Plating Industry Research Articles

“Physico-Chemical analysis and detection of Heavy Metals in water through electro plating Industries by ICP-AES technique”

Abstract: The physico-chemical properties and detection of heavy metals (Viz. Pb, As, Cd, Ni, Cu, Fe, Zn, Cr) and their accumulation have been studied in electroplating industrial waste water. This work describes the detection of concentration of these metals in industrial waste water by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) technique. In electroplating industrial waste water samples Pb, As, Ni, Cu, Fe, Cr are detected while Cd, Zn, As, Cu are detected in trace amount in some samples. For the accumulation of metals by the waste water samples were collected and analysed. This concentration of metals is due to various electro plating industries. The waste water samples were collected from MIDC, Ambad, Nashik. Maharashtra. At this point the soil is getting polluted by the disposal of different electro plating industrial waste water. Detected some of the metals are toxic. Keywords: Accumulation, Heavy Metals, ICP-AES, waste water, detection, physico-chemical

The Effect of Naphthalene‐Based Additives on the Kinetics of Tin Electrodeposition on Boron‐Doped Diamond Electrodes

AbstractThe effect of naphthalene‐based additives: naphthalene (NPT), naphthalenesulfonate (NPTS) and hydroxynaphthalenesulfonate (HNPTS) on the kinetics of tin electrodeposition on a boron‐doped diamond (BDD) electrode has been studied by means of chronoamperometry and scanning electron microscopy (SEM). Potentiostatic current transients in the absence and the presence of naphthalene‐based additives are analyzed by using the Scharifker‐Hills model. A strong decrease of the kinetics of tin nucleation on BDD was observed in the presence of naphthalene‐based additives, NPT showing the smallest effect and HNPTS showing the largest effect. From the long‐term Cottrell behavior of the transients, similar values of tin(II) diffusion coefficients were obtained for all additives, suggesting that there is no complexation of Sn(II) by the additives and that the charge‐transfer kinetics itself is not substantially influenced by the presence of the additives. In the absence of additives, tin deposition on BDD displays a progressive nucleation and growth mechanism at the least negative potentials, switching to instantaneous nucleation and growth at more negative potential. In the presence of NPTS and HNPTS, progressive nucleation and growth transients are observed. The growth mode results are confirmed by the tin features observed in the scanning electron micrographs. In conclusion, NPT, NPTS and HNPTS mainly decrease the rate of the nucleation of tin deposition, most likely by blocking or reducing access to active nucleation sites. In comparison, ethoxylated α‐napthalenesulfonic acid (ENSA, a commonly used additive in the tin plating industry) inhibits tin deposition process on BDD even more strongly. These observations show a striking similarity to our previous study of tin deposition on gold electrodes.

Remediation of Cr(VI) from wastewater using biochar of Indian Grass

Chromium is extremely noxious unneeded for any living organism and its occurrence is unusual in nature. Many industrial activities such as mining, metal plating, wood preservation, dyes, pigments, tanning and textile industries makes pollution which cause major health hazards. The present study explores the possibilities using biochar from any carbonized material to use as source to remove the toxic material from any industrial effluent and particularly for Cr(VI). Batch process was accomplished to examine the outcome of various parameters to eliminate the Cr (VI) from the solutions. The rate of adsorption has been interrelated with all the parameters. The Cr(VI) adsorbed bio-char may be used as a fuel in Ferrochrome industry. From the study, it was experimental that adsorption kinetics obeys the pseudo second order kinetics. Experimental data follows the Langmuir isotherm. Intra-particle diffusion is most sluggish steps which determine the rate.

Removal of Ni(II) and Cr(VI) Ions From Electroplating Wastewater Using Ferrous Sulfate

Background: In this study, the ferrous sulfate was used to remove Cr(VI) and Ni(II) ions from a real Ni-Cr plating industry wastewater. Methods: This is an applied study. The type of sampling was composite by three 5 L containers. Wastewater chemical and physical characteristics were measured in accordance with the standard methods. The concentration of un-removed metal ions was estimated by ICP-OES. The Jar test was used to carry out the chemical coagulation experiment. The results indicated that the rate of removal depended on the pH of 1.5-11, the diverse contact time of 30-120 min, and the coagulant measurement ranging from 0.5-2 g/l. Results: The optimum removal of Cr(VI) ions was observed at a pH of 7 up to 83.88% in 0.5 g/l of coagulant for 40 min. While the optimum removal of Ni(II) ions was found at a pH of 5 up to 56.33 % in 0.5 g/l of coagulant for 40 min. The scanning electron microscopy results revealed the difference between the coagulant surface while coagulation. Also, the Energy-Dispersive X-ray spectroscopy (EDX) analysis showed the presence of Cr(VI) and Ni(II) ions on the surface of the ferrous sulfate after coagulation. Conclusion: Ultimately, the results indicated that ferrous sulfate could be an operative chemical coagulant to remove Cr(VI) and Ni(II) ions from the plating industry wastewater, especially for Cr(VI) particles. The results of this study can be a useful guide to the real plating industry wastewater treatment operators.

