Cover Image

Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater

The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies...

Full description

Saved in:
Bibliographic Details
Main Authors: Salihu, Simon Olonkwoh, Bakar, Nor Kartini Abu
Format: Article
Published: Springer 2018
Subjects:
Q Science (General)
QD Chemistry
Online Access:http://eprints.um.edu.my/20801/
https://doi.org/10.1007/s10661-018-6727-y
Tags: Add Tag
No Tags, Be the first to tag this record!
id my.um.eprints.20801
record_format eprints
spelling my.um.eprints.208012019-04-03T08:44:22Z http://eprints.um.edu.my/20801/ Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater Salihu, Simon Olonkwoh Bakar, Nor Kartini Abu Q Science (General) QD Chemistry The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K2CrO4) to generate the K2Cr2O7 on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO3) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L−1 for APHA, and 4.95 and 16.95 mg L−1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016. Springer 2018 Article PeerReviewed Salihu, Simon Olonkwoh and Bakar, Nor Kartini Abu (2018) Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater. Environmental Monitoring and Assessment, 190 (6). p. 369. ISSN 0167-6369 https://doi.org/10.1007/s10661-018-6727-y doi:10.1007/s10661-018-6727-y
institution Universiti Malaya
building UM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Malaya
content_source UM Research Repository
url_provider http://eprints.um.edu.my/
topic Q Science (General)
QD Chemistry
spellingShingle Q Science (General)
QD Chemistry
Salihu, Simon Olonkwoh
Bakar, Nor Kartini Abu
Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
description The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K2CrO4) to generate the K2Cr2O7 on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO3) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L−1 for APHA, and 4.95 and 16.95 mg L−1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016.
format Article
author Salihu, Simon Olonkwoh
Bakar, Nor Kartini Abu
author_facet Salihu, Simon Olonkwoh
Bakar, Nor Kartini Abu
author_sort Salihu, Simon Olonkwoh
title Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
title_short Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
title_full Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
title_fullStr Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
title_full_unstemmed Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
title_sort modified apha closed-tube reflux colorimetric method for toc determination in water and wastewater
publisher Springer
publishDate 2018
url http://eprints.um.edu.my/20801/
https://doi.org/10.1007/s10661-018-6727-y
_version_ 1643691383728373760
score 13.211869

Similar Items