Recycling Aluminum Chemically
Adapted for Use at Collin College by
Amina K. El-Ashmawy, Ph.D. and C. Frederick Jury, Ph.D.
Collin College Department of Chemistry
Objectives:
 Recycle elemental aluminum into alum
 Crystallize synthesized alum
 Determine percent yield
Introduction:
Aluminum is the third most abundant element in the earth’s crust. However, vast
amounts of energy are necessary for the production of aluminum from its ore sources.
This is why many communities have programs in place to recycle aluminum cans. The
lifetime of an aluminum can on average is about 100 years.
The littering of cans along roadways are not only an eyesore but also a drain on
natural resources. This experiment will demonstrate a chemical technique for
recycling used aluminum. From elemental aluminum, you will prepare the
compound potassium aluminum sulfate dodecahydrate, KAl(SO4)2•12H2O, called alum
for short. Alum is used in the paper industry, in processing pickles, in dying fabrics
and in water purification as well as wastewater treatment. This technique can be
used with aluminum cans but only after removing the exterior paint and the interior
plastic coating.
Aluminum is a reactive metal that reacts slowly with dilute acids. An aluminum oxide
layer that protects the surface of the metal slows the rate of reaction. Alkaline (basic)
solutions attack the metal surface after dissolving the oxide layer. Excess base converts
the aluminum to the tetrahydroxoaluminate(III) ion. This ion is only stable in basic
s