Interactions between aluminium ions and acrylic acid—acrylamide copolymers in aqueous solution: 1. Study by 27Al nuclear magnetic resonance

Abstract

Aluminium binding to acrylic acid-acrylamide copolymers at different pH values has been studied by 27Al n.m.r. at 104.2 MHz. The study of a pure AlCl 3 solution of 1 × 10 −3 moll −1 concentration (at 25°C) allowed us, using a computer calculation, to define the concentration of different presumed Al species during the Al 3+ hydrolysis, when the OH − Al varied from 0 to 3. A model is proposed which takes into account the electrostatic interaction between trivalent Al species (Al 3+ and Al 13(OH) 3+ 27) and the carboxylate groups of the copolymers. The amount of Al cations bound to the copolymers was then calculated as a function of the pH.