinized titanium cathode. These electrodes used for COD and color removal from OID wastewater in Inegol, Bursa, Turkey. Five operational parameters were evaluated for electrochemical COD and color removal processes, such as pH, salt content, applied voltage/current, current efficiency and contact time. Experimental results showed that after 30 min the electrochemical oxidation efficiency of COD and color could reach up to 98% and 99% respectively at pH 8.2 and temperature of 25°C as the optimum conditions. Current density observed as the most effective parameter for COD and color removal efficiencies. The lowest energy consumption was between 10-25 mA cm-2 of current density with only 0.6 kWh gCOD−1, while the highest energy consumption was 100 mA cm-2 of current density with 9.12 kWh gCOD−1 . The optimum current density value has been found as 50 mA cm-2 with 4.05 kWh gCOD−1 . These results were also supported with ANOVA test.</p>

Download Full-text

Electrochemical deposition of La-Mg alloys in LaCl3-MgCl2-KCl system with molten salt electrolysis process

Journal of Mining and Metallurgy Section B Metallurgy ◽

10.2298/jmmb130214013k ◽

2014 ◽

Vol 50 (2) ◽

pp. 109-114 ◽

Cited By ~ 4

Author(s):

Kumar Sahoo ◽

H. Singh ◽

N. Krishnamurthy

Keyword(s):

Current Efficiency ◽

Current Density ◽

Inductively Coupled Plasma ◽

Atomic Emission ◽

Bath Temperature ◽

Magnesium Content ◽

Cathode Current Density ◽

Mg Alloys ◽

Chemical Compositions ◽

Molten Salt Electrolysis

La-Mg alloys of different compositions were prepared by electrolysis of LaCl3-MgCl2-KCl melts. Different phases of La-Mg alloys were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Energy dispersive spectrometry (EDS) and Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) analyses showed that chemical compositions of La-Mg alloys were consistent with phase structures of XRD pattern, and magnesium content in the alloy could be controlled by electrolysis parameters. The effects of various process parameters such as concentration of magnesium chloride in the bath, temperature of electrolysis and cathode current density on the current efficiency have been investigated. A maximum current efficiency of 85% and yield of 80% was obtained from the bath at 12.5A/cm2 current density at an operating temp 850?C.

Download Full-text

Static Electroplating of Iron Triad on Fastener Washers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.879.275 ◽

2021 ◽

Vol 879 ◽

pp. 275-283

Author(s):

Koay Mei Hyie ◽

Salina Budin ◽

Normariah Che Maideen ◽

Yudi Rahmawan

Keyword(s):

Carbon Steel ◽

Low Cost ◽

Sem Analysis ◽

Nickel Iron ◽

Cobalt Nickel ◽

Protection Layer ◽

And Performance ◽

Resistant Layer ◽

Corrosion Protection Coating ◽

Protection Coating

Fasteners are commonly used in construction industry for parts joining purpose. There are many types of construction fasteners such as stud, bolt, anchor, nut, screw, and washer. The major problem of the fastener made by carbon steel is the poor resistance to corrosion. Electroplating is a simple yet low-cost tool to give a strong corrosion protection coating layer on the carbon steel. This study was performed to investigate the effect of current and deposition time on the iron triad (cobalt-nickel-iron) electroplating on the fastener washer. The experiment was conducted at 50 °C, pH 1-3 and at different electroplating time (30 minutes to 90 minutes) and current (0.2 A to 0.5 A). Burnt-out surface coating was observed on the fastener washer when the current was more than 0.4 A. A field test was carried out for 60 days to observe the corrosion behavior and performance of the products. Scanning electron microscope (SEM) analysis showed that a thin protection layer with 5.64 µm was formed at 60 minutes of electroplating time and 0.4 A of current. The surface roughness of the fastener washer was increased by increasing the electroplating time and current. The hardness was also improved with higher current and electroplating time if compared to the original fastener washer. The result of this study confirmed that a strong adhesive corrosion resistant layer to the fastener washer was using the current of 0.4 A (77 mA/cm2) and the electroplating time of 60 minutes.

