Determination of Thiocyanate in Waste Water

Abstract

The present work proposes a new, simple, selective, and sensitive method for the on‐site spectrophotometric determination of SCN⁻ ions in the industrial and municipal waste water. The method is based on color reaction of SCN⁻ ions with V(V) and chelating agent: N‐hydroxy‐N,N′‐diphenylbenzamidine (HODPBA), and subsequent extraction of the deep green colored complex into chloroform. The value of apparent molar absorptivity (at enrichment factor of 5) is 7.00 × 10³ L mol⁻¹ cm⁻¹ at λ_max = 610 nm. The calibration curve is linear up to 5.0 µg mL⁻¹ SCN⁻ with slope, intercept, and correlation coefficient of 0.120, 0, and +0.99, respectively. The detection limit (an absorbance identical to blank absorbance +thrice of std. dev.) of the method is 66 ng mL⁻¹ SCN⁻ of the aqueous solution. Most of the ions associated did not interfere in the determination of SCN⁻. Only phenol interfered in the determination of SCN⁻, and could be removed by the prior extraction with chloroform solution. The method has been used for analysis of SCN⁻ in industrial and municipal waste water samples.

E‐mail: [email protected]‐darmstadt.de.

Keywords:

• Thiocyanate
• Spectrophotometry
• Solvent‐extraction
• Vanadium(V)
• N‐Hydroxy‐N,N′‐diphenylbenzamidine
• Waste water

Acknowledgments

We are thankful to the Volkswagen Foundation, Hannover, and the Alexander von Humboldt Foundation, Bonn, Germany for financial assistance to complete this work.

Notes

E‐mail: [email protected]‐darmstadt.de.