Статті в журналах з теми "Electroplating Environmental aspects"

The purpose of this study was to investigate the application of waste minimization technology to electroplating plants and to evaluate the economic aspects of such an application. Waste minimization in electroplating plants can be classified into two categories: recycling and source reduction. Generally, source reduction takes priority before the other and is the most economic tool for waste minimization. Reduction of spent cleaning solutions and drag-out minimization are two major tasks, in which 86% and 60%, respectively, of the plants reviewed were involved, while 74% of the electroplating plants utilized purification equipment to recycle raw materials. In the electroplating process, some heavy metals and rinse water can be recycled. Most of the plants that were investigated recycle the effluent water to the rinse process for further use. From the results of the case study, the cost of the equipment and the utilization rate of the facilities have greater influence on the net present value (NPV) than other factors. Therefore, if the cost or the utilization rate of the facilities varies, re-evaluation will be needed.

This paper examines the environmental conditions at the premises of printed circuit boards (PCBs) manufacturers, which have electroplating plants. It provides a brief overview of the key aspects of adverse environmental impacts of wastes generated by PCB manufacture and electroplating plants. The aim of this research was to improve the test method for evaluation of wastewater effect on the soil salinity at the premises of PCBs manufacturers. The object of research was the process of extraction and use of copper from wastewater generated by PCBs manufacture and electroplating. As an example, the process of sludge formation during PCBs etching has been reviewed. With the etching line capacity of 14 m2/h, one-shift manufacturing process will result in the production of up to 2,500 kg of sludge monthly. For enterprises with capacities of 2,000–4,000 m2 circuits, this means annual accumulation at their premises of up to 70 tons of wastes in the form of sludge. Estimates suggest that the upper half-meter layer of the aeration zone will be qualified as slightly saline in one year after accumulation of the sludge. In subsequent years, the salt content will increase and saline soil can be found at the depths of 1.5–2 m over ten years of storage. The authors of this paper propose to treat spent etching solutions applying regeneration technology in order to reduce the amount of sludge. With this technology, it is possible to use the extracted metal as a secondary raw material for copper production and re-use the regenerated solution in PCBs etching. This paper provides estimated hazard indices calculated for the storage of sludge at the manufacturer’s premises before and after the implementation of the proposed technology. With regards to findings of the study, it has been proposed to reuse copper recovered from wastes as a raw material for the industry.

The article provides a systemic analysis of environmental aspects of galvanic metallisation and examines a galvanising plant as a chemically hazardous facility using extremely/highly dangerous substances and creating a high risk of accidents and occupational diseases for the personnel. The indicators of energy and water consumption given in the article as well as the analysis of the consumption of chemical substances indicate irrationality in the use of energy and material resources. The article further shows that the best available technologies recommended for implementation in the Russian information and technical guide do not resolve environmental problems; a large part of electroplating processes are now outdated, even though many technological tasks involving the application of anticorrosive, special or decorative coatings could be performed in a more environmentally sound way. The article concludes by an overview of alternatives and innovations in the methods for the modification of surface properties

