Water reclamation and chemicals recovery from a novel cyanide-free copper plating bath using electrodialysis membrane process

[EN] One of the industrial concerns is to change procedures into sustainable and cleaner processes. In electroplating, researches have been developed to replace toxic materials for safer alternatives. Cyanide salts are toxic compounds used as complexing agents in alkaline baths. This work focused in a cyanide-free copper alkaline bath developed for copper coating onto zinc alloys. Electrodialysis was evaluated to obtain a concentrated solution from a model rinsing water and simultaneously to treat the effluent for further reuse. Membrane properties after electrodialysis were analyzed, before and after cleaning procedures. Deposition tests were performed using electrolytes containing the recycled inputs and the coatings were analyzed. As results, a solution 5 to 6 times more concentrated than the initial one was obtained. The average demineralization was 90% and the percent extraction of ions was higher than 80%. Interactions between the organic acid and the exchange groups may affect membrane properties. Nevertheless, FTIR analyses and the applied cleaning procedures showed that bonds between phosphorus and quaternary amine may be reversible. Both cleaning procedures presented similar performance and partially restored the membrane properties. The concentrate could be added to the copper bath to compensate eventual drag-out losses without affecting the quality of the coatings.Authors would like to thank the Institute for Technological Research (IPT), the Institute for Technological Research Foundation (FIPT), to the Sao Paulo Research Foundation (Fapesp - processes 2012/51871-9, 2016/17527-0 and 2014/13351-9) and the National Council for Scientific and Technological Development.Scarazzato, T.; Panossian, Z.; Tenorio, J.; Pérez-Herranz, V.; Espinosa, D. (2018). Water reclamation and chemicals recovery from a novel cyanide-free copper plating bath using electrodialysis membrane process. Desalination. 436:114-124. https://doi.org/10.1016/j.desal.2018.01.005S11412443

A review of cleaner production in electroplating industries using electrodialysis

[EN] Cleaner production is an industrial preventive strategy created to promote benefits for the environment and for human beings. Its basic principle lies in using natural energy resources in an efficient way and yet in reducing risks and impacts on the environment and on human beings throughout the life cycle of a product. Electrodialysis is a membrane separation process which uses an electrical potential difference as a driving force to promote ionic separation in aqueous solutions. The technique was initially developed for the production of drinking water from brackish water. However, the use of electrodialysis in the treatment of industrial wastewaters is becoming more attractive, due to its characteristics. The technique is considered a clean process, since it allows the reuse of water and the recovery of substances. In this work, the advancement of electrodialysis applied to cleaner production in electroplating industry will be discussed. The aim of this work is to present electrodialysis as a technology which can fulfill the requirements of cleaner production concepts in the electroplating industry. The research was performed starting from a predefined question: "how is electrodialysis becoming a cleaner production strategy in the electroplating industry?". The research was divided in two main themes. The first search was related to the most important cleaner production practices applied for the plating industry. The second search was associated with the electrodialysis application in the electroplating industry. The results obtained from the collected publications were compared in order to propose an answer to the research question. The results showed that almost a half of the published articles evaluated the improvement of the wastewater treatment as a cleaner production strategy to be applied in plating industries. In addition, the wastewater treatment was the most cited application of electrodialysis in the plating industry, especially for copper, nickel and zinc recovery and for chromium VI removal. Results shows that electrodialysis is becoming an important and solid strategy to promote cleaner production in the plating industry. The two most important issues to be improved for this application are the system efficiency for macromolecules and the energy waste when dilute solutions are used. For the latter, the use of hybrid techniques such as electrodeionization was the most evaluated alternative. (C) 2017 Elsevier Ltd. All rights reserved.Authors would like to thank the Institute for Technological Research (IPT), the Institute for Technological Research Foundation (FIPT) and to The Sao Paulo Research Foundation (Fapesp - grants 2012/51871-9; 2014/13351-9 and 2014/21943-3).Scarazzato, T.; Panossian, Z.; Tenório, J.; Pérez-Herranz, V.; Espinosa, D. (2017). A review of cleaner production in electroplating industries using electrodialysis. Journal of Cleaner Production. 168:1590-1602. https://doi.org/10.1016/j.jclepro.2017.03.152S1590160216

Evaluation of the transport properties of copper ions through a heterogeneous ion-exchange membrane in etidronic acid solutions by chronopotentiometry