Competitiveness in removing copper, zinc and chromium trivalent in plating industrial effluent by using hydroxide precipitation versus sulphide precipitation

Plating industry wastewater is one of the processes that may contain various types of heavy metals. The most common heavy metals that mostly found are copper, nickel, cadmium, chromium, silver, zinc, and lead. In this study, three types of metals which are copper, zinc and chromium trivalent were removed using hydroxide precipitation and sulphide precipitation. Both performances of the method were observed and compared. A jar test was used to determine the optimum pH, coagulant dosage and precipitant dosage. The coagulant and precipitant used in this experiment was ferric chloride (FeCl3), poly aluminium chloride (PAC), sodium hydroxide (hydroxide precipitant) and sodium sulphide (sulphide precipitation) respectively. In order to remove chromium trivalent, sodium metabisulfite was used to reduce chromium hexavalent to chromium trivalent. Based on the result, hydroxide precipitation can remove 86.61% of copper, 99.81% of zinc and 99.99% of chromium trivalent. While, for sulphide precipitation, 93.91% of copper, 99.37% of zinc and 99.99% of chromium trivalent were removed. Therefore, sulphide precipitation can remove better mixed heavy metals, thus it also produces less total suspended solid compared to hydroxide precipitation.

Trends and Levels of Perfluorinated Compounds in Soil and Sediment Surrounding a Cluster of Metal Plating Industries

ABSTRACT The occurrence of 16 perfluorinated compounds (PFCs) in soil and sediment from the surroundings of a metal plating industrial park was investigated. The PFCs were quantified using isotope dilution ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS). The ranges of the most commonly detected nine PFCs were 1.71–16.3 ng g−1 dry weight (dw) and 4.72–58.7 ng g−1 dw for soil and sediment, respectively. Higher frequencies of long-chain PFCs were observed in sediment than in soil, which is likely due to the higher organic carbon in the sediment than in soil. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the two dominant compounds in soil and sediment. A significant decreasing trend was observed for PFOS as the distance from the metal plating plants increased. In contrast, the concentrations of PFOA were of the same order of magnitude at all sites in soil and sediment. Direct emission from metal plating plants could be the primary source of PFOS. No ecological risks of PFOS were found in the soil and sediment. However, more attention should be paid to the potential risks at the sites near the plating plants, where a slight increase was observed for PFOS and PFOA during 2016–2019.

Fenton/ozone-based oxidation and coagulation processes for removing metals (Cu, Ni)-EDTA from plating wastewater

Wastewater containing heavy metals has caused many serious problems to land and marine environments. These heavy metal-laden wastewaters containing organic complexing agents are the consequence of using large-scale industrial applications for dissolving metals. Ethylenediaminetetraacetate (EDTA) is a widely used complexing agent in plating, metal finishing and chemical cleaning industries. However, due to the dramatic increase in the solubility of metal ions, EDTA has negative impact on heavy metals removed in wastewaters by conventional precipitation processes. This study aims to find the optimal conditions of combined/hybrid process of advanced oxidation and coagulation to treat metals-EDTA containing Cu, Ni plating wastewater from an electroplating manufacturer in Vietnam. The effects of pH, H2O2 dose, Fe2+ dose, ozone, reaction time and poly acrylic acid (PAA) dose were investigated. Results indicated that the 3-stage treatment process at the optimal conditions could remove 99.7 % of Ni and 99.72 % of Cu. The effluent of wastewater after the whole treatment process met the Vietnamese national regulation on industrial wastewater (QCVN 40:2011/BTNMT) for NH4+, Cu and Ni at column A and COD at column B. In short, the combined advanced oxidation processes and coagulation/flocculation could successfully be applied for plating wastewater treatment.

