Technical Note

Effect of Cu(II) doping on physical properties of synthetic goethite and their reactivity in SO2-H2SO4-H2O medium

M. Mohapatra, S. Anand*, R.P. Das

Regional Research Laboratory, Bhubaneswar, 751 013, Orissa, India

Accepted 7 February 2005


Pure and copper-doped goethite samples were prepared by precipitation/co-precipitation method. The XRD patterns of both un-doped and Cu(II)-doped samples showed goethite as the only crystalline phase with slight shift in d-values for doped samples. Based on the weight loss measurements in the temperature region of 393-673K, % age goethite in those samples was estimated and it was found that % age goethite was nearly 100% for the samples containing nil or upto 0.4% Cu and decreased to 90 and 65% with the increase in % age of copper to 1.15 and 2.7% respectively. Surface area of samples increased from 47.9m2/g to 105m2/g by increasing the % age of doped copper from nil to 2.7%. The dissolution of these samples in H2SO4-SO2-H2O media showed interesting trends. The dissolution of iron was found to be complex due to difference in (a) goethite content of doped samples (b) nature of goethite due to Cu(II) ion incorporation and (c) surface area of various samples. At lower concentrations of Cu(II), ratio of % dissolution of Fe to Cu was nearly one indicating uniform distribution of Cu in iron matrix. In case of samples containing 2.7% Cu, ratio of % dissolution of Fe to Cu increased to ~2 indicating preference of Cu incorporation in iron oxide other than goethite.

Keywords: Copper, Iron, Goethite, Reduction, Precipitation

* Corresponding author
   E-mail : sanand@rrlbhu.res.in