Phase transformations of α-alumina made from waste aluminum via a precipitation technique

Int J Mol Sci. 2012 Dec 7;13(12):16812-21. doi: 10.3390/ijms131216812.

Abstract

We report on a recycling project in which α-Al(2)O(3) was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H(2)SO(4) solution to form an Al(2)(SO(4))(3) solution. The Al(2)(SO(4))(3) salt was contained in a white semi-liquid solution with excess H(2)SO(4); some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al(2)(SO(4))(3)·18H(2)O. The Al(2)(SO(4))(3)·18H(2)O was calcined in an electrical furnace for 3 h at temperatures of 400-1400 °C. The heating and cooling rates were 10 °C /min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al(2)(SO(4))(3)·18H(2)O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al(2)O(3) at high temperatures. The X-ray diffraction results indicated that the α-Al(2)O(3) phase was realized when the calcination temperature was at 1200 °C or higher.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum / chemistry*
  • Aluminum Oxide / chemistry*
  • Chemical Precipitation*
  • Hot Temperature
  • Oxides / chemistry
  • Phase Transition
  • Recycling
  • Waste Products*
  • X-Ray Diffraction

Substances

  • Oxides
  • Waste Products
  • Aluminum
  • Aluminum Oxide