Hydroxyacetic acid, inhibition

Organic acid oxidation in conjugation with oxidation of CaS03 slurry was studied for seven acids. Degradation of adipic acid and other aliphatic and sulfo carboxylic acids was least at pH 4.3 with 1.0 mM dissolved Mn and greatest at pH 5.5 without Mn. Hydroxypropionic and hydroxyacetic acids inhibited sulfite oxidation and were less subject to degradation. Fumaric acid degraded faster than the other alternatives. 

Hydroxyacetic and hydroxypropionic acids inhibited sulfite oxidation at concentrations as low as 10 mM. At pH 5.0, 0.3 mM Mn was sufficient to overcome the inhibiting effects of 10 mM hydroxyacetic acid (HA4, HA5). In general, the hydroxy acids had little effect on the oxidation rate in the presence of 1 mM Mn. 

Mixtures of EDTA with hydrazine (frequently also containing citric acid) received extensive evaluation as solvents for deposits found in nuclear steam generators. Pitzer made the first solvents containing EDTA and hydrazine but did not conduct corrosion tests. Pocock and Leedy tested a number of potential steam-generator cleaners at 149°F and 203°F (65°C and 95°C). An EDTA/citric acid hydrazine mixture was compared with thioglycolic acid, hydroxyacetic/formic, citric/formic, and citric/formic-hydrazine. All of the solvents were inhibited with commercial inhibitors. The EDTA... 

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