Title: Effect of NTA and pH on Lead(II) Adsorption by the Hydrous Oxides of Mn, Fe, and A1
Authors: Abraham, Beena T; Anirudhan, T S
Abstract: The object of this work was to study the influence
of nitrilotriacetic acid (NTA) on Pb(II) adsorption by different hydrous oxide
gels (MnOOH, FeOOH and AlOOH) at different pH levels. The surface charge density
as a function of pH in aqueous solution of NaNO3, NTA and Pb-NTA has
been determined. In the presence of NTA the values of zero point charge (pHzpc)
for AlOOH, FeOOH and MnOOH were shifted downwards from 9.2 to 8.5, 7.3 to 6.5 and
3.8 to 3.6 respectively. The pHzpc values for AlOOH, FeOOH and MnOOH
in the presence of Pb and NTA were found to be 7.3, 6.0, and 3.2 respectively. An
empirical
relationship has been obtained to predict
the pHzpc at any amount of NTA adsorption on AlOOH. The adsorption characteristics
of Pb and NTA in presence of each other has been studied. The adsorption of Pb(II)
in presence of NTA was greater than NTA adsorption in presence of Pb(II). The maximum
adsorption of Pb (II) in presence of NTA occur at a pH range of 3.0-4.0. The oxide
surface carries a net positive charge at pH range 3.0-4.0 thus negatively charged
Pb-NTA2- complex can be readily adsorbed.
Page(s): 145-150
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