Selective recovery of zinc from spent pickling baths by the combination of membrane-based solvent extraction and electrowinning technologies

This work deals with the analysis of an integrated zinc recovery process by means of electrowinning of the stripping solutions coming from the treatment of spent pickling baths (SPB) by a membrane-based solvent extraction (MBSX) process able of increasing the initial Zn/Fe molar ratio. Several stripping solutions containing different concentrations of zinc and iron in acid media obtained previously by the treatment of SPB by MBSX, were subjected to electrowinning to assess the efficiency and selectivity of zinc electrodeposition over iron under different operation conditions. At similar values of the zinc concentration in the stripping solution, the influence of the Zn/Fe molar ratio on the zinc electrodeposition process was negligible. On the other hand, although the variation of the initial concentration of zinc in the stripping solution neither affected the efficiency of zinc electrowinning, it increased the minimum value of zinc concentration in solution beyond which iron co-deposition started. Finally, the increase in the applied current, promoted the increase in zinc fractional conversion and in the zinc space–time yield, while the zinc current efficiency was reduced due to the stronger effect of secondary reactions. Although the change in the stripping characteristics seems not to strongly affect the zinc electrodeposition process, the use of a pretreatment step based on MBSX technology improved the results in terms of zinc percentage recovered and the rest of figures of merit, in comparison with those obtained by the direct electrowinning of SPB

Treatment of spent pickling baths coming from hot dip galvanizing by means of an electrochemical membrane reactor

The performance of a one (OCR) and a two-compartment electrochemical reactor in the presence of a cation-exchange membrane (CEM) for the zinc recovery present in the spent pickling baths is analyzed in this paper under galvanostatic control. These solutions, which mainly contain ZnCl2 and FeCl2 in aqueous HCl media, come from the hot dip galvanizing industry. The effect of the applied current, the dilution factor of the baths and the presence or absence of initial cathodic zinc is also studied. For the 1:50 diluted spent bath, OCR experiments initially present higher values of the figures of merit than those obtained in the presence of the CEM since zinc is close to the cathode from the first electrolysis instants. However, at long electrolysis times, OCR presents zinc redissolution for all the current values tested due to the chlorine and iron presence close to the zinc deposits. In addition, the iron codeposition phenomenon is also observed in the OCR experiments when pH values are close to 2. On the other hand, CEM experiments become very similar to the OCR experiments at long time values since the CEM under these experimental conditions prevents zinc redissolution phenomenon and also iron codeposition. When the 1:50 diluted bath is concentred to 1:10, OCR experiments present the same tendency as that observed for the 1:50 dilution factor but the effect of zinc redissolution is increased due to the greater amount of chlorine generated in the anode. Under these experimental conditions, iron deposition has also been observed in the presence of the cation-exchange membrane as the rate of zinc deposition is greater than that of zinc transport through the membrane, and the zinc/iron ratio in the cathodic compartment is not high enough to prevent iron codeposition. In both cases, the pH values when iron codeposits with zinc are close to 2 and the zinc/iron ratio is below 0.6. The presence of initial zinc in the cathodic compartment of the electrochemical reactor enhances the reactor performance since it allows the zinc–iron separation in one single step and avoids the zinc redissolution phenomenon.The authors want to express their gratitude to the Generalitat Valenciana for a postgraduate grant (GV/2010/029) and to the Ministerio de Economia y Competitividad for financing the project number CTQ2012-37450-C02-01/PPQ.Carrillo Abad, J.; García Gabaldón, M.; Pérez Herranz, V. (2014). Treatment of spent pickling baths coming from hot dip galvanizing by means of an electrochemical membrane reactor. Desalination. 343:38-47. https://doi.org/10.1016/j.desal.2013.11.040S384734

Estudio de la recuperación del zinc presente en los baños agotados de decapado procedentes de las industrias de galvanizado de zinc en caliente mediante técnicas electroquímicas