Hydrogen Limitation By Background Salts in the Case of Trivalent Chromium Electrolytes

The toxicity of some chemical compounds for humans and the environment encouraged health authorities to adopt new legislations. This is the case for hexavalent chromium salts, CMR known, which are targeted by the REACH European regulation. These salts are used in various surface treatments processes and their use is subjected to authorization. This situation has severely impacted the 'hard' chromium plating industry. Several projects all over the world deal with alternative solution and most of them are based on non toxic trivalent chromium salts, but more difficult to implement. The present work is undertaken within CRONOS 2024 project supported by a consortium of 20 companies and led by the IRT M2P (Institute for Technological Research Metallurgy Materials Processes in Metz).Trivalent chromium ions form very stable hexa-aqueous complexes in solution, difficult to reduce. It is therefore necessary to introduce complexing agents in order to facilitate their reduction [1]–[3]. These complexing agents, mostly organic, add a difficulty in the realization of trivalent chromium electrolytes since various phenomena must be considered. In addition, the chromium based electrolytes have a low faradic yield which induces permanent competition between its own reduction and the one of protons to dihydrogen. Excessive consumption of protons near the cathode leads to a pH rise which can cause precipitation and incorporation of chromium hydroxides.In order to improve the performance of trivalent chromium electrolytes, it is possible to adjust different parameters such as the nature and concentration of the complexing agents, the pH, the temperature, the addition of additives, etc. In this study, we focused mainly on the nature and concentration of the support salt. Previous works demonstrated that over a given concentration of Na2SO4 or K2SO4 support salts, a diffusion plateau appears, which can be attributed to the reduction of protons to dihydrogen [4]. Irrespective of the substrate nature, the composition and concentration of the support salts have an impact. It has been shown that a modulation of this plateau towards the most negative potential values would be able to help in decreasing the part of current attributed to the generation of dihydrogen. Moreover, as demonstrated by Phuong et al. [5], a comparison is possible with faradaic yields. Finally, the influence of organic and inorganic complexing agents has also been studied.[1] S. Imer et T. Varnali, « Modeling chromium sulfate complexes in relation to chromium tannage in leather technology: a computational study », Applied Organometallic Chemistry, vol. 14, no 10, p. 660-669, 2000, doi: 10.1002/1099-0739(200010)14:10<660::AID-AOC55>3.0.CO;2-P.[2] Z. Zeng, Y. Sun, et J. Zhang, « The electrochemical reduction mechanism of trivalent chromium in the presence of formic acid », Electrochemistry Communications, vol. 11, no 2, p. 331-334, févr. 2009, doi: 10.1016/j.elecom.2008.11.055.[3] Y. . Song et D.-T. Chin, « Current efficiency and polarization behavior of trivalent chromium electrodeposition process », Electrochimica Acta, vol. 48, no 4, p. 349-356, déc. 2002, doi: 10.1016/S0013-4686(02)00678-3.[4] Y. Mukouyama, M. Kikuchi, et H. Okamoto, « Appearance of new potential oscillation during hydrogen evolution reaction by addition of Na2SO4 and K2SO4 », Journal of Electroanalytical Chemistry, vol. 617, no 2, p. 179-184, juin 2008, doi: 10.1016/j.jelechem.2008.02.006.[5] S. De, J. White, T. Brusuelas, C. Patton, A. Koh, et Q. Huang, « Electrochemical behavior of protons and cupric ions in water in salt electrolytes with alkaline metal chloride », Electrochimica Acta, vol. 338, p. 135852, avr. 2020, doi: 10.1016/j.electacta.2020.135852.

An analytical study of optimal roller intermeshes for the plate leveling process

Leveling process is usually used to minimize the plate defects including flatness imperfections and uniformity of internal stress in the plate industry. Roller intermeshes are important parameters in the leveling process to ensure the high-quality leveled plate. Some current researches treat the plate as a simple beam and ignore the stress superimposed effect to study how to set the roller intermeshes. This article presents an analytical optimization model to search the optimal entry and exit intermeshes for each incoming plate with consideration of the relationship between the roller intermeshes and bending curvatures during the whole leveling process. The optimization model was solved and the results were verified with production data. The relationship between the optimal roller intermeshes and plate thickness, yield stress, and Young’s modulus were discussed in details. It was found out that the roller intermeshes can be set the same for different incoming plates but with equal elastic limit curvature. A four-dimensional database of optimal roller intermeshes about different elastic limit curvature, expected plastic strain ratios, and roller spaces was built. The roller intermeshes can be quickly tracked in less than 1 s as long as the thickness, yield stress, and Young’s modulus of incoming plate and roller space are given according to the database so that it can be used effectively on the leveling production line.