[EN] The transport properties of copper chelates across an anion-exchange membrane were investigated by means of chronopotentiometry. Several solutions containing etidronic acid, copper sulfate and potassium chloride were evaluated. Tests were accomplished in a three-compartment reactor using a heterogeneous membrane containing quaternary ammonium functional groups. Results showed a strong relation between the amount of chelated anions and the limiting current density, the electrical resistance and the concentration polarization. An increase in the anionic equivalent charge of the solutions modified the three regions of the current-voltage curves. The acid medium was found to be less favorable because of the possibility of the formation of non-charged species in overlimiting regions. The presence of chloride anions increased the limiting current density, especially when the chloride concentration exceeded the etidronic acid concentration.Authors would like to thank the Institute for Technological Research (IPT), the Institute for Technological Research Foundation (FIPT), to the São Paulo Research Foundation (Fapesp - processes 2012/51871-9, 2014/21943-3 and 2014/13351-9) and the National Council for Scientific and Technological Development.Scarazzato, T.; Panossian, Z.; García Gabaldón, M.; Ortega Navarro, EM.; Tenório, J.; Pérez-Herranz, V.; Espinosa, D. (2017). Evaluation of the transport properties of copper ions through a heterogeneous ion-exchange membrane in etidronic acid solutions by chronopotentiometry. Journal of Membrane Science. 535:268-278. https://doi.org/10.1016/j.memsci.2017.04.048S26827853

Steel cathodic protection afforded by zinc, aluminium and zinc/aluminium alloy coatings in the atmosphere

Zinc has traditionally been the metallic material most widely used to protect steel against atmospheric corrosion due to its ability to afford cathodic protection to steel in all types of natural atmospheres. In recent decades, aluminium and zinc/aluminium alloy coatings have been used instead of zinc in certain atmospheric applications. Although these coatings present some advantages over zinc, they are not able to cathodically protect steel substrates in all types of natural atmospheres. The present paper assesses the cathodic protection afforded by Al (flame spraying), Al/13 Si (hot dipping), 55Al/Zn (hot dipping), Zn/15Al (flame spraying), Zn/5Al (hot dipping), Zn (hot dipping), Zn (discontinuous hot dipping) and Zn (electroplating). Aluminium and aluminium-rich alloy coatings (55%Al/Zn) provide cathodic protection to the steel substrate only in atmospheres that are highly contaminated with chloride ions (>100 mg Cl- m-2 day-1) where these coatings become active. © 2004 Elsevier B.V. All rights reserved.Peer Reviewe

Using metrics and sustainability considerations to evaluate the use of bio-based and non-renewable Brønsted acidic ionic liquids to catalyse Fischer esterification reactions

Background Ionic liquids have found uses in many applications, one of which is the joint solvation and catalysis of chemical transformations. Suitable Brønsted acidic ionic liquids can be formed by combining lactams with sulphonic acids. This work weighs up the relative benefits and disadvantages of applying these Brønsted acidic ionic liquid catalysts in esterifications through a series of comparisons using green chemistry metrics. Results A new bio-based ionic liquid was synthesised from N-methyl pyrrolidinone and p-cymenesulphonic acid, and tested as a catalyst in three Fischer esterifications under different conditions. An evaluation of the performance of this Brønsted acidic ionic liquid was made through the comparison to other ionic liquid catalysts as well as conventional homogeneous Brønsted acids. Conclusion Extending the argument to feedstock security as well as mass utilisation, ultimately in most instances traditional mineral acids appear to be the most sensible option for Brønsted acid esterification catalysts. Ester yields obtained from Brønsted acidic ionic liquid catalysed procedures were modest. This calls into question the diversity of research exploring esterification catalysis and the role of ionic liquids in esterifications

A wake-active locomotion circuit depolarizes a sleep-active neuron to switch on sleep

Sleep-active neurons depolarize during sleep to suppress wakefulness circuits. Wake-active wake-promoting neurons in turn shut down sleep-active neurons, thus forming a bipartite flip-flop switch. However, how sleep is switched on is unclear because it is not known how wakefulness is translated into sleep-active neuron depolarization when the system is set to sleep. Using optogenetics in Caenorhabditis elegans, we solved the presynaptic circuit for depolarization of the sleep-active RIS neuron during developmentally regulated sleep, also known as lethargus. Surprisingly, we found that RIS activation requires neurons that have known roles in wakefulness and locomotion behavior. The RIM interneurons-which are active during and can induce reverse locomotion-play a complex role and can act as inhibitors of RIS when they are strongly depolarized and as activators of RIS when they are modestly depolarized. The PVC command interneurons, which are known to promote forward locomotion during wakefulness, act as major activators of RIS. The properties of these locomotion neurons are modulated during lethargus. The RIMs become less excitable. The PVCs become resistant to inhibition and have an increased capacity to activate RIS. Separate activation of neither the PVCs nor the RIMs appears to be sufficient for sleep induction; instead, our data suggest that they act in concert to activate RIS. Forward and reverse circuit activity is normally mutually exclusive. Our data suggest that RIS may be activated at the transition between forward and reverse locomotion states, perhaps when both forward (PVC) and reverse (including RIM) circuit activity overlap. While RIS is not strongly activated outside of lethargus, altered activity of the locomotion interneurons during lethargus favors strong RIS activation and thus sleep. The control of sleep-active neurons by locomotion circuits suggests that sleep control may have evolved from locomotion control. The flip-flop sleep switch in C. elegans thus requires an additional component, wake-active sleep-promoting neurons that translate wakefulness into the depolarization of a sleep-active neuron when the worm is sleepy. Wake-active sleep-promoting circuits may also be required for sleep state switching in other animals, including in mammals