Actualmente, el 43% de la producción mundial de zinc se destina al proceso de galvanizado por inmersión en caliente. Previamente a la introducción de las piezas en el baño de zinc fundido, éstas necesitan una serie de tratamientos superficiales. Entre estos tratamientos cabe destacar la etapa de decapado, que consiste en la inmersión de las piezas en un baño de ácido clorhídrico para eliminar de su superficie cáscaras y restos de óxido, como la etapa más contaminante del proceso de galvanizado, ya que los baños agotados de decapado contienen elevadas concentraciones de ZnCl2 y FeCl2 en HCl. En la presente Tesis Doctoral se realiza un estudio en profundidad de la recuparación electroquímica del zinc, presentándola como una alternativa limpia y eficaz en la que se pretende recuperar el componente de mayor valor añadido, en su estado metálico, que podría ser directamente reintroducido en el proceso de galvanizado de zinc por inmersión en caliente. Previamente al uso de la electrólisis como tratamiento de los baños agotados de decapado se realizó un estudio electroquímico de la disolución mediante la técnica de la voltametría cíclica. Este estudio determinó que el zinc se deposita en masa a partir de -1V, situándose su pico de reducción próximo a los -1.5V. Del análisis de las diferentes voltametrías cíclicas realizadas se dedujo que la deposición del zinc es un proceso irreversible, controlado tanto por la transferencia de materia como por la transferencia de carga, y transcurre mediante la formación de una película de hidróxidos de zinc sobre la superficie del electrodo gracias a aumentos locales del pH promovidos por la HER. También se determinó que el zinc y el hierro se depositan siguiendo un proceso de co-deposición anómala que permite que el zinc se deposite preferentemente al hierro sobre la superficie del electrodo, pues la película de Zn(OH)2 inhibe la deposición del hierro. No obstante, la estabilidad de la película de Zn(OH)2 depende, en gran medida, de la relación existente entre las concentraciones de Zn y Fe, del pH y de la intensidad aplicada. A partir del estudio electroquímico se determinaron los potenciales e intensidades a aplicar en el reactor electroquímico para los modos potenciostático y galvanostático de operación. Del análisis de las diferentes figuras de mérito (X, ϕ, η y Es), se concluyó que debido a la influencia del proceso HER (reacción de evolución del hidrógeno), el modo potenciostático perdía la selectividad característica de este modo de operación. Así mismo, se determinó que el cloro gas generado en el ánodo ataca a los depósitos de zinc provocando su redisolución y que la presencia de hierro favorece dicha redisolución del zinc y también disminuye el rendimiento eléctrico del proceso. Por otra parte, la co-deposición del zinc y el hierro se detectó una vez la conversión del zinc sobrepasó el 50% y cuando el pH era mayor o igual a 2. Debido al efecto negativo de la presencia de cloro en las cercanías del cátodo, se decidió usar un reactor electroquímico de membranas que actuaran como separador de ambos compartimentos. El uso de una MIA (membrana de intercambio aniónico) evitó el fenómeno de redisolución del zinc, mejorando los resultados obtenidos respecto a los experimentos realizados en ausencia de separador. No obstante, esta membrana no solucionó el problema de la co-deposición del hierro. Para evitar este fenómeno se decidió cambiar la membrana y se pasó a utilizar una MIC (membrana de intercambio catiónico). Gracias a esta nueva configuración se consiguió evitar la co-deposición del hierro aunque empeoraron los resultados del proceso debido a la ausencia de zinc en la cámara catódica durante los primeros instantes de la electrólisis. Añadir zinc en la cámara catódica en los experimentos con la MIC permitió la obtención de resultados similares a los obtenidos con la MIA. De los estudios realizados sobre el reactor con la MIC en presencia de zinc en la cámara catódica, se desprendió que elevadas intensidades favorecen los resultados obtenidos para la recuperación del zinc pero permiten la co-deposición del hierro. Además, de las curvas de polarización de la membrana se determinó que trabajar con intensidades superiores a la límite provoca el ensuciamiento de la misma. No obstante, se encontraron combinaciones de intensidad aplicada y concentración inicial de zinc en la cámara catódica que permiten la obtención de un equilibrio entre la cantidad de zinc que pasa a través de la MIC y la que se deposita sobre la superficie del cátodo, evitando además la co-deposición del hierro.Carrillo Abad, J. (2014). Estudio de la recuperación del zinc presente en los baños agotados de decapado procedentes de las industrias de galvanizado de zinc en caliente mediante técnicas electroquímicas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/39370TESI

Study of the zinc recovery from spent pickling baths by means of an electrochemical membrane reactor using a cation-exchange membrane under galvanostatic control