Treatment of Chromium in Wastewater by using Loquat Leaves as Biosorbent

Heavy metal pollution generating from industries is a serious issue in China as it causes severe environmental pollution and health problems. Chromium is one of the common heavy metal appeared in wastewater of metal plating and processing industries and has to reduce its concentration to permissible levels before discharge by law. This study focused on removing chromium ion present in wastewater by using bioresource material loquat leaves as an adsorbent. The extent of adsorption of chromium ion was studied and found to be dependent on solution contact time with the adsorbent, particle size and dosage of the loquat leaves and chromium concentration. The result showed that the loquat leaves have a 70% efficiency in removing chromium ions. The experimental equilibrium biosorption data were analyzed by two widely used isotherms namely Langmuir, and Freundlich. The Langmuir isotherm model better fits the experimental data than the Freundlich isotherm model by high correlation coefficients R2. The maximum monolayer capacity of loquat leaves was found to be 0.0201 mg/g for Chromium ions.

Effect of Organic Nano-Materials on Heavy Metals Concentration of Wheat Plants Inoculated With Piriformospora indica Fungus and Irrigated With Wastewater of Plating Industry

Removal of heavy metals from industrial effluents is one of the most important in environmental research. This research was done to investigate the adsorption effect of multiwall carbon nanotubes (MWNTs) and nano Zn-oxide on decreasing chromium (Cr) and cadmium (Cd) concentration in wheat inoculated with Piriformospora indica (P.indica) that irrigated with wastewater of plating industry. Treatments were consist of applying MWCNs (0 and 0.5 % (W/W)) and nano Zn-oxide (0 and 1.5 % (W/W)) in the soil irrigated with the wastewater of plating industry under wheat inoculated with P.indica. This research was done as a factorial experiment in the layout of completely randomized block design in three replication After 90 days, plants were harvested and plant Cd and Cr were measured using atomic absorption spectroscopy. Using MWCNs had significant effect on increasing cation exchangeable capacity of soil. Applying 0.5 % (W/W) MWCNs in the soil irrigated with waste water significantly decreased the soil Cd concentration by 11.7%, while the plant biomass was increased by 13.4%. In addition, applying 1.5 % (W/W) nano Zn-oxide significantly decreased the negative effect of heavy metal toxicity that can be related to the role of nano Zn-oxide on increasing soil sorption properties. However, the interaction effect of Zn and Cd cannot be ignored. The results of this study showed that applying MWCNs and nano Zn-oxide has a significant effect on decreasing phytoremediation efficiency in soil irrigated with wastewater of plating industries. However, the type and the amount of heavy metals in wastewater cannot be ignored.

Utilization of Modified Zeolite Materials as Chromium Cation Exchanger for Treatment of Liquid Waste from Electroplating Industries

Chromium absorption using modified zeolites in the form of mono-cation (H-Zeolite) was carried out. Modifications are intended to increase the ability of ion exchange. Modifications made were chemical activation by adding ammonium chloride solution and physically by calcination. Zeolite used came from Kasongan, while as an activity test liquid waste from the electro plating industry PT. Mega Andalan Electro Plating. The parameter used for this study is the comparison of zeolite mass with waste samples. Comparisons used are 1: 5, 1: 7, 1:10, 1:20 and 1:50. From the results of the study it can be seen that there is an increase in the ability of ion exchange in the modified zeolite and produces an optimum ratio of 1: 7 with an absorption efficiency of 13.44%..

Legacy and emerging per- and polyfluoroalkyl substances (PFASs) in the coastal environment of Korea: Occurrence, spatial distribution, and bioaccumulation potential

Contamination by per- and polyfluoroalkyl substances (PFASs) is of great concern in global environments. Due to strong regulation of legacy PFASs, emerging PFASs including alternatives and precursors have been introduced to the industrial market. In this study, legacy and emerging PFASs were measured in seawater, sediment, and bivalves collected along the Korean coast to investigate the occurrence, distribution, contamination sources, and bioaccumulation potential of PFASs. Wide concentration ranges of legacy PFASs were detected in multiple environmental samples, indicating widespread contamination. C8-based PFASs (e.g., PFOA and PFOS) were still major contaminants in all of the environmental samples. Some precursors, such as 8:2 fluorotelomer sulfonate (8:2 FTS) and N-ethyl-perfluorooctane sulfonamidoacetic acid (N-EtFOSAA), and perfluoro-2-propoxypropanoic potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (F–53B), an alternative to PFOS, were detected in sediment or bivalve samples, implying a shift in consumption patterns from legacy to emerging PFASs. The highest concentrations of PFASs in environmental samples were found at the locations near industrial complexes, such as those for the semi-conductor, paper mill, automobile, and metal-plating industry. This result indicates that PFAS contamination is associated with intensive industrial activities in the coastal environment. Matrix-dependent contamination and profiles of PFASs were observed. Seawater was dominated by short-chained PFASs as a prompt reflection of regulation, while the sediment and bivalves were dominated by long-chained PFASs. Carbon-chain length was a major factor governing environmental behavior and bioaccumulation of PFASs. This was the first nation-wide survey on legacy and emerging PFASs in the coastal environment of Korea.

