Determination of chromium in chromite rocks by different Methods

Abstract

Samples of chromite rocks were collected from different parts of the Sudan, namely Hamassana, Onib Region North East of the Red Sea Area, Gebl Rahib, North West of the Sudan, Oshib North West the Red Sea mountains and Jam area Blue Nile Region. The samples were treated by fusion with sodium peroxide to bring about all raw chromium into chromium (VI). The chromium content was determined by different methods, namely the classical titration method where barium diphenyl sulphonate was used as indicator, the direct spectrophotometry using diphenyl carbazide as chelating complex, and the indirect spectrophotometry, by extraction with N-phenylbenzohydroxamic acid. Through comparison of the different methods it was found that all the results are close to each others; however, the results of the spectophotometric method (with some exceptions) are generally the best of them.