The performance of a cation-exchange membrane (CEM) used for recovering zinc from real spent pickling baths is studied in this work. These spent baths contain high amounts of ZnCl2 and FeCl2 in aqueous HCl media. The results obtained with this membrane are compared with those obtained with an anion-exchange membrane (AEM) treating the same effluent. The effect of the presence or absence of initial zinc in the cathodic compartment is also studied. The absence of initial zinc in the cathodic compartment in the CEM experiments permits iron codeposition. Furthermore, the results obtained with the CEM are worse than those obtained with the AEM for all the figures of merit. This fact shows the need of filling the cathodic compartment with a synthetic zinc solution. The presence of zinc in the cathodic compartment from the beginning of the electrolysis not only inhibits iron codeposition but also favors zinc deposition as the hydrogen evolution reaction becomes a secondary reaction, improving by this way the results of all the figures of merit of the reactor with the CEM. A deep study about the effect of the applied current and the concentration of the synthetic zinc solution placed in the cathodic compartment permits to reach the equilibrium between the zinc transferred through the membrane and that deposited on the cathode. Therefore, the synthetic cathodic zinc is not consumed at any time. Moreover, under this circumstances iron codeposition is also avoided.The authors want to express their gratitude to the Generalitat Valenciana for a postgraduate Grant (GV/2010/029) and to the Ministerio de Economia y Competitividad for financing the project number CTQ2012-37450-C02-01/PPQ.Carrillo Abad, J.; García Gabaldón, M.; Pérez Herranz, V. (2014). Study of the zinc recovery from spent pickling baths by means of an electrochemical membrane reactor using a cation-exchange membrane under galvanostatic control. Separation and Purification Technology. 132:479-486. https://doi.org/10.1016/j.seppur.2014.05.052S47948613

pH effect on zinc recovery from the spent pickling baths of hot dip galvanizing industries

[EN] In this work, the pH effect on the zinc electrowinning present in the spent pickling baths (SPBs) is analysed with the aim of decreasing the energetic cost of the process. Specifically, the effect of increasing the initial pH with and without its control during the whole electrolysis experiment is studied on synthetic solutions with concentration values similar to those present in the spent pickling baths. Finally, real SPBs are treated under pH control and the results obtained are also compared with those acquired with the direct electrolysis of these SPBs in a membrane reactor. The modification of the initial pH on synthetic solutions shows an increase in zinc deposition rate as the initial pH is risen. However, the zinc redissolution phenomenon is present during the whole experiment. On the other hand, when the pH is controlled, the results obtained are much better as zinc redissolution is prevented and the hydrogen evolution reaction rate is decreased. Comparing the behaviour between the reactor under pH control and that in the presence of an anion exchange membrane, reflects zinc conversion values slightly higher for the membrane reactor due to the zinc precipitation occurring in the reactor under pH control, which is higher as the pH rises. However, the specific energy consumption is considerably higher in the membrane reactor mainly due to the ohmic drop introduced by the membrane. (C) 2016 Elsevier B.V. All rights reserved.Carrillo Abad, J.; García Gabaldón, M.; Pérez-Herranz, V. (2017). pH effect on zinc recovery from the spent pickling baths of hot dip galvanizing industries. Separation and Purification Technology. 177:21-28. doi:10.1016/j.seppur.2016.12.034S212817

BDD anodic treatment of 6:2 fluorotelomer sulfonate (6:2 FTSA). Evaluation of operating variables and by-product formation

The concerns about the undesired impacts on human health and the environment of long chain perfluorinated alkyl substances (PFASs) have driven industrial initiatives to replace PFASs by shorter chain fluorinated homologues. 6:2 fluorotelomer sulfonic acid (6:2 FTSA) is applied as alternative to PFOS in metal plating and fluoropolymer manufacture. This study reports the electrochemical treatment of aqueous 6:2 FTSA solutions on microcrystalline BDD anodes. Bench scale batch experiments were performed, focused on assessing the effect of the electrolyte and the applied current density (5-600 A m-2) on the removal of 6:2 FTSA, the reduction of total organic carbon (TOC) and the fluoride release. Results showed that at the low range of applied current density (J=50 A m-2), using NaCl, Na2SO4 and NaClO4, the electrolyte exerted a minimal effect on removal rates. The formation of toxic inorganic chlorine species such as ClO4- was not observed. When using Na2SO4 electrolyte, increasing the applied current density to 350-600 A m-2 promoted a notable enhancement of the 6:2 FTSA removal and defluorination rates, pointing to the positive contribution of electrogenerated secondary oxidants to the overall removal rate. 6:2 FTSA was transformed into shorter-chain PFCAs, and eventually into CO2 and fluoride, as TOC reduction was >90%. Finally, it was demonstrated that diffusion in the liquid phase was controlling the overall kinetic rate, although with moderate improvements due to secondary oxidants at very high current densities.Support from MINECO and SPAIN-FEDER 2014–2020 to project CTM2016-75509-R and to the Spanish Excellence Network E3TECH (CTQ2015-71650-RDT) is acknowledged. J. Carrillo-Abad thanks the Generalitat Valenciana for granting a post doctoral fellowship (APOSTD/2015/019). The authors are thankful to Dr. R. Buck (Chemours Co.) for kindly providing samples of Capstone FS10

