A new experimental approach for liquid-liquid extractive spectrophotometric determination of chromium(VI) in tannery wastewater and alloy samples

ABSTRACT

In this research work, a new approach is developed for the extractive determination of chromium. The principle of this approach is based on the complexation reaction between 4-(4ʹ-chlorobenzylideneimino)-3-methyl-5-mercapto-1,2,4-triazole (CBIMMT) in dichloromethane as a complexing reagent and chromium(III) in presence of potassium iodide to form a yellow coloured complex at room temperature. The 1:2:2 [Cr(III)-CBIMMT-iodide] ternary complex was quantitatively extracted in dichloromethane from 2.5 mol L⁻¹ of hydrochloric acid medium which showed maximum absorption intensity at λ_max 411 nm and was stable for more than 72 h. The values of molar absorption coefficient and Sandell’s sensitivity of the complex were found to be 0.7019 × 10⁴ L mol⁻¹ cm⁻¹ and 0.00748 µg cm⁻², respectively. The system adheres to Beer’s law from 1.5 to 6.0 µg mL⁻¹; however, Ringbom’s plot suggests optimal concentration range was 1.8–5.8 µg mL^−1. The limit of detection and limit of quantification of the approach is 0.26 and 0.79 µg mL⁻¹. This approach was successfully used for the determination of chromium from wastewater effluents from the tannery industries (Kolhapur, MS, India), alloy samples and for separation of it from synthetic mixtures. The present experimental approach is apparently much simpler than the conventional method comprising multistep processes.

KEYWORDS:

• Alloy samples
• CBIMMT
• chromium(VI)
• water samples
• spectrophotometric determination

Acknowledgments

Authors are highly thankful to Dr Despo Fatta Kassinos, Associate Professor, Department of Civil and Environmental Engineering, University of Cyprus, Cyprus and Dr Prosun Bhattacharya, Professor, KTH Royal Institute of Technology, Stockholm, Sweden for fruitful discussions during this research and we are also thankful to Dr B. Y. Yadav, Chairman, Shri Shivaji Shikshan Prasarak Mandal, Barshi and Principal Dr P. R. Thorat for providing necessary facilities.

Disclosure statement

No potential conflict of interest was reported by the authors.