Use of a single air segment to minimise dispersion and improve mixing in sequential injection: turbidimetric determination of sulphate in waters

Inês P. A. Morais, M. Renata S. Souto, Teresa I. M. S. Lopes, António O. S. S. Rangel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

In this work, we propose the use of an air segment in a sequential injection system to simultaneously improve the overlapping of the stacked zones and minimise dispersion. This strategy was developed for the determination of sulphate in natural and wastewaters. Barium chloride was used as a precipitating agent and the turbidity of the suspension formed was measured at 420nm. Analysis was performed without sample pre-treatment and the system was able to monitor sulphate concentration at a rate of at least 20 determinations per hour. Slightly different analytical sequences were developed for natural and wastewaters in order to minimise specific interferences. Direct determination of sulphate was possible within a concentration range of 10-100 and 16-100mg SO42-L-1 for natural and wastewaters, respectively. Results obtained were comparable with those of the reference method with relative deviations lower than 5%. Relative standard deviations between 1.6% and 3.3% were found.

Original languageEnglish
Pages (from-to)4243-4249
Number of pages7
JournalWater Research
Volume37
Issue number17
DOIs
Publication statusPublished - Oct 2003

Keywords

  • Air segment
  • Natural and wastewaters
  • Sequential injection
  • Sulphate determination
  • Turbidimetry

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