Quantitative assessment of red mud constituents by combined thin layer chromatography and scanning densitometry

Quantitative analysis of aluminium, iron, silicon and titanium present in bauxite residue (red mud) has been achieved by thin layer chromatography coupled with optical scanning densitometry. Silicon in red mud sample is detected at pH range 0.75-0.95 on chromatography plates prepared with microcrystalline cellulose modified with 10% sodium molybdate. Aluminium, iron and titanium are detected on silica gel H layers impregnated with 0.2% sodium formate and developed with mixture of 10% aqueous solutions of sodium chloride and formic acid in 8:2 v/v. The chromatograms obtained for the cations are quantitatively evaluated by optical scanning densitometry by measuring absorbance at 530-520 nm for aluminium, 660-528 nm for iron and 395-410 nm for titanium and silicon in reflectance mode. The quantitative densitometric data has been evaluated with analogous data obtained by wet analysis.