A simple electrogravimetric experimental setup to determine Cu in alloy samples for teaching purposes
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ORIGINAL PAPER
A simple electrogravimetric experimental setup to determine Cu in alloy samples for teaching purposes João Pedro Silva1 · Kallyni Irikura1 · Maria Valnice Boldrin Zanoni1 · Paulo Clairmont F. Lima Gomes1 Received: 3 April 2020 / Accepted: 13 August 2020 © Institute of Chemistry, Slovak Academy of Sciences 2020
Abstract Electrogravimetry is a traditional analytical method for the determination of cations in aqueous solution, but the use of platinum as cathode and anode electrodes hinders its implementation in undergraduate chemistry courses with limited resources. This study proposes the replacement of expensive platinum electrodes by cheaper materials such as the dimensionally stable anode and Ni–Cr alloy as the cathode, which showed good performance in the determination of Cu by electrolysis at constant current (in galvanostatic mode). The proposed method achieved an electrogravimetric yield of 97.3 ± 0.9%, from a solution of CuSO4 during electrolysis carried out at 0.26 A for 60 min. The experimental setup was used to determine Cu in commercial scrap alloy waste samples containing Cu, Sn, Pb, and Zn, following a simple pretreatment employing ammonia solution. The Cu weight percentage obtained was 58.6 ± 0.5%, which was in agreement with a value of 59.4 ± 1.7% obtained using a comparative spectrophotometric method. Graphic abstract
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11696-020-01322-y) contains supplementary material, which is available to authorized users. Extended author information available on the last page of the article
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Chemical Papers
Keywords Electrogravimetry · Electroanalytical chemistry · Instrumental method · Quantitative analysis · Laboratory instruction
Introduction The first analytical determination using electrogravimetry was performed in 1864 by Wolcott Gibbs, (Szabadvary 1964; Stock 1989) using an electrolytic cell for the determination of Cu and Ni. Subsequently, electrogravimetry has become established as an excellent technique for the fast and precise determination of divalent metals such as Cu, Ni, and Co in aqueous solutions (Owen et al. 1983). In addition to quantitative determinations, electrogravimetry is also an important tool for the separation of elements and the removal of metals from solution (DeFord and Bowers 1958). Electrogravimetric determination can be performed at controlled potential (potentiostatic method) or controlled current (galvanostatic method) (Skoog et al. 2004). However, electrolysis at controlled potential is known to provide the best selectivity in the determination of metals. The main disadvantage is the experimental setup, which requires a three-electrode system (working, counter, and reference electrodes) and a potentiostat. This is more expensive than the laboratory equipment required for electrogravimetric determinations according to the galvanostatic method, based on only two electrodes, employing a simple experimental setup that requires a power
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