Synergistic effect of the fresh Co, Ni, and anion ions on aluminum or magnesium with water reactions

Abstract

Summary To analyze the effect of Co and Ni on hydrogen generation in water, the reactions of Mg and Al with water in CoCl2 and NiCl2 solutions are studied in terms of amount of H2 produced and rate of reaction. Mg rapidly reacts with water in CoCl2 and NiCl2, producing high amount of H2 without induction time. While there is a short induction time is detected for Al─H2O reaction in CoCl2 and NiCl2. In addition to the galvanic cell behavior of the Mg (Al)/Co (Ni) compounds formed, Co and Ni catalyze the hydrogen production reaction; however, the agglomeration of Co or Ni leads to a noticeable decrease in H2 production. The open‐circuit potential in CoCl2 and NiCl2 solutions after the addition of Mg or Al at ambient temperature shows an obvious change, coinciding with the initiation of the hydrogen generation process. Mg rapidly reacts with water in Co (Ac)2, CoSO4, Ni (Ac)2 and NiSO4 solutions as a consequence of its intrinsic metallic properties and of the formation of Co or Ni. The hydrogen production amount is lower (<200 ml g−1) in Co (NO3)2 and Ni (NO3)2, even after adding NaCl. No reaction occurs when adding Al in CoSO4, Co (Ac)2, Co (NO3)2, NiSO4, Ni (Ac)2, and Ni (NO3)2. The synergistic effect of Co, Ni, and anion ions in water affects the rate of Al or Mg corrosion and hydrogen generation.

Highly efficient hydrolysis of magnetic milled powder from waste aluminum (Al) cans with low‐concentrated alkaline solution for hydrogen generation

“…Besides these peaks, ground Al cans exhibit two apparent peaks at 43°and 84°, indicating that the existence of other metal elements such as manganese, iron, and zinc in the Al cans. 31 This result will be further confirmed by AAS analysis.…”

“…Therefore, the hydrolysis of Al cans flakes with NaOH solution is diffusively controlled, rather than kinetically controlled. The reaction rate constant value was calculated to be 0.2479 and 0.5761 min −1 for commercial Al powder and Al cans powder with the yield of first 5 minutes, suggesting that the hydrolysis was increased by the formation of the micro‐galvanic cells …”

“…The reaction rate constant value was calculated to be 0.2479 and 0.5761 min −1 for commercial Al powder and Al cans powder with the yield of first 5 minutes, suggesting that the hydrolysis was increased by the formation of the micro-galvanic cells. 30,31 Based on the above discussions, the reaction mechanism of Al cans flakes and powder with NaOH solution were studied and shown in Figure 13. For hydrolysis of Al cans flakes, diffusion is the main rate-controlled factor, and it is difficult for OH − to diffuse into the Al surface, especially in the initial reaction times.…”

“…Therefore, recycling and using of these waste Al materials are interesting topics for both improving the economic efficiency and reducing environmental pollution. Waste Al cans mainly contains Al, Fe, Zn, Mn, and Cu elements, making it a promising alloy material for hydrogen production because of the formation of the micro‐galvanic cells . Therefore, producing hydrogen from waste Al cans solves the problems of solid waste emission, waste of natural resources, and CO 2 emissions.…”

“…Waste Al cans mainly contains Al, Fe, Zn, Mn, and Cu elements, making it a promising alloy material for hydrogen production because of the formation of the micro-galvanic cells. 30,31 Therefore, producing hydrogen from waste Al cans solves the problems of solid waste emission, waste of natural resources, and CO 2 emissions. As previous reported, the energy requirement of the waste Al can for hydrogen generation is 2%, while the CO 2 emission is 4% of the current industrial method.…”