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