Although technological and processing advancements occurred in the past forty years, industrial firms are still struggling to provide solutions to corrosion protection as well as reduction of toxic wastes. Specifically, large-scale industrialization of electroplating techniques will continue to be limited by strict environmental regulations. Moreover, price volatility of the highly demanding electroplated materials like gold, palladium, copper and nickel will heavily impact the market in the next years. In that respect, alloy plating offers better answers in terms of economic growth and environmental sustainability due to fine tuning composition, morphology and crystallinity [1]. The main categories of alloy compounds are presented and the most important properties for the manufacturing process discussed. Particular attention is devoted to advances in industrial quality control and viable solutions for the reduction of precious metal content in electroplated accessories as well as replacement of cyanide and nickel baths with non-toxic compounds, also considering the commercial needs of wear resistance and aesthetic characteristics of gloss. The electrodeposition of Cu-Sn alloys (bronze) has earned considerable interest thanks to the chemical-physical properties of this alloy, which make it a valid substitute for nickel in fashion industry. Generally, most of the bronze coatings are electroplated starting from baths containing cyanides, and the metal precursors are selected as cyanide compounds. Free cyanide is a well-known problem in the galvanic production cycle both in terms of toxicity for the workers as well as for the environment, and in terms of costs associated with its disposal. The aim of this study is to develop an electroplating bath totally cyanide-free, therefore formulated in an innovative way and which, in addition to being free from this dangerous species, has an eco-friendly support electrolyte. To achieve this goal, methanesulfonic acid (MSA) was chosen as electrolyte, which is biodegradable as part of the natural sulfur cycle. We've studied different formulations in terms of metal precursors, organic additives and their concentrations [2-3]. The same cyanide issue is present also in for the electrodeposition of silver, for this reason the influence of polyethyleneimine (PEI) as additive for cyanide-free silver bath, in combination with 5,5-dimethylhydantoin (DMH) as complexing agent, was studied [4]. Chronoamperometry was used to investigate the electrodeposition mechanism, which is found to be a three-dimensional diffusion-controlled nucleation and growth mechanism, according to the Scharifker–Mostany’s model. Smoother, brighter and blue colored silver deposits are obtained in the presence of PEI in a Hull’s cell test, at low density current. Eventually, the influence of nitrate anion is also investigated. The presence of nitrate increases the range of current density allowing for an effective Ag deposition. We also investigated the use of modulated currents to increase the throwing power of electroplating, obtaining a more uniform deposition and reducing the amount of metals but maintaining the required characteristics. Pulsed current justifies its practical application mainly through its ability to influence the mechanisms of electrocrystallisation, which in turn control the mechanical and physical properties of the deposited metal. By simply adjusting the amplitude and length of the pulses, it is possible to control not only the composition and thickness, in atomic order, of the deposits, but to improve their characteristics such as grain size, porosity and homogeneity [5]. The authors acknowledge Regione Toscana POR CreO FESR 2014-2020 – azione 1.1.5 sub-azione a1 – Bando 1 “Progetti Strategici di ricerca e sviluppo” which made possible the projects “A.C.A.L. 4.0” (CUP 3553.04032020.158000165_1385), “A.M.P.E.R.E.” (CUP 3553.04032020.158000223_1538) and “GoodGalv” (3647.04032020.157000060). References [1] Giurlani, W.; Zangari, G.; Gambinossi, F.; Passaponti, M.; Salvietti, E.; Di Benedetto, F.; Caporali, S.; Innocenti, M. Electroplating for Decorative Applications: Recent Trends in Research and Development. Coatings 2018, 8, 260, doi:10.3390/coatings8080260. [2] Fabbri, L.; Sun, Y.; Piciollo, E.; Salvietti, E.; Zangari, G.; Passaponti, M.; Innocenti, M. Electrodeposition of White Bronzes on the Way to CZTS Absorber Films. J. Electrochem. Soc. 2020 , 167, 022513, doi: 10.1149/1945-7111/ab6c59. [3] Fabbri, L.; Giurlani, W.; Mencherini, G.; De Luca, A.; Passaponti, M.; Piciollo, E.; Fontanesi, C.; Caneschi, A.; Innocenti, M. Optimisation of Thiourea Concentration in a Decorative Copper Plating Acid Bath Based on Methanesulfonic Electrolyte. Coatings 2022, 12, 376, doi:10.3390/coatings12030376. [4] Pizzetti, F.; Salvietti, E.; Giurlani, W.; Emanuele, R.; Fontanesi, C.; Innocenti, M. Cyanide-free silver electrodeposition with polyethyleneimine and 5,5-dimethylhydantoin as organic additives for an environmentally friendly formulation. J. Electroanal. Chem. 2022, 911, 116196, doi:10.1016/j.jelechem.2022.116196. [5] Popov, K.I.; Nikolić, N.D. General Theory of Disperse Metal Electrodeposits Formation. In; Djokić, S.S., Ed.; Modern Aspects of Electrochemistry; Springer US: Boston, MA, 2012; Vol. 54, pp. 1–62 ISBN 978-1-4614-2379-9.

