Simultaneous uptake of Ni2+, NH+4 and PO3-4 by amorphous CaO-Al2O3-SiO2 compounds

Kiyoshi Okada, Megumi Shimazu, Yoshikazu Kameshima, Akira Nakajima, Kenneth J.D. MacKenzie

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Simultaneous uptake of Ni2+, NH+4, and PO3-4 by amorphous CaO-Al2O3-SiO2 (C-A-S) compounds was investigated using batch and column methods. Fifteen different C-A-S samples with systematically varied chemical compositions were prepared by coprecipitation from ethanol-water solutions containing Ca(NO3)2ṡ4H2O, Al(NO3)3ṡ9H2O, and Si(OC2H5)4, using NH4OH as the precipitating agent. The resulting precipitates were dried and heated at various temperatures to produce the C-A-S samples, which were then characterized by XRD, FTIR, solid state MAS NMR, DTA-TG, and N2 adsorption. All the C-A-S samples prepared at 600-900 °C were amorphous, apart from the CaO-rich samples. Simultaneous uptake of Ni2+, NH+4, and PO3-4 was determined by a batch method using a solution with an initial concentration of 2 mM. In these experiments, the uptake abilities of the C-A-S samples for Ni2+ and PO3-4 were high, but were relatively low for NH+4. The uptake abilities for Ni2+ and PO3-4 increased but that for NH+4 decreased as the silica content in the C-A-S decreased, suggesting that similar uptake mechanisms (ion substitution and/or precipitation) are operating for Ni2+ and PO3-4, but the uptake mechanism for NH+4 is different (physical adsorption). The column experiments indicate that the order of uptake ability of C-A-S for the three ions is NH+4 ≪ PO3-4 < Ni2+. Although the silica content of the C-A-S does not have the expected influence on the uptake of these three ions, for NH+4 it plays an important role in the formation of the amorphous phase and also in the suppression of Ca2+ and/or Al3+ release from the C-A-S during the uptake experiments. The optimum uptake properties of the C-A-S can thus be controlled by adjusting the chemical compositions and heating conditions under which the samples are prepared.

Original languageEnglish
Pages (from-to)229-238
Number of pages10
JournalJournal of Colloid And Interface Science
Volume305
Issue number2
DOIs
Publication statusPublished - Jan 15 2007
Externally publishedYes

Keywords

  • Ammonium ion
  • Calcium aluminosilicate
  • Heavy metal ion
  • Phosphate ion
  • Simultaneous uptake

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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