The design of inhibitors of crystallization is aided by an understanding of the binding of the inhibitors at the molecular level and the influence of the binding on crystal morphology. Binding of citrate and phosphocitrate to calcium oxalate monohydrate (COM) crystals has been studied using scanning electron microscopy and molecular modeling. The COM crystal lattice presents two distinct surfaces that are not only calcium-rich but also have oxalate groups that are perpendicular to the liquid interface. This offers the best possibility for interaction with incoming anionic groups of an inhibitor molecule, allowing the most effective coordination with calcium ions of the lattice surface. For example, conformation and binding energies of citrate and phosphocitrate at (-1 0 1) and (0 1 0) surfaces of COM have been evaluated. The superior performance of phosphocitrate as an inhibitor of COM formation can be attributed to the more favorable coordination of its functional groups with calcium ions of the (-1 0 1) and (0 1 0) surfaces. These concepts may be relevant to the design of new antiscalants.

Subject
Scanning electron microscopy, Ions, Binding energy, Modeling, Geometry, Calcium, Surfaces, Molecular structure, Crystal growth, Calcium oxalate, Carboxylates, Corrosion inhibitors, Hydrogen
Keywords:
antiscalants, calcium oxalate, citrate, phosphocitrate, molecular modeling
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.