Chromium is a transition metal with a wide range of applications in leather tanning, textile, electroplating, stainless steel production, inorganic chemical production and wood preservation industries due to yellow colouration, corrosion resistance, higher melting-point and crystalline structure with raging of oxidation states from 0 to +6. Trivalent and hexavalent chromium are the most abundant forms of chromium discharged into the aquatic environment by industries. It has been reported that hexavalent chromium is highly toxic than trivalent chromium due to the higher solubility, mobility and tendency to accumulate in higher trophic levels, which, therefore, become bioavailable and causes carcinogenic, mutagenic and teratogenic effects on most microorganisms and animals, growth inhibition, morphological and physiological changes and yield reductions in plants. Therefore, it is essential to detoxify the above hazardous pollutants up to permissible limits, which local and international authorities have legislated concerning its threat towards biotic components. Hexavalent chromium detoxification is possible to achieve using three methods i.e. physical, chemical and biological methods. These remediation processes can eliminate highly toxic hexavalent chromium or transform it into a less toxic form of trivalent chromium, completely or partially by adsorption and reduction. Biological remediation is considered a cost-effective and ecofriendly method compared to physical and chemical remediation. Further, many biological agents have been identified as agents that can tolerate the hexavalent chromium toxicity up to certain higher levels depending on the internal and external environmental factors, indicating different metal tolerance mechanisms that are assumed to be applied in metal remediation aspects. According to the testimonies of novel bioremediation studies, some hexavalent chromium tolerant organisms such as plants, bacteria, unicellular and multicellular fungi and algae are promising eco-friendly alternatives in detoxification and hexavalent chromium removal perspective. This article reviews the bioremediation approaches available for hexavalent chromium detoxification and removal and highlights the strengths and weaknesses of current bioremediation methods.

An overview dedicates to the directions of scientific research and achieved results in the field of electrochemistry, initiated by scientific institutions and in higher educational institutions of Kyiv. Academician O.V. Plotnikov is the forerunner of the world- known Kyiv School of Electrochemistry, formed in the last century's twenties: M.I. Usanovych, V.O. Izbekov, Ya.A. Fialkov, Yu.K. Delimarskyi, I.A. Sheka, and many other scientists known to the general scientific community. O.V. Plotnikov and his followers are one of the first to attempt to combine the most progressive theoretical provisions on electrolytic dissociation, the chemical theory of solutions, and the chemistry of complex compounds for that time. World achievements of the Kyiv School of Electrochemistry were provided by the results of such fundamental research as the chemical theory of solutions, acid-base interactions (Usanovich's theory), the structure of the electric double layer (the Yesin-Markov effect, the reduced Antropov scale of potentials), physical chemistry and electrochemistry of molten electrolytes, kine­tics electrode processes, electrometallurgy, electrochemical materials science, electrochemical power engineering. Representatives of our School significantly expanded the knowledge of mass transfer in electrochemical systems with molten electrolytes (the phenomenon of the transfer of metals from the anode to the cathode). New technological processes of obtaining and refining heavy non-ferrous metals (bismuth, lead, indium, etc.), finishing metal surfaces, extraction of radionuclides, electroplating technology, and environmental monitoring have been introduced into the practice of industrial production. Research in electrochemical materials science is closely connected to solving the problems of electrochemical energy, particularly, the creation of new sources of current, including solid-state, hydrogen generators, and converters of solar energy into electrical power. The studies of electrochemical aspects of the extraction of some refractory metals from natural raw materials, the creation of new materials with specified functional properties, catalysts, and electrocatalysts, the latest galvanic coatings, electrode and electrolyte materials for chemical current sources and supercapacitors, valuable inorganic compounds, metal and carbon nanophases, corrosion inhibitors are expanding the scientific direction of elect­rochemical materials science.

