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Effect of soluble Mn concentration on oxidation kinetics
Author(s) -
Gregory Dean,
Carlson Kenneth
Publication year - 2003
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2003.tb10273.x
Subject(s) - chemistry , potassium permanganate , permanganate , manganese , ozone , kinetics , chlorine , inorganic chemistry , nuclear chemistry , oxide , physics , organic chemistry , quantum mechanics
This study examined the effect of initial manganous ion (Mn 2+ ) concentration and oxidant dose on the oxidation of Mn 2+ to Mn oxide during water treatment. The oxidants studied were chlorine dioxide (ClO 2 ), potassium permanganate (KMnO 4 ), and ozone. Initial Mn 2+ concentrations were 60, 200, and 1,000 μg/L, and the goal of the treatment was a final Mn 2+ <10 μg/L. Bench‐scale experiments were performed by applying different doses of each oxidant to a raw surface water and measuring Mn 2+ residuals over time. For all experiments, the ambient raw water conditions were pH 7.0, 9°C, and total organic carbon = 3.4 mg/L. Oxidation kinetics for low initial Mn 2+ concentrations (60 and 200 μg/L) were significantly slower than for high concentrations (1,000 μg/L). For the lower initial Mn 2+ levels, ClO 2 was the only oxidant that consistently produced final Mn 2+ <10 μg/L, generally within 60–120 s. All oxidants produced final Mn 2+ <10 μg/L when the initial Mn 2+ concentration was 1,000 μg/L. Oxidation with ozone consistently resulted in soluble Mn 2+ >20 μg/L after 5 min, with the formation of permanganate ion in many cases. For low Mn 2+ concentrations, 90% oxidation by KMnO 4 required 15–30 min.