Abstract |
Pollution from acid mine drainage is a chronic problem. The current vigorous interest has led to a re-examination of the methods of measuring total acidity, which are clearly based on the limited laboratory capabilities of prior years. Defined acid-metal mixtures containing iron(III), aluminum(III), iron(II), and hydrogen ion were reacted with sodium hydroxide under varying titration conditions. Results showed that at 25C a reliable measure of the total acidity can be obtained by oxidizing iron(II) with hydrogen peroxide and stopping the titration at pH 7.3. Hydroloysis of Fe(III) and Al(III) was complete at pH 7.3 before formation of aluminate ion. Positive interference due to manganese and hardness can be held to a minimum by proper selection of sample volume. Acidity due to carbon dioxide is easily removed by aeration. The procedure was applied to the analysis of acid mine sample with added standards with recoveries of 98 to 103%. (Author) |