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, DOI https://doi.org/10.1007/s10661-018-6727-y.
Full text not available from this repository.Abstract
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.
| Item Type: | Article |
|---|---|
| Funders: | University of Malaya, Kuala Lumpur, through the Institut Pengurusan dan Perkhidmatan Penyelidikan (IPPP) grant no. PG057 2013B, The Federal University of Technology, Minna, Nigeria, in conjunction with the Tertiary Education Trust Fund (TETFund) Abuja, Nigeria, granted study fellowship to the University of Malaya |
| Uncontrolled Keywords: | APHA; DBPs; K2Cr2O7; K2CrO4; NaBiO3; TOC |
| Subjects: | Q Science > Q Science (General) Q Science > QD Chemistry |
| Divisions: | Faculty of Science > Department of Chemistry |
| Depositing User: | Ms. Juhaida Abd Rahim |
| Date Deposited: | 03 Apr 2019 08:44 |
| Last Modified: | 03 Apr 2019 08:44 |
| URI: | http://eprints.um.edu.my/id/eprint/20801 |
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