This paper outlines the requirements for metal recovery from wastewater, with particular reference to electroplating. The technical features of three alternative membrane processes are described. Nanofiltration is shown to separate ionic species on the basis of coulombic interactions or hydrated ion size, which leads to either a ‘charge' pattern or a ‘hydration' pattern of rejection. These rejection patterns provide ion selectivity. Ultrafiltration (UF), coupled with ion-complexing polymers or ion exchange resin, also provides efficient removal of metal ions, at high flux. The effectiveness of the UF-resin process is considerably increased as the resin size is decreased. Solvent extraction in a Liquid Membrane Contactor (LMC), which is based on microporous hollow fibre modules with aqueous and organic phases circulating through the shell or fibre lumens, achieves high fluxes of metal ions. A limitation of the LMC is the need to avoid phase leakage. The factors governing the critical displacement pressure and the effective transmembrane pressure are discussed. An LMC with a high packing density of fibres in the shell is preferred. Finally, the paper discusses criteria for selection of ‘user friendly' technologies for the electroplating industry. The membrane technologies, particularly in combined form, score highly except in terms of simplicity. This aspect needs further development.

The main goal of this research study was the removal of Cu(II), Ni(II) and Zn(II) from aqueous solutions using peanut hulls. This work was mainly focused on the following aspects: chemical characterization of the biosorbent, kinetic studies, study of the pH influence in mono-component systems, equilibrium isotherms and column studies, both in mono and tri-component systems, and with a real industrial effluent from the electroplating industry. The chemical characterization of peanut hulls showed a high cellulose (44.8%) and lignin (36.1%) content, which favours biosorption of metal cations. The kinetic studies performed indicate that most of the sorption occurs in the first 30 min for all systems. In general, a pseudo-second order kinetics was followed, both in mono and tri-component systems. The equilibrium isotherms were better described by Freundlich model in all systems. Peanut hulls showed higher affinity for copper than for nickel and zinc when they are both present. The pH value between 5 and 6 was the most favourable for all systems. The sorbent capacity in column was 0.028 and 0.025 mmol g-1 for copper, respectively in mono and tri-component systems. A decrease of capacity for copper (50%) was observed when dealing with the real effluent. The Yoon-Nelson, Thomas and Yan’s models were fitted to the experimental data, being the latter the best fit.

Heavy metal is one of the major environmental and ecological problems in this world. The presence of heavy metals in water andwastewater causes toxic effects to the living beings and the environment. Compared to other heavy metals (such as Cr6+, Pb2+, Zn2+ etc.,) the presence of chromium in industrial effluents has become a major problem worldwide as hexavalent chromium is highly toxic to animals due to its ability to generate reactive oxygen species in cells. The excess amount of chromium affects the lungs and lead to respiratory disorders in the human beings. It also contaminates the soil and groundwater. Due to a large number of industries that generate hexavalent chromium in its effluents such as tanneries and electroplating industries, the chromium contamination in the wastewater and aqueous solutions exceeds the tolerance limits. Many remediation processes for removal of hexavalent chromium have been researched and reviewed extensively. Many methods are used to remove the chromium from the aqueous solutions and industrial effluents. This paper reviewed different remediation methods namely: the using of natural absorbent; the conventional chemical reduction method; the bio-absorbent method, nano-technology application; and other remediation methods. For each method, information about major parameters affecting theefficiency of removal of hexavalent chromium (Cr6+) from industrial effluent are stated. Brief discussion is included relating the different methods, in addition to some future aspects for the remediation process.

Abstract To meet the diversified development of electronics, it is essential to develop 3D metal microstructures with high performance. However, 3D thick silver forming is still a challenge due to high internal stresses and defects. Here we proposed a method for the thick Ag electrodeposition with low-stress and high chemical stability for 3D Ag-based microstructures. We carried out systematic studies through electrochemical measurements, morphological characterization, micro-texture analysis, internal and stability examination. The results show that the nucleation mechanism of electroplating Ag is transformed from progressive nucleation to instantaneous nucleation through the coordinated control of current density and temperature. Higher temperature and lower deposition potential are preferred to form the large-grained crystallization. Additionally, the external parameters for fabricating Ag coating were optimized, and the correlation between micro-texture and internal stress was also verified. The feasibility of thick Ag preparation process was demonstrated by extending the electroplating time, showing excellent performance. Finally, 3D Ag micropillar arrays with the height of 577 µm and the high aspect ratio close to 3 were fabricated by MEMS techniques, displaying satisfied 3D forming ability. This work presents a new approach for manufacturing the 3D Ag microstructures and lays foundation for the multi-functionalization Ag-based devices.