Industrial cooling water systems will undergo more and more environmental constraints and the recycling of these waters will increase the risks of scale deposition and corrosion. The use of environmentally friendly chemical additives to inhibit these phenomena is necessary.

Polyaspartates (PASP) have been proposed as potential green multifunctional inhibitors. Their inhibition efficiency on both the nucleation and growth of calcium carbonate (CaCO3) deposits and on the formation of corrosion products has been studied, under hydrodynamic conditions, by electrochemical techniques such as the use of the quartz crystal microbalance and impedance spectroscopy. Nucleation and growth of CaCO3 crystals have also been viewed in situ in a flow cell fitted with a specially designed microvision device.

PASP are found to act as multifunctional green inhibitors with a threshold effect for cooling water systems. These polymers decrease the mass of calcium carbonate deposited: the corrosion rate is lower in the presence of both PASP and calcium than in their absence. The morphologies of calcium carbonate and corrosion products obtained in these assays are also greatly modified in the presence of PASP.

The mechanism of action of polyaspartates combines adsorption, dispersion, complexation (with both iron and calcium ions) and insertion in the crystal lattice. Models for the mechanisms of action of polyaspartates are proposed. A first one deals with the inhibition of calcite in combination with enhancement of vaterite and a second with the inhibition of corrosion.

Subject
Water, Polyaspartates, Ions, Additives, Adsorption, Scale inhibitors, Molecular weight, Calcium, Calcite, Metallic surfaces, Corrosion scales, Corrosion inhibitors, Scaling
Keywords:
Inhibitors, Polyaspartates, Mechanisms of inhibition, Corrosion, Scale, Biodegradable, EQCM, EIS
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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