Highly efficient ultrasonic-assisted pre-concentration and simultaneous determination of trace amounts of Pb (II) and Cd (II) ions using modified magnetic natural clinoptilolite zeolite: Response surface methodology

Abstract

In this work, the synthesis of the magnetic natural clinoptilolite (CP) zeolite modified by cetyltrimethyl ammonium bromide hexadecyl trimethyl ammonium bromide (CTAB) and dithizone was utilized for simultaneous determination of trace amounts of lead (II) and cadmium (II) ions by flame atomic absorption spectrophotometry (FAAS). Characterization of the prepared adsorbent was carried out using various techniques such as XRD, FT-IR, SEM, EDS mapping and BET analyses. Central composite design (CCD) under response surface methodology (RSM) was used for obtaining the most important parameters and probable interactions between variables. In this favor, parameters including adsorbent dosage, pH, adsorption time and desorption time using ultrasound were optimized. Sonication had an important role in shortening the adsorption and desorption times of lead (II) and cadmium (II) ions by enhancing the dispersion of adsorbent in solution. Under optimum conditions, the proposed method represented linear ranges of 2.0–130.0 and 5.0–150.0 μg l−1 for lead and cadmium, respectively; while their corresponding values for limit of detection (LOD) using this method were found to be 0.93 and 1.08 μg l−1. Moreover, these ions exhibited relative standard deviation (RSD %) values of 2.13 and 2.78, respectively. Finally, the application of the synthesized material was evaluated for pre-concentration and determination of Pb (II) and Cd (II) ions from environmental water samples.