Occupational risk assessment of exposure to metals in chrome plating workers

Inhalation of xenobiotics during manufacture process in chrome plating bath produce hazards to workers’ health. Chromium (Cr) is a metal widely used by industry, and its hexavalent (VI) form has been classified as mutagenic and carcinogenic. This study aimed to evaluate the occupational risk of exposure to metals in chrome plating workers. Biological monitoring was performed through quantification of Cr, Pb, As, Ni, and V in blood by ICP-MS in 50 male chrome-plating workers from the exposed group and 50 male non-exposed workers. The inflammatory parameters assessed were β-2 integrin, intercellular adhesion molecule-1 (ICAM-1), and L-selectin expression in lymphocytes. The genotoxicity was evaluated with comet and micronucleus (MN) assays and as a biomarker of oxidative damage the lipid peroxidation (MDA) and protein carbonyl (PCO). The results demonstrated that Cr levels in blood and urine were increased in the exposed group compared to the non-exposed group. Although the biomarkers of exposure proved to be within the levels considered safe in exposed individuals, chrome plating workers presented significantly increase in the percentage of lymphocytes expressing β-2 integrin, ICAM-1, and L-selectin as well as DNA damage (comet assay) and plasmatic MDA and PCO levels. Therefore, it is possible also assign the injuries caused to lipids, proteins, and DNA assessed due to the increased presence of other metals such as Pb, As, Ni, and V in exposed subjects. These results suggest that exposure to xenobiotics present in the occupational environment in chrome plating industry could play a crucial role toward the inflammation, genetic, and oxidative damage.

F–53B and PFOS treatments skew human embryonic stem cell in vitro cardiac differentiation towards epicardial cells by partly disrupting the WNT signaling pathway

F–53B and PFOS are two per- and polyfluoroalkyl substances (PFASs) widely utilized in the metal plating industry as mist suppressants. Recent epidemiological studies have linked PFASs to cardiovascular diseases and alterations in heart geometry. However, we still have limited understanding of the effects of F–53B and PFOS on the developing heart. In this study, we employed a human embryonic stem cell (hESC)-based cardiac differentiation system and whole transcriptomics analyses to evaluate the potential developmental cardiac toxicity of F–53B and PFOS. We utilized F–53B and PFOS concentrations of 0.1–60 μM, covering the levels detected in human blood samples. We demonstrated that both F–53B and PFOS inhibited cardiac differentiation and promoted epicardial specification via upregulation of the WNT signaling pathway. Most importantly, the effects of F–53B were more robust than those of PFOS. This was because F–53B treatment disrupted the expression of more genes and led to lower cardiac differentiation efficiency. These findings imply that F–53B may not be a safe replacement for PFOS.

Ⅰ Current Status and Issues of Plating Industry:

Ⅰ Current Status and Issues of Plating Industry:

Superiority of Modified Polymeric Membrane with Nanomaterial on Temperature and Mechanical Stability and Application in Industrial Waste Water

In this paper, we investigated the superiotires of carbon-based nanomaterial polymer inclusion membrane (PIM-GO) against to polymer inclusion membrane and removed Cr(VI), a highly toxic element typically used in chromate conversion coating in the plating industry, from the chrome plating water by using a PIM-GO modified with graphene oxide (GO), which strengthens the mechanical structure and permeability of PIMs. We performed experiments to investigate the membrance performance and structural ability ofthe PIM-GO, and lastly compared its performance to that of the PIM. We observed the PIM-GO’s high selectivity and recovery (96.83%) in the removal of Cr(VI). GO added to the membrane structure caused a visible increase in the rate constant, permeability and flux.The PIM-GO affords opportunities to work with a wider range of pH levels, changes of which in membrane-based experiments with unmodified PIM shave caused significant decreases in flux and permeability. The ease of use, applicability, high permeability of the PIM-GO at high temperatures afford significant advantages over the unmodified membrane as well. The results of this study can aid the development of next-generation membranes with increased mechanical stability, the resistance to multilayered GO membranes, and the use of the membranes in industrial applications. Moreover, the high transport efficiency of the PIM-GO at temperatures exceeding room temperature is evidence of the improved thermal stability of the PIM-GO. In effect, our findings can inform the production of new membranes with increased mechanical stability, membrane lifetime, and usability in industrial applications.

