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

ABSTRACT

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 λ_max 560 nm. The molar absorptivity of the colour is 9.51 × 10⁵ L mol⁻¹ cm⁻¹ at λ_max 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.

KEYWORDS:

• Egyptian ilmenite
• chromium
• flotation
• Rhodamine B
• spectrophotometric

Disclosure statement

No potential conflict of interest was reported by the author.