comparison of the two modified colorimetric methods on the feasibility of measuring oxygen in acidic mine water
Date Issued
2007
Date
2007
Author(s)
Cheng, Chia-Lun
DOI
zh-TW
Abstract
Oxygen in acidic mine water is difficult to measure by colorimetry because such water contains high amount of dissolved iron which interferes. Both ferric and ferrous ions produce excess molecular iodine and triiodide thus leading to overestimated results. To solve this problem, a modified colorimetric method is proposed in which the sample is added with permanganate prior to the pickling procedure and all ferrous ions are converted to ferric ions. The sample was further treated with K2C2O4 and KF to remove the interference of permanganate and ferric ions. After acidification iodine and triiodide are formed and the color of the final solution was measured at 456 nm. Another simplified procedure was also compared by neglecting the addition of KF. Excess iodine generated due to ferric ions is compensated by a parallel sample that is pickled with the same reagent but in reverse order. The methods have been applied to measure the oxygen in the run-off water from an abandoned mining area, and the results are in agreement with data obtained by modified titration method and a well-calibrated oxygen sensor.
Subjects
酸礦水
溶氧
光度法
Acidic mine water
Colorimetric methods
Dissolved oxygen
Type
thesis
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