Determination of the potential gold electrowinning from an amoniacal thiosulphate solution applied to recycling of printed circuit board scraps

The use of electrochemical techniques in the selective recovery of gold from a solution containing thiosulphate, ammonia, and copper, obtained from the leaching of printed circuit boards from mobile phones using ammoniacal thiosulphate, are shown in this work. First, cyclic voltammetry tests were performed to determine the potential of electrodeposition of gold and copper, and then, electrowinning tests at different potentials for checking the rates of recovery of these metals were performed. The results of the cyclic voltammetry show that copper deposition occurs at potentials more negative than −600mV (Ag/AgCl), whereas the gold deposition can be performed at potentials more positives than −600mV (Ag/AgCl). The results of electrowinning show that 99% of the gold present in solutions containing thiosulphate and copper can be selectively recovered in a potential range between −400mV (vs Ag/ AgCl) and −500mV (vs Ag/AgCl). Furthermore, 99% of copper can be recovered in potentials more negative than −700mV (vs Ag/ AgCl)The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors received financial support for the research from CAPES and CNPq from Brazil.Kasper, AC.; Carrillo Abad, J.; García Gabaldón, M.; Veit, HM.; Pérez-Herranz, V. (2015). Determination of the potential gold electrowinning from an amoniacal thiosulphate solution applied to recycling of printed circuit board scraps. Waste Management and Research. 34(1):47-57. doi:10.1177/0734242X15607425S4757341Abbruzzese, C., Fornari, P., Massidda, R., Vegliò, F., & Ubaldini, S. (1995). Thiosulphate leaching for gold hydrometallurgy. Hydrometallurgy, 39(1-3), 265-276. doi:10.1016/0304-386x(95)00035-fAlonso, A. R., Lapidus, G. T., & González, I. (2007). A strategy to determine the potential interval for selective silver electrodeposition from ammoniacal thiosulfate solutions. Hydrometallurgy, 85(2-4), 144-153. doi:10.1016/j.hydromet.2006.08.009Arslan, F., & Sayiner, B. (2007). EXTRACTION OF GOLD AND SILVER FROM TURKISH GOLD ORE BY AMMONIACAL THIOSULPHATE LEACHING. Mineral Processing and Extractive Metallurgy Review, 29(1), 68-82. doi:10.1080/08827500601141784Aylmore, M. G. (2005). Alternative lixiviants to cyanide for leaching gold ores. Advances in Gold Ore Processing, 501-539. doi:10.1016/s0167-4528(05)15021-2Aylmore, M. ., & Muir, D. . (2001). Thiosulfate leaching of gold—A review. Minerals Engineering, 14(2), 135-174. doi:10.1016/s0892-6875(00)00172-2Balakrishnan Ramesh Babu, Anand Kuber Parande, & Chiya Ahmed Basha. (2007). Electrical and electronic waste: a global environmental problem. Waste Management & Research, 25(4), 307-318. doi:10.1177/0734242x07076941Breuer, P. L., & Jeffrey, M. I. (2000). Thiosulfate leaching kinetics of gold in the presence of copper and ammonia. Minerals Engineering, 13(10-11), 1071-1081. doi:10.1016/s0892-6875(00)00091-1Carrillo-Abad, J., García-Gabaldón, M., Ortega, E., & Pérez-Herranz, V. (2012). Recovery of zinc from spent pickling solutions using an electrochemical reactor in presence and absence of an anion-exchange membrane: Galvanostatic operation. Separation and Purification Technology, 98, 366-374. doi:10.1016/j.seppur.2012.08.006Chancerel, P., Bolland, T., & Rotter, V. S. (2010). Status of pre-processing of waste electrical and electronic equipment in Germany and its influence on the recovery of gold. Waste