Selective flotation-spectrophotometric determination of chromium using Rhodamine B in Egyptian ilmenite phosphate solution

摘要

The method is sensitive and it is the novelty of the work for flotation-spectrophotometric determination of Cr(III). This method is based on the formation of ion associate complex between Cr(III), KI and Rhodamine B (RhB). The formed complex is floated in the interface of aqueous solution and 1,2-dichloroethane via vigorous shaking. By discarding the aqueous solution and 1,2-dichloroethane, the floated ion associate [(CrI4)−] [(RhB)+] complex on the wall of a separating funnel was then dissolved in a small volume of methanol solvent. By studying different affecting parameters, it was found that the maximum absorbance of the formed ion associate complex was 0.675 at λmax 560 nm. The molar absorptivity of the colour is 9.51 × 105 L mol−1 cm−1 at λmax 560 nm and the colour was stable for 1 h. The calibration graph was linear in the concentration range of 0.1–100 mg L−1 of Cr(III). The low limit of detection (LOD) was 0.1 mg L−1. The relative standard deviations (RSD) at 0.1 and 100 mg L−1 of Cr(III) were 4.7% and 7.2% (n = 10), respectively. The method was successfully applied for the determination of Cr(III) in different Egyptian ilmenite phosphate solution.