TITLE:
pH Dependence of Lead Adsorption on Zeolites
AUTHORS:
Ponyadira Kabwadza-Corner, Erni Johan, Naoto Matsue
KEYWORDS:
Lead Adsorption, Zeolites, pH Dependence, Selectivity, Isotherms
JOURNAL NAME:
Journal of Environmental Protection,
Vol.6 No.1,
January
15,
2015
ABSTRACT: The
adsorption of Pb on zeolites A4, X, Y and mordenite was studied at various
initial pH with the purpose of assessing the pH dependence of Pb adsorption.
The adsorption was conducted using 0 - 0.6 mM Pb(NO3)2 in the presence
of 100 mM NH4NO3 and pH adjustment done using HNO3.
The coexisting NH4NO3 served as a representative of other
cations available in nature. The study was conducted at initial solution pH
ranging from 3 - 5. Adsorption results were analyzed using Langmuir isotherm
analysis. Adsorption was noted to be dependent on pH with increasing adsorption
as pH increased from 3 - 5 for zeolites A4, X and Y. The adsorption of Pb on
mordenite on the other hand did not show any dependence on pH since it was
almost constant within the studied pH range. The adsorptive capacities were
2500, 2000, 588 and 179 mmol·kg-1 for A4, X, Y and mordenite,
respectively. The results of this study can be used in designing or planning
for the clean-up of polluted water using adsorption techniques. An important
attribute of these findings was that the samples studied were shown to have the
capacity of removing even very low concentration of Pb, a property which is
hardly achievable by most adsorbents.