Management & Research, 29(3), 309-317. doi:10.1177/0734242x10368303Chancerel, P., Meskers, C. E. M., Hagelüken, C., & Rotter, V. S. (2009). Assessment of Precious Metal Flows During Preprocessing of Waste Electrical and Electronic Equipment. Journal of Industrial Ecology, 13(5), 791-810. doi:10.1111/j.1530-9290.2009.00171.xFeng, D., & van Deventer, J. S. J. (2006). Ammoniacal thiosulphate leaching of gold in the presence of pyrite. Hydrometallurgy, 82(3-4), 126-132. doi:10.1016/j.hydromet.2006.03.006Feng, D., & van Deventer, J. S. J. (2007). Interactions between sulphides and manganese dioxide in thiosulphate leaching of gold ores. Minerals Engineering, 20(6), 533-540. doi:10.1016/j.mineng.2006.10.012Fourcade, F., Tzedakis, T., & Bergel, A. (2003). Electrochemical process for metal recovery from iodized silver derivatives in liquid/solid mixture: Experimental and theoretical approaches. Chemical Engineering Science, 58(15), 3507-3522. doi:10.1016/s0009-2509(03)00198-2Friege, H. (2012). Review of material recovery from used electric and electronic equipment-alternative options for resource conservation. Waste Management & Research, 30(9_suppl), 3-16. doi:10.1177/0734242x12448521García-Gabaldón, M., Pérez-Herranz, V., García-Antón, J., & Guiñón, J. L. (2005). Electrochemical recovery of tin and palladium from the activating solutions of the electroless plating of polymers. Separation and Purification Technology, 45(3), 183-191. doi:10.1016/j.seppur.2005.03.008GARCIAGABALDON, M., PEREZHERRANZ, V., GARCIAANTON, J., & GUINON, J. (2006). Electrochemical recovery of tin from the activating solutions of the electroless plating of polymersGalvanostatic operation. Separation and Purification Technology, 51(2), 143-149. doi:10.1016/j.seppur.2005.12.028Giannopoulou, I., Panias, D., & Paspaliaris, I. (2009). Electrochemical modeling and study of copper deposition from concentrated ammoniacal sulfate solutions. Hydrometallurgy, 99(1-2), 58-66. doi:10.1016/j.hydromet.2009.06.009Gromov, O. G., Kuz’min, A. P., Kunshina, G. B., Lokshin, E. P., & Kalinnikov, V. T. (2004). Electrochemical Recovery of Silver from Secondary Raw Materials. Russian Journal of Applied Chemistry, 77(1), 62-66. doi:10.1023/b:rjac.0000024577.90857.07Grosse, A. C., Dicinoski, G. W., Shaw, M. J., & Haddad, P. R. (2003). Leaching and recovery of gold using ammoniacal thiosulfate leach liquors (a review). Hydrometallurgy, 69(1-3), 1-21. doi:10.1016/s0304-386x(02)00169-xHa, V. H., Lee, J., Jeong, J., Hai, H. T., & Jha, M. K. (2010). Thiosulfate leaching of gold from waste mobile phones. Journal of Hazardous Materials, 178(1-3), 1115-1119. doi:10.1016/j.jhazmat.2010.01.099Hagelüken, C., & Corti, C. W. (2010). Recycling of gold from electronics: Cost-effective use through ‘Design for Recycling’. Gold Bulletin, 43(3), 209-220. doi:10.1007/bf03214988Harrison, J. A., & Thompson, J. (1973). The electrodeposition of precious metals; a review of the fundamental electrochemistry. Electrochimica Acta, 18(11), 829-834. doi:10.1016/0013-4686(73)85034-0Jeffrey, M. . (2001). Kinetic aspects of gold and silver leaching in ammonia–thiosulfate solutions. Hydrometallurgy, 60(1), 7-16. doi:10.1016/s0304-386x(00)00151-1Kasper, A. C., Bernardes, A. M., & Veit, H. M. (2011). Characterization and recovery of polymers from mobile phone scrap. Waste Management & Research, 29(7), 714-726. doi:10.1177/0734242x10391528Kasper, A. C., Berselli, G. B. T., Freitas, B. D., Tenório, J. A. S., Bernardes, A. M., & Veit, H. M. (2011). Printed