Download Full-text

Optimization for white organic light-emitting diode based on DCJTB as color conversion layer

International Journal of Modern Physics B ◽

10.1142/s0217979218502995 ◽

2018 ◽

Vol 32 (27) ◽

pp. 1850299

Author(s):

Pei Wang ◽

Zhen Wang ◽

Ai Chen ◽

Jia-Feng Xie ◽

Xin Zheng

Keyword(s):

Current Efficiency ◽

Current Density ◽

White Light ◽

Power Efficiency ◽

Light Emitting Diode ◽

Light Emitting ◽

Organic Light Emitting Diode ◽

Organic Light ◽

High Efficient ◽

Color Conversion

In this paper, combining phosphorescence and fluorescence to form white light was realized based on DCJTB:PMMA/ITO/NPB/TCTA/FIrpic:TCTA/TPBi/Ir(ppy)3:TPBi/TPBi/Cs2CO3/Al. The effects of red fluorescence on this white light device was studied by adjusting the concentration of DCJTB. The study shows that the device with a DCJTB concentration of 0.7% in the color conversion layer (CCL) generates a peak current efficiency and power efficiency of 23.4 cd ⋅ A[Formula: see text] and 7.5 lm ⋅ W[Formula: see text], respectively. And it is closest to the equal-energy white point of (0.33, 0.33) which shows a CIE (Commission Internationale de L’Eclairage) coordinate of (0.35, 0.43) and a color rendering index (CRI) of 70 at current density of 10 mA ⋅ cm[Formula: see text]. In order to improve the efficiency, we design and fabricate both high efficient and pure white organic light-emitting diode (WOLED) by replacing the single blue emission layer (EML) with double EMLs of FIrpic:TCTA and FIrpic:TPBi. The further study shows that, when the layers of EML is three and the concentration of DCJTB at 0.7%, the device exhibits good performance specifically, at current density of 10 mA ⋅ cm[Formula: see text], the current efficiency of 28.2 cd ⋅ A[Formula: see text] (power efficiency of 10.3 lm ⋅ W[Formula: see text]), and the CIE coordinate of (0.33, 0.31) (CRI of 80.38).

Download Full-text

Comparative Cathodic Behavior of ~9% Cr and Plain Steel Reinforcement in Concrete

CORROSION ◽

10.5006/0010-9312-68-4-4 ◽

2012 ◽

Vol 68 (4) ◽

pp. 045003-1-045003-10 ◽

Cited By ~ 9

Author(s):

M. Akhoondan ◽

A.A. Sagüés

Keyword(s):

Carbon Steel ◽

Oxygen Reduction ◽

Current Density ◽

Surface Condition ◽

Corrosion Current ◽

Reduction Reaction ◽

Cathodic Current Density ◽

Cathodic Current ◽

Steel Rebar ◽

Cathodic Region

The extent of the oxygen reduction reaction in concrete was evaluated for ~9% Cr rebar approaching the ASTM A1035 specification and compared to that of conventional carbon steel rebar, at ages of up to ~1 year. Cathodic strength was measured by the cathodic current density developed at −0.35 V vs. copper/copper sulfate (Cu/CuSO4 [CSE]) and −0.40 VCSE in cyclic cathodic potentiodynamic polarization tests, both in the as-received condition with mill scale and with scale removed by glass bead surface blasting. In both conditions the ~9% Cr alloy was a substantially weaker cathode, by a factor of several fold, than carbon steel. Within each material, the surface-blasted condition yielded also much lower cathodic current density than the as-received condition. For a small anode-large cathode system with a given anode polarization function, and no important oxygen reduction concentration polarization, the corrosion current was projected to be significantly lower if the cathodic region were ~9% Cr instead of plain steel rebar with comparable surface condition. There was strong correlation between the charge storage capability of the interface and the extent of cathodic reaction of oxygen. The result cannot be ascribed solely to differences in effective surface area between the different materials and conditions.

Download Full-text

Critical Current Density for Zinc Deposition from Impurity-containing Electrowinning Solutions.

