Aluminium standard reduction potentials

The trend shown by the standard reduction potentials lor the reductions of sodium, magnesium and aluminium ions to their respective metals... 

With a standard reduction potential of -1.7 volt aluminium ought to corrode relatively easy by being exposed to water and oxygen. Nevertheless a thin layer of aluminium oxide AI2O3 is formed by contact with oxygen as sketched on the figure below ... 

Whereas the oxidation of aluminium metal has a standard reduction potential of-1.7 volt the oxidation of AI2O3 has only a standard reduction potential of -0.6 volt making aluminium oxide almost as corrosion resistant as the noble metal gold. 

Musculoskeletal Bone area and bone mineral content in lumbar spine, hip, and whole body were measured with dual radiograph absorptiometry in 59 children aged 13-15 who had been bom preterm and randomly assigned standard or aluminium-depleted parenteral nutrition solutions during the neonatal period. Those who had been randomly assigned to standard parenteral nutrition solutions had lower lumbar spine bone mineral content, apparently explained by a reduction in bone size. In nonrandomized analyses, children who were exposed as neonates to aluminium above the median (55 micrograms/kg) had lower hip bone mineral content, independent of bone or body size. The authors concluded that neonates who are exposed to parenteral aluminium may have reduced lumbar spine and hip bone mass during adolescence, potential risk factors for later osteoporosis, and hip fracture. 

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