COMPARATIVE STUDY OF COLORIMETRIC DETERMINATION AND SOLVENT EXTRACTION OF COPPER [II] WITH METHYLENE BLUE AND CRYSTAL VIOLET

Authors

  • E.O. Ojeka
  • A.I. Ambo
  • I. Hashim

Abstract

Methylene Blue and Crystal violet cationic dyes were evaluated as reagents for the extraction and spectrophotometric determination of copper. The method is based on the reduction of copper [II] to copper [I] with cyanide and the formation of dicyanocuprate [I] and its extraction into toluene as an ion associate with Methylene Blue [MB]. The result for Methylene blue was more reproducible than Crystal Violet [CV] dye. For copper determination, the absorbance of a toluene solution at 660 nm was measured against a reagent blank for Methylene blue and 530 nm for Crystal Violet, respectively. The apparent molar absorptivity, were 7.50× 􀀄􀀅   􀀆􀀇􀀀 􀀇􀀈􀀉􀀁􀀂 􀀊􀀇􀀁􀀂 for MB and 5.00× 􀀄􀀅 􀀆􀀇􀀀 􀀇􀀈􀀉􀀁􀀂 􀀊􀀇􀀁􀀂 for CV, respectively at pH 6.60. Copper was determined in the range of 0.17-1.36 mg in 10 mL sample with a relative standard deviation of 0.83% in MB and 1.71% in CV for copper concentration of 6.0× 􀀄􀀅􀀁􀀃 M. The composition of the ion associate is probably MB+.Cu(CN)2-.KEYWORDS: Comparative, Colorimetric, Extraction, Methylene blue, Crystal violet

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Published

2020-05-23