wiring boards for mobile phones: Characterization and recycling of copper. Waste Management, 31(12), 2536-2545. doi:10.1016/j.wasman.2011.08.013Koyama, K., Tanaka, M., Miyasaka, Y., & Lee, J. (2006). Electrolytic Copper Deposition from Ammoniacal Alkaline Solution Containing Cu(I). MATERIALS TRANSACTIONS, 47(8), 2076-2080. doi:10.2320/matertrans.47.2076Lack, B., Duncan, J., & Nyokong, T. (1999). Adsorptive cathodic stripping voltammetric determination of gold(III) in the presence of yeast mannan. Analytica Chimica Acta, 385(1-3), 393-399. doi:10.1016/s0003-2670(98)00736-3Mironov, I. V., & Makotchenko, E. V. (2009). The Hydrolysis of AuCl 4 − and the Stability of Aquachlorohydroxocomplexes of Gold(III) in Aqueous Solution. Journal of Solution Chemistry, 38(6), 725-737. doi:10.1007/s10953-009-9400-9Navarro, P., Vargas, C., Villarroel, A., & Alguacil, F. . (2002). On the use of ammoniacal/ammonium thiosulphate for gold extraction from a concentrate. Hydrometallurgy, 65(1), 37-42. doi:10.1016/s0304-386x(02)00062-2Peng, C., Liu, Y., Bi, J., Xu, H., & Ahmed, A.-S. (2011). Recovery of copper and water from copper-electroplating wastewater by the combination process of electrolysis and electrodialysis. Journal of Hazardous Materials, 189(3), 814-820. doi:10.1016/j.jhazmat.2011.03.034Reyes Cruz, V., Oropeza, M. T., González, I., & Ponce‐De‐León, C. (2002). Journal of Applied Electrochemistry, 32(5), 473-479. doi:10.1023/a:1016529314840Senanayake, G. (2004). Analysis of reaction kinetics, speciation and mechanism of gold leaching and thiosulfate oxidation by ammoniacal copper(II) solutions. Hydrometallurgy, 75(1-4), 55-75. doi:10.1016/j.hydromet.2004.06.004Senanayake, G. (2007). Review of rate constants for thiosulphate leaching of gold from ores, concentrates and flat surfaces: Effect of host minerals and pH. Minerals Engineering, 20(1), 1-15. doi:10.1016/j.mineng.2006.04.011Trejo, G., Gil, A. F., & Gonz�lez, I. (1996). Electrodeposition of gold in ammoniacal medium: influence of substrate and temperature. Journal of Applied Electrochemistry, 26(12). doi:10.1007/bf00249932Trindade RBE, Barbosa Filho O (2002) Extração de Ouro - Princípios, Tecnologia e Meio Ambiente. Rio de Janeiro, CETEM, Centro de Tecnologia Mineral, Ministério da Ciência e Tecnologia.Tripathi, A., Kumar, M., C. Sau, D., Agrawal, A., Chakravarty, S., & R. Mankhand, T. (2012). Leaching of Gold from the Waste Mobile Phone Printed Circuit Boards (PCBs) with Ammonium Thiosulphate. International Journal of Metallurgical Engineering, 1(2), 17-21. doi:10.5923/j.ijmee.20120102.02UNEP (United Nations Environmental Programme) and UNU (United Nations University) (2009) Recycling – From e-waste to resources, Final report. Berlin.UNEP (International Panel for Sustainable Resource Management, United Nations Environmental Programme) (2013) Metal recycling – opportunities, limits, infrastructure. Paris.Vazquez-Arenas, J., Lazaro, I., & Cruz, R. (2007). Electrochemical study of binary and ternary copper complexes in ammonia-chloride medium. Electrochimica Acta, 52(20), 6106-6117. doi:10.1016/j.electacta.2007.03.062Veit, H. M., Bernardes, A. M., Ferreira, J. Z., Tenório, J. A. S., & Malfatti, C. de F. (2006). Recovery of copper from printed circuit boards scraps by mechanical processing and electrometallurgy. 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Effluents from the copper electrorefining as a secondary source of antimony: Role of mass transfer on the recovery by electrodeposition

