The deoxygenation of boiler water by malto-oligosaccharide (MO) was studied in the range of
NG values from 1 to 13.9 as a function of the number of glucose units
NG, constituting MO. Phosphate was always added to MO as an indicator. The amount of P-alkalinity of boiler water decreased with
NG, reached a minimum at
NG=5.9, and then increased with
NG. It corresponds to the fact that the amount of mono-carboxylic acids produced by the reaction reach a maximum at
NG=5.9. The amount of (free) phosphate inos released from MO,
rp, decreased with an increase in
NG, reached a minimum value of 72% at
NG=5.9, and then increased up to nearly 100% at
NG=13.9. Diacethyl (CH
3COCOCH
3) having odor was produced in the reaction. The evolution amount of the diacethyl increased with
NG, and had the maximum value at
NG=2. This amount decreased with the
NG over
NG=2, and then reached a constant small value at
NG=5.9.
From these results, it was found that the MO with
NG=13.9 is superior for the oxygen scavenger.
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