TITLE:
Linde Type a Zeolite and Type Y Faujasite as a Solid-Phase for Lead, Cadmium, Nickel and Cobalt Preconcentration and Determination Using a Flow Injection System Coupled to Flame Atomic Absorption Spectrometry
AUTHORS:
Yaneira Petit de Peña, Wendy Rondón
KEYWORDS:
Cobalt; Nickel; Cadmium; Lead; Flow Injection; Preconcentration; Zeolites; Atomic Absorption
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.4 No.8,
August
9,
2013
ABSTRACT: In this work, a flow injection analysis (FIA) method for the trace determination of
lead, cadmium, nickel and cobalt in natural waters by formation of neutral
chelates with ammonium pyrrolidine dithiocarbamate
(APDC) was developed. The neutral chelates formed was retained in a mini-column
packed with Linde type A zeolite (LTA) and type Y Faujasite zeolite (FAU) and
then eluted with methyl isobutyl ketone (MIBK) to flame atomic absorption
spectrometry (EAA) for its detection. Physicochemical characterization of this
zeolite was carried out by Fourier Transform infrared spectroscopy and
attenuated total reflectance (FTIR and IR-ATR), scanning electron microscopy
and energy dispersive X-ray microanalysis (SEM-EDX) and X-ray power diffraction
(XRD). Then, a FIA configuration was used with a column preconcentration system
coupled to the detection system at room temperature (22?C). The detection limit
and the relative standard deviation for 5 determinations of different solutions
of Pb2+, Co2+, Ni2+ and Cd2+ for
FAU and LTA zeolite were calculated. The sampling frequency ranged from 18-35 h-1 and preconcentration factors from 21-250 were achieved, for a sample volume of 6 mL
using 20 mg of sorbents, indicating a high retention of the analytes on the
zeolites material. The recoveries obtained in natural waters samples were close
to 100% for all ions metal using synthetic zeolites, confirming the
applicability of the method. The isotherm models of Langmuir, Scatchard,
Freundlich and Dubinin-Radushkevich were used to study the equilibrium data, indicating that successfully followed the
Freundlich and Dubinin-Radushkevich (D-R) isotherms at low metal ion concentration.
The Freundlich parameter n varied between 0.35-1.01, whereas D-R isotherm yields the sorption free energy E 8 kJ.mol-1 indicating
psysisorption.