Occurrence, removal and emission of per- and polyfluorinated alkyl substances (PFASs) from chrome plating industry: A case study in Southeast China

Per- and polyfluorinated alkyl substances (PFASs) have been used since the 1950s as chrome mist suppressant (CMS) in the electroplating industry. In this study, various samples within an electroplating factory, the related wastewater treatment facilities and surrounding environment at Hangzhou Bay in Southeast China were investigated for the occurrence and removal of PFASs. PFOS and 6:2 Cl-PFAES are predominant compounds in the samples. The PFASs in the bath solution of the workshops had some differences from the final releases, partly because of the historic usage and memory effects. PFOS and 6:2 Cl-PFAES were found in high concentration (5500 and 154.5 μg/L in influent, 795 and 985 μg/L in effluent) in the electroplating Wastewater Treatment Plant (WWTP). The ultrafiltration and reverse osmosis (RO) treatment had a significant removal efficiency (74%–100%). On the other hand the reduction, precipitation and anaerobic/anoxic/oxic (A2/O) treatment had poor removal efficiency for PFASs. The receiving river samples had levels of PFASs between 300 and 1500 ng/L, and the concentrations of PFOS and 6:2 Cl-PFAES decreased with increasing distance to the municipal WWTP outlet due to dilution. The concentrations of PFOA in the river water samples were also high but might originate from other sources. The relevant ecological risk is noteworthy, especially for PFOS and PFOA for which limits have been defined. There is an urgent need to control plating industries in China and worldwide. Currently a GEF project related to Stockholm Convention implementation has reduced and possibly eliminated PFOS use and release in the plating industry in China. In addition, it will be important to evaluate and control the alternatives used.

Mathematical Model of Electromembrane Separation of Copper-Electroplating Production Solutions

This study is devoted to the development of a mathematical model of electromembrane separation of copper-containing solutions in copper plating industry based on the solution of the Nernst–Planck and Poisson–Boltzmann equations. The model tracks the dependence of the volumetric permeate flows and solution concentration on the time of the electromembrane process. The mathematical model allows us to calculate the concentration at the outlet of the electromembrane apparatus, specific outlet flow of the solvent, and energy consumption for membrane separation of solutions. The equations of the model allow for mass transfer and solution flow hydrodynamics in the intermembrane channel. The adequacy of the mathematical model was verified by comparing the calculated and experimental data on the change in the concentration of the desired substance in the retentate relative to pressure at a constant current density.

Decomplexation of Cu(II)/Ni(II)-EDTA by ozone-oxidation process.

In this study, ozone-oxidation was used to treat synthetic chemical plating solution containing Cu(II)/Ni(II)-EDTA solution to realize the purpose of decomplexation. The effects of solution pH, initial concentration of Cu(II)/Ni(II)-EDTA, the molar ratio of EDTA to Cu(II)/Ni(II), and the coexistence of Cu(II)/Ni(II) on their removal efficiencies were investigated. The degradation of EDTA-Cu(II) and EDTA-Ni(II) were mainly attributed to OH oxidation, and the removal rates of Cu(II)/Ni(II) depend on the complete decomplexation. The removal rates of Cu(II) and Ni(II) was affected by the pH of solution, and the optimal pH was found to be 7-9; nevertheless, their removal rates can still be up to 90% even in acidic pHs of 3~5. When the molar ratio of EDTA to Cu(II)/Ni(II) increased from 1:1 to 3:1, the kinetics of metal ion removal rate declined from 0.0788 and 0.1139 min-1 to 0.0250 and 0.0271 min-1. The synergistic effect was found in the Cu(II)/Ni(II) blended system due to the higher catalytic capability and the lower complexation affinity toward EDTA for Ni(II). In summary, ozone oxidation can be considered as an effective technology to realize the complete decomplexation of Cu(II)/Ni(II)-EDTA that contained in chemical plating industry wastewater. Graphical Abstract.