EXTRACTION-ABSORPTIOMETRIC DETERMINATION OF COPPER BY RHODAMINE 6G IN NATURAL AND WASTE WATERS

Abstract

One of the modern environmental problems is the pollution of the environment objects with heavy metals, including copper. Sources of pollution of the biosphere with copper compounds are nonferrous metallurgy enterprises (aerosol emissions, industrial waste waters) and machine building (electroplating copper baths).

Copper, as well as other heavy metals, can accumulate in living organisms, causing various diseases. In this regard, there is an obvious need to develop new, more sensitive, selective, express and cost-effective methods of copper determination at the level of fractions of maximum permissible concentrations.

In the present work, an extraction-absorptiometric method for the determination of microgramme quantities of copper using the basic dye of xanthene series – rhodamine 6G is proposed. Basic dyes with anionic complexes of metals form ionic associations, which are extracted by organic solvents, leaving excess dye and accompanying ions in aqueous solution. Thus, the sensitivity and selectivity of the method are increased.

The interaction chloride anion complex of copper (II) with xanthene dye – rhodamine 6G has been studied. The optimal conditions for the formation and extraction of the ionic association have been established: the acidity of the aqueous phase; the concentrations of dye and copper, the composition of the ionic association, the extraction factor, etc. The compliance with the basic law of photometry is observed in the copper concentration interval of 0.625…10 µg/ml. The molar absorption coefficient is 56000±300 l·mol^-1·cm^-1. By Asmus direct line and equilibrium shift methods it was found that the molar ratio of dye cation to copper in the ionic association is 1:1.

The developed method was applied for the determination of copper in industrial waste waters of electroplating production and river water.