Enhancement of hydrogen generation using waste aluminum cans hydrolysis in low alkaline de-ionized water

•Hydrolyzed waste Al can in low NaOH is more efficient compared with Al powders.•Elevating Temp or Ni/Bi additives obviously enhance hydrogen generation (HG) rate.•Planetary milling of waste Al scraps increase reactive area and HG efficiency.•The linear-parabolic law is introduced to explain Al oxidation mechanism.•Optimize the HG efficiency using waste Al can without high NaOH is achieved.

In this study, hydrogen generation using hydrolyzed waste aluminum can in low alkaline aqueous solution is evaluated and the result is efficient in comparison with Al powders. Waste Al can was pretreated using a series of methods, such as paint removal in concentrated sulfuric acid and fragmented Al pieces in planetary ball milling, and then characterized with BET, XRD and SEM techniques. During hydrogen generation, low alkaline solution combined with elevating temperature and Ni or Ni/Bi additives in waste Al can-water hydrolysis system could achieve rapid hydrogen generation rate to 150 ml s−1 g−1 and total volume 1350 ml g−1. Moreover, planetary ball-milling of waste Al scraps could increase effective reactive area to improve generated hydrogen. The optimized results, which are attributed from micro-galvanic cell formation between Al/Ni closely contact, and accelerating reaction activity, are comparable with Al powders. In this report we successfully optimize the generated hydrogen efficiency of waste Al can base without high alkaline concentration which could cause environmental pollution and instrument damage problems.