Hydrogen generation through metal waste corrosion: a systematic investigation on old/post-consumer scrap Al6063-series alloy

Materials for Renewable and Sustainable Energy https://doi.org/10.1007/s40243-024-00287-2 (2025) 14:16 ORIGINAL PAPER Hydrogen generation through metal waste corrosion: a systematic investigation on old/post‑consumer scrap Al6063‑series alloy Meenal Gupta1 · Filippo Selleri2 · Antonio Ficarella1 · Patrizia Bocchetta1 Received: 25 April 2024 / Accepted: 10 December 2024 © The Author(s) 2025 Abstract In this study, aluminum-based wastes are used as energy carriers for on-demand hydrogen production through sustainable, eco-friendly, and cost-effective controlled electrochemical corrosion in aqueous solution. The electrochemical process is very effective because it (i) uses waste metals to produce hydrogen, (ii) corroborates to circular economy, (iii) produces high purity hydrogen, (iv) is based on simple hydrolysis reaction of metals in relevant solutions, (v) electricity is not required and (iv) recovers part of the chemical Gibbs energy of the electrochemical corrosion usually entirely lost in the environment. We systematically studied the generation of hydrogen from industrial waste Dust Scrap Aluminum Alloy (DSAA) belonging to Al 6063 series for the first time. The process is investigated in a novel hand-made batch reactor with a low-cost commercial body suitable to an easy scale-up. Kinetics of DSAA hydrolysis reaction was explored by measuring the variation of aluminium ion concentration at different immersion times through Inductively Coupled Plasma (ICP) and weight loss measurements at different temperatures and NaOH catalyst concentrations. The effect of hydrolysis reaction on the composition and morphology of the metal surfaces in terms of formed oxide layers was studied in detail using Optical Polarizing Microscopy (OPM), Energy dispersive X-ray (EDX) and Scanning Electron Microscopy (SEM) techniques. The criteria used to evaluate the hydrogen reactor performance were hydrogen (i) yield and (ii) production rate. The experimental results showed that a strong increase in NaOH concentration (from 0.75 to 5 M) corresponding to a slow increase in hydrolysis reaction temperature (from 38.8 to 49.9 °C) lead to an improvement in hydrogen generation rate of one order of magnitude, i.e. from 35.71 to 421.41 ml/(g∙min). Low but constant rate of hydrogen can be generated for longer times at low NaOH concentrations (0.75 M), while fast and variable hydrogen generation rate occurs at higher concentrations (5 M) in short times. In the case study of Al 6063 series waste scrap, the hydrolysis reactor parameters can be regulated to deliver hydrogen generation rates from 35.71 to 421.41 ml/(g min) according to requirements. We expect that the results presented in this work will encourage researchers to study the possible use of other metal-based and multi-material plastic/metal wastes thermodynamically prone to electrochemical corrosion process as possible source of hydrogen. * Patrizia Bocchetta 1 Department of Innovation Engineering, University of Salento, 73100 Lecce, Italy 2 EcoSel S.R.L., Lequile, 73100 Lecce, Italy Vol.:(0123456789) 16 Page 2 of 18 Materials for Renewable and Sustainable Energy (2025) 14:16 Graphical Abstract Keywords Electrochemical corrosion · Hydrogen generation · Scrap aluminum alloys · Metal wastes · Waste valorization · Hydrogen energy Introduction Chemical surface treatment is an essential step in Al alloys industry [1–3]. Alkaline etching is well known treatment for adhesive treatment of organic coating on Al alloys in field of engineering [4–6]. It also helps to change the corrosion properties of the alloys smoothing the surface/layers occurred during cold/hot rolling of Al alloys [7–9]. Nowadays alkaline etching is also used to remove the dirt and thick layer of oxides formed from the surface of Al alloys to generate green hydrogen for its future use as fuel. Hydrogen production using metals with alkaline treatment is one of the methods without requirement of any kind of input energy which makes this method a most adaptable among other existing methods [10–15]. Energy emergency may be one of the biggest threats to the whole world in near future without adopting new energy carriers as hydrogen. Therefore, the environment requires new methods for hydrogen generation able to solve multiple problems, like waste management, absence of input energy, cost effective, adoptable at laboratory scale or industrial scale. The long-term development of any country depends on working the judiciary by adopting sustainable methods at industrial level because of environmental concern. Therefore, many countries are trying to restrict hydrogen generation using combustion of fossil fuels or using natural gases to consider global climate changes and local air pollution issues. Research is going on towards fulfilling energy demand by industries to household equipment’s with the intention to prevent the environment from air pollution. Researchers are getting motivated to develop economical, safe and environmentally friendly methods to fulfill the energy need using hydrogen production [10–15]. European union have already made rules in this aspect that only CO2-neutral fuels-based combustion engines can be registered after 2035 [16]. Sustainable hydrogen production shows a path to countries with their policies, using which future energy demands can be fulfilled without impacting the environment. It seems a possible carbon free solution to solve environmental pollution issues, which are caused by conventional energy production sources based on natural gases and coals. Lots of efforts are being done to produce hydrogen using replenished energy sources, eg. solar power, wind energy, hydro, biomasses and geothermal [17–23]. Hydrogen production using nuclear energy is another developing technological areas to control environment pollution [24]. The hydrogen production method decides production of blue, purple, turquoise, grey or green hydrogen [25]. Energy generation by reacting hydrogen with oxygen generates only water and heat, reducing environmental impact near to zero. Still, the energy production using hydrogen is almost negligible at industrial level in many countries and need immediate consideration by the whole world to reduce the environment treat. Certainly, the production and storage of hydrogen pose certain challenges, primarily due to its low density and high reactivity. Traditional storage methods often involve compressing hydrogen gas into high-pressure tanks or liquefying it at extremely low temperatures, both of which require significant energy input and specialized infrastructure. Additionally, hydrogen can be explosive when mixed with air, necessitating careful handling and storage procedures. To overcome these challenges, alternative approaches such as in-situ hydrogen production methods are being Materials for Renewable and Sustainable Energy Page 3 of 18 (2025) 14:16 explored. In the context described, in-situ hydrogen production inv (...truncated)