Applied Surface Science 396 (2017) 1067–1075 Contents lists available at ScienceDirect Applied Surface Science jou rn al h om ep age: www.elsevier.com/locate/apsusc Full Length Article Silver deposition on stainless steel container surfaces in contact with disinfectant silver aqueous solutions M. Petala a,∗ , V. Tsiridis a , I. Mintsouli b , N. Pliatsikas c , Th. Spanos d , P. Rebeyre e , E. Darakas a , P. Patsalas c , G. Vourlias c , M. Kostoglou b , S. Sotiropoulos b , Th. Karapantsios b a Department of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece b Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece c Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece d Department of Petroleum and Mechanical Engineering Sciences, Eastern Macedonia and Thrace Institute of Technology, Kavala, 65404, Greece e ESA/ESTEC, P.O.Box 299, 2200 AG, Noordwijk, The Netherlands a r t i c l e i n f o Article history: Received 29 July 2016 Received in revised form 30 September 2016 Accepted 13 November 2016 Available online 14 November 2016 Keywords: Silver deposition Potable water International Space Station Stainless steel Galvanic deposition a b s t r a c t Silver is the preservative used on the Russian segment of the International Space Station (ISS) to pre- vent microbial proliferation within potable water supplies. Yet, in the frame of the European Automated Transfer Vehicle (ATV) missions to ISS, silver depletion from water has been detected during ground transportation of this water to launch site, thereby indicating a degradation of water quality. This study investigates the silver loss from water when in contact with stainless steel surfaces. Experiments are conducted with several types of stainless steel surfaces being exposed to water containing 10 or 0.5 mg/L silver ions. Results show that silver deposits on stainless steel surfaces even when a passivation layer protects the metallic surface. The highest protection to silver deposition is offered by acid passivated and electropolished SS 316L. SEM and XPS experiments were carried out at several locations of the sample area that was in contact with the Ag solution and found similar morphological (SEM) and compositional (sputter-etch XPS) results. The results reveal that silver deposits uniformly across the wetted surface to a thickness larger than 3 nm. Moreover, evidence is provided that silver deposits in its metallic form on all stainless steel surfaces, in line with a galvanic deposition mechanism. Combination of ICP-MS and XPS results suggests a mechanism for Ag deposition/reduction with simultaneous substrate oxidation resulting in oxide growth at the exposed stainless steel surface. © 2016 Elsevier B.V. All rights reserved. 1. Introduction The disinfection capacity of ionic silver has been acknowledged against numerous types of microbes, bacteria, viruses, protozoa, algae etc. [1]. In addition, silver may enhance processes, e.g. improve the photocatalytic activity of TiO 2 [2]. Biocide properties of ionic silver and silver nanoparticles rely on several mechanisms and modes of action including reactive oxygen species (ROS) formation, DNA multiplication disruption and cell membrane malfunction [3]. These mechanisms are provoked considerably by ionic silver that will be eventually present even in the case of silver nanoparticles dispersions [4,5]. Ionic silver is used as a preservative for water used aboard the Russian segment of the ISS. NASA plans also to use silver as a preser- vative for potable water in their future manned space missions. The availability of potable water is essential both in terms of quality ∗ Corresponding author. E-mail address: petala@civil.auth.gr (M. Petala). and quantity. Currently, potable water according to either Russian or American quality standards is prepared on Earth and is regu- larly re-supplied to ISS. ATV has been designed by the European Space Agency (ESA) to provide potable water instead of payloads, consumables, etc. [6]. For each ATV flight water tank to be loaded, three water tanks are prepared: one tank that contains water with elevated silver content (10 mg/L) for the pre-conditioning of the ATV flight tank and two other tanks that contain potable water of 0.5 mg/L silver concentration for flushing and loading of ATV flight tank, respectively. During ATV launch campaigns, a fluctu- ation of silver was observed by performing water quality analyses at different steps of the ATV water process [7]. Although there is extensive literature about silver coatings on other metals for decorative, anticorrosion, antimicrobial, electronic and optical applications [8–11], a very limited number of publica- tions associated with silver deposition on water container walls exist. The few relevant studies found in literature show that silver depletion from bulk water might occur depending on various fac- tors, such as the wetted surface area to water volume ratio (S/V), wetted surface type, etc. [12–14]. http://dx.doi.org/10.1016/j.apsusc.2016.11.090 0169-4332/© 2016 Elsevier B.V. All rights reserved.