Application of N′N′-tetrasubstituted malonamides to the recovery of iron(III) from chloride solutions

In this work, three N,N'-tetrasubstituted malonamides, namely N,N'-dimethyl-N,N'-dibutylmalonamide (DNMBMA), N,N'-dimethyl-NN-diphenylmalonamide (DMDPHMA) and N,N'-dimethyl-N,N'-diphenyltetradecylmalonamide (DMDPHTDMA), are presented as suitable agents for use in a solvent extraction approach to efficiently and selectively remove Fe(III) from concentrated chloride solutions. The efficiency found for Fe(III) extraction from 4 M and higher concentrated hydrochloric acid solutions, the ease of Fe(III) stripping from the loaded solvents with distilled water, the selectivity towards Fe(III) over several other metal ions and the promising results achieved in successive extraction-stripping tests are relevant features that justify further research in view of a practical application. Evidences of the occurrence of different Fe(III) extraction reactions, depending on the malonamide structure, have also been collected and herein summarized. (c) 2005 Elsevier B.V. All rights reserved.