ABSTRACT
Hydroxyapatite (HAp) has been investigated for the removal of heavy metals in
environmental application. However, little is known about the influences of surface
modifications of the HAp. In this paper nano- HAp - polyvinyl alcohol (PVAL) gel was
synthesized under pH control and the formed gel was used for removing nickel ions.
The influence of nickel ions on the surface of HAp was studied. Reaction
mechanisms were followed by ICP-MS and discussed via continuous variations
method (CVM), mole ratio method (MRM) and slope-ratio method (SRM). The formed
gel with nickel ions was characterized by various methods including UV, FTIR, XRD,
and SEM. The ICP-MS was used to analyze the supernatant solution to confirm the
presence of Ca and/or Ni ions. The nickel ions were found to reduce the degree of
crystallinity of the synthesized HAp phase. The present results indicate that nickel
ions were completely adsorbed on the HAp structure with its anion. The validation of
the nature of HAp gel as chelating agent, or complex formation as well as physical
sorption was discussed.