The limited availability of antimony has increased the need for exploiting alternative sources to its direct extraction from stibnite deposits. Furthermore, introducing recovery techniques in industries where antimony is released in wastewaters leads to more responsible production routes. In this work, electrodeposition is employed to recover the antimony present in a secondary waste effluent of the copper electrorefining that is highly concentrated in hydrochloric acid. The electrochemical characterization of the system was conducted by voltammetry to identify a range of suitable operating conditions for the potentiostatic and galvanostatic electro-recovery of antimony. In potentiostatic mode, the progress of the secondary electrode reactions of hydrogen and chlorine evolution at potentials more cathodic than −0.38 V vs. Ag/AgCl causes the detachment and redissolution of the deposited antimony. Operating under galvanostatic control, similar effects were observed when the limiting current density is exceeded. Current efficiency and specific energy consumption values above 50 % and below 65 kW·h·kg−1, were achieved below the limiting current density (1.265 mA·cm−2). The operational range where electrodeposition of antimony is accelerated at increasing current densities can be broadened at intensified hydrodynamic conditions and higher concentrations of antimony. The detrimental effect of the hydrogen evolution reaction on the recovery of antimony decreases at high HCl concentrations

Effluents from the copper electrorefining as a secondary source of antimony: Role of mass transfer on the recovery by electrodeposition

[EN] The limited availability of antimony has increased the need for exploiting alternative sources to its direct extraction from stibnite deposits. Furthermore, introducing recovery techniques in industries where antimony is released in wastewaters leads to more responsible production routes. In this work, electrodeposition is employed to recover the antimony present in a secondary waste effluent of the copper electrorefining that is highly concentrated in hydrochloric acid. The electrochemical characterization of the system was conducted by voltammetry to identify a range of suitable operating conditions for the potentiostatic and galvanostatic electro-recovery of antimony. In potentiostatic mode, the progress of the secondary electrode reactions of hydrogen and chlorine evolution at potentials more cathodic than ¿0.38 V vs. Ag/AgCl causes the detachment and redissolution of the deposited antimony. Operating under galvanostatic control, similar effects were observed when the limiting current density is exceeded. Current efficiency and specific energy consumption values above 50 % and below 65 kW·h·kg¿1, were achieved below the limiting current density (1.265 mA·cm¿2). The operational range where electrodeposition of antimony is accelerated at increasing current densities can be broadened at intensified hydrodynamic conditions and higher concentrations of antimony. The detrimental effect of the hydrogen evolution reaction on the recovery of antimony decreases at high HCl concentrations.The authors thank the financial support from the Agencia Estatal de Investigacion (AEI/10.13039/501100011033) (Spain) under the project PCI2019-103535 and by FEDER A way of making Europe. Funding for open access charge: CRUE-Universitat Politecnica de Valencia.Hernández-Pérez, L.; Carrillo-Abad, J.; Pérez-Herranz, V.; Montañés, M.; Martí Calatayud, MC. (2023). Effluents from the copper electrorefining as a secondary source of antimony: Role of mass transfer on the recovery by electrodeposition. Desalination. 549. https://doi.org/10.1016/j.desal.2022.11632254

Enhanced Atenolol oxidation by ferrites photoanodes grown on ceramic SnO2-Sb2O3 anodes

The increase in the consumption of pharmaceutical compounds has caused the increment of their presence in different body waters. β-blockers are one of the most dangerous even at low concentrations (ng L−1). Anodic oxidation with a boron-doped diamond (BDD) anode presents good results to remove these compounds. However, since this anode is expensive, some cheaper materials are under study. In this work, Sb-doped SnO2 ceramic anodes (BCE) coated with Zn or Cd ferrites, in order to provide photocatalytic properties, have been applied to the degradation of the Atenolol (ATL) β-blocker. Increasing the applied current increased ATL degradation and mineralization but caused a decrease in mineralization current efficiency (MCE) and an increase in energy consumption (ETOC). Additionally, light irradiation enhanced the ATL mineralization rate between 10% and 20% for both ferrites, although this increase was higher for the cadmium ferrite one. Finally, when the ferrites were compared with BDD and BCE anodes, the oxidizing power of the different anodic materials can be ordered as follows BDD> Cd-Fe> Zn-Fe> BCE. Therefore, both ferrites improved the BCE performance but only the cadmium one appeared as an alternative to the BDD, especially for MCE and ETOC, reaching values of 15% and 0.5 kWh gTOC−1, respectively