Aluminum Fixation in a Synthetic Cation Exchanger1
- Pa Ho Hsu and
- C. I. Rich2
Previous studies of soils have indicated fixation of Al as a poistively charged ion or polymer by some clay minerals. To avoid reactions with structural Al in clays, a synthetic cation-exchange resin, Dowex-50, was employed in a preliminary study of Al fixation. This resin was Al-saturated and then serially titrated with NaOH. In a similar experiment, AlCl3 was added in an amount equivalent to the Al in the resin, prior to titration. In a third experiment the same amount of Al-saturated resin was added to different volumes of solutions containing NaOH and AlCl3 in molar ratios of 0.296, 1.185, and 2.37, respectively. All of these experiments indicate that the only exchangeable Al ion was Al3+ and that in the acid range nonexchangeable Al was fixed so that on the average one positive charge of the resin was countered by one Al ion. A gibbsite-like ring structure having 6 Al ions, 12 OH ions and 12 water molecules is proposed as the principal fixed hydroxy-Al polymer. The polymer may be formed in place from smaller chain-like polymers and fixed because of its large size and high charge.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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