Chemical cleaning of service water systems with ammoniated citric acid has revealed the need for more precise monitoring and control of solvent parameters than normally required in other uses of this solvent. Precipitation was encountered in early attempts to utilize this solvent to remove the large amounts of iron oxide scale commonly encountered in these systems. Laboratory analysis of the precipitate formed in these solvents revealed it was most likely a hydrated iron citrate of approximate composition FeC6H6O7·H2O.

Laboratory experiments designed to determine the cause of precipitation in citric acid indicate formation of the precipitate is most likely due to saturation of the solvent with ferrous citrate. The saturation concentration appears to be highly dependent upon solvent pH, and precipitation can be eliminated by utilizing an initial solvent pH of at least 4.5.

Subject
Acids, Water, Precipitation (solids), Iron oxide, Precipitates, Iron, Solvents, Ammonium, Acidity, Solutions, Deposit corrosion, Cleaning, Samples
© 1987 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1987
Association for Materials Protection and Performance (AMPP)
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