Application of 3A Zeolite Prepared from Venezuelan Kaolin for Removal of Pb (II) from Wastewater and Its Determination by Flame Atomic Absorption Spectrometry

Abstract

This work consists in the use of a 3A zeolite (K-LTA) obtained by a process of exchange of sodium for potassium (4A zeolite), synthesized from Venezuelan kaolin for the removal of Pb (II) ions from aqueous solutions by batch process mode in order to consider its application in treating industrial wastewaters. The 3A zeolite was characterized for X-ray powder diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy and en-ergy dispersive X-ray microanalysis (SEM-EDX). The metal concentration in the equilibrium C e (mg·L −1) after adsorp-tion with 3A zeolite was analyzed using flame atomic absorption spectrometry (FAAS). The influences of the solution pH, contact time, metal initial concentration and adsorbent dosage have been studied. The retention of metal occurring at pH values around 6.5 and the adsorption equilibrium was obtained at 60 min. The equilibrium process was well de-scribed by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The Langmuir parameters q m (mg·g −1) and b (L·mg −1) (which are related to the sorption capacity and constant of sorption energy) obtained were 14.64 and 5.42 respectively. The Pb (II) experimental uptake was about 14.56 mg·g −1 , a little smaller than the theoreti-cal one given by Langmuir isotherm model. The regression parameters and correlation coefficients (R) indicate that the adsorption data for Pb (II) removal fit better the Langmuir isotherm model. Moreover, 0 < 1/n < 1 (1/n is 0.13), indi-cating that adsorption of metal ions on the zeolite, is a favorable physical process. The application of removing of the metal lead from real samples was examined by industrial wastewater samples. For all samples, the percentage of re-covery was found with accuracy of more than 98%. The present work suggests 3A zeolite used as a sorbent material with relatively low cost, obtained from Venezuelan raw material; it is a candidate for removal lead ion and probably other cationic heavy metal species from wastewater.