Shigen-to-Sozai ◽

10.2473/shigentosozai.110.967 ◽

1994 ◽

Vol 110 (12) ◽

pp. 967-972 ◽

Cited By ~ 9

Author(s):

Hisaaki FUKUSHIMA ◽

Tetsuya AKIYAMA ◽

Takeshi OHGAI

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Zinc Deposition

Download Full-text

The study of Zn–Co alloy coatings electrochemically deposited by pulse current

Hemijska industrija ◽

10.2298/hemind111215035b ◽

2012 ◽

Vol 66 (5) ◽

pp. 749-757 ◽

Cited By ~ 1

Author(s):

Jelena Bajat ◽

Miodrag Maksimovic ◽

Milorad Tomic ◽

Miomir Pavlovic

Keyword(s):

Surface Roughness ◽

Current Efficiency ◽

Direct Current ◽

Current Density ◽

Pulse Current ◽

Pulse Plating ◽

Cathodic Current ◽

Average Current Density ◽

Corrosion Stability ◽

Average Current

The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2).

Download Full-text

Electrowinning of Iron from Spent Leaching Solutions Using Novel Anion Exchange Membranes

Membranes ◽

10.3390/membranes9110137 ◽

2019 ◽

Vol 9 (11) ◽

pp. 137

Author(s):

Wouter Dirk Badenhorst ◽

Cloete Rossouw ◽

Hyeongrae Cho ◽

Jochen Kerres ◽

Dolf Bruinsma ◽

...

Keyword(s):

Current Efficiency ◽

Anion Exchange ◽

Mechanical Stability ◽

Specific Energy Consumption ◽

Flow Cell ◽

Process Efficiency ◽

Side Reactions ◽

Anion Exchange Membranes ◽

Acid Generation ◽

Exchange Membrane

In the Pyror process, electrowinning (EW) is used to recover acid and iron from spent leaching solutions (SLS), where a porous Terylene membrane acts as a separator between the cathode and anode. In this study, a novel anion exchange membrane (AEM)-based EW process is benchmarked against a process without and with a porous Terylene membrane by comparing the current efficiency, specific energy consumption (SEC), and sulfuric acid generation using an in-house constructed EW flow cell. Using an FAP-PK-130 commercial AEM, it was shown that the AEM-based process was more efficient than the traditional processes. Subsequently, 11 novel polybenzimidazole (PBI)-based blend AEMs were compared with the commercial AEM. The best performing novel AEM (BM-5), yielded a current efficiency of 95% at an SEC of 3.53 kWh/kg Fe, which is a 10% increase in current efficiency and a 0.72 kWh/kg Fe decrease in SEC when compared to the existing Pyror process. Furthermore, the use of the novel BM-5 AEM resulted in a 0.22 kWh/kg Fe lower SEC than that obtained with the commercial AEM, also showing mechanical stability in the EW flow cell. Finally, it was shown that below 5 g/L Fe, side reactions at the cathode resulted in a decrease in process efficiency, while 40 g/L yielded the highest efficiency and lowest SECs.

Download Full-text

A Field Pilot Study on Treating Groundwater Contaminated with Sulfolane Using UV/H2O2

Water ◽

10.3390/w12041200 ◽

2020 ◽

Vol 12 (4) ◽

pp. 1200 ◽

Cited By ~ 1

Author(s):

Linlong Yu ◽

Sobhan Iranmanesh ◽

Ian Keir ◽

Gopal Achari

Keyword(s):

Water Flow ◽

Cost Model ◽

Electrical Energy ◽

Pilot Scale ◽

Process Efficiency ◽

Contaminated Groundwater ◽

Operational Parameters ◽

Flow Rates ◽

Electrical Energy Per Order ◽

H2o2 System

Sulfolane is an emerging contaminant in the groundwater and soil nearby gas plants, which has attracted much attention from many researchers and regulatory agencies in the past ten years. In this paper, a field pilot-scale ultraviolet (UV)/hydrogen peroxide (H2O2) system was investigated for treating sulfolane contaminated groundwater. Different groundwater, as well as different operational parameters such as influent sulfolane concentration, H2O2 dosage, and water flow rates, were studied. The results showed that a pilot-scale UV/H2O2 system can successfully treat sulfolane contaminated groundwater in the field, although the presence of iron and other groundwater limited the process efficiency. The lowest electrical energy per order of reduction for treating sulfolane in groundwater by using the pilot-scale UV/H2O2 system was 1.4 kWh m−3 order−1. The investigated sulfolane initial concentrations and the water flow rates did not impact the sulfolane degradation. The enhancement of sulfolane degradation in an open reservoir by adding ozone was not observed in this study. Furthermore, an operational cost model was formulated to optimize the dosage of H2O2, and a stepwise procedure was developed to determine the power necessary of the UV unit.

Download Full-text