Evaluation of the dithizone colorimetric method in the determination of mercury (II) in industrial effluents

Date

4-1992

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Aloysius U. Baes

Abstract

TARUN, MARICAR C. College of Arts and Sciences, University of the Philippines Los Bafios. April, 1993. EVALUATION OF THE DITHIZONE COLORIMETRIC METHOD IN THE DETERMINATION OF MERCURY (II) IN INDUSTRIAL EFFLUENTS.

Adviser: Dr. Aloysius U. Baes.

An assessment of the dithizone colorimetric method for analyzing mercury (II) was conducted. The procedure involved the adjustment of the aqueous Hg(II) solutions to pH 0-1 using sulfuric acid, shaking with acetic acid, three successive extractions with dithizone solution in carbon tetrachloride, washing three times with dilute ammonia solution and once with acetic acid, and colorimetric analysis at 485 nm. The detection limit of the procedure was determined by taking 20 blank absorbance readings, and was calculated to be 0.090 (absorbance) corresponding to 0.43 ppm Hg(II). Calibration sensitivity was determined by taking the slope of the standard curve, and was found to be 0.05. The stability of mercuric dithizonate was determined by taking absorbance readings of solutions containing 0.5, 1.0, 3.0 and 5.0 ppm Hg(II) after 1, 3, 5, 7 and 10 hours of preparation. The analytical sensitivity at 0.5, 1.0, 3.0 and 5.0 ppm Hg(II) was determined by taking the standard deviation at each concentration of interest and the slope of the standard curve. The smallest concentration difference that can be measured by the procedure was also calculated and was found to be 0.04, 0.10, 0.15 and 0.13 ppm for solutions containing 0.5, 1.0, 3.0 and 5.0 ppm Hg(1I), respectively. Interference by Cu(I1) was evaluated, though no quantitative conclusions were made. It was found out that Cu(II) interference gave higher absorbance readings, yielding higher values for Hg(II) concentrations. The test method was applied to an industrial effluent and compared with Cold Vapor Atomic Absorption Spectrophotometry results. The dithizone colorimetric method was not able to detect 0.17 ppm Hg(II) as determined by AAS. A comparison of the two methods using a laboratory prepared Hg-Cu mixture (2.0 ppm Hg(II), 0.02 ppm Cu(II)) showed the dithizone colorimetric method to give a lower Hg(II) concentration.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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