The Determination of Acid-Volatile Sulphide in Sediments Using Microwave- Assisted Chemical Vapour Generation: An Alternative to the US EPA Method

Title:The Determination of Acid-Volatile Sulphide in Sediments Using Microwave- Assisted Chemical Vapour Generation: An Alternative to the US EPA Method

Volume: 4 Issue: 1

Author(s): Ricardo E. Santelli, Aline S. Freire, Bernardo F. Braz, Francis A. Meireles, Maria de F.B. de Carvalho and John E.L. Maddock

Affiliation:

Keywords: Acid-volatile sulphides, chemical vapour generation, microwave radiation, sample pre-treatment.

Abstract: Background: Acid-volatile sulphides (AVS) and simultaneously extracted metals (SEM) have been used as sediment quality criteria in both contaminated or non-contaminated sediments. The AVS/SEM model is based on the criterion that metal toxicity is absent when the sum of the acid-labile divalent metal concentrations ([ΣSEM]) is less than the concentration of acid-volatile sulphides ([AVS]) expressed as a molar ratio.

Method: The US EPA-recommended method for AVS extraction and determination uses 6 mol L^-1 HCl solution for 1 hour and NaOH solution to absorb the H²S generated in the previous step. Sulphide ions can be determined by different procedures, such as gravimetry, spectrophotometry and ion-selective electrode.

Results: The aim of this work was the use of microwave radiation as a fast alternative for the generation of H²S. For this procedure, a glass apparatus was developed, adapting a digestion tube that is generally used in a focused microwave oven. The chemical extraction conditions were evaluated. A flow injection analysis (FIA) system was applied to the determination of sulphide.

Conclusion: The developed procedure results in a total time for the AVS determination method that is one-tenth of that of the recommended method (12 minutes compared to approximately 2 hours). The results obtained show that AVS was accurately quantified in a range of 1.5 to µ290mol S g^-1 sediment (RSD < 13 %). Surficial and core sediment samples from several impacted areas were analysed by both the standard (US EPA) procedure and the developed method, and no significant differences were observed.

Cite this article as:

Santelli E. Ricardo, Freire S. Aline, Braz F. Bernardo, Meireles A. Francis, Carvalho de F.B. de Maria and Maddock E.L. John, The Determination of Acid-Volatile Sulphide in Sediments Using Microwave- Assisted Chemical Vapour Generation: An Alternative to the US EPA Method, Current Microwave Chemistry 2017; 4 (1) . https://dx.doi.org/10.2174/2213335603666151113213822

DOI https://dx.doi.org/10.2174/2213335603666151113213822	Print ISSN 2213-3356
Publisher Name Bentham Science Publisher